Zola 2025-03-29T00:00:00+00:00 https://wapl.es/atom.xml 2025-03-29T00:00:00+00:00 2025-03-29T00:00:00+00:00 James Waples https://wapl.es/ethercrab-0-6/

<p><a href="https://crates.io/crates/ethercrab/0.6.0">EtherCrab 0.6.0</a> (<a href="https://lib.rs/crates/ethercrab">lib.rs</a>) is out as the next release of this pure Rust EtherCAT MainDevice! I'll go over some of the bigger features in this post, and for the full changelog you can check it out <a href="https://github.com/ethercrab-rs/ethercrab/blob/master/CHANGELOG.md">here</a>. The MSRV has been bumped from 1.77 to 1.81.</p>

2025-02-08T00:00:00+00:00 2025-02-08T00:00:00+00:00 James Waples https://wapl.es/ethercat-sii-eeprom-checksum/ <p>This is an answer to <a href="https://electronics.stackexchange.com/q/33821/2212">this StackExchange question</a> which I'm posting here instead as I refuse to add any more of my time or energy to that website.</p> <p>I'm using Rust and the <a href="https://crates.io/crates/crc"><code>crc</code></a> crate to calculate the checksum of the first 14 bytes of an EtherCAT SubDevice EEPROM. I first tried <code>CRC-8/ROHC</code> (<code>crc::CRC_8_ROHC</code>) as suggested <a href="https://electronics.stackexchange.com/a/196840/2212">by @craig-mcqueen</a> but it gave me incorrect results when checking a few known-good EEPROM dump files I have.</p> <p>I also iterated through every <code>CRC_8_*</code> constant in <code>crc</code> and none of them gave the correct result.</p> <p>The SOEM EtherCAT MainDevice has its CRC implementation <a href="https://github.com/OpenEtherCATsociety/SOEM/blob/2752dc25882ab24d7cfcad674226b65270fb0c61/test/linux/eepromtool/eepromtool.c#L64">here</a> which I used to cross check my Rust "implementation":</p> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-storage z-type z-rust">const</span> <span class="z-constant z-other z-rust">ECAT_CRC</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-meta z-path z-rust">crc<span class="z-punctuation z-accessor z-rust">::</span></span>Algorithm<span class="z-meta z-generic z-rust"><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span><span class="z-storage z-type z-rust">u8</span><span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span> <span class="z-keyword z-operator z-assignment z-rust">=</span> <span class="z-meta z-path z-rust">crc<span class="z-punctuation z-accessor z-rust">::</span></span>Algorithm <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> width<span class="z-punctuation z-separator z-rust">:</span> <span class="z-constant z-numeric z-integer z-decimal z-rust">8</span><span class="z-punctuation z-separator z-rust">,</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> poly<span class="z-punctuation z-separator z-rust">:</span> <span class="z-constant z-numeric z-integer z-hexadecimal z-rust">0x07</span><span class="z-punctuation z-separator z-rust">,</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> init<span class="z-punctuation z-separator z-rust">:</span> <span class="z-constant z-numeric z-integer z-hexadecimal z-rust">0xff</span><span class="z-punctuation z-separator z-rust">,</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> refin<span class="z-punctuation z-separator z-rust">:</span> <span class="z-constant z-language z-rust">false</span><span class="z-punctuation z-separator z-rust">,</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> refout<span class="z-punctuation z-separator z-rust">:</span> <span class="z-constant z-language z-rust">false</span><span class="z-punctuation z-separator z-rust">,</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> xorout<span class="z-punctuation z-separator z-rust">:</span> <span class="z-constant z-numeric z-integer z-hexadecimal z-rust">0x00</span><span class="z-punctuation z-separator z-rust">,</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> check<span class="z-punctuation z-separator z-rust">:</span> <span class="z-constant z-numeric z-integer z-hexadecimal z-rust">0x80</span><span class="z-punctuation z-separator z-rust">,</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> residue<span class="z-punctuation z-separator z-rust">:</span> <span class="z-constant z-numeric z-integer z-hexadecimal z-rust">0x00</span><span class="z-punctuation z-separator z-rust">,</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span><span class="z-punctuation z-terminator z-rust">;</span> </span><span class="z-source z-rust"> </span><span class="z-source z-rust"><span class="z-storage z-type z-rust">const</span> <span class="z-constant z-other z-rust">EEPROM_CRC</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-meta z-path z-rust">crc<span class="z-punctuation z-accessor z-rust">::</span></span>Crc<span class="z-meta z-generic z-rust"><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span><span class="z-storage z-type z-rust">u8</span><span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span> <span class="z-keyword z-operator z-assignment z-rust">=</span> <span class="z-meta z-path z-rust">crc<span class="z-punctuation z-accessor z-rust">::</span></span><span class="z-meta z-path z-rust">Crc<span class="z-punctuation z-accessor z-rust">::</span></span><span class="z-meta z-generic z-rust"><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span><span class="z-storage z-type z-rust">u8</span><span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span><span class="z-meta z-path z-rust"><span class="z-punctuation z-accessor z-rust">::</span></span>new<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-keyword z-operator z-bitwise z-rust">&amp;</span><span class="z-constant z-other z-rust">ECAT_CRC</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-terminator z-rust">;</span> </span></code></pre> <p>This is very close to <code>CRC-8/ROHC</code> but I had to change <code>check</code> from <code>0xd0</code> to <code>0x80</code>. My checksums now line up with the presumably more exercised SOEM implementation and the actual value in the dumped EEPROM files so I believe it's correct, however I couldn't find a match in <a href="https://reveng.sourceforge.io/crc-catalogue/1-15.htm">the catalogue</a> which is weird.</p> <p>I've also ported SOEM's implementation over to Rust if you don't want to use a whole crate:</p> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">calc_crc</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">crc</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-keyword z-operator z-rust">&amp;</span><span class="z-storage z-modifier z-rust">mut</span> <span class="z-storage z-type z-rust">u8</span>, <span class="z-variable z-parameter z-rust">b</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">u8</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-keyword z-operator z-arithmetic z-rust">*</span>crc <span class="z-keyword z-operator z-assignment z-rust">^=</span> b<span class="z-punctuation z-terminator z-rust">;</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-keyword z-control z-rust">for</span> <span class="z-keyword z-operator z-rust">_</span> <span class="z-keyword z-operator z-rust">in</span> <span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-keyword z-operator z-range z-rust">..</span><span class="z-constant z-numeric z-integer z-decimal z-rust">8</span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> <span class="z-keyword z-control z-rust">if</span> <span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-keyword z-operator z-arithmetic z-rust">*</span>crc <span class="z-keyword z-operator z-bitwise z-rust">&amp;</span> <span class="z-constant z-numeric z-integer z-hexadecimal z-rust">0x80</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-comparison z-rust">&gt;</span> <span class="z-constant z-numeric z-integer z-decimal z-rust">0</span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> <span class="z-keyword z-operator z-arithmetic z-rust">*</span>crc <span class="z-keyword z-operator z-assignment z-rust">=</span> <span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-keyword z-operator z-arithmetic z-rust">*</span>crc <span class="z-keyword z-operator z-comparison z-rust">&lt;</span><span class="z-keyword z-operator z-comparison z-rust">&lt;</span> <span class="z-constant z-numeric z-integer z-decimal z-rust">1</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-bitwise z-rust">^</span> <span class="z-constant z-numeric z-integer z-hexadecimal z-rust">0x07</span><span class="z-punctuation z-terminator z-rust">;</span> </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> <span class="z-keyword z-control z-rust">else</span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> <span class="z-keyword z-operator z-arithmetic z-rust">*</span>crc <span class="z-keyword z-operator z-assignment z-rust">=</span> <span class="z-keyword z-operator z-arithmetic z-rust">*</span>crc <span class="z-keyword z-operator z-comparison z-rust">&lt;</span><span class="z-keyword z-operator z-comparison z-rust">&lt;</span> <span class="z-constant z-numeric z-integer z-decimal z-rust">1</span><span class="z-punctuation z-terminator z-rust">;</span> </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span><span class="z-source z-rust"> </span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">sii_crc</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">buf</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-keyword z-operator z-rust">&amp;</span>[<span class="z-storage z-type z-rust">u8</span>]</span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-storage z-type z-rust">u16</span></span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> <span class="z-storage z-modifier z-rust">mut</span> crc <span class="z-keyword z-operator z-assignment z-rust">=</span> <span class="z-constant z-numeric z-integer z-hexadecimal z-rust">0xff</span><span class="z-storage z-type z-numeric z-rust">u8</span><span class="z-punctuation z-terminator z-rust">;</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-keyword z-control z-rust">for</span> i <span class="z-keyword z-operator z-rust">in</span> <span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-keyword z-operator z-range z-rust">..</span><span class="z-constant z-numeric z-integer z-decimal z-rust">14</span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> <span class="z-support z-function z-rust">calc_crc</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-keyword z-operator z-bitwise z-rust">&amp;</span><span class="z-storage z-modifier z-rust">mut</span> crc<span class="z-punctuation z-separator z-rust">,</span> buf<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span>i<span class="z-punctuation z-section z-group z-end z-rust">]</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-terminator z-rust">;</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">u16</span><span class="z-meta z-path z-rust"><span class="z-punctuation z-accessor z-rust">::</span></span>from<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>crc</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span></code></pre> <p>Hope this helps :)</p> 2024-07-28T00:00:00+00:00 2024-07-28T00:00:00+00:00 James Waples https://wapl.es/ethercrab-0-5/

<p>I've just released <a href="https://crates.io/crates/ethercrab/0.5.0">EtherCrab 0.5.0</a> (<a href="https://lib.rs/crates/ethercrab">lib.rs</a>), the pure Rust EtherCAT MainDevice. This is a smaller release than usual, with added support for FreeBSD/NetBSD and a bunch of renamed items in the public API. The full changelog can be found <a href="https://github.com/ethercrab-rs/ethercrab/blob/master/CHANGELOG.md">here</a>.</p>

2024-06-23T10:43:04+00:00 2024-06-23T10:43:04+00:00 James Waples https://wapl.es/esp32-tlc5940-rmt/

<p>The <a href="https://www.ti.com/product/TLC5940">TLC5940</a> is a "16-channel LED driver w/EEprom dot correction &amp; grayscale PWM control" IC, used for driving up to 16 constant current outputs (typically LEDs) using a number of control lines. It's more complex to drive than the <a href="https://www.ti.com/product/TLC5947">TLC5947</a> which uses a simple I2C interface, but leaves more control to the application developer by letting them set the LED PWM frequency, among other things.</p> <p>The TLC5940 uses SPI to transfer brightness data, but also requires an external PWM clock, as well as a periodic pulse on the BLANK pin to ensure the outputs remain enabled. This is annoying to do in software, but by abusing the RMT peripheral in an ESP32, we can let the microcontroller hardware do all of the heavy lifting for us.</p>

2024-03-31T00:00:00+00:00 2024-03-31T00:00:00+00:00 James Waples https://wapl.es/ethercrab-0-4-io-uring-derives-ethercat-distributed-clocks/

<p><a href="https://crates.io/crates/ethercrab/0.4.0">EtherCrab 0.4.0</a> (<a href="https://lib.rs/crates/ethercrab">lib.rs</a>), the pure Rust EtherCAT MainDevice is out! I've added a lot of features and fixes to this release, including Distributed Clocks support, an <code>io_uring</code>-based network driver for better performance, and a brand new set of derive-able traits to make getting data into and out of your EtherCAT network easier than ever! The full changelog including breaking changes can be found <a href="https://github.com/ethercrab-rs/ethercrab/blob/master/CHANGELOG.md">here</a>, but for the rest of this article let's dig a little deeper into some of the headline features.</p>

2024-03-15T00:00:00+00:00 2024-03-15T00:00:00+00:00 James Waples https://wapl.es/electriq-iqool-aircon-esphome-home-assistant/

<p>I recently got a pretty neat all-in-one air conditioner to heat my frigid Scottish garage in the winter. CNC machines don't like the cold, and neither do I! My unit is an "electriQ iQool 12000 BTU Wall Mounted Air Conditioner with Heating Function", product code <code>IQOOL-SMART15HP</code>. I quite like it, but when I got it I <em>really</em> wanted to be able to shout at Siri to turn the garage heat on so it'd be warmer by the time I went out. And I succeeded in this mission! By flashing ESPHome to the integrated Tuya TYJW2S-5V-YA module, I can now control this AC perfectly from Home Assistant and, by extension, Apple's Home app.</p>

2024-01-10T10:50:40+00:00 2024-01-10T10:50:40+00:00 James Waples https://wapl.es/linuxcnc-simulator-linux-mint-21-3/

<p>An update on my <a href="https://wapl.es/cnc/2020/01/25/linuxcnc-simulator-build-linux-mint.html/">previous guide for LM 19.3</a> on how to set up a LinuxCNC simulator on Linux Mint 21.3 Virginia. The LinuxCNC simulator is useful for testing/debugging drivers, gcode parsing and other non-realtime features without having to crawl around under your machine's actual control.</p>

2024-01-06T20:20:48+00:00 2024-01-06T20:20:48+00:00 James Waples https://wapl.es/a-collection-of-rust-optimisation-results/ <p>In working on <a href="https://crates.io/crates/ethercrab"><code>ethercrab</code></a> I found myself down the rabbit hole of trying to reduce binary size, in this case for the <code>thumbv7m-none-eabi</code> architecture used in embedded. This post is a collection of examples of attempted code size reductions by refactoring sometimes the most tiny of functions. It will hopefully serve as a reference to both me and you, dear reader, in your travels through the Rust lands.</p> <p>I don't have much knowledge of the deeper bits of the optimisation pipeline in both LLVM or Rust, so these experiments are probably super obvious to anyone with an inkling, but it was a good learning experience for me either way so I thought I'd share.</p> <h2 id="1-clamp-length-offsets-to-the-buffer-length"><a class="zola-anchor" href="#1-clamp-length-offsets-to-the-buffer-length" aria-label="Anchor link for: 1-clamp-length-offsets-to-the-buffer-length">1. Clamp length offsets to the buffer length</a></h2> <p><a href="https://godbolt.org/z/cfG1o11ff">Godbolt</a></p> <p>This is code that will quite happily panic for what it's worth. The <code>skip</code> function is part of a larger set of uh "generator-combinator" functions (generate stuff instead of parsing it like <code>nom</code>) and will jump over a given number of bytes in the provided buffer, returning the rest.</p> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-comment z-line z-double-slash z-rust"><span class="z-punctuation z-definition z-comment z-rust">//</span> Original impl </span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">skip</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">len</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">usize</span>, <span class="z-variable z-parameter z-rust">buf</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-keyword z-operator z-rust">&amp;</span><span class="z-storage z-modifier z-rust">mut</span> [<span class="z-storage z-type z-rust">u8</span>]</span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-keyword z-operator z-rust">&amp;</span><span class="z-storage z-modifier z-rust">mut</span> </span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-storage z-type z-rust">u8</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> <span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-keyword z-operator z-rust">_</span><span class="z-punctuation z-separator z-rust">,</span> rest</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-assignment z-rust">=</span> buf<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">split_at_mut</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>len</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-terminator z-rust">;</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> rest </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> </span><span class="z-source z-rust"> </span><span class="z-source z-rust"><span class="z-comment z-line z-double-slash z-rust"><span class="z-punctuation z-definition z-comment z-rust">//</span> Naive attempt: a little improvement </span></span><span class="z-source z-rust"><span class="z-comment z-line z-double-slash z-rust"><span class="z-punctuation z-definition z-comment z-rust">//</span> </span></span><span class="z-source z-rust"><span class="z-comment z-line z-double-slash z-rust"><span class="z-punctuation z-definition z-comment z-rust">//</span> Important note: the actual asm compiles to the same 4 instructions as `skip` above, however it </span></span><span class="z-source z-rust"><span class="z-comment z-line z-double-slash z-rust"><span class="z-punctuation z-definition z-comment z-rust">//</span> generates one less exception jump and one less string in the final binary. </span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">skip2</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">len</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">usize</span>, <span class="z-variable z-parameter z-rust">buf</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-keyword z-operator z-rust">&amp;</span><span class="z-storage z-modifier z-rust">mut</span> [<span class="z-storage z-type z-rust">u8</span>]</span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-keyword z-operator z-rust">&amp;</span><span class="z-storage z-modifier z-rust">mut</span> </span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-storage z-type z-rust">u8</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> <span class="z-keyword z-operator z-bitwise z-rust">&amp;</span><span class="z-storage z-modifier z-rust">mut</span> buf<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span>len<span class="z-keyword z-operator z-range z-rust">..</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> </span><span class="z-source z-rust"> </span><span class="z-source z-rust"><span class="z-comment z-line z-double-slash z-rust"><span class="z-punctuation z-definition z-comment z-rust">//</span> Clamp length: maybe now LLVM knows this won&#39;t panic? </span></span><span class="z-source z-rust"><span class="z-comment z-line z-double-slash z-rust"><span class="z-punctuation z-definition z-comment z-rust">//</span> </span></span><span class="z-source z-rust"><span class="z-comment z-line z-double-slash z-rust"><span class="z-punctuation z-definition z-comment z-rust">//</span> There are no more assertion checks so we&#39;re pretty much as small as we can get. </span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">skip3</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">len</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">usize</span>, <span class="z-variable z-parameter z-rust">buf</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-keyword z-operator z-rust">&amp;</span><span class="z-storage z-modifier z-rust">mut</span> [<span class="z-storage z-type z-rust">u8</span>]</span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-keyword z-operator z-rust">&amp;</span><span class="z-storage z-modifier z-rust">mut</span> </span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-storage z-type z-rust">u8</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> len <span class="z-keyword z-operator z-assignment z-rust">=</span> len<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">min</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>buf<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">len</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-terminator z-rust">;</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> <span class="z-keyword z-operator z-bitwise z-rust">&amp;</span><span class="z-storage z-modifier z-rust">mut</span> buf<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span>len<span class="z-keyword z-operator z-range z-rust">..</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> </span><span class="z-source z-rust"> </span><span class="z-source z-rust"><span class="z-comment z-line z-documentation z-rust"><span class="z-punctuation z-definition z-comment z-rust">///</span> Slightly more instructions than `skip3` but maybe a little bit clearer if that matters to you. </span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">skip4</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">len</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">usize</span>, <span class="z-variable z-parameter z-rust">buf</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-keyword z-operator z-rust">&amp;</span><span class="z-storage z-modifier z-rust">mut</span> [<span class="z-storage z-type z-rust">u8</span>]</span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-keyword z-operator z-rust">&amp;</span><span class="z-storage z-modifier z-rust">mut</span> </span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-storage z-type z-rust">u8</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> <span class="z-keyword z-control z-rust">if</span> len <span class="z-keyword z-operator z-comparison z-rust">&gt;=</span> buf<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">len</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> <span class="z-keyword z-control z-rust">return</span> <span class="z-keyword z-operator z-bitwise z-rust">&amp;</span><span class="z-storage z-modifier z-rust">mut</span> buf<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-keyword z-operator z-range z-rust">..</span><span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> <span class="z-keyword z-operator z-bitwise z-rust">&amp;</span><span class="z-storage z-modifier z-rust">mut</span> buf<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span>len<span class="z-keyword z-operator z-range z-rust">..</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> </span></code></pre> <p><code>skip3</code> seems to be the best here. If the returned buffer length is zero, the other original code that uses it will panic instead so we've probably just moved the assertion check in the wide program than removed it entirely.</p> <h2 id="2-idiomatic-method-chaining-is-smarter-than-you-think"><a class="zola-anchor" href="#2-idiomatic-method-chaining-is-smarter-than-you-think" aria-label="Anchor link for: 2-idiomatic-method-chaining-is-smarter-than-you-think">2. Idiomatic method chaining is smarter than you think</a></h2> <p><a href="https://godbolt.org/z/T5xTK83dM">Godbolt</a></p> <p>Fewer lines really is faster!</p> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-keyword z-other z-rust">use</span> <span class="z-meta z-path z-rust">core<span class="z-punctuation z-accessor z-rust">::</span></span><span class="z-meta z-path z-rust">hint<span class="z-punctuation z-accessor z-rust">::</span></span>unreachable_unchecked<span class="z-punctuation z-terminator z-rust">;</span> </span><span class="z-source z-rust"><span class="z-keyword z-other z-rust">use</span> <span class="z-meta z-path z-rust">core<span class="z-punctuation z-accessor z-rust">::</span></span><span class="z-meta z-path z-rust">convert<span class="z-punctuation z-accessor z-rust">::</span></span>TryInto<span class="z-punctuation z-terminator z-rust">;</span> </span><span class="z-source z-rust"> </span><span class="z-source z-rust"><span class="z-comment z-line z-documentation z-rust"><span class="z-punctuation z-definition z-comment z-rust">///</span> Original attempt at getting optimised output, with sad trombone bonus `unsafe`` :( </span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">unpack_from_slice_naive</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">buf</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-keyword z-operator z-rust">&amp;</span>[<span class="z-storage z-type z-rust">u8</span>]</span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-meta z-generic z-rust"><span class="z-support z-type z-rust">Result</span><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span><span class="z-storage z-type z-rust">u32</span>, <span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-punctuation z-section z-group z-end z-rust">)</span><span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span></span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-keyword z-control z-rust">if</span> buf<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">len</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-comparison z-rust">&lt;</span> <span class="z-constant z-numeric z-integer z-decimal z-rust">4</span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> <span class="z-keyword z-control z-rust">return</span> <span class="z-support z-type z-rust">Err</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-terminator z-rust">;</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> arr <span class="z-keyword z-operator z-assignment z-rust">=</span> <span class="z-keyword z-control z-rust">match</span> buf<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-keyword z-operator z-range z-rust">..</span><span class="z-constant z-numeric z-integer z-decimal z-rust">4</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span><span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">try_into</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> <span class="z-support z-type z-rust">Ok</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>arr</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-rust">=&gt;</span> arr<span class="z-punctuation z-separator z-rust">,</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> <span class="z-comment z-line z-double-slash z-rust"><span class="z-punctuation z-definition z-comment z-rust">//</span> SAFETY: We check the buffer size above </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> <span class="z-support z-type z-rust">Err</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-keyword z-operator z-rust">_</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-rust">=&gt;</span> <span class="z-storage z-modifier z-rust">unsafe</span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> <span class="z-support z-function z-rust">unreachable_unchecked</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span><span class="z-punctuation z-separator z-rust">,</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span><span class="z-punctuation z-terminator z-rust">;</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-support z-type z-rust">Ok</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-storage z-type z-rust">u32</span><span class="z-meta z-path z-rust"><span class="z-punctuation z-accessor z-rust">::</span></span>from_le_bytes<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>arr</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span><span class="z-source z-rust"> </span><span class="z-source z-rust"><span class="z-comment z-line z-documentation z-rust"><span class="z-punctuation z-definition z-comment z-rust">///</span> Look at this nice API! </span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">unpack_from_slice_pleasant</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">buf</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-keyword z-operator z-rust">&amp;</span>[<span class="z-storage z-type z-rust">u8</span>]</span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-meta z-generic z-rust"><span class="z-support z-type z-rust">Result</span><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span><span class="z-storage z-type z-rust">u32</span>, <span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-punctuation z-section z-group z-end z-rust">)</span><span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span></span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> buf<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">get</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-keyword z-operator z-range z-rust">..</span><span class="z-constant z-numeric z-integer z-decimal z-rust">4</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">ok_or</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">and_then</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">|</span></span></span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-variable z-parameter z-rust">raw</span><span class="z-punctuation z-section z-parameters z-end z-rust">|</span></span> </span><span class="z-meta z-function z-closure z-rust">raw<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">try_into</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">map_err</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">|</span></span></span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-function z-parameters z-rust">_<span class="z-punctuation z-section z-parameters z-end z-rust">|</span></span> </span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">map</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-storage z-type z-rust">u32</span><span class="z-meta z-path z-rust"><span class="z-punctuation z-accessor z-rust">::</span></span>from_le_bytes</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span></code></pre> <p>The two latter solutions produce identical assembly, so there's no need for <code>unsafe</code> here - the performance is already there.</p> <p>There's also an in-between if you find a lot of chained methods hard to read, which is understandable:</p> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">unpack_from_slice_naive</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">buf</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-keyword z-operator z-rust">&amp;</span>[<span class="z-storage z-type z-rust">u8</span>]</span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-meta z-generic z-rust"><span class="z-support z-type z-rust">Result</span><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span><span class="z-storage z-type z-rust">u32</span>, <span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-punctuation z-section z-group z-end z-rust">)</span><span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span></span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-keyword z-control z-rust">if</span> buf<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">len</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-comparison z-rust">&lt;</span> <span class="z-constant z-numeric z-integer z-decimal z-rust">4</span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> <span class="z-keyword z-control z-rust">return</span> <span class="z-support z-type z-rust">Err</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-terminator z-rust">;</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> buf<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-keyword z-operator z-range z-rust">..</span><span class="z-constant z-numeric z-integer z-decimal z-rust">4</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span><span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">try_into</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">map</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-storage z-type z-rust">u32</span><span class="z-meta z-path z-rust"><span class="z-punctuation z-accessor z-rust">::</span></span>from_le_bytes</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">map_err</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">|</span></span></span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-function z-parameters z-rust">_<span class="z-punctuation z-section z-parameters z-end z-rust">|</span></span> </span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span></code></pre> <p>Again, identical assembly as the two above.</p> <h2 id="3-currently-nightly-slice-first-last-chunk"><a class="zola-anchor" href="#3-currently-nightly-slice-first-last-chunk" aria-label="Anchor link for: 3-currently-nightly-slice-first-last-chunk">3. (currently) nightly: <code>slice_first_last_chunk</code></a></h2> <p><a href="https://godbolt.org/z/vev6hz8cc">Godbolt</a></p> <p><a href="https://github.com/rust-lang/rust/pull/117561">This PR</a> will soon stabilise some methods that make parsing integers from slices much more pleasant, but do they help with performance?</p> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-meta z-annotation z-rust"><span class="z-punctuation z-definition z-annotation z-rust">#!</span><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-variable z-annotation z-rust">no_std</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> </span><span class="z-source z-rust"><span class="z-comment z-line z-double-slash z-rust"><span class="z-punctuation z-definition z-comment z-rust">//</span> Requires Rust nightly at time of writing </span></span><span class="z-source z-rust"><span class="z-meta z-annotation z-rust"><span class="z-punctuation z-definition z-annotation z-rust">#!</span><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-variable z-annotation z-rust">feature</span><span class="z-meta z-annotation z-parameters z-rust"><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span></span><span class="z-meta z-annotation z-parameters z-rust"><span class="z-meta z-group z-rust">slice_first_last_chunk</span></span><span class="z-meta z-annotation z-parameters z-rust"><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> </span><span class="z-source z-rust"> </span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">unpack</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">buf</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-keyword z-operator z-rust">&amp;</span>[<span class="z-storage z-type z-rust">u8</span>]</span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-meta z-generic z-rust"><span class="z-support z-type z-rust">Result</span><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span><span class="z-storage z-type z-rust">u32</span>, <span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-punctuation z-section z-group z-end z-rust">)</span><span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span></span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> buf<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">get</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-keyword z-operator z-range z-rust">..</span><span class="z-constant z-numeric z-integer z-decimal z-rust">4</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">ok_or</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">map</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">|</span></span></span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-variable z-parameter z-rust">arr</span><span class="z-punctuation z-section z-parameters z-end z-rust">|</span></span> </span><span class="z-meta z-function z-closure z-rust"><span class="z-storage z-type z-rust">u32</span><span class="z-meta z-path z-rust"><span class="z-punctuation z-accessor z-rust">::</span></span>from_le_bytes<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>arr<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">try_into</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">unwrap</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">map_err</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">|</span></span></span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-function z-parameters z-rust">_<span class="z-punctuation z-section z-parameters z-end z-rust">|</span></span> </span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span><span class="z-source z-rust"> </span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">unpack_improved</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">buf</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-keyword z-operator z-rust">&amp;</span>[<span class="z-storage z-type z-rust">u8</span>]</span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-meta z-generic z-rust"><span class="z-support z-type z-rust">Result</span><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span><span class="z-storage z-type z-rust">u32</span>, <span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-punctuation z-section z-group z-end z-rust">)</span><span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span></span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> buf<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">get</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-keyword z-operator z-range z-rust">..</span><span class="z-constant z-numeric z-integer z-decimal z-rust">4</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">ok_or</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">and_then</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">|</span></span></span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-variable z-parameter z-rust">raw</span><span class="z-punctuation z-section z-parameters z-end z-rust">|</span></span> </span><span class="z-meta z-function z-closure z-rust">raw<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">try_into</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">map_err</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">|</span></span></span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-function z-parameters z-rust">_<span class="z-punctuation z-section z-parameters z-end z-rust">|</span></span> </span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">map</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-storage z-type z-rust">u32</span><span class="z-meta z-path z-rust"><span class="z-punctuation z-accessor z-rust">::</span></span>from_le_bytes</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span><span class="z-source z-rust"> </span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">unpack_new</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">buf</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-keyword z-operator z-rust">&amp;</span>[<span class="z-storage z-type z-rust">u8</span>]</span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-meta z-generic z-rust"><span class="z-support z-type z-rust">Result</span><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span><span class="z-storage z-type z-rust">u32</span>, <span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-punctuation z-section z-group z-end z-rust">)</span><span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span></span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> buf<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-meta z-path z-rust">first_chunk<span class="z-punctuation z-accessor z-rust">::</span></span><span class="z-meta z-generic z-rust"><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span>4<span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">ok_or</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">map</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">|</span></span></span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-variable z-parameter z-rust">arr</span><span class="z-punctuation z-section z-parameters z-end z-rust">|</span></span> </span><span class="z-meta z-function z-closure z-rust"><span class="z-storage z-type z-rust">u32</span><span class="z-meta z-path z-rust"><span class="z-punctuation z-accessor z-rust">::</span></span>from_le_bytes<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-keyword z-operator z-arithmetic z-rust">*</span>arr</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">map_err</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">|</span></span></span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-function z-parameters z-rust">_<span class="z-punctuation z-section z-parameters z-end z-rust">|</span></span> </span><span class="z-meta z-function z-closure z-rust"><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span><span class="z-source z-rust"> </span></code></pre> <p>The methods all generate the same assembly.</p> <h2 id="4-another-scenario"><a class="zola-anchor" href="#4-another-scenario" aria-label="Anchor link for: 4-another-scenario">4. Another scenario</a></h2> <p><a href="https://godbolt.org/z/Gar1MbKWf">Godbolt</a></p> <p>Alright now I'm just impressed. The two following functions generate the same assembly both for x64 and <code>thumbv7m-none-eabi</code>.</p> <p>Note that the first function is copied from the output of <code>cargo expand</code> - it's generated by a proc macro derive, therefore is pretty terrible code. But the optimiser doesn't seem to care.</p> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-meta z-annotation z-rust"><span class="z-punctuation z-definition z-annotation z-rust">#!</span><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-variable z-annotation z-rust">feature</span><span class="z-meta z-annotation z-parameters z-rust"><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span></span><span class="z-meta z-annotation z-parameters z-rust"><span class="z-meta z-group z-rust">slice_first_last_chunk</span></span><span class="z-meta z-annotation z-parameters z-rust"><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> </span><span class="z-source z-rust"><span class="z-meta z-annotation z-rust"><span class="z-punctuation z-definition z-annotation z-rust">#!</span><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-variable z-annotation z-rust">no_std</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> </span><span class="z-source z-rust"> </span><span class="z-source z-rust"><span class="z-comment z-line z-double-slash z-rust"><span class="z-punctuation z-definition z-comment z-rust">//</span> https://github.com/rust-lang/rust/pull/117561 </span></span><span class="z-source z-rust"> </span><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-struct z-rust">struct</span> </span><span class="z-meta z-struct z-rust"><span class="z-entity z-name z-struct z-rust">Pdo</span> </span><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"> <span class="z-variable z-other z-member z-rust">index</span><span class="z-punctuation z-separator z-type z-rust">:</span> <span class="z-storage z-type z-rust">u16</span>, </span></span></span><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"> <span class="z-variable z-other z-member z-rust">num_entries</span><span class="z-punctuation z-separator z-type z-rust">:</span> <span class="z-storage z-type z-rust">u8</span>, </span></span></span><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"> <span class="z-variable z-other z-member z-rust">sync_manager</span><span class="z-punctuation z-separator z-type z-rust">:</span> <span class="z-storage z-type z-rust">u8</span>, </span></span></span><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"> <span class="z-variable z-other z-member z-rust">dc_sync</span><span class="z-punctuation z-separator z-type z-rust">:</span> <span class="z-storage z-type z-rust">u8</span>, </span></span></span><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"> <span class="z-variable z-other z-member z-rust">name_string_idx</span><span class="z-punctuation z-separator z-type z-rust">:</span> <span class="z-storage z-type z-rust">u8</span>, </span></span></span><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span><span class="z-source z-rust"> </span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-storage z-type z-impl z-rust">impl</span> </span><span class="z-meta z-impl z-rust"><span class="z-entity z-name z-impl z-rust">Pdo</span> </span><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"> <span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">unpack_from_slice_orig</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">buf</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-keyword z-operator z-rust">&amp;</span>[<span class="z-storage z-type z-rust">u8</span>]</span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-meta z-generic z-rust"><span class="z-support z-type z-rust">Result</span><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span><span class="z-storage z-type z-rust">Self</span>, <span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-punctuation z-section z-group z-end z-rust">)</span><span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span></span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> buf <span class="z-keyword z-operator z-assignment z-rust">=</span> buf </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">get</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-keyword z-operator z-range z-rust">..</span><span class="z-constant z-numeric z-integer z-decimal z-rust">6</span><span class="z-storage z-type z-numeric z-rust">usize</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">ok_or</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-keyword z-operator z-rust">?</span><span class="z-punctuation z-terminator z-rust">;</span> </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-support z-type z-rust">Ok</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-storage z-type z-rust">Self</span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"><span class="z-meta z-block z-rust"> index<span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">u16</span><span class="z-meta z-path z-rust"><span class="z-punctuation z-accessor z-rust">::</span></span>from_le_bytes<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>buf<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-keyword z-operator z-range z-rust">..</span><span class="z-constant z-numeric z-integer z-decimal z-rust">2</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span><span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">try_into</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">unwrap</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-separator z-rust">,</span> </span></span></span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"><span class="z-meta z-block z-rust"> num_entries<span class="z-punctuation z-separator z-rust">:</span> <span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>buf<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-constant z-numeric z-integer z-decimal z-rust">2</span><span class="z-storage z-type z-numeric z-rust">usize</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> <span class="z-keyword z-operator z-bitwise z-rust">&amp;</span> <span class="z-constant z-numeric z-integer z-binary z-rust">0b11111111</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-comparison z-rust">&gt;</span><span class="z-keyword z-operator z-comparison z-rust">&gt;</span> <span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-storage z-type z-numeric z-rust">usize</span><span class="z-punctuation z-separator z-rust">,</span> </span></span></span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"><span class="z-meta z-block z-rust"> sync_manager<span class="z-punctuation z-separator z-rust">:</span> <span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>buf<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-constant z-numeric z-integer z-decimal z-rust">3</span><span class="z-storage z-type z-numeric z-rust">usize</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> <span class="z-keyword z-operator z-bitwise z-rust">&amp;</span> <span class="z-constant z-numeric z-integer z-binary z-rust">0b11111111</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-comparison z-rust">&gt;</span><span class="z-keyword z-operator z-comparison z-rust">&gt;</span> <span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-storage z-type z-numeric z-rust">usize</span><span class="z-punctuation z-separator z-rust">,</span> </span></span></span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"><span class="z-meta z-block z-rust"> dc_sync<span class="z-punctuation z-separator z-rust">:</span> <span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>buf<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-constant z-numeric z-integer z-decimal z-rust">4</span><span class="z-storage z-type z-numeric z-rust">usize</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> <span class="z-keyword z-operator z-bitwise z-rust">&amp;</span> <span class="z-constant z-numeric z-integer z-binary z-rust">0b11111111</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-comparison z-rust">&gt;</span><span class="z-keyword z-operator z-comparison z-rust">&gt;</span> <span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-storage z-type z-numeric z-rust">usize</span><span class="z-punctuation z-separator z-rust">,</span> </span></span></span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"><span class="z-meta z-block z-rust"> name_string_idx<span class="z-punctuation z-separator z-rust">:</span> <span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>buf<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-constant z-numeric z-integer z-decimal z-rust">5</span><span class="z-storage z-type z-numeric z-rust">usize</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> <span class="z-keyword z-operator z-bitwise z-rust">&amp;</span> <span class="z-constant z-numeric z-integer z-binary z-rust">0b11111111</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-comparison z-rust">&gt;</span><span class="z-keyword z-operator z-comparison z-rust">&gt;</span> <span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-storage z-type z-numeric z-rust">usize</span><span class="z-punctuation z-separator z-rust">,</span> </span></span></span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"> </span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"> <span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">unpack_from_slice_new</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">buf</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-keyword z-operator z-rust">&amp;</span>[<span class="z-storage z-type z-rust">u8</span>]</span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-meta z-generic z-rust"><span class="z-support z-type z-rust">Result</span><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span><span class="z-storage z-type z-rust">Self</span>, <span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-punctuation z-section z-group z-end z-rust">)</span><span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span></span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> <span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>index<span class="z-punctuation z-separator z-rust">,</span> buf</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-assignment z-rust">=</span> buf<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-meta z-path z-rust">split_first_chunk<span class="z-punctuation z-accessor z-rust">::</span></span><span class="z-meta z-generic z-rust"><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span>2<span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">ok_or</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-keyword z-operator z-rust">?</span><span class="z-punctuation z-terminator z-rust">;</span> </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> <span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>num_entries<span class="z-punctuation z-separator z-rust">,</span> buf</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-assignment z-rust">=</span> buf<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-meta z-path z-rust">split_first_chunk<span class="z-punctuation z-accessor z-rust">::</span></span><span class="z-meta z-generic z-rust"><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span>1<span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">ok_or</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-keyword z-operator z-rust">?</span><span class="z-punctuation z-terminator z-rust">;</span> </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> <span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>sync_manager<span class="z-punctuation z-separator z-rust">,</span> buf</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-assignment z-rust">=</span> buf<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-meta z-path z-rust">split_first_chunk<span class="z-punctuation z-accessor z-rust">::</span></span><span class="z-meta z-generic z-rust"><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span>1<span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">ok_or</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-keyword z-operator z-rust">?</span><span class="z-punctuation z-terminator z-rust">;</span> </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> <span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>dc_sync<span class="z-punctuation z-separator z-rust">,</span> buf</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-assignment z-rust">=</span> buf<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-meta z-path z-rust">split_first_chunk<span class="z-punctuation z-accessor z-rust">::</span></span><span class="z-meta z-generic z-rust"><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span>1<span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">ok_or</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-keyword z-operator z-rust">?</span><span class="z-punctuation z-terminator z-rust">;</span> </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> <span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>name_string_idx<span class="z-punctuation z-separator z-rust">,</span> buf</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-assignment z-rust">=</span> buf<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-meta z-path z-rust">split_first_chunk<span class="z-punctuation z-accessor z-rust">::</span></span><span class="z-meta z-generic z-rust"><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span>1<span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">ok_or</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-keyword z-operator z-rust">?</span><span class="z-punctuation z-terminator z-rust">;</span> </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-support z-type z-rust">Ok</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-storage z-type z-rust">Self</span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"><span class="z-meta z-block z-rust"> index<span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">u16</span><span class="z-meta z-path z-rust"><span class="z-punctuation z-accessor z-rust">::</span></span>from_le_bytes<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-keyword z-operator z-arithmetic z-rust">*</span>index</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-separator z-rust">,</span> </span></span></span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"><span class="z-meta z-block z-rust"> num_entries<span class="z-punctuation z-separator z-rust">:</span> num_entries<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span><span class="z-punctuation z-separator z-rust">,</span> </span></span></span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"><span class="z-meta z-block z-rust"> sync_manager<span class="z-punctuation z-separator z-rust">:</span> sync_manager<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span><span class="z-punctuation z-separator z-rust">,</span> </span></span></span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"><span class="z-meta z-block z-rust"> dc_sync<span class="z-punctuation z-separator z-rust">:</span> dc_sync<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span><span class="z-punctuation z-separator z-rust">,</span> </span></span></span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"><span class="z-meta z-block z-rust"> name_string_idx<span class="z-punctuation z-separator z-rust">:</span> name_string_idx<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span><span class="z-punctuation z-separator z-rust">,</span> </span></span></span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-impl z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span></code></pre> <p><code>unpack_from_slice_new</code> is prettier if that matters. Either way it's nice to see that prettier code doesn't make for worse code.</p> <h2 id="4-pointer-offsets-just-turn-into-numbers"><a class="zola-anchor" href="#4-pointer-offsets-just-turn-into-numbers" aria-label="Anchor link for: 4-pointer-offsets-just-turn-into-numbers">4. Pointer offsets just turn into numbers</a></h2> <p><a href="https://godbolt.org/z/G6jTaWWrj">Godbolt</a></p> <p>As you might expect, but it's nice to have the confirmation. Original code is this:</p> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-storage z-modifier z-rust">unsafe</span> <span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">ethercat_payload_ptr</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">this</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-meta z-generic z-rust">NonNull<span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span><span class="z-meta z-generic z-rust">FrameElement<span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span>N<span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span><span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-meta z-generic z-rust">NonNull<span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span><span class="z-storage z-type z-rust">u8</span><span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span></span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-meta z-path z-rust">NonNull<span class="z-punctuation z-accessor z-rust">::</span></span>new_unchecked<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"> <span class="z-storage z-type z-rust">Self</span><span class="z-meta z-path z-rust"><span class="z-punctuation z-accessor z-rust">::</span></span>ptr<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>this</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">as_ptr</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">byte_add</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-path z-rust">EthernetFrame<span class="z-punctuation z-accessor z-rust">::</span></span><span class="z-meta z-generic z-rust"><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span><span class="z-keyword z-operator z-rust">&amp;</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-storage z-type z-rust">u8</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span><span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span><span class="z-meta z-path z-rust"><span class="z-punctuation z-accessor z-rust">::</span></span>header_len<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">byte_add</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-path z-rust">EthercatFrameHeader<span class="z-punctuation z-accessor z-rust">::</span></span>header_len<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-separator z-rust">,</span> <span class="z-comment z-line z-double-slash z-rust"><span class="z-punctuation z-definition z-comment z-rust">//</span> .byte_add(PduFrame::header_len()), </span></span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"> </span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span></code></pre> <p>This just turns into</p> <pre data-lang="asm" class="language-asm z-code"><code class="language-asm" data-lang="asm"><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly">e</span><span class="z-entity z-name z-function z-assembly">x</span><span class="z-entity z-name z-function z-assembly">a</span><span class="z-entity z-name z-function z-assembly">m</span><span class="z-entity z-name z-function z-assembly">p</span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly">e</span><span class="z-entity z-name z-function z-assembly">:</span><span class="z-entity z-name z-function z-assembly">:</span><span class="z-entity z-name z-function z-assembly">e</span><span class="z-entity z-name z-function z-assembly">t</span><span class="z-entity z-name z-function z-assembly">h</span><span class="z-entity z-name z-function z-assembly">e</span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">c</span><span class="z-entity z-name z-function z-assembly">a</span><span class="z-entity z-name z-function z-assembly">t</span><span class="z-entity z-name z-function z-assembly">_</span><span class="z-entity z-name z-function z-assembly">p</span><span class="z-entity z-name z-function z-assembly">a</span><span class="z-entity z-name z-function z-assembly">y</span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly">o</span><span class="z-entity z-name z-function z-assembly">a</span><span class="z-entity z-name z-function z-assembly">d</span><span class="z-entity z-name z-function z-assembly">_</span><span class="z-entity z-name z-function z-assembly">p</span><span class="z-entity z-name z-function z-assembly">t</span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">:</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">lea</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">rax</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-source z-assembly">[</span><span class="z-variable z-parameter z-register z-assembly">rdi</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-source z-assembly">+</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-constant z-character z-decimal z-assembly">16</span><span class="z-source z-assembly">]</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">ret</span> </span></code></pre> <p>Because both <code>byte_add</code>s are given constants.</p> <h2 id="5-converting-duration-into-u64-nanoseconds-isn-t-that-bad"><a class="zola-anchor" href="#5-converting-duration-into-u64-nanoseconds-isn-t-that-bad" aria-label="Anchor link for: 5-converting-duration-into-u64-nanoseconds-isn-t-that-bad">5. Converting <code>Duration</code> into <code>u64</code> nanoseconds isn't that bad</a></h2> <p><a href="https://ethercat.org">EtherCAT</a> uses nanosecond time everywhere, stored as a <code>u64</code>. I'm using <code>core::time::Duration</code> for convenience, but wanted to know if there's much of a performance hit when doing some conversions.</p> <h3 id="just-converting-a-duration-to-u64"><a class="zola-anchor" href="#just-converting-a-duration-to-u64" aria-label="Anchor link for: just-converting-a-duration-to-u64">Just converting a <code>Duration</code> to <code>u64</code></a></h3> <p><a href="https://godbolt.org/z/ad9571jsf">Godbolt</a></p> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-meta z-annotation z-rust"><span class="z-punctuation z-definition z-annotation z-rust">#!</span><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-variable z-annotation z-rust">no_std</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> </span><span class="z-source z-rust"> </span><span class="z-source z-rust"><span class="z-meta z-annotation z-rust"><span class="z-punctuation z-definition z-annotation z-rust">#</span><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-variable z-annotation z-rust">no_mangle</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> </span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">nanos_u64</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">input</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-meta z-path z-rust">core<span class="z-punctuation z-accessor z-rust">::</span></span><span class="z-meta z-path z-rust">time<span class="z-punctuation z-accessor z-rust">::</span></span>Duration</span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-storage z-type z-rust">u64</span></span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> input<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">as_nanos</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-rust">as</span> <span class="z-storage z-type z-rust">u64</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span><span class="z-source z-rust"> </span><span class="z-source z-rust"><span class="z-meta z-annotation z-rust"><span class="z-punctuation z-definition z-annotation z-rust">#</span><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-variable z-annotation z-rust">no_mangle</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> </span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">nanos_u128</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">input</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-meta z-path z-rust">core<span class="z-punctuation z-accessor z-rust">::</span></span><span class="z-meta z-path z-rust">time<span class="z-punctuation z-accessor z-rust">::</span></span>Duration</span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-storage z-type z-rust">u128</span></span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> input<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">as_nanos</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span></code></pre> <p>The assembly for <code>thumbv7</code> comes out as this:</p> <pre data-lang="asm" class="language-asm z-code"><code class="language-asm" data-lang="asm"><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly">n</span><span class="z-entity z-name z-function z-assembly">a</span><span class="z-entity z-name z-function z-assembly">n</span><span class="z-entity z-name z-function z-assembly">o</span><span class="z-entity z-name z-function z-assembly">s</span><span class="z-entity z-name z-function z-assembly">_</span><span class="z-entity z-name z-function z-assembly">u</span><span class="z-entity z-name z-function z-assembly">6</span><span class="z-entity z-name z-function z-assembly">4</span><span class="z-entity z-name z-function z-assembly">:</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">m</span><span class="z-entity z-name z-function z-assembly">o</span><span class="z-entity z-name z-function z-assembly">v</span><span class="z-entity z-name z-function z-assembly">w</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">3</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">51712</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">m</span><span class="z-entity z-name z-function z-assembly">o</span><span class="z-entity z-name z-function z-assembly">v</span><span class="z-entity z-name z-function z-assembly">t</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">3</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">15258</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">m</span><span class="z-entity z-name z-function z-assembly">u</span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly">s</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">1</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">3</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">1</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">u</span><span class="z-entity z-name z-function z-assembly">m</span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly">a</span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">2</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">1</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">3</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">mov</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">2</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">bx</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly">r</span> </span><span class="z-source z-assembly"> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly">n</span><span class="z-entity z-name z-function z-assembly">a</span><span class="z-entity z-name z-function z-assembly">n</span><span class="z-entity z-name z-function z-assembly">o</span><span class="z-entity z-name z-function z-assembly">s</span><span class="z-entity z-name z-function z-assembly">_</span><span class="z-entity z-name z-function z-assembly">u</span><span class="z-entity z-name z-function z-assembly">1</span><span class="z-entity z-name z-function z-assembly">2</span><span class="z-entity z-name z-function z-assembly">8</span><span class="z-entity z-name z-function z-assembly">:</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">push</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">{</span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">4</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">6</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">7</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">}</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">add</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">7</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">sp</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">8</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">m</span><span class="z-entity z-name z-function z-assembly">o</span><span class="z-entity z-name z-function z-assembly">v</span><span class="z-entity z-name z-function z-assembly">w</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">r12</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">51712</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">movs</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">4</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">0</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">m</span><span class="z-entity z-name z-function z-assembly">o</span><span class="z-entity z-name z-function z-assembly">v</span><span class="z-entity z-name z-function z-assembly">t</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">r12</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">15258</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">mov</span><span class="z-entity z-name z-function z-assembly">.</span><span class="z-entity z-name z-function z-assembly">w</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">0</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">u</span><span class="z-entity z-name z-function z-assembly">m</span><span class="z-entity z-name z-function z-assembly">u</span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">3</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">r12</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">u</span><span class="z-entity z-name z-function z-assembly">m</span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly">a</span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">3</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">4</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">1</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">r12</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">a</span><span class="z-entity z-name z-function z-assembly">d</span><span class="z-entity z-name z-function z-assembly">d</span><span class="z-entity z-name z-function z-assembly">s</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">2</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">a</span><span class="z-entity z-name z-function z-assembly">d</span><span class="z-entity z-name z-function z-assembly">c</span><span class="z-entity z-name z-function z-assembly">s</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">1</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">3</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">0</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">a</span><span class="z-entity z-name z-function z-assembly">d</span><span class="z-entity z-name z-function z-assembly">c</span><span class="z-entity z-name z-function z-assembly">s</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">2</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">4</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">0</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">adc</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">3</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">0</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">pop</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">{</span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">4</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">6</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">7</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">p</span><span class="z-entity z-name z-function z-assembly">c</span><span class="z-entity z-name z-function z-assembly">}</span> </span></code></pre> <h3 id="closer-to-real-life"><a class="zola-anchor" href="#closer-to-real-life" aria-label="Anchor link for: closer-to-real-life">Closer to real life</a></h3> <p><a href="https://godbolt.org/z/nK16bb9oc">Godbolt</a></p> <p>The IRL code does a bit more maths. Let's see how that checks out.</p> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-struct z-rust">struct</span> </span><span class="z-meta z-struct z-rust"><span class="z-entity z-name z-struct z-rust">Conf</span> </span><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"> <span class="z-variable z-other z-member z-rust">sync0_period</span><span class="z-punctuation z-separator z-type z-rust">:</span> Duration, </span></span></span><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"> <span class="z-variable z-other z-member z-rust">sync0_shift</span><span class="z-punctuation z-separator z-type z-rust">:</span> Duration, </span></span></span><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span><span class="z-source z-rust"> </span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">nanos_irl</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">time</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">u64</span>, <span class="z-variable z-parameter z-rust">conf</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-keyword z-operator z-rust">&amp;</span>Conf</span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> Duration</span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> cycle_start_offset <span class="z-keyword z-operator z-assignment z-rust">=</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-meta z-path z-rust">Duration<span class="z-punctuation z-accessor z-rust">::</span></span>from_nanos<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>time <span class="z-keyword z-operator z-arithmetic z-rust">%</span> conf<span class="z-punctuation z-accessor z-dot z-rust">.</span>sync0_period<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">as_nanos</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-rust">as</span> <span class="z-storage z-type z-rust">u64</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-terminator z-rust">;</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> time_to_next_iter <span class="z-keyword z-operator z-assignment z-rust">=</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> conf<span class="z-punctuation z-accessor z-dot z-rust">.</span>sync0_period <span class="z-keyword z-operator z-arithmetic z-rust">+</span> <span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>conf<span class="z-punctuation z-accessor z-dot z-rust">.</span>sync0_shift <span class="z-keyword z-operator z-arithmetic z-rust">-</span> cycle_start_offset</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-terminator z-rust">;</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> time_to_next_iter </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span></code></pre> <p>171 lines of assembly. <code>ROBLOX_OOF.mp3</code>. Lots of divisions and overflow checks.</p> <h3 id="optimising-make-everything-u64"><a class="zola-anchor" href="#optimising-make-everything-u64" aria-label="Anchor link for: optimising-make-everything-u64">Optimising: make everything <code>u64</code></a></h3> <p><a href="https://godbolt.org/z/8Kr6vsvTj">Godbolt</a></p> <p>The real code is library-internal, so we can just pass <code>u64</code>s around and convert to a <code>Duration</code> at the public boundary.</p> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-struct z-rust">struct</span> </span><span class="z-meta z-struct z-rust"><span class="z-entity z-name z-struct z-rust">Conf</span> </span><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"> <span class="z-variable z-other z-member z-rust">sync0_period</span><span class="z-punctuation z-separator z-type z-rust">:</span> <span class="z-storage z-type z-rust">u64</span>, </span></span></span><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"> <span class="z-variable z-other z-member z-rust">sync0_shift</span><span class="z-punctuation z-separator z-type z-rust">:</span> <span class="z-storage z-type z-rust">u64</span>, </span></span></span><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span><span class="z-source z-rust"> </span><span class="z-source z-rust"><span class="z-meta z-annotation z-rust"><span class="z-punctuation z-definition z-annotation z-rust">#</span><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-variable z-annotation z-rust">no_mangle</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> </span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">nanos_irl</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">time</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">u64</span>, <span class="z-variable z-parameter z-rust">conf</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-keyword z-operator z-rust">&amp;</span>Conf</span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> Duration</span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> cycle_start_offset <span class="z-keyword z-operator z-assignment z-rust">=</span> time <span class="z-keyword z-operator z-arithmetic z-rust">%</span> conf<span class="z-punctuation z-accessor z-dot z-rust">.</span>sync0_period<span class="z-punctuation z-terminator z-rust">;</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> time_to_next_iter <span class="z-keyword z-operator z-assignment z-rust">=</span> conf<span class="z-punctuation z-accessor z-dot z-rust">.</span>sync0_period <span class="z-keyword z-operator z-arithmetic z-rust">+</span> <span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>conf<span class="z-punctuation z-accessor z-dot z-rust">.</span>sync0_shift <span class="z-keyword z-operator z-arithmetic z-rust">-</span> cycle_start_offset</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-terminator z-rust">;</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-meta z-path z-rust">Duration<span class="z-punctuation z-accessor z-rust">::</span></span>from_nanos<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>time_to_next_iter</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span></code></pre> <p>Much less assembly now with fewer branches to boot.</p> <h3 id="optimising-checked-saturating-operations"><a class="zola-anchor" href="#optimising-checked-saturating-operations" aria-label="Anchor link for: optimising-checked-saturating-operations">Optimising: checked/saturating operations</a></h3> <p><a href="https://godbolt.org/z/fzYz5qG7W">Godbolt</a></p> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-meta z-annotation z-rust"><span class="z-punctuation z-definition z-annotation z-rust">#</span><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-variable z-annotation z-rust">no_mangle</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> </span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">nanos_irl</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">time</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">u64</span>, <span class="z-variable z-parameter z-rust">conf</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-keyword z-operator z-rust">&amp;</span>Conf</span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> Duration</span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> cycle_start_offset <span class="z-keyword z-operator z-assignment z-rust">=</span> time </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">checked_rem</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>conf<span class="z-punctuation z-accessor z-dot z-rust">.</span>sync0_period</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">unwrap_or</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-constant z-numeric z-integer z-decimal z-rust">0</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-terminator z-rust">;</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> time_to_next_iter <span class="z-keyword z-operator z-assignment z-rust">=</span> conf<span class="z-punctuation z-accessor z-dot z-rust">.</span>sync0_period<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">saturating_add</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"> conf<span class="z-punctuation z-accessor z-dot z-rust">.</span>sync0_shift<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">saturating_sub</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>cycle_start_offset</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-group z-rust"> </span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-terminator z-rust">;</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-meta z-path z-rust">Duration<span class="z-punctuation z-accessor z-rust">::</span></span>from_nanos<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>time_to_next_iter</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span></code></pre> <p>No more panics which is nice, but still quite a bit of branching. I'll leave this here for now and revisit if performance becomes an issue on embedded systems.</p> <h2 id="6-packing-two-u16s-into-a-u8-4"><a class="zola-anchor" href="#6-packing-two-u16s-into-a-u8-4" aria-label="Anchor link for: 6-packing-two-u16s-into-a-u8-4">6. Packing two <code>u16</code>s into a <code>[u8; 4]</code></a></h2> <p><a href="https://godbolt.org/z/57cszev38">Godbolt</a></p> <p>Quite a specific one this, but I need to pack a device address plus register pair of <code>u16</code>s into an array so it can be written into a network packet buffer.</p> <p>Original code:</p> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">pack1</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">address</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">u16</span>, <span class="z-variable z-parameter z-rust">register</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">u16</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> </span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-storage z-type z-rust">u8</span><span class="z-punctuation z-separator z-rust">;</span> <span class="z-constant z-numeric z-integer z-decimal z-rust">4</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> address <span class="z-keyword z-operator z-assignment z-rust">=</span> address<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">to_le_bytes</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-terminator z-rust">;</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> register <span class="z-keyword z-operator z-assignment z-rust">=</span> register<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">to_le_bytes</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-terminator z-rust">;</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> <span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span>address<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span><span class="z-punctuation z-separator z-rust">,</span> address<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-constant z-numeric z-integer z-decimal z-rust">1</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span><span class="z-punctuation z-separator z-rust">,</span> register<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-constant z-numeric z-integer z-decimal z-rust">0</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span><span class="z-punctuation z-separator z-rust">,</span> register<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-constant z-numeric z-integer z-decimal z-rust">1</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> </span></code></pre> <p>And the simpler version:</p> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">pack2</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">address</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">u16</span>, <span class="z-variable z-parameter z-rust">register</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">u16</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> </span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-storage z-type z-rust">u8</span><span class="z-punctuation z-separator z-rust">;</span> <span class="z-constant z-numeric z-integer z-decimal z-rust">4</span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">let</span> res <span class="z-keyword z-operator z-assignment z-rust">=</span> <span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-storage z-type z-rust">u32</span><span class="z-meta z-path z-rust"><span class="z-punctuation z-accessor z-rust">::</span></span>from<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>register</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-comparison z-rust">&lt;</span><span class="z-keyword z-operator z-comparison z-rust">&lt;</span> <span class="z-constant z-numeric z-integer z-decimal z-rust">16</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-arithmetic z-rust">+</span> <span class="z-storage z-type z-rust">u32</span><span class="z-meta z-path z-rust"><span class="z-punctuation z-accessor z-rust">::</span></span>from<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>address</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span><span class="z-punctuation z-terminator z-rust">;</span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"> res<span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">to_le_bytes</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span><span class="z-source z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> </span></code></pre> <p>ARM (<code>--target thumbv7m-none-eabi</code>) assembly is pleasantly reduced for <code>pack2</code>:</p> <pre data-lang="asm" class="language-asm z-code"><code class="language-asm" data-lang="asm"><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly">p</span><span class="z-entity z-name z-function z-assembly">a</span><span class="z-entity z-name z-function z-assembly">c</span><span class="z-entity z-name z-function z-assembly">k</span><span class="z-entity z-name z-function z-assembly">1</span><span class="z-entity z-name z-function z-assembly">:</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">mov</span><span class="z-entity z-name z-function z-assembly">.</span><span class="z-entity z-name z-function z-assembly">w</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">2</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-source z-assembly">-</span><span class="z-constant z-character z-decimal z-assembly">16777216</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">and</span><span class="z-entity z-name z-function z-assembly">.</span><span class="z-entity z-name z-function z-assembly">w</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">2</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">2</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">1</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">lsl</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">16</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">u</span><span class="z-entity z-name z-function z-assembly">x</span><span class="z-entity z-name z-function z-assembly">t</span><span class="z-entity z-name z-function z-assembly">b</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">1</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">1</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">o</span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">.</span><span class="z-entity z-name z-function z-assembly">w</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">1</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">2</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">1</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">lsl</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">16</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">and</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">2</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">65280</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">add</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">1</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">2</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">u</span><span class="z-entity z-name z-function z-assembly">x</span><span class="z-entity z-name z-function z-assembly">t</span><span class="z-entity z-name z-function z-assembly">b</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">add</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">1</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">bx</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly">r</span> </span><span class="z-source z-assembly"> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly">p</span><span class="z-entity z-name z-function z-assembly">a</span><span class="z-entity z-name z-function z-assembly">c</span><span class="z-entity z-name z-function z-assembly">k</span><span class="z-entity z-name z-function z-assembly">2</span><span class="z-entity z-name z-function z-assembly">:</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">u</span><span class="z-entity z-name z-function z-assembly">x</span><span class="z-entity z-name z-function z-assembly">t</span><span class="z-entity z-name z-function z-assembly">h</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">o</span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">.</span><span class="z-entity z-name z-function z-assembly">w</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">1</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">lsl</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">16</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">bx</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly">r</span> </span></code></pre> <p>As is the <code>x86_64</code> which is to be expected:</p> <pre data-lang="asm" class="language-asm z-code"><code class="language-asm" data-lang="asm"><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly">p</span><span class="z-entity z-name z-function z-assembly">a</span><span class="z-entity z-name z-function z-assembly">c</span><span class="z-entity z-name z-function z-assembly">k</span><span class="z-entity z-name z-function z-assembly">1</span><span class="z-entity z-name z-function z-assembly">:</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">movzx</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">ecx</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">s</span><span class="z-entity z-name z-function z-assembly">i</span><span class="z-entity z-name z-function z-assembly">l</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">shl</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">esi</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-constant z-character z-decimal z-assembly">16</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">and</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">esi</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-source z-assembly">-</span><span class="z-constant z-character z-decimal z-assembly">16777216</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">shl</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">ecx</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-constant z-character z-decimal z-assembly">16</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">or</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">ecx</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">esi</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">movzx</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">eax</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">d</span><span class="z-entity z-name z-function z-assembly">i</span><span class="z-entity z-name z-function z-assembly">l</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">and</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">edi</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-constant z-character z-decimal z-assembly">65280</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">or</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">edi</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">ecx</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">or</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">eax</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">edi</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">ret</span> </span><span class="z-source z-assembly"> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly">p</span><span class="z-entity z-name z-function z-assembly">a</span><span class="z-entity z-name z-function z-assembly">c</span><span class="z-entity z-name z-function z-assembly">k</span><span class="z-entity z-name z-function z-assembly">2</span><span class="z-entity z-name z-function z-assembly">:</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">shl</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">esi</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-constant z-character z-decimal z-assembly">16</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">movzx</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">eax</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">di</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">or</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">eax</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">esi</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">ret</span> </span></code></pre> <h2 id="7-returning-1-or-1-from-a-boolean-comparison"><a class="zola-anchor" href="#7-returning-1-or-1-from-a-boolean-comparison" aria-label="Anchor link for: 7-returning-1-or-1-from-a-boolean-comparison">7. Returning <code>1</code> or <code>-1</code> from a boolean comparison</a></h2> <p><a href="https://godbolt.org/z/G1n1cc418">Godbolt</a></p> <p>I needed this for some <code>embedded-graphics</code> stuff where I'm changing the sign of another variable based on a condition.</p> <p>Easy to read:</p> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">f</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">a</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">i32</span>, <span class="z-variable z-parameter z-rust">b</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">i32</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-storage z-type z-rust">i32</span></span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-keyword z-control z-rust">if</span> a <span class="z-keyword z-operator z-comparison z-rust">==</span> <span class="z-keyword z-operator z-arithmetic z-rust">-</span>b <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> <span class="z-constant z-numeric z-integer z-decimal z-rust">1</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> <span class="z-keyword z-control z-rust">else</span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> <span class="z-keyword z-operator z-arithmetic z-rust">-</span><span class="z-constant z-numeric z-integer z-decimal z-rust">1</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span></code></pre> <p>Job Security Edition:</p> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">f</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">a</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">i32</span>, <span class="z-variable z-parameter z-rust">b</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">i32</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-storage z-type z-rust">i32</span></span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-storage z-type z-rust">i32</span><span class="z-meta z-path z-rust"><span class="z-punctuation z-accessor z-rust">::</span></span>from<span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span>a <span class="z-keyword z-operator z-comparison z-rust">==</span> <span class="z-keyword z-operator z-arithmetic z-rust">-</span>b</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> <span class="z-keyword z-operator z-rust">as</span> <span class="z-storage z-type z-rust">u8</span> <span class="z-keyword z-operator z-arithmetic z-rust">*</span> <span class="z-constant z-numeric z-integer z-decimal z-rust">2</span> <span class="z-keyword z-operator z-arithmetic z-rust">-</span><span class="z-constant z-numeric z-integer z-decimal z-rust">1</span></span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span></code></pre> <p>The assembly for both versions is similar:</p> <pre data-lang="asm" class="language-asm z-code"><code class="language-asm" data-lang="asm"><span class="z-source z-assembly"><span class="z-comment z-assembly">; Easy to read</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly">f</span><span class="z-entity z-name z-function z-assembly">:</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">xor</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">eax</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">eax</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">add</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">edi</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">esi</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">sete</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">al</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">lea</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">eax</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-source z-assembly">[</span><span class="z-constant z-character z-decimal z-assembly">2</span><span class="z-source z-assembly">*</span><span class="z-variable z-parameter z-register z-assembly">rax</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-source z-assembly">-</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-constant z-character z-decimal z-assembly">1</span><span class="z-source z-assembly">]</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">ret</span> </span><span class="z-source z-assembly"> </span><span class="z-source z-assembly"><span class="z-comment z-assembly">; Job Security Edition</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly">f</span><span class="z-entity z-name z-function z-assembly">:</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">add</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">edi</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">esi</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">mov</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">ecx</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-constant z-character z-decimal z-assembly">1</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">mov</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">eax</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-constant z-character z-decimal z-assembly">255</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">cmove</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">eax</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">ecx</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">ret</span> </span></code></pre> <h3 id="bonus-round-thumbv6-and-thumbv7"><a class="zola-anchor" href="#bonus-round-thumbv6-and-thumbv7" aria-label="Anchor link for: bonus-round-thumbv6-and-thumbv7">Bonus round: <code>thumbv6</code> and <code>thumbv7</code></a></h3> <p><a href="https://godbolt.org/z/z4Tx7jh66">Godbolt</a></p> <p><code>embedded-graphics</code> is designed to run on tiny microcontrollers, not x86_64, so let's see if there's much difference down in the low power stuff:</p> <p><code>thumbv6m-none-eabi</code>:</p> <pre data-lang="asm" class="language-asm z-code"><code class="language-asm" data-lang="asm"><span class="z-source z-assembly"><span class="z-comment z-assembly">; Easy to read</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly">f</span><span class="z-entity z-name z-function z-assembly">:</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">c</span><span class="z-entity z-name z-function z-assembly">m</span><span class="z-entity z-name z-function z-assembly">n</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">1</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">b</span><span class="z-entity z-name z-function z-assembly">e</span><span class="z-entity z-name z-function z-assembly">q</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">.</span><span class="z-entity z-name z-function z-assembly">L</span><span class="z-entity z-name z-function z-assembly">B</span><span class="z-entity z-name z-function z-assembly">B</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-entity z-name z-function z-assembly">_</span><span class="z-entity z-name z-function z-assembly">2</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">movs</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">0</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">m</span><span class="z-entity z-name z-function z-assembly">v</span><span class="z-entity z-name z-function z-assembly">n</span><span class="z-entity z-name z-function z-assembly">s</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">bx</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly">r</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly">.</span><span class="z-entity z-name z-function z-assembly">L</span><span class="z-entity z-name z-function z-assembly">B</span><span class="z-entity z-name z-function z-assembly">B</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-entity z-name z-function z-assembly">_</span><span class="z-entity z-name z-function z-assembly">2</span><span class="z-entity z-name z-function z-assembly">:</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">movs</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">1</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">bx</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly">r</span> </span><span class="z-source z-assembly"> </span><span class="z-source z-assembly"><span class="z-comment z-assembly">; Job Security Edition</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly">f</span><span class="z-entity z-name z-function z-assembly">:</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">c</span><span class="z-entity z-name z-function z-assembly">m</span><span class="z-entity z-name z-function z-assembly">n</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">1</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">b</span><span class="z-entity z-name z-function z-assembly">e</span><span class="z-entity z-name z-function z-assembly">q</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">.</span><span class="z-entity z-name z-function z-assembly">L</span><span class="z-entity z-name z-function z-assembly">B</span><span class="z-entity z-name z-function z-assembly">B</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-entity z-name z-function z-assembly">_</span><span class="z-entity z-name z-function z-assembly">2</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">movs</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">255</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">bx</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly">r</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly">.</span><span class="z-entity z-name z-function z-assembly">L</span><span class="z-entity z-name z-function z-assembly">B</span><span class="z-entity z-name z-function z-assembly">B</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-entity z-name z-function z-assembly">_</span><span class="z-entity z-name z-function z-assembly">2</span><span class="z-entity z-name z-function z-assembly">:</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">movs</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">1</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">bx</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly">r</span> </span></code></pre> <p>Not much difference, although it's interesting there's a jump in there.</p> <p><code>thumbv7-none-eabi</code>:</p> <pre data-lang="asm" class="language-asm z-code"><code class="language-asm" data-lang="asm"><span class="z-source z-assembly"><span class="z-comment z-assembly">; Easy to read</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly">f</span><span class="z-entity z-name z-function z-assembly">:</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">mov</span><span class="z-entity z-name z-function z-assembly">.</span><span class="z-entity z-name z-function z-assembly">w</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">2</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-source z-assembly">-</span><span class="z-constant z-character z-decimal z-assembly">1</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">c</span><span class="z-entity z-name z-function z-assembly">m</span><span class="z-entity z-name z-function z-assembly">n</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">1</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">i</span><span class="z-entity z-name z-function z-assembly">t</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">e</span><span class="z-entity z-name z-function z-assembly">q</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">m</span><span class="z-entity z-name z-function z-assembly">o</span><span class="z-entity z-name z-function z-assembly">v</span><span class="z-entity z-name z-function z-assembly">e</span><span class="z-entity z-name z-function z-assembly">q</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">2</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">1</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">mov</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">2</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">bx</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly">r</span> </span><span class="z-source z-assembly"> </span><span class="z-source z-assembly"><span class="z-comment z-assembly">; Job Security Edition</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly">f</span><span class="z-entity z-name z-function z-assembly">:</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">movs</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">2</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">255</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">c</span><span class="z-entity z-name z-function z-assembly">m</span><span class="z-entity z-name z-function z-assembly">n</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">1</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">i</span><span class="z-entity z-name z-function z-assembly">t</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">e</span><span class="z-entity z-name z-function z-assembly">q</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">m</span><span class="z-entity z-name z-function z-assembly">o</span><span class="z-entity z-name z-function z-assembly">v</span><span class="z-entity z-name z-function z-assembly">e</span><span class="z-entity z-name z-function z-assembly">q</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">2</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">#</span><span class="z-constant z-character z-decimal z-assembly">1</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">mov</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">0</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">r</span><span class="z-entity z-name z-function z-assembly">2</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">bx</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-entity z-name z-function z-assembly">r</span> </span></code></pre> <p>The only difference here is <code>mov.w r2,#-1</code> turns into a <code>movs r2,#255</code>.</p> <p>I much prefer the "easy to read" variant as it's obvious what the code is doing. The performance hit is nonexistent.</p> <h2 id="8-checking-if-a-variable-is-one-of-several-other-values"><a class="zola-anchor" href="#8-checking-if-a-variable-is-one-of-several-other-values" aria-label="Anchor link for: 8-checking-if-a-variable-is-one-of-several-other-values">8. Checking if a variable is one of several other values</a></h2> <p><a href="https://godbolt.org/z/Wzsz3roTq">Godbolt</a></p> <p>This is a check to see if <code>[].contains()</code> is the same as a naive <code>if</code> chain.</p> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-meta z-annotation z-rust"><span class="z-punctuation z-definition z-annotation z-rust">#</span><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-variable z-annotation z-rust">unsafe</span><span class="z-meta z-annotation z-parameters z-rust"><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span></span><span class="z-meta z-annotation z-parameters z-rust"><span class="z-meta z-group z-rust">no_mangle</span></span><span class="z-meta z-annotation z-parameters z-rust"><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> </span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">is_one_of</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">a</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">i32</span>, <span class="z-variable z-parameter z-rust">b</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">i32</span>, <span class="z-variable z-parameter z-rust">c</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">i32</span>, <span class="z-variable z-parameter z-rust">d</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">i32</span>, <span class="z-variable z-parameter z-rust">num</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">i32</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-storage z-type z-rust">bool</span></span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">[</span>a<span class="z-punctuation z-separator z-rust">,</span> b<span class="z-punctuation z-separator z-rust">,</span> c<span class="z-punctuation z-separator z-rust">,</span> d<span class="z-punctuation z-section z-group z-end z-rust">]</span></span><span class="z-punctuation z-accessor z-dot z-rust">.</span><span class="z-support z-function z-rust">contains</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span><span class="z-keyword z-operator z-bitwise z-rust">&amp;</span>num</span><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span></code></pre> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-meta z-annotation z-rust"><span class="z-punctuation z-definition z-annotation z-rust">#</span><span class="z-punctuation z-section z-group z-begin z-rust">[</span><span class="z-variable z-annotation z-rust">unsafe</span><span class="z-meta z-annotation z-parameters z-rust"><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-begin z-rust">(</span></span></span><span class="z-meta z-annotation z-parameters z-rust"><span class="z-meta z-group z-rust">no_mangle</span></span><span class="z-meta z-annotation z-parameters z-rust"><span class="z-meta z-group z-rust"><span class="z-punctuation z-section z-group z-end z-rust">)</span></span></span><span class="z-punctuation z-section z-group z-end z-rust">]</span></span> </span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-function z-rust"><span class="z-storage z-modifier z-rust">pub</span> <span class="z-storage z-type z-function z-rust">fn</span> </span><span class="z-entity z-name z-function z-rust">is_one_of</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-begin z-rust">(</span><span class="z-variable z-parameter z-rust">a</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">i32</span>, <span class="z-variable z-parameter z-rust">b</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">i32</span>, <span class="z-variable z-parameter z-rust">c</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">i32</span>, <span class="z-variable z-parameter z-rust">d</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">i32</span>, <span class="z-variable z-parameter z-rust">num</span><span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">i32</span></span><span class="z-meta z-function z-rust"><span class="z-meta z-function z-parameters z-rust"><span class="z-punctuation z-section z-parameters z-end z-rust">)</span></span></span></span><span class="z-meta z-function z-rust"> <span class="z-meta z-function z-return-type z-rust"><span class="z-punctuation z-separator z-rust">-&gt;</span> <span class="z-storage z-type z-rust">bool</span></span> </span><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"> <span class="z-keyword z-control z-rust">if</span> num <span class="z-keyword z-operator z-comparison z-rust">==</span> a <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> <span class="z-constant z-language z-rust">true</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> <span class="z-keyword z-control z-rust">else</span> <span class="z-keyword z-control z-rust">if</span> num <span class="z-keyword z-operator z-comparison z-rust">==</span> b <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> <span class="z-constant z-language z-rust">true</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> <span class="z-keyword z-control z-rust">else</span> <span class="z-keyword z-control z-rust">if</span> num <span class="z-keyword z-operator z-comparison z-rust">==</span> c <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> <span class="z-constant z-language z-rust">true</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> <span class="z-keyword z-control z-rust">else</span> <span class="z-keyword z-control z-rust">if</span> num <span class="z-keyword z-operator z-comparison z-rust">==</span> d <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> <span class="z-constant z-language z-rust">true</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> <span class="z-keyword z-control z-rust">else</span> <span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> <span class="z-constant z-language z-rust">false</span> </span></span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"><span class="z-meta z-block z-rust"> </span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-function z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span></code></pre> <p>The assembly is nearly identical, but uses registers in a different order which I thought was odd.</p> <pre data-lang="asm" class="language-asm z-code"><code class="language-asm" data-lang="asm"><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly">i</span><span class="z-entity z-name z-function z-assembly">s</span><span class="z-entity z-name z-function z-assembly">_</span><span class="z-entity z-name z-function z-assembly">o</span><span class="z-entity z-name z-function z-assembly">n</span><span class="z-entity z-name z-function z-assembly">e</span><span class="z-entity z-name z-function z-assembly">_</span><span class="z-entity z-name z-function z-assembly">o</span><span class="z-entity z-name z-function z-assembly">f</span><span class="z-entity z-name z-function z-assembly">:</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">cmp</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">edi</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">r8d</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">sete</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">al</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">cmp</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">esi</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">r8d</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">sete</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">s</span><span class="z-entity z-name z-function z-assembly">i</span><span class="z-entity z-name z-function z-assembly">l</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">or</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">s</span><span class="z-entity z-name z-function z-assembly">i</span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">al</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">cmp</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">edx</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">r8d</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">sete</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">dl</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">cmp</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">ecx</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">r8d</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">sete</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">al</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">or</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">al</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">dl</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">or</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">al</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">s</span><span class="z-entity z-name z-function z-assembly">i</span><span class="z-entity z-name z-function z-assembly">l</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">ret</span> </span></code></pre> <pre data-lang="asm" class="language-asm z-code"><code class="language-asm" data-lang="asm"><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly">i</span><span class="z-entity z-name z-function z-assembly">s</span><span class="z-entity z-name z-function z-assembly">_</span><span class="z-entity z-name z-function z-assembly">o</span><span class="z-entity z-name z-function z-assembly">n</span><span class="z-entity z-name z-function z-assembly">e</span><span class="z-entity z-name z-function z-assembly">_</span><span class="z-entity z-name z-function z-assembly">o</span><span class="z-entity z-name z-function z-assembly">f</span><span class="z-entity z-name z-function z-assembly">:</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">cmp</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">r8d</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">edi</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">sete</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">al</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">cmp</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">r8d</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">esi</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">sete</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">s</span><span class="z-entity z-name z-function z-assembly">i</span><span class="z-entity z-name z-function z-assembly">l</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">or</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">s</span><span class="z-entity z-name z-function z-assembly">i</span><span class="z-entity z-name z-function z-assembly">l</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">al</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">cmp</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">r8d</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">edx</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">sete</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">dl</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">cmp</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">r8d</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">ecx</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">sete</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">al</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">or</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">al</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">dl</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">or</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-variable z-parameter z-register z-assembly">al</span><span class="z-source z-assembly">,</span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">s</span><span class="z-entity z-name z-function z-assembly">i</span><span class="z-entity z-name z-function z-assembly">l</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-keyword z-control z-assembly">ret</span> </span><span class="z-source z-assembly"><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly"> </span><span class="z-entity z-name z-function z-assembly">`</span><span class="z-entity z-name z-function z-assembly">`</span><span class="z-entity z-name z-function z-assembly">`</span> </span></code></pre> 2023-10-12T14:11:00+00:00 2023-10-12T14:11:00+00:00 James Waples https://wapl.es/announcing-ethercrab-the-rust-ethercat-controller/

<p>The EtherCrab story started with my dream of writing a motion controller in Rust to provide a modern alternative to the venerable <a href="https://github.com/LinuxCNC/linuxcnc/">LinuxCNC project</a>. But motion controllers are hard, even with the right books, so I did what any good programmer would do: procrastinate by implementing an entire industrial fieldbus protocol instead! <strong>Say hello to <a href="https://crates.io/crates/ethercrab">EtherCrab</a> - a pure Rust EtherCAT controller that supports Linux, macOS, Windows and even <code>no_std</code>.</strong></p> <p><strong>Heads up! EtherCrab 0.4.0 was released in March 2024 with some breaking changes. Why not head over to <a href="https://wapl.es/ethercrab-0-4-io-uring-derives-ethercat-distributed-clocks/">the announcement post</a> to see what's new?</strong></p>

2023-08-11T19:25:19+00:00 2023-08-11T19:25:19+00:00 James Waples https://wapl.es/morefine-s500-fan-mod/

<p>I got a Ryzen 5625U Morefine S500+ Mini PC <a href="https://www.aliexpress.com/item/1005004673937974.html">from Aliexpress</a> for <a href="https://github.com/ethercrab-rs/ethercrab">EtherCrab</a> development recently. It's a lovely little machine for the price and about 7x faster than my previous dev box. There's one very annoying issue though: the noisy little fan installed on the CPU heatsink. Let's fix that.</p>

2022-07-03T14:43:59+00:00 2022-07-03T14:43:59+00:00 James Waples https://wapl.es/rust/2022/07/03/const-builder-pattern.html/

<p>During the creation of <a href="https://github.com/ethercrab-rs/ethercrab">EtherCrab</a>, a pure-Rust EtherCAT master, one of the core structs in the crate started growing quite a few const generic parameters. Here's a reduced example of what I'm talking about:</p> <pre data-lang="rust" class="language-rust z-code"><code class="language-rust" data-lang="rust"><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-storage z-type z-struct z-rust">struct</span> </span><span class="z-meta z-struct z-rust"><span class="z-meta z-generic z-rust"><span class="z-entity z-name z-struct z-rust">Client</span><span class="z-meta z-generic z-rust"><span class="z-punctuation z-definition z-generic z-begin z-rust">&lt;</span><span class="z-storage z-modifier z-rust">const</span> N<span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">usize</span>, <span class="z-storage z-modifier z-rust">const</span> D<span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">usize</span>, <span class="z-storage z-modifier z-rust">const</span> TIMEOUT<span class="z-punctuation z-separator z-rust">:</span> <span class="z-storage z-type z-rust">u64</span><span class="z-punctuation z-definition z-generic z-end z-rust">&gt;</span></span></span></span><span class="z-meta z-struct z-rust"> </span><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-begin z-rust">{</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"> <span class="z-variable z-other z-member z-rust">foo</span><span class="z-punctuation z-separator z-type z-rust">:</span> [<span class="z-storage z-type z-rust">u8</span>; N], </span></span></span><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"> <span class="z-variable z-other z-member z-rust">bar</span><span class="z-punctuation z-separator z-type z-rust">:</span> [<span class="z-storage z-type z-rust">u8</span>; D], </span></span></span><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"> <span class="z-variable z-other z-member z-rust">idx</span><span class="z-punctuation z-separator z-type z-rust">:</span> <span class="z-storage z-type z-rust">u8</span> </span></span></span><span class="z-source z-rust"><span class="z-meta z-struct z-rust"><span class="z-meta z-block z-rust"></span><span class="z-meta z-block z-rust"><span class="z-punctuation z-section z-block z-end z-rust">}</span></span></span> </span></code></pre>

2021-07-24T20:35:38+00:00 2021-07-24T20:35:38+00:00 James Waples https://wapl.es/rust/2021/07/24/dont-forget-to-change-pin-mode.html/

<p>A quick PSA in case you're at a loss as to why you're seeing strange behaviour from your STM32 MCU pins when running higher frequencies through them like I was.</p> <p>After successfully getting MCO (Microcontroller Clock Output) working on the only STM32L031 I could find in the universe, I was seeing some strange behaviour when attempting to push the output frequency above 2MHz.</p>

2020-07-26T09:30:00+00:00 2020-07-26T09:30:00+00:00 James Waples https://wapl.es/rust/2020/07/26/perf-addendum.html/

<p>A quick update on my <a href="/rust/2020/07/25/optimising-with-cmp-and-ordering.html">previous article</a>.</p> <p><a href="https://twitter.com/redbluemonkey/status/1287186446986514432">Nicholas Wilcox (@redbluemonkey) on Twitter</a> made a very good point:</p>

2020-07-25T16:00:00+00:00 2020-07-25T16:00:00+00:00 James Waples https://wapl.es/rust/2020/07/25/optimising-with-cmp-and-ordering.html/

<p>Welcome to another pointless tangent into the exciting world of line joints in <a href="https://crates.io/crates/embedded-graphics">embedded-graphics</a>! <code>embedded-graphics</code> is an integer only, iterator based no-std graphics library for environments with low resource availability. This time, we'll be looking at some not-so-great optimisations made to a point sorting function.</p> <p><strong>Update: A kind Twitter user pointed out a more optimised solution for triangles which you can find <a href="/rust/2020/07/26/perf-addendum.html">here</a>.</strong></p>

2020-07-09T17:11:00+00:00 2020-07-09T17:11:00+00:00 James Waples https://wapl.es/rust/embedded-graphics/2020/07/09/integer-graphics-line-intersection.html/

<p>Graphics can be a tricky topic, particularly when attempting to find anything on the internet these days that provides solution in terms of integer-only maths. <a href="https://crates.io/crates/embedded-graphics">embedded-graphics</a> is a (mostly) integer-only library, so in pursuing a solution to good line joints for the <code>Polyline</code> and <code>Polygon</code> shape implementations, a bit of interweb detective work was required.</p>

2020-02-23T12:06:37+00:00 2020-02-23T12:06:37+00:00 James Waples https://wapl.es/cnc/2020/02/23/linuxcnc-jog-wheel-setup.html/

<p>CNC jog pendants are super useful devices for quick setup and configuration of CNC machines. A quick search for <a href="https://www.aliexpress.com/wholesale?catId=0&amp;initiative_id=SB_20200223040744&amp;SearchText=cnc+jog+wheel">CNC jog pendant</a> on AliExpress turns up a bunch of results. For this post, I'll cover connecting a wired jog pendant with ESTOP to a Mesa 5i25 FPGA card to control a 3 axis CNC mill.</p>

2020-01-27T23:26:43+00:00 2020-01-27T23:26:43+00:00 James Waples https://wapl.es/cnc/rust/2020/01/27/writing-a-linuxcnc-driver.html/

<p>I'd like to announce two crates I've been working to integrate Rust components into LinuxCNC. You can find them at <a href="https://crates.io/crates/linuxcnc-hal">linuxcnc-hal</a> (high-level interface) and <a href="https://crates.io/crates/linuxcnc-hal-sys">linuxcnc-hal-sys</a> (low-level interface). The rest of this post is a getting started tutorial, so follow along if you have a cool idea for a custom bit of CNC hardware and an itch to write the interface in Rust!</p>

2020-01-25T12:21:06+00:00 2020-01-25T12:21:06+00:00 James Waples https://wapl.es/cnc/2020/01/25/linuxcnc-simulator-build-linux-mint.html/

<p><strong>This guide has been upated for Linux Mint 21.3. Check it out <a href="https://wapl.es/linuxcnc-simulator-linux-mint-21-3/">here</a>.</strong></p> <p>A quick guide on how to set up a LinuxCNC simulator on Linux Mint. The LinuxCNC simulator is useful for testing/debugging drivers, gcode parsing and other non-realtime features without having to crawl around under your machine's actual control.</p>

2019-06-16T16:00:00+00:00 2019-06-16T16:00:00+00:00 James Waples https://wapl.es/rust/2019/06/16/embedded-graphics-0-5-0.html/

<p>Version 0.5.0 is released! This is a pretty big one, focussed around ergonomics. There are new macros to make drawing and positioning primitives and text much less noisy, as well as changes to the <code>Drawing</code> trait to remove the explicit <code>.into_iter()</code> call when passing objects to it.</p>

2019-06-03T13:34:00+00:00 2019-06-03T13:34:00+00:00 James Waples https://wapl.es/rust/2019/06/03/diesel-and-tower-web.html/

<p>We're building a new product at <a href="https://repositive.io/">work</a>, for which we've decided to use Rust and <a href="https://crates.io/crates/tower-web">tower-web</a> for the backend. There don't seem to be any Tower examples using state in request handlers, so this is a quick copypasta showing how to add Diesel so request handlers can do database operations.</p>

2019-03-14T09:25:00+00:00 2019-03-14T09:25:00+00:00 James Waples https://wapl.es/typescript/2019/03/14/xml-jsx-sitemaps-in-typescript.html/

<p>I maintain the <a href="https://repositive.io">Repositive website</a> which uses React for the frontend and a server that supports server side rendering for the speed and SEO benefits of SSR. I'm currently in the process of porting it over to Typescript which is kickass, but the type checker kept borking on the XML tags used in the sitemap component. What follows is a quick "note to self" on how to fix that error. There might be <em>much</em> better solutions out there, but this is the one that worked for me.</p>

2019-03-04T19:04:00+00:00 2019-03-04T19:04:00+00:00 James Waples https://wapl.es/rust/2019/03/04/embedded-graphics-0.4.7-bmp-support.html/

<p><a href="https://crates.io/crates/embedded-graphics">Embedded graphics</a> 0.4.7 has been released, along with a new sister crate, <a href="https://crates.io/crates/tinybmp">tinybmp</a>! TinyBMP aims to parse BMP-format image data using no dynamic allocations. It targets embedded environments but can be used in any place a small BMP parser is required. Thanks to TinyBMP, Embedded Graphics now supports loading this simple image format. The header photo was made using Embedded Graphics and the <a href="https://crates.io/crates/ssd1331">SSD1331 driver</a> in pure Rust. In this post, I'll talk through how the BMP file is parsed in no_std environments with <a href="https://crates.io/crates/nom">nom</a> and how to get BMP images working with embedded_graphics.</p>

2019-02-17T13:40:00+00:00 2019-02-17T13:40:00+00:00 James Waples https://wapl.es/rust/2019/02/17/rust-cross-compile-linux-to-macos.html/

<p>I've recently been working on a Rust project at <a href="https://repositive.io/">work</a> which requires compiling for Linux (GNU), Linux (musl - for Alpine Linux) and macOS. I use Linux Mint nearly all the time, so building for macOS targets has required asking very nicely to borrow a spare Macbook Air. This is naturally a bit crap, so I set out to find a Linux-only solution to cross compile for macOS using <a href="https://github.com/tpoechtrager/osxcross">osxcross</a>. A weekend of pain later, and I have the following post. Hopefully it spares you a weekend of your own pain.</p>

2019-02-13T20:47:00+00:00 2019-02-13T20:47:00+00:00 James Waples https://wapl.es/electronics/rust/2019/02/13/sh1106-driver.html/

<p>Similar to the <a href="/electronics/rust/2018/04/30/ssd1306-driver.html">SSD1306</a> covered previously, the SH1106 OLED display is a small, self contained module perfect for hacking into a project or prototype. It's available on AliExpress and eBay for peanuts, but is lacking a Rust driver. Until now with the <a href="https://crates.io/crates/sh1106"><code>sh1106</code> crate</a>!</p>

2018-12-13T20:13:21+00:00 2018-12-13T20:13:21+00:00 James Waples https://wapl.es/rust/2018/12/13/optimising-new.html/

<p>Rust (and LLVM) are <em>really</em> good at optimising things.</p> <p>I have a struct, <code>TrajectoryStep</code>, that I pass to some methods in my program. I don't want to use positional arguments as it's impossible to tell what <code>some_func(f32, f32, f32)</code> might actually require. It looks like this:</p>

2018-12-10T22:02:59+00:00 2018-12-10T22:02:59+00:00 James Waples https://wapl.es/typescript/2018/12/10/default-arguments-for-cooler-testing.html/

<p>In my <a href="/typescript/2018/12/10/typechecking-helper-functions-in-typescript.html">other post</a> about creating properly typechecked helper functions in Typescript, I missed something out from the examples that's present in the real code: default parameters! There's a function, <code>createEvent</code>, that returns an object with a dynamically generated UUID value in it. It also includes the current timestamp. This is great from the programmer's point of view as there's no need to wire up these values manually, but it sucks for unit tests because the values always change! The solution is to use <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Default_parameters">default parameters</a> to keep the ergonomics of a clean public API, but still support unit testing and special cases gracefully.</p>

2018-12-10T21:30:36+00:00 2018-12-10T21:30:36+00:00 James Waples https://wapl.es/typescript/2018/12/10/typechecking-helper-functions-in-typescript.html/

<p>I've been working on toasting a lot of our tech debt <a href="https://repositive.io">at Repositive</a> recently. We use an event driven microservice architecture which has various benefits, but some drawbacks concerning what data is sent where due in part to the liberal use of <code>any</code> in our Typescript codebases. During my refactoring rampage, I encountered some places where event objects were missing fields or otherwise weren't being generated properly. To this end, I set out to create a type-checked solution to this problem.</p>

2018-09-03T11:42:00+00:00 2018-09-03T11:42:00+00:00 James Waples https://wapl.es/linux/2018/09/03/linux-mint-19-office-365.html/

<ol> <li>Install Evolution with the Exchange addons</li> </ol> <pre data-lang="bash" class="language-bash z-code"><code class="language-bash" data-lang="bash"><span class="z-source z-shell z-bash"><span class="z-meta z-function-call z-shell"><span class="z-variable z-function z-shell">apt</span></span><span class="z-meta z-function-call z-arguments z-shell"> install evolution evolution-ews evolution-plugins</span> </span></code></pre>

2018-04-30T11:34:00+00:00 2018-04-30T11:34:00+00:00 James Waples https://wapl.es/electronics/rust/2018/04/30/ssd1306-driver.html/

<p>As part of the <a href="https://github.com/rust-lang-nursery/embedded-wg/issues/39">weekly driver initiative</a>, myself (<a href="https://github.com/jamwaffles"><strong>@jamwaffles</strong></a>), <a href="https://github.com/therealprof"><strong>@therealprof</strong></a> and <a href="https://github.com/scowcron"><strong>@scowcron</strong></a> have been working on <a href="https://crates.io/crates/ssd1306">a Rust driver for the common as mud SSD1306-based OLED display modules</a>. This little chip is found in the majority of inexpensive OLED display modules found on Ebay and AliExpress. It supports either an SPI or I2C interface, both of which the driver supports.</p>

2018-02-19T20:52:00+00:00 2018-02-19T20:52:00+00:00 James Waples https://wapl.es/rust/2018/02/19/cross-platform-gdb-safe-path.html/

<p>I've been developing an embedded Rust app (yay!) on Windows (blegh) recently. The Rust team have put incredible effort into making Rust itself work great in Windows environments, but the tooling around it can be difficult to get working correctly. My current problem was making GDB load a <code>.gdbinit</code> file from the current projecting when doing <code>xargo run</code>. Here's how I fixed it in <code>.cargo/config</code>:</p>

2017-12-12T14:03:18+00:00 2017-12-12T14:03:18+00:00 James Waples https://wapl.es/elm/2017/12/12/elm-counting-occurrences.html/

<p>So. Elm. It's been an interesting experience for me, coming from a procedural language (JS) background. The learning curve is steep, but the functional nature of Elm, along with its compile time type safety really pays off. One of the (few!) problems I've found as a newcomer however, is that the documentation can be really frustrating sometimes. In this post, I hope to remedy that slightly by providing a newcomer's perspective on a little bit of data processing in Elm.</p>

2017-10-06T04:42:52+00:00 2017-10-06T04:42:52+00:00 James Waples https://wapl.es/rust/2017/10/06/git2-rs-cloning-private-github-repos.html/

<p>Cloning a private Github repo using SSH auth in Rust has proved to be a pretty gnarly problem (for my anyway), so I thought I'd share this quick tutorial to help anyone else out that might be struggling with the same issue. I'm using <a href="https://github.com/alexcrichton/git2-rs">git2-rs</a> which has good interface documentation, but <em>very few pieces of example code</em>, so I set out to fix that somewhat with this post.</p>

2017-09-21T09:36:15+00:00 2017-09-21T09:36:15+00:00 James Waples https://wapl.es/web/2017/09/21/analytics-events-with-redux-and-react.html/

<p>One of my main responsibilites at <a href="https://www.totallymoney.com/">TotallyMoney</a> was to take care of the in-house analytics/event logging framework. Like lots of companies, understanding what users do and how they interact with a product is to get good insight on. In this regard, people reinvent the logging wheel with various <a href="https://en.wiktionary.org/wiki/krimskrams">krimskrams</a> attached, me being no exception. What I want to show in this post is how to integrate an event logging framework into a React/Redux application in a way that's scaleable and testable. Unit testable logging is important when the rest of the business relies heavily on the events and the data in them like many companies do.</p>

2016-11-12T22:04:14+00:00 2016-11-12T22:04:14+00:00 James Waples https://wapl.es/workshop/2016/11/12/scraping-without-a-scraper.html/

<p>In between watching the rain and emptying all the shmoo out of my air compressor (long overdue), I decided to try my hand at some impromptu scraping this weekend. Matters were complicated somewhat due to me not owning a scraping tool, but I worked with what I have to make what I think are some satisfctory results. This post will be a short log of what went down and will hopefully demonstrate that one can achieve reasonably good (i.e. flat) results without having a real scraper.</p>

2016-10-24T22:55:05+00:00 2016-10-24T22:55:05+00:00 James Waples https://wapl.es/rust/2016/10/24/rust-christmas-colour-wheel.html/

<p>Here's a quick one; I'm making a Christmas display out of a bunch of serially controllable APA106 RGB LEDs, but how do I turn a value of <code>0 – 255</code> into a glorious RGW (Red Green White) struct with the correct colour, and the correct wrapping rules?</p>

2016-04-26T10:14:03+00:00 2016-04-26T10:14:03+00:00 James Waples https://wapl.es/rust/2016/04/26/rust-logentries-docker.html/

<p>I'm fascinated by Rust for it's safety and speed, but also because it's simple to write low level code in what feels like a high level language. To that end, I've been working on a small Rust project at <a href="http://www.totallymoney.com">TotallyMoney.com</a> (where I work) for the last week or so to see if it's viable for production use. It's a simple service that polls a <a href="https://logentries.com">Logentries</a> endpoint for JSON, parses it and saves some values in a Postgres database. It's not a very complicated task, but I saw this as a good opportunity to try Rust in a production-ish role.</p>

2016-03-07T10:22:55+00:00 2016-03-07T10:22:55+00:00 James Waples https://wapl.es/airsoft/2016/03/07/gng-p90-mag-fix.html/

<p>Disclaimer: This is an article for an <em>airsoft</em> gun only. None of this pertains to real firearms.</p> <p>I have a G&amp;G P90 (in tan, in case you were wondering) and like many others suffer from the hicap mags failing to feed. Half filling them kind of works, but the feed mechanism always seems to jam. I've got a half solution here in this article. It doesn't completely fix the problem, but my hicaps feed a lot more reliably now, particularly in semi-auto, than they did before.</p>

2016-02-04T22:03:30+00:00 2016-02-04T22:03:30+00:00 James Waples https://wapl.es/cnc/2016/02/04/cnc-steppers-bipolar-parallel-faster-smoother.html/

<p>Quick tip: if you're looking for higher maximum speeds with your bipolar stepper motors, try wiring the windings in parallel instead of series. According to <a href="http://digital.ni.com/public.nsf/allkb/B1CC4C64ABBC7D3C86257BC70017B9E2">a short National Instruments article</a>, it can increase torque at higher speeds, reducing the chance that the motor will stall during fast rapids.</p>

2015-12-04T20:14:47+00:00 2015-12-04T20:14:47+00:00 James Waples https://wapl.es/huanyang-linuxcnc-2-7-speed-control/

<p>Huanyang branded VFD drives are ubiquitous on eBay and other sites like AliExpress. I bought one some time ago with a 1.5KW spindle and have been controlling the speed manually with the difficult to use control panel on the front. It is, however, possible to control the VFD from within LinuxCNC using the <a href="http://linuxcnc.org/docs/html/gcode/m-code.html#mcode:m3-m4-m5"><code>M3</code> and <code>M5</code> commands</a> (I haven't been able to get <code>M4</code>, reverse rotation, working yet). What's also neat is we can get the machine to wait for the spindle to come up to speed before moving to the next line of GCode.</p>