77 lines
17 KiB
HTML
77 lines
17 KiB
HTML
<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="This crate gives small utilities for casting between plain data types."><title>bytemuck - Rust</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Italic-81dc35de.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-MediumItalic-ccf7e434.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2"href="../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../static.files/rustdoc-ca0dd0c4.css"><meta name="rustdoc-vars" data-root-path="../" data-static-root-path="../static.files/" data-current-crate="bytemuck" data-themes="" data-resource-suffix="" data-rustdoc-version="1.93.1 (01f6ddf75 2026-02-11) (Arch Linux rust 1:1.93.1-1)" data-channel="1.93.1" data-search-js="search-9e2438ea.js" data-stringdex-js="stringdex-a3946164.js" data-settings-js="settings-c38705f0.js" ><script src="../static.files/storage-e2aeef58.js"></script><script defer src="../crates.js"></script><script defer src="../static.files/main-a410ff4d.js"></script><noscript><link rel="stylesheet" href="../static.files/noscript-263c88ec.css"></noscript><link rel="alternate icon" type="image/png" href="../static.files/favicon-32x32-eab170b8.png"><link rel="icon" type="image/svg+xml" href="../static.files/favicon-044be391.svg"></head><body class="rustdoc mod crate"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><rustdoc-topbar><h2><a href="#">Crate bytemuck</a></h2></rustdoc-topbar><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../bytemuck/index.html">bytemuck</a><span class="version">1.25.0</span></h2></div><div class="sidebar-elems"><ul class="block"><li><a id="all-types" href="all.html">All Items</a></li></ul><section id="rustdoc-toc"><h3><a href="#">Sections</a></h3><ul class="block top-toc"><li><a href="#basics" title="Basics">Basics</a></li><li><a href="#failures" title="Failures">Failures</a></li><li><a href="#using-your-own-types" title="Using Your Own Types">Using Your Own Types</a></li><li><a href="#cargo-features" title="Cargo Features">Cargo Features</a></li><li><a href="#related-crates" title="Related Crates">Related Crates</a></li></ul><h3><a href="#reexports">Crate Items</a></h3><ul class="block"><li><a href="#reexports" title="Re-exports">Re-exports</a></li><li><a href="#modules" title="Modules">Modules</a></li><li><a href="#macros" title="Macros">Macros</a></li><li><a href="#enums" title="Enums">Enums</a></li><li><a href="#traits" title="Traits">Traits</a></li><li><a href="#functions" title="Functions">Functions</a></li></ul></section><div id="rustdoc-modnav"></div></div></nav><div class="sidebar-resizer" title="Drag to resize sidebar"></div><main><div class="width-limiter"><section id="main-content" class="content"><div class="main-heading"><h1>Crate <span>bytemuck</span> <button id="copy-path" title="Copy item path to clipboard">Copy item path</button></h1><rustdoc-toolbar></rustdoc-toolbar><span class="sub-heading"><a class="src" href="../src/bytemuck/lib.rs.html#1-578">Source</a> </span></div><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>This crate gives small utilities for casting between plain data types.</p>
|
||
<h3 id="basics"><a class="doc-anchor" href="#basics">§</a>Basics</h3>
|
||
<p>Data comes in five basic forms in Rust, so we have five basic casting
|
||
functions:</p>
|
||
<ul>
|
||
<li><code>T</code> uses <a href="fn.cast.html" title="fn bytemuck::cast"><code>cast</code></a></li>
|
||
<li><code>&T</code> uses <a href="fn.cast_ref.html" title="fn bytemuck::cast_ref"><code>cast_ref</code></a></li>
|
||
<li><code>&mut T</code> uses <a href="fn.cast_mut.html" title="fn bytemuck::cast_mut"><code>cast_mut</code></a></li>
|
||
<li><code>&[T]</code> uses <a href="fn.cast_slice.html" title="fn bytemuck::cast_slice"><code>cast_slice</code></a></li>
|
||
<li><code>&mut [T]</code> uses <a href="fn.cast_slice_mut.html" title="fn bytemuck::cast_slice_mut"><code>cast_slice_mut</code></a></li>
|
||
</ul>
|
||
<p>Depending on the function, the <a href="trait.NoUninit.html" title="trait bytemuck::NoUninit"><code>NoUninit</code></a> and/or <a href="trait.AnyBitPattern.html" title="trait bytemuck::AnyBitPattern"><code>AnyBitPattern</code></a> traits
|
||
are used to maintain memory safety.</p>
|
||
<p><strong>Historical Note:</strong> When the crate first started the <a href="trait.Pod.html" title="trait bytemuck::Pod"><code>Pod</code></a> trait was used
|
||
instead, and so you may hear people refer to that, but it has the strongest
|
||
requirements and people eventually wanted the more fine-grained system, so
|
||
here we are. All types that impl <code>Pod</code> have a blanket impl to also support
|
||
<code>NoUninit</code> and <code>AnyBitPattern</code>. The traits unfortunately do not have a
|
||
perfectly clean hierarchy for semver reasons.</p>
|
||
<h3 id="failures"><a class="doc-anchor" href="#failures">§</a>Failures</h3>
|
||
<p>Some casts will never fail, and other casts might fail.</p>
|
||
<ul>
|
||
<li><code>cast::<u32, f32></code> always works (and <a href="https://doc.rust-lang.org/1.93.1/core/primitive.f32.html#method.from_bits" title="associated function f32::from_bits"><code>f32::from_bits</code></a>).</li>
|
||
<li><code>cast_ref::<[u8; 4], u32></code> might fail if the specific array reference
|
||
given at runtime doesn’t have alignment 4.</li>
|
||
</ul>
|
||
<p>In addition to the “normal” forms of each function, which will panic on
|
||
invalid input, there’s also <code>try_</code> versions which will return a <code>Result</code>.</p>
|
||
<p>If you would like to statically ensure that a cast will work at runtime you
|
||
can use the <code>must_cast</code> crate feature and the <code>must_</code> casting functions. A
|
||
“must cast” that can’t be statically known to be valid will cause a
|
||
compilation error (and sometimes a very hard to read compilation error).</p>
|
||
<h3 id="using-your-own-types"><a class="doc-anchor" href="#using-your-own-types">§</a>Using Your Own Types</h3>
|
||
<p>All the functions listed above are guarded by the <a href="trait.Pod.html" title="trait bytemuck::Pod"><code>Pod</code></a> trait, which is a
|
||
sub-trait of the <a href="trait.Zeroable.html" title="trait bytemuck::Zeroable"><code>Zeroable</code></a> trait.</p>
|
||
<p>If you enable the crate’s <code>derive</code> feature then these traits can be derived
|
||
on your own types. The derive macros will perform the necessary checks on
|
||
your type declaration, and trigger an error if your type does not qualify.</p>
|
||
<p>The derive macros might not cover all edge cases, and sometimes they will
|
||
error when actually everything is fine. As a last resort you can impl these
|
||
traits manually. However, these traits are <code>unsafe</code>, and you should
|
||
carefully read the requirements before using a manual implementation.</p>
|
||
<h3 id="cargo-features"><a class="doc-anchor" href="#cargo-features">§</a>Cargo Features</h3>
|
||
<p>The crate supports Rust 1.34 when no features are enabled, and so there’s
|
||
cargo features for thing that you might consider “obvious”.</p>
|
||
<p>The cargo features <strong>do not</strong> promise any particular MSRV, and they may
|
||
increase their MSRV in new versions.</p>
|
||
<ul>
|
||
<li><code>derive</code>: Provide derive macros for the various traits.</li>
|
||
<li><code>extern_crate_alloc</code>: Provide utilities for <code>alloc</code> related types such as
|
||
Box and Vec.</li>
|
||
<li><code>zeroable_maybe_uninit</code> and <code>zeroable_atomics</code>: Provide more <a href="trait.Zeroable.html" title="trait bytemuck::Zeroable"><code>Zeroable</code></a>
|
||
impls.</li>
|
||
<li><code>pod_saturating</code>: Provide more <a href="trait.Pod.html" title="trait bytemuck::Pod"><code>Pod</code></a> and <a href="trait.Zeroable.html" title="trait bytemuck::Zeroable"><code>Zeroable</code></a> impls.</li>
|
||
<li><code>wasm_simd</code> and <code>aarch64_simd</code>: Support more SIMD types.</li>
|
||
<li><code>min_const_generics</code>: Provides appropriate impls for arrays of all lengths
|
||
instead of just for a select list of array lengths.</li>
|
||
<li><code>must_cast</code>: Provides the <code>must_</code> functions, which will compile error if
|
||
the requested cast can’t be statically verified.</li>
|
||
<li><code>const_zeroed</code>: Provides a const version of the <code>zeroed</code> function.</li>
|
||
</ul>
|
||
<h3 id="related-crates"><a class="doc-anchor" href="#related-crates">§</a>Related Crates</h3>
|
||
<ul>
|
||
<li><a href="https://docs.rs/pack1"><code>pack1</code></a>, which contains <code>bytemuck</code>-compatible
|
||
packed little-endian, big-endian and native-endian integer and floating
|
||
point number types.</li>
|
||
</ul>
|
||
</div></details><h2 id="reexports" class="section-header">Re-exports<a href="#reexports" class="anchor">§</a></h2><dl class="item-table reexports"><dt id="reexport.CheckedBitPattern"><code>pub use checked::<a class="trait" href="checked/trait.CheckedBitPattern.html" title="trait bytemuck::checked::CheckedBitPattern">CheckedBitPattern</a>;</code></dt><dt><code>pub use <a class="mod" href="allocation/index.html" title="mod bytemuck::allocation">allocation</a>::*;</code></dt></dl><h2 id="modules" class="section-header">Modules<a href="#modules" class="anchor">§</a></h2><dl class="item-table"><dt><a class="mod" href="allocation/index.html" title="mod bytemuck::allocation">allocation</a></dt><dd>Stuff to boost things in the <code>alloc</code> crate.</dd><dt><a class="mod" href="checked/index.html" title="mod bytemuck::checked">checked</a></dt><dd>Checked versions of the casting functions exposed in crate root
|
||
that support <a href="checked/trait.CheckedBitPattern.html" title="trait bytemuck::checked::CheckedBitPattern"><code>CheckedBitPattern</code></a> types.</dd></dl><h2 id="macros" class="section-header">Macros<a href="#macros" class="anchor">§</a></h2><dl class="item-table"><dt><a class="macro" href="macro.offset_of.html" title="macro bytemuck::offset_of">offset_<wbr>of</a></dt><dd>Find the offset in bytes of the given <code>$field</code> of <code>$Type</code>. Requires an
|
||
already initialized <code>$instance</code> value to work with.</dd></dl><h2 id="enums" class="section-header">Enums<a href="#enums" class="anchor">§</a></h2><dl class="item-table"><dt><a class="enum" href="enum.PodCastError.html" title="enum bytemuck::PodCastError">PodCast<wbr>Error</a></dt><dd>The things that can go wrong when casting between <a href="trait.Pod.html" title="trait bytemuck::Pod"><code>Pod</code></a> data forms.</dd></dl><h2 id="traits" class="section-header">Traits<a href="#traits" class="anchor">§</a></h2><dl class="item-table"><dt><a class="trait" href="trait.AnyBitPattern.html" title="trait bytemuck::AnyBitPattern">AnyBit<wbr>Pattern</a></dt><dd>Marker trait for “plain old data” types that are valid for any bit pattern.</dd><dt><a class="trait" href="trait.Contiguous.html" title="trait bytemuck::Contiguous">Contiguous</a></dt><dd>A trait indicating that:</dd><dt><a class="trait" href="trait.NoUninit.html" title="trait bytemuck::NoUninit">NoUninit</a></dt><dd>Marker trait for “plain old data” types with no uninit (or padding) bytes.</dd><dt><a class="trait" href="trait.Pod.html" title="trait bytemuck::Pod">Pod</a></dt><dd>Marker trait for “plain old data”.</dd><dt><a class="trait" href="trait.PodInOption.html" title="trait bytemuck::PodInOption">PodIn<wbr>Option</a></dt><dd>Trait for types which are <a href="trait.Pod.html" title="trait bytemuck::Pod">Pod</a> when wrapped in
|
||
<a href="https://doc.rust-lang.org/1.93.1/core/option/enum.Option.html" title="enum core::option::Option">Option</a>.</dd><dt><a class="trait" href="trait.TransparentWrapper.html" title="trait bytemuck::TransparentWrapper">Transparent<wbr>Wrapper</a></dt><dd>A trait which indicates that a type is a <code>#[repr(transparent)]</code> wrapper
|
||
around the <code>Inner</code> value.</dd><dt><a class="trait" href="trait.Zeroable.html" title="trait bytemuck::Zeroable">Zeroable</a></dt><dd>Trait for types that can be safely created with
|
||
<a href="https://doc.rust-lang.org/1.93.1/core/mem/fn.zeroed.html" title="fn core::mem::zeroed"><code>zeroed</code></a>.</dd><dt><a class="trait" href="trait.ZeroableInOption.html" title="trait bytemuck::ZeroableInOption">Zeroable<wbr>InOption</a></dt><dd>Trait for types which are <a href="trait.Zeroable.html" title="trait bytemuck::Zeroable">Zeroable</a> when wrapped in
|
||
<a href="https://doc.rust-lang.org/1.93.1/core/option/enum.Option.html" title="enum core::option::Option">Option</a>.</dd></dl><h2 id="functions" class="section-header">Functions<a href="#functions" class="anchor">§</a></h2><dl class="item-table"><dt><a class="fn" href="fn.bytes_of.html" title="fn bytemuck::bytes_of">bytes_<wbr>of</a></dt><dd>Re-interprets <code>&T</code> as <code>&[u8]</code>.</dd><dt><a class="fn" href="fn.bytes_of_mut.html" title="fn bytemuck::bytes_of_mut">bytes_<wbr>of_<wbr>mut</a></dt><dd>Re-interprets <code>&mut T</code> as <code>&mut [u8]</code>.</dd><dt><a class="fn" href="fn.cast.html" title="fn bytemuck::cast">cast</a></dt><dd>Cast <code>A</code> into <code>B</code></dd><dt><a class="fn" href="fn.cast_mut.html" title="fn bytemuck::cast_mut">cast_<wbr>mut</a></dt><dd>Cast <code>&mut A</code> into <code>&mut B</code>.</dd><dt><a class="fn" href="fn.cast_ref.html" title="fn bytemuck::cast_ref">cast_<wbr>ref</a></dt><dd>Cast <code>&A</code> into <code>&B</code>.</dd><dt><a class="fn" href="fn.cast_slice.html" title="fn bytemuck::cast_slice">cast_<wbr>slice</a></dt><dd>Cast <code>&[A]</code> into <code>&[B]</code>.</dd><dt><a class="fn" href="fn.cast_slice_mut.html" title="fn bytemuck::cast_slice_mut">cast_<wbr>slice_<wbr>mut</a></dt><dd>Cast <code>&mut [A]</code> into <code>&mut [B]</code>.</dd><dt><a class="fn" href="fn.fill_zeroes.html" title="fn bytemuck::fill_zeroes">fill_<wbr>zeroes</a></dt><dd>Fill all bytes of <code>slice</code> with zeroes (see <a href="trait.Zeroable.html" title="trait bytemuck::Zeroable"><code>Zeroable</code></a>).</dd><dt><a class="fn" href="fn.from_bytes.html" title="fn bytemuck::from_bytes">from_<wbr>bytes</a></dt><dd>Re-interprets <code>&[u8]</code> as <code>&T</code>.</dd><dt><a class="fn" href="fn.from_bytes_mut.html" title="fn bytemuck::from_bytes_mut">from_<wbr>bytes_<wbr>mut</a></dt><dd>Re-interprets <code>&mut [u8]</code> as <code>&mut T</code>.</dd><dt><a class="fn" href="fn.pod_align_to.html" title="fn bytemuck::pod_align_to">pod_<wbr>align_<wbr>to</a></dt><dd>As <a href="https://doc.rust-lang.org/std/primitive.slice.html#method.align_to"><code>align_to</code></a>,
|
||
but safe because of the <a href="trait.Pod.html" title="trait bytemuck::Pod"><code>Pod</code></a> bound.</dd><dt><a class="fn" href="fn.pod_align_to_mut.html" title="fn bytemuck::pod_align_to_mut">pod_<wbr>align_<wbr>to_<wbr>mut</a></dt><dd>As <a href="https://doc.rust-lang.org/std/primitive.slice.html#method.align_to_mut"><code>align_to_mut</code></a>,
|
||
but safe because of the <a href="trait.Pod.html" title="trait bytemuck::Pod"><code>Pod</code></a> bound.</dd><dt><a class="fn" href="fn.pod_read_unaligned.html" title="fn bytemuck::pod_read_unaligned">pod_<wbr>read_<wbr>unaligned</a></dt><dd>Reads the slice into a <code>T</code> value.</dd><dt><a class="fn" href="fn.try_cast.html" title="fn bytemuck::try_cast">try_<wbr>cast</a></dt><dd>Try to cast <code>A</code> into <code>B</code>.</dd><dt><a class="fn" href="fn.try_cast_mut.html" title="fn bytemuck::try_cast_mut">try_<wbr>cast_<wbr>mut</a></dt><dd>Try to convert a <code>&mut A</code> into <code>&mut B</code>.</dd><dt><a class="fn" href="fn.try_cast_ref.html" title="fn bytemuck::try_cast_ref">try_<wbr>cast_<wbr>ref</a></dt><dd>Try to convert a <code>&A</code> into <code>&B</code>.</dd><dt><a class="fn" href="fn.try_cast_slice.html" title="fn bytemuck::try_cast_slice">try_<wbr>cast_<wbr>slice</a></dt><dd>Try to convert <code>&[A]</code> into <code>&[B]</code> (possibly with a change in length).</dd><dt><a class="fn" href="fn.try_cast_slice_mut.html" title="fn bytemuck::try_cast_slice_mut">try_<wbr>cast_<wbr>slice_<wbr>mut</a></dt><dd>Try to convert <code>&mut [A]</code> into <code>&mut [B]</code> (possibly with a change in
|
||
length).</dd><dt><a class="fn" href="fn.try_from_bytes.html" title="fn bytemuck::try_from_bytes">try_<wbr>from_<wbr>bytes</a></dt><dd>Re-interprets <code>&[u8]</code> as <code>&T</code>.</dd><dt><a class="fn" href="fn.try_from_bytes_mut.html" title="fn bytemuck::try_from_bytes_mut">try_<wbr>from_<wbr>bytes_<wbr>mut</a></dt><dd>Re-interprets <code>&mut [u8]</code> as <code>&mut T</code>.</dd><dt><a class="fn" href="fn.try_pod_read_unaligned.html" title="fn bytemuck::try_pod_read_unaligned">try_<wbr>pod_<wbr>read_<wbr>unaligned</a></dt><dd>Reads from the bytes as if they were a <code>T</code>.</dd><dt><a class="fn" href="fn.write_zeroes.html" title="fn bytemuck::write_zeroes">write_<wbr>zeroes</a></dt><dd>Fill all bytes of <code>target</code> with zeroes (see <a href="trait.Zeroable.html" title="trait bytemuck::Zeroable"><code>Zeroable</code></a>).</dd></dl></section></div></main></body></html> |