| <!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="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/bytemuck-1.13.1/src/internal.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>internal.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../normalize.css"><link rel="stylesheet" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../ayu.css" disabled><link rel="stylesheet" href="../../dark.css" disabled><link rel="stylesheet" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script><script defer src="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../bytemuck/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../bytemuck/index.html"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="doccomment">//! Internal implementation of casting functions not bound by marker traits |
| //! and therefore marked as unsafe. This is used so that we don't need to |
| //! duplicate the business logic contained in these functions between the |
| //! versions exported in the crate root, `checked`, and `relaxed` modules. |
| </span><span class="attribute">#![allow(unused_unsafe)] |
| |
| </span><span class="kw">use </span><span class="kw">crate</span>::PodCastError; |
| <span class="kw">use </span>core::{marker::<span class="kw-2">*</span>, mem::<span class="kw-2">*</span>}; |
| |
| <span class="comment">/* |
| |
| Note(Lokathor): We've switched all of the `unwrap` to `match` because there is |
| apparently a bug: https://github.com/rust-lang/rust/issues/68667 |
| and it doesn't seem to show up in simple godbolt examples but has been reported |
| as having an impact when there's a cast mixed in with other more complicated |
| code around it. Rustc/LLVM ends up missing that the `Err` can't ever happen for |
| particular type combinations, and then it doesn't fully eliminated the panic |
| possibility code branch. |
| |
| */ |
| |
| </span><span class="doccomment">/// Immediately panics. |
| </span><span class="attribute">#[cfg(not(target_arch = <span class="string">"spirv"</span>))] |
| #[cold] |
| #[inline(never)] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>something_went_wrong<D: core::fmt::Display>( |
| _src: <span class="kw-2">&</span>str, _err: D, |
| ) -> ! { |
| <span class="comment">// Note(Lokathor): Keeping the panic here makes the panic _formatting_ go |
| // here too, which helps assembly readability and also helps keep down |
| // the inline pressure. |
| </span><span class="macro">panic!</span>(<span class="string">"{src}>{err}"</span>, src = _src, err = _err); |
| } |
| |
| <span class="doccomment">/// Immediately panics. |
| </span><span class="attribute">#[cfg(target_arch = <span class="string">"spirv"</span>)] |
| #[cold] |
| #[inline(never)] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>something_went_wrong<D>(_src: <span class="kw-2">&</span>str, _err: D) -> ! { |
| <span class="comment">// Note: On the spirv targets from [rust-gpu](https://github.com/EmbarkStudios/rust-gpu) |
| // panic formatting cannot be used. We we just give a generic error message |
| // The chance that the panicking version of these functions will ever get |
| // called on spir-v targets with invalid inputs is small, but giving a |
| // simple error message is better than no error message at all. |
| </span><span class="macro">panic!</span>(<span class="string">"Called a panicing helper from bytemuck which paniced"</span>); |
| } |
| |
| <span class="doccomment">/// Re-interprets `&T` as `&[u8]`. |
| /// |
| /// Any ZST becomes an empty slice, and in that case the pointer value of that |
| /// empty slice might not match the pointer value of the input reference. |
| </span><span class="attribute">#[inline(always)] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>bytes_of<T: Copy>(t: <span class="kw-2">&</span>T) -> <span class="kw-2">&</span>[u8] { |
| <span class="kw">if </span>size_of::<T>() == <span class="number">0 </span>{ |
| <span class="kw-2">&</span>[] |
| } <span class="kw">else </span>{ |
| <span class="kw">match </span>try_cast_slice::<T, u8>(core::slice::from_ref(t)) { |
| <span class="prelude-val">Ok</span>(s) => s, |
| <span class="prelude-val">Err</span>(<span class="kw">_</span>) => <span class="macro">unreachable!</span>(), |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Re-interprets `&mut T` as `&mut [u8]`. |
| /// |
| /// Any ZST becomes an empty slice, and in that case the pointer value of that |
| /// empty slice might not match the pointer value of the input reference. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>bytes_of_mut<T: Copy>(t: <span class="kw-2">&mut </span>T) -> <span class="kw-2">&mut </span>[u8] { |
| <span class="kw">if </span>size_of::<T>() == <span class="number">0 </span>{ |
| <span class="kw-2">&mut </span>[] |
| } <span class="kw">else </span>{ |
| <span class="kw">match </span>try_cast_slice_mut::<T, u8>(core::slice::from_mut(t)) { |
| <span class="prelude-val">Ok</span>(s) => s, |
| <span class="prelude-val">Err</span>(<span class="kw">_</span>) => <span class="macro">unreachable!</span>(), |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Re-interprets `&[u8]` as `&T`. |
| /// |
| /// ## Panics |
| /// |
| /// This is [`try_from_bytes`] but will panic on error. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>from_bytes<T: Copy>(s: <span class="kw-2">&</span>[u8]) -> <span class="kw-2">&</span>T { |
| <span class="kw">match </span>try_from_bytes(s) { |
| <span class="prelude-val">Ok</span>(t) => t, |
| <span class="prelude-val">Err</span>(e) => something_went_wrong(<span class="string">"from_bytes"</span>, e), |
| } |
| } |
| |
| <span class="doccomment">/// Re-interprets `&mut [u8]` as `&mut T`. |
| /// |
| /// ## Panics |
| /// |
| /// This is [`try_from_bytes_mut`] but will panic on error. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>from_bytes_mut<T: Copy>(s: <span class="kw-2">&mut </span>[u8]) -> <span class="kw-2">&mut </span>T { |
| <span class="kw">match </span>try_from_bytes_mut(s) { |
| <span class="prelude-val">Ok</span>(t) => t, |
| <span class="prelude-val">Err</span>(e) => something_went_wrong(<span class="string">"from_bytes_mut"</span>, e), |
| } |
| } |
| |
| <span class="doccomment">/// Reads from the bytes as if they were a `T`. |
| /// |
| /// ## Failure |
| /// * If the `bytes` length is not equal to `size_of::<T>()`. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>try_pod_read_unaligned<T: Copy>( |
| bytes: <span class="kw-2">&</span>[u8], |
| ) -> <span class="prelude-ty">Result</span><T, PodCastError> { |
| <span class="kw">if </span>bytes.len() != size_of::<T>() { |
| <span class="prelude-val">Err</span>(PodCastError::SizeMismatch) |
| } <span class="kw">else </span>{ |
| <span class="prelude-val">Ok</span>(<span class="kw">unsafe </span>{ (bytes.as_ptr() <span class="kw">as </span><span class="kw-2">*const </span>T).read_unaligned() }) |
| } |
| } |
| |
| <span class="doccomment">/// Reads the slice into a `T` value. |
| /// |
| /// ## Panics |
| /// * This is like `try_pod_read_unaligned` but will panic on failure. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>pod_read_unaligned<T: Copy>(bytes: <span class="kw-2">&</span>[u8]) -> T { |
| <span class="kw">match </span>try_pod_read_unaligned(bytes) { |
| <span class="prelude-val">Ok</span>(t) => t, |
| <span class="prelude-val">Err</span>(e) => something_went_wrong(<span class="string">"pod_read_unaligned"</span>, e), |
| } |
| } |
| |
| <span class="doccomment">/// Re-interprets `&[u8]` as `&T`. |
| /// |
| /// ## Failure |
| /// |
| /// * If the slice isn't aligned for the new type |
| /// * If the slice's length isn’t exactly the size of the new type |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>try_from_bytes<T: Copy>( |
| s: <span class="kw-2">&</span>[u8], |
| ) -> <span class="prelude-ty">Result</span><<span class="kw-2">&</span>T, PodCastError> { |
| <span class="kw">if </span>s.len() != size_of::<T>() { |
| <span class="prelude-val">Err</span>(PodCastError::SizeMismatch) |
| } <span class="kw">else if </span>(s.as_ptr() <span class="kw">as </span>usize) % align_of::<T>() != <span class="number">0 </span>{ |
| <span class="prelude-val">Err</span>(PodCastError::TargetAlignmentGreaterAndInputNotAligned) |
| } <span class="kw">else </span>{ |
| <span class="prelude-val">Ok</span>(<span class="kw">unsafe </span>{ <span class="kw-2">&*</span>(s.as_ptr() <span class="kw">as </span><span class="kw-2">*const </span>T) }) |
| } |
| } |
| |
| <span class="doccomment">/// Re-interprets `&mut [u8]` as `&mut T`. |
| /// |
| /// ## Failure |
| /// |
| /// * If the slice isn't aligned for the new type |
| /// * If the slice's length isn’t exactly the size of the new type |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>try_from_bytes_mut<T: Copy>( |
| s: <span class="kw-2">&mut </span>[u8], |
| ) -> <span class="prelude-ty">Result</span><<span class="kw-2">&mut </span>T, PodCastError> { |
| <span class="kw">if </span>s.len() != size_of::<T>() { |
| <span class="prelude-val">Err</span>(PodCastError::SizeMismatch) |
| } <span class="kw">else if </span>(s.as_ptr() <span class="kw">as </span>usize) % align_of::<T>() != <span class="number">0 </span>{ |
| <span class="prelude-val">Err</span>(PodCastError::TargetAlignmentGreaterAndInputNotAligned) |
| } <span class="kw">else </span>{ |
| <span class="prelude-val">Ok</span>(<span class="kw">unsafe </span>{ <span class="kw-2">&mut *</span>(s.as_mut_ptr() <span class="kw">as </span><span class="kw-2">*mut </span>T) }) |
| } |
| } |
| |
| <span class="doccomment">/// Cast `T` into `U` |
| /// |
| /// ## Panics |
| /// |
| /// * This is like [`try_cast`](try_cast), but will panic on a size mismatch. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>cast<A: Copy, B: Copy>(a: A) -> B { |
| <span class="kw">if </span>size_of::<A>() == size_of::<B>() { |
| <span class="kw">unsafe </span>{ <span class="macro">transmute!</span>(a) } |
| } <span class="kw">else </span>{ |
| something_went_wrong(<span class="string">"cast"</span>, PodCastError::SizeMismatch) |
| } |
| } |
| |
| <span class="doccomment">/// Cast `&mut T` into `&mut U`. |
| /// |
| /// ## Panics |
| /// |
| /// This is [`try_cast_mut`] but will panic on error. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>cast_mut<A: Copy, B: Copy>(a: <span class="kw-2">&mut </span>A) -> <span class="kw-2">&mut </span>B { |
| <span class="kw">if </span>size_of::<A>() == size_of::<B>() && align_of::<A>() >= align_of::<B>() { |
| <span class="comment">// Plz mr compiler, just notice that we can't ever hit Err in this case. |
| </span><span class="kw">match </span>try_cast_mut(a) { |
| <span class="prelude-val">Ok</span>(b) => b, |
| <span class="prelude-val">Err</span>(<span class="kw">_</span>) => <span class="macro">unreachable!</span>(), |
| } |
| } <span class="kw">else </span>{ |
| <span class="kw">match </span>try_cast_mut(a) { |
| <span class="prelude-val">Ok</span>(b) => b, |
| <span class="prelude-val">Err</span>(e) => something_went_wrong(<span class="string">"cast_mut"</span>, e), |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Cast `&T` into `&U`. |
| /// |
| /// ## Panics |
| /// |
| /// This is [`try_cast_ref`] but will panic on error. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>cast_ref<A: Copy, B: Copy>(a: <span class="kw-2">&</span>A) -> <span class="kw-2">&</span>B { |
| <span class="kw">if </span>size_of::<A>() == size_of::<B>() && align_of::<A>() >= align_of::<B>() { |
| <span class="comment">// Plz mr compiler, just notice that we can't ever hit Err in this case. |
| </span><span class="kw">match </span>try_cast_ref(a) { |
| <span class="prelude-val">Ok</span>(b) => b, |
| <span class="prelude-val">Err</span>(<span class="kw">_</span>) => <span class="macro">unreachable!</span>(), |
| } |
| } <span class="kw">else </span>{ |
| <span class="kw">match </span>try_cast_ref(a) { |
| <span class="prelude-val">Ok</span>(b) => b, |
| <span class="prelude-val">Err</span>(e) => something_went_wrong(<span class="string">"cast_ref"</span>, e), |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Cast `&[A]` into `&[B]`. |
| /// |
| /// ## Panics |
| /// |
| /// This is [`try_cast_slice`] but will panic on error. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>cast_slice<A: Copy, B: Copy>(a: <span class="kw-2">&</span>[A]) -> <span class="kw-2">&</span>[B] { |
| <span class="kw">match </span>try_cast_slice(a) { |
| <span class="prelude-val">Ok</span>(b) => b, |
| <span class="prelude-val">Err</span>(e) => something_went_wrong(<span class="string">"cast_slice"</span>, e), |
| } |
| } |
| |
| <span class="doccomment">/// Cast `&mut [T]` into `&mut [U]`. |
| /// |
| /// ## Panics |
| /// |
| /// This is [`try_cast_slice_mut`] but will panic on error. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>cast_slice_mut<A: Copy, B: Copy>(a: <span class="kw-2">&mut </span>[A]) -> <span class="kw-2">&mut </span>[B] { |
| <span class="kw">match </span>try_cast_slice_mut(a) { |
| <span class="prelude-val">Ok</span>(b) => b, |
| <span class="prelude-val">Err</span>(e) => something_went_wrong(<span class="string">"cast_slice_mut"</span>, e), |
| } |
| } |
| |
| <span class="doccomment">/// Try to cast `T` into `U`. |
| /// |
| /// Note that for this particular type of cast, alignment isn't a factor. The |
| /// input value is semantically copied into the function and then returned to a |
| /// new memory location which will have whatever the required alignment of the |
| /// output type is. |
| /// |
| /// ## Failure |
| /// |
| /// * If the types don't have the same size this fails. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>try_cast<A: Copy, B: Copy>( |
| a: A, |
| ) -> <span class="prelude-ty">Result</span><B, PodCastError> { |
| <span class="kw">if </span>size_of::<A>() == size_of::<B>() { |
| <span class="prelude-val">Ok</span>(<span class="kw">unsafe </span>{ <span class="macro">transmute!</span>(a) }) |
| } <span class="kw">else </span>{ |
| <span class="prelude-val">Err</span>(PodCastError::SizeMismatch) |
| } |
| } |
| |
| <span class="doccomment">/// Try to convert a `&T` into `&U`. |
| /// |
| /// ## Failure |
| /// |
| /// * If the reference isn't aligned in the new type |
| /// * If the source type and target type aren't the same size. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>try_cast_ref<A: Copy, B: Copy>( |
| a: <span class="kw-2">&</span>A, |
| ) -> <span class="prelude-ty">Result</span><<span class="kw-2">&</span>B, PodCastError> { |
| <span class="comment">// Note(Lokathor): everything with `align_of` and `size_of` will optimize away |
| // after monomorphization. |
| </span><span class="kw">if </span>align_of::<B>() > align_of::<A>() |
| && (a <span class="kw">as </span><span class="kw-2">*const </span>A <span class="kw">as </span>usize) % align_of::<B>() != <span class="number">0 |
| </span>{ |
| <span class="prelude-val">Err</span>(PodCastError::TargetAlignmentGreaterAndInputNotAligned) |
| } <span class="kw">else if </span>size_of::<B>() == size_of::<A>() { |
| <span class="prelude-val">Ok</span>(<span class="kw">unsafe </span>{ <span class="kw-2">&*</span>(a <span class="kw">as </span><span class="kw-2">*const </span>A <span class="kw">as </span><span class="kw-2">*const </span>B) }) |
| } <span class="kw">else </span>{ |
| <span class="prelude-val">Err</span>(PodCastError::SizeMismatch) |
| } |
| } |
| |
| <span class="doccomment">/// Try to convert a `&mut T` into `&mut U`. |
| /// |
| /// As [`try_cast_ref`], but `mut`. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>try_cast_mut<A: Copy, B: Copy>( |
| a: <span class="kw-2">&mut </span>A, |
| ) -> <span class="prelude-ty">Result</span><<span class="kw-2">&mut </span>B, PodCastError> { |
| <span class="comment">// Note(Lokathor): everything with `align_of` and `size_of` will optimize away |
| // after monomorphization. |
| </span><span class="kw">if </span>align_of::<B>() > align_of::<A>() |
| && (a <span class="kw">as </span><span class="kw-2">*mut </span>A <span class="kw">as </span>usize) % align_of::<B>() != <span class="number">0 |
| </span>{ |
| <span class="prelude-val">Err</span>(PodCastError::TargetAlignmentGreaterAndInputNotAligned) |
| } <span class="kw">else if </span>size_of::<B>() == size_of::<A>() { |
| <span class="prelude-val">Ok</span>(<span class="kw">unsafe </span>{ <span class="kw-2">&mut *</span>(a <span class="kw">as </span><span class="kw-2">*mut </span>A <span class="kw">as </span><span class="kw-2">*mut </span>B) }) |
| } <span class="kw">else </span>{ |
| <span class="prelude-val">Err</span>(PodCastError::SizeMismatch) |
| } |
| } |
| |
| <span class="doccomment">/// Try to convert `&[A]` into `&[B]` (possibly with a change in length). |
| /// |
| /// * `input.as_ptr() as usize == output.as_ptr() as usize` |
| /// * `input.len() * size_of::<A>() == output.len() * size_of::<B>()` |
| /// |
| /// ## Failure |
| /// |
| /// * If the target type has a greater alignment requirement and the input slice |
| /// isn't aligned. |
| /// * If the target element type is a different size from the current element |
| /// type, and the output slice wouldn't be a whole number of elements when |
| /// accounting for the size change (eg: 3 `u16` values is 1.5 `u32` values, so |
| /// that's a failure). |
| /// * Similarly, you can't convert between a [ZST](https://doc.rust-lang.org/nomicon/exotic-sizes.html#zero-sized-types-zsts) |
| /// and a non-ZST. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>try_cast_slice<A: Copy, B: Copy>( |
| a: <span class="kw-2">&</span>[A], |
| ) -> <span class="prelude-ty">Result</span><<span class="kw-2">&</span>[B], PodCastError> { |
| <span class="comment">// Note(Lokathor): everything with `align_of` and `size_of` will optimize away |
| // after monomorphization. |
| </span><span class="kw">if </span>align_of::<B>() > align_of::<A>() |
| && (a.as_ptr() <span class="kw">as </span>usize) % align_of::<B>() != <span class="number">0 |
| </span>{ |
| <span class="prelude-val">Err</span>(PodCastError::TargetAlignmentGreaterAndInputNotAligned) |
| } <span class="kw">else if </span>size_of::<B>() == size_of::<A>() { |
| <span class="prelude-val">Ok</span>(<span class="kw">unsafe </span>{ core::slice::from_raw_parts(a.as_ptr() <span class="kw">as </span><span class="kw-2">*const </span>B, a.len()) }) |
| } <span class="kw">else if </span>size_of::<A>() == <span class="number">0 </span>|| size_of::<B>() == <span class="number">0 </span>{ |
| <span class="prelude-val">Err</span>(PodCastError::SizeMismatch) |
| } <span class="kw">else if </span>core::mem::size_of_val(a) % size_of::<B>() == <span class="number">0 </span>{ |
| <span class="kw">let </span>new_len = core::mem::size_of_val(a) / size_of::<B>(); |
| <span class="prelude-val">Ok</span>(<span class="kw">unsafe </span>{ core::slice::from_raw_parts(a.as_ptr() <span class="kw">as </span><span class="kw-2">*const </span>B, new_len) }) |
| } <span class="kw">else </span>{ |
| <span class="prelude-val">Err</span>(PodCastError::OutputSliceWouldHaveSlop) |
| } |
| } |
| |
| <span class="doccomment">/// Try to convert `&mut [A]` into `&mut [B]` (possibly with a change in |
| /// length). |
| /// |
| /// As [`try_cast_slice`], but `&mut`. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>try_cast_slice_mut<A: Copy, B: Copy>( |
| a: <span class="kw-2">&mut </span>[A], |
| ) -> <span class="prelude-ty">Result</span><<span class="kw-2">&mut </span>[B], PodCastError> { |
| <span class="comment">// Note(Lokathor): everything with `align_of` and `size_of` will optimize away |
| // after monomorphization. |
| </span><span class="kw">if </span>align_of::<B>() > align_of::<A>() |
| && (a.as_mut_ptr() <span class="kw">as </span>usize) % align_of::<B>() != <span class="number">0 |
| </span>{ |
| <span class="prelude-val">Err</span>(PodCastError::TargetAlignmentGreaterAndInputNotAligned) |
| } <span class="kw">else if </span>size_of::<B>() == size_of::<A>() { |
| <span class="prelude-val">Ok</span>(<span class="kw">unsafe </span>{ |
| core::slice::from_raw_parts_mut(a.as_mut_ptr() <span class="kw">as </span><span class="kw-2">*mut </span>B, a.len()) |
| }) |
| } <span class="kw">else if </span>size_of::<A>() == <span class="number">0 </span>|| size_of::<B>() == <span class="number">0 </span>{ |
| <span class="prelude-val">Err</span>(PodCastError::SizeMismatch) |
| } <span class="kw">else if </span>core::mem::size_of_val(a) % size_of::<B>() == <span class="number">0 </span>{ |
| <span class="kw">let </span>new_len = core::mem::size_of_val(a) / size_of::<B>(); |
| <span class="prelude-val">Ok</span>(<span class="kw">unsafe </span>{ |
| core::slice::from_raw_parts_mut(a.as_mut_ptr() <span class="kw">as </span><span class="kw-2">*mut </span>B, new_len) |
| }) |
| } <span class="kw">else </span>{ |
| <span class="prelude-val">Err</span>(PodCastError::OutputSliceWouldHaveSlop) |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="bytemuck" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
