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<!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="API documentation for the Rust `Cread` trait in crate `scroll`."><meta name="keywords" content="rust, rustlang, rust-lang, Cread"><title>scroll::Cread - Rust</title><link rel="stylesheet" type="text/css" href="../normalize.css"><link rel="stylesheet" type="text/css" href="../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../dark.css"><link rel="stylesheet" type="text/css" href="../light.css" id="themeStyle"><script src="../storage.js"></script><noscript><link rel="stylesheet" href="../noscript.css"></noscript><link rel="shortcut icon" href="../favicon.ico"><style type="text/css">#crate-search{background-image:url("../down-arrow.svg");}</style></head><body class="rustdoc trait"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">☰</div><a href='../scroll/index.html'><div class='logo-container'><img src='../rust-logo.png' alt='logo'></div></a><p class='location'>Trait Cread</p><div class="sidebar-elems"><div class="block items"><a class="sidebar-title" href="#provided-methods">Provided Methods</a><div class="sidebar-links"><a href="#method.cread">cread</a><a href="#method.cread_with">cread_with</a></div><a class="sidebar-title" href="#implementors">Implementors</a></div><p class='location'><a href='index.html'>scroll</a></p><script>window.sidebarCurrent = {name: 'Cread', ty: 'trait', relpath: ''};</script><script defer src="sidebar-items.js"></script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><a id="settings-menu" href="../settings.html"><img src="../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class='fqn'><span class='out-of-band'><span id='render-detail'><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class='inner'>−</span>]</a></span><a class='srclink' href='../src/scroll/greater.rs.html#35-85' title='goto source code'>[src]</a></span><span class='in-band'>Trait <a href='index.html'>scroll</a>::<wbr><a class="trait" href=''>Cread</a></span></h1><div class="docblock type-decl hidden-by-usual-hider"><pre class='rust trait'>pub trait Cread<Ctx, I = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>>: <a class="trait" href="https://doc.rust-lang.org/nightly/core/ops/index/trait.Index.html" title="trait core::ops::index::Index">Index</a><I> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/ops/index/trait.Index.html" title="trait core::ops::index::Index">Index</a><<a class="struct" href="https://doc.rust-lang.org/nightly/core/ops/range/struct.RangeFrom.html" title="struct core::ops::range::RangeFrom">RangeFrom</a><I>> <span class="where fmt-newline">where<br> Ctx: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Copy.html" title="trait core::marker::Copy">Copy</a>, </span>{
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fn <a href='#method.cread_with' class='fnname'>cread_with</a><'a, N: <a class="trait" href="../scroll/ctx/trait.FromCtx.html" title="trait scroll::ctx::FromCtx">FromCtx</a><Ctx, Self::<a class="type" href="https://doc.rust-lang.org/nightly/core/ops/index/trait.Index.html#associatedtype.Output" title="type core::ops::index::Index::Output">Output</a>>>(<br> &'a self, <br> offset: I, <br> ctx: Ctx<br> ) -> N { ... }
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<div class='item-spacer'></div> fn <a href='#method.cread' class='fnname'>cread</a><'a, N: <a class="trait" href="../scroll/ctx/trait.FromCtx.html" title="trait scroll::ctx::FromCtx">FromCtx</a><Ctx, Self::<a class="type" href="https://doc.rust-lang.org/nightly/core/ops/index/trait.Index.html#associatedtype.Output" title="type core::ops::index::Index::Output">Output</a>>>(&'a self, offset: I) -> N<br> <span class="where">where<br> Ctx: <a class="trait" href="https://doc.rust-lang.org/nightly/core/default/trait.Default.html" title="trait core::default::Default">Default</a></span>,
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{ ... }
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}</pre></div><div class='docblock'><p>Core-read - core, no_std friendly trait for reading basic traits from byte buffers. Cannot fail unless the buffer is too small, in which case an assert fires and the program panics.</p>
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<p>If your type implements <a href="trait.FromCtx.html">FromCtx</a> then you can <code>cread::<YourType>(offset)</code>.</p>
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<h1 id="example" class="section-header"><a href="#example">Example</a></h1>
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<div class="example-wrap"><pre class="rust rust-example-rendered">
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<span class="kw">use</span> <span class="ident">scroll</span>::{<span class="ident">ctx</span>, <span class="ident">Cread</span>, <span class="ident">LE</span>};
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<span class="attribute">#[<span class="ident">repr</span>(<span class="ident">packed</span>)]</span>
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<span class="kw">struct</span> <span class="ident">Bar</span> {
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<span class="ident">foo</span>: <span class="ident">i32</span>,
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<span class="ident">bar</span>: <span class="ident">u32</span>,
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}
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<span class="kw">impl</span> <span class="ident">ctx</span>::<span class="ident">FromCtx</span><span class="op"><</span><span class="ident">scroll</span>::<span class="ident">Endian</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Bar</span> {
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<span class="kw">fn</span> <span class="ident">from_ctx</span>(<span class="ident">bytes</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>], <span class="ident">ctx</span>: <span class="ident">scroll</span>::<span class="ident">Endian</span>) <span class="op">-</span><span class="op">></span> <span class="self">Self</span> {
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<span class="kw">use</span> <span class="ident">scroll</span>::<span class="ident">Cread</span>;
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<span class="ident">Bar</span> { <span class="ident">foo</span>: <span class="ident">bytes</span>.<span class="ident">cread_with</span>(<span class="number">0</span>, <span class="ident">ctx</span>), <span class="ident">bar</span>: <span class="ident">bytes</span>.<span class="ident">cread_with</span>(<span class="number">4</span>, <span class="ident">ctx</span>) }
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}
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}
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<span class="kw">let</span> <span class="ident">bytes</span> <span class="op">=</span> [<span class="number">0xff</span>, <span class="number">0xff</span>, <span class="number">0xff</span>, <span class="number">0xff</span>, <span class="number">0xef</span>,<span class="number">0xbe</span>,<span class="number">0xad</span>,<span class="number">0xde</span>,];
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<span class="kw">let</span> <span class="ident">bar</span> <span class="op">=</span> <span class="ident">bytes</span>.<span class="ident">cread_with</span>::<span class="op"><</span><span class="ident">Bar</span><span class="op">></span>(<span class="number">0</span>, <span class="ident">LE</span>);
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<span class="comment">// Remember that you need to copy out fields from packed structs</span>
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<span class="comment">// with a `{}` block instead of borrowing them directly</span>
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<span class="comment">// ref: https://github.com/rust-lang/rust/issues/46043</span>
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<span class="macro">assert_eq</span><span class="macro">!</span>({<span class="ident">bar</span>.<span class="ident">foo</span>}, <span class="op">-</span><span class="number">1</span>);
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<span class="macro">assert_eq</span><span class="macro">!</span>({<span class="ident">bar</span>.<span class="ident">bar</span>}, <span class="number">0xdeadbeef</span>);</pre></div>
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</div>
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<h2 id='provided-methods' class='small-section-header'>Provided methods<a href='#provided-methods' class='anchor'></a></h2><div class='methods'><h3 id='method.cread_with' class='method'><code id='cread_with.v'>fn <a href='#method.cread_with' class='fnname'>cread_with</a><'a, N: <a class="trait" href="../scroll/ctx/trait.FromCtx.html" title="trait scroll::ctx::FromCtx">FromCtx</a><Ctx, Self::<a class="type" href="https://doc.rust-lang.org/nightly/core/ops/index/trait.Index.html#associatedtype.Output" title="type core::ops::index::Index::Output">Output</a>>>(<br> &'a self, <br> offset: I, <br> ctx: Ctx<br>) -> N</code></h3><div class='docblock'><p>Reads a value from <code>Self</code> at <code>offset</code> with <code>ctx</code>. Cannot fail.
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If the buffer is too small for the value requested, this will panic.</p>
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<h1 id="example-1" class="section-header"><a href="#example-1">Example</a></h1>
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<div class="example-wrap"><pre class="rust rust-example-rendered">
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<span class="kw">use</span> <span class="ident">scroll</span>::{<span class="ident">Cread</span>, <span class="ident">BE</span>, <span class="ident">LE</span>};
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<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">i64</span>::<span class="ident">MAX</span>;
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<span class="kw">let</span> <span class="ident">bytes</span> <span class="op">=</span> [<span class="number">0x7f</span>,<span class="number">0xff</span>,<span class="number">0xff</span>,<span class="number">0xff</span>,<span class="number">0xff</span>,<span class="number">0xff</span>,<span class="number">0xff</span>,<span class="number">0xff</span>, <span class="number">0xef</span>,<span class="number">0xbe</span>,<span class="number">0xad</span>,<span class="number">0xde</span>,];
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<span class="kw">let</span> <span class="ident">foo</span> <span class="op">=</span> <span class="ident">bytes</span>.<span class="ident">cread_with</span>::<span class="op"><</span><span class="ident">i64</span><span class="op">></span>(<span class="number">0</span>, <span class="ident">BE</span>);
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<span class="kw">let</span> <span class="ident">bar</span> <span class="op">=</span> <span class="ident">bytes</span>.<span class="ident">cread_with</span>::<span class="op"><</span><span class="ident">u32</span><span class="op">></span>(<span class="number">8</span>, <span class="ident">LE</span>);
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">foo</span>, <span class="ident">MAX</span>);
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">bar</span>, <span class="number">0xdeadbeef</span>);</pre></div>
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</div><h3 id='method.cread' class='method'><code id='cread.v'>fn <a href='#method.cread' class='fnname'>cread</a><'a, N: <a class="trait" href="../scroll/ctx/trait.FromCtx.html" title="trait scroll::ctx::FromCtx">FromCtx</a><Ctx, Self::<a class="type" href="https://doc.rust-lang.org/nightly/core/ops/index/trait.Index.html#associatedtype.Output" title="type core::ops::index::Index::Output">Output</a>>>(&'a self, offset: I) -> N <span class="where fmt-newline">where<br> Ctx: <a class="trait" href="https://doc.rust-lang.org/nightly/core/default/trait.Default.html" title="trait core::default::Default">Default</a>, </span></code></h3><div class='docblock'><p>Reads a value implementing <code>FromCtx</code> from <code>Self</code> at <code>offset</code>,
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with the <strong>target machine</strong>'s endianness.
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For the primitive types, this will be the <strong>target machine</strong>'s endianness.</p>
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<h1 id="example-2" class="section-header"><a href="#example-2">Example</a></h1>
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<div class="example-wrap"><pre class="rust rust-example-rendered">
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<span class="kw">use</span> <span class="ident">scroll</span>::<span class="ident">Cread</span>;
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<span class="kw">let</span> <span class="ident">bytes</span> <span class="op">=</span> [<span class="number">0x01</span>,<span class="number">0x00</span>,<span class="number">0x00</span>,<span class="number">0x00</span>,<span class="number">0x00</span>,<span class="number">0x00</span>,<span class="number">0x00</span>,<span class="number">0x00</span>, <span class="number">0xef</span>,<span class="number">0xbe</span>,<span class="number">0x00</span>,<span class="number">0x00</span>,];
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<span class="kw">let</span> <span class="ident">foo</span> <span class="op">=</span> <span class="ident">bytes</span>.<span class="ident">cread</span>::<span class="op"><</span><span class="ident">i64</span><span class="op">></span>(<span class="number">0</span>);
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<span class="kw">let</span> <span class="ident">bar</span> <span class="op">=</span> <span class="ident">bytes</span>.<span class="ident">cread</span>::<span class="op"><</span><span class="ident">u32</span><span class="op">></span>(<span class="number">8</span>);
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<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">target_endian</span> <span class="op">=</span> <span class="string">"little"</span>)]</span>
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">foo</span>, <span class="number">1</span>);
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<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">target_endian</span> <span class="op">=</span> <span class="string">"big"</span>)]</span>
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">foo</span>, <span class="number">0x100_0000_0000_0000</span>);
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<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">target_endian</span> <span class="op">=</span> <span class="string">"little"</span>)]</span>
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">bar</span>, <span class="number">0xbeef</span>);
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<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">target_endian</span> <span class="op">=</span> <span class="string">"big"</span>)]</span>
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<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">bar</span>, <span class="number">0xefbe0000</span>);</pre></div>
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</div></div><span class='loading-content'>Loading content...</span>
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<h2 id='implementors' class='small-section-header'>Implementors<a href='#implementors' class='anchor'></a></h2><div class='item-list' id='implementors-list'><h3 id='impl-Cread%3CCtx%2C%20I%3E' class='impl'><code class='in-band'>impl<Ctx: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Copy.html" title="trait core::marker::Copy">Copy</a>, I, R: ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/ops/index/trait.Index.html" title="trait core::ops::index::Index">Index</a><I> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/ops/index/trait.Index.html" title="trait core::ops::index::Index">Index</a><<a class="struct" href="https://doc.rust-lang.org/nightly/core/ops/range/struct.RangeFrom.html" title="struct core::ops::range::RangeFrom">RangeFrom</a><I>>> Cread<Ctx, I> for R</code><a href='#impl-Cread%3CCtx%2C%20I%3E' class='anchor'></a><a class='srclink' href='../src/scroll/greater.rs.html#87' title='goto source code'>[src]</a></h3><div class='impl-items'></div></div><span class='loading-content'>Loading content...</span><script type="text/javascript">window.inlined_types=new Set([]);</script><script type="text/javascript" async
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src="../implementors/scroll/trait.Cread.js">
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