| <!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="The `BlockRngCore` trait and implementation helpers"><meta name="keywords" content="rust, rustlang, rust-lang, block"><title>rand_core::block - Rust</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="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="icon" href="https://www.rust-lang.org/favicon.ico"></head><body class="rustdoc mod"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle">☰</button><a class="sidebar-logo" href="../../rand_core/index.html"><div class="logo-container"><img src="https://www.rust-lang.org/logos/rust-logo-128x128-blk.png" alt="logo"></div></a><h2></h2></nav><nav class="sidebar"><a class="sidebar-logo" href="../../rand_core/index.html"><div class="logo-container"> |
| <img src="https://www.rust-lang.org/logos/rust-logo-128x128-blk.png" alt="logo"></div></a><h2 class="location"><a href="#">Module block</a></h2><div class="sidebar-elems"><section><ul class="block"><li><a href="#structs">Structs</a></li><li><a href="#traits">Traits</a></li></ul></section></div></nav><main><div class="width-limiter"><nav class="sub"><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="main-heading"><h1 class="fqn">Module <a href="../index.html">rand_core</a>::<wbr><a class="mod" href="#">block</a><button id="copy-path" onclick="copy_path(this)" title="Copy item path to clipboard"><img src="../../clipboard.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="srclink" href="../../src/rand_core/block.rs.html#9-539">source</a> · <a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span></div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>The <code>BlockRngCore</code> trait and implementation helpers</p> |
| <p>The <a href="trait.BlockRngCore.html"><code>BlockRngCore</code></a> trait exists to assist in the implementation of RNGs |
| which generate a block of data in a cache instead of returning generated |
| values directly.</p> |
| <p>Usage of this trait is optional, but provides two advantages: |
| implementations only need to concern themselves with generation of the |
| block, not the various <a href="../trait.RngCore.html" title="RngCore"><code>RngCore</code></a> methods (especially <a href="../trait.RngCore.html#tymethod.fill_bytes"><code>fill_bytes</code></a>, where |
| the optimal implementations are not trivial), and this allows |
| <code>ReseedingRng</code> (see <a href="https://docs.rs/rand"><code>rand</code></a> crate) perform periodic |
| reseeding with very low overhead.</p> |
| <h2 id="example"><a href="#example">Example</a></h2> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>rand_core::{RngCore, SeedableRng}; |
| <span class="kw">use </span>rand_core::block::{BlockRngCore, BlockRng}; |
| |
| <span class="kw">struct </span>MyRngCore; |
| |
| <span class="kw">impl </span>BlockRngCore <span class="kw">for </span>MyRngCore { |
| <span class="kw">type </span>Item = u32; |
| <span class="kw">type </span>Results = [u32; <span class="number">16</span>]; |
| |
| <span class="kw">fn </span>generate(<span class="kw-2">&mut </span><span class="self">self</span>, results: <span class="kw-2">&mut </span><span class="self">Self</span>::Results) { |
| <span class="macro">unimplemented!</span>() |
| } |
| } |
| |
| <span class="kw">impl </span>SeedableRng <span class="kw">for </span>MyRngCore { |
| <span class="kw">type </span>Seed = [u8; <span class="number">32</span>]; |
| <span class="kw">fn </span>from_seed(seed: <span class="self">Self</span>::Seed) -> <span class="self">Self </span>{ |
| <span class="macro">unimplemented!</span>() |
| } |
| } |
| |
| <span class="comment">// optionally, also implement CryptoRng for MyRngCore |
| |
| // Final RNG. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>rng = BlockRng::<MyRngCore>::seed_from_u64(<span class="number">0</span>); |
| <span class="macro">println!</span>(<span class="string">"First value: {}"</span>, rng.next_u32());</code></pre></div> |
| </div></details><h2 id="structs" class="small-section-header"><a href="#structs">Structs</a></h2><div class="item-table"><div class="item-row"><div class="item-left module-item"><a class="struct" href="struct.BlockRng.html" title="rand_core::block::BlockRng struct">BlockRng</a></div><div class="item-right docblock-short">A wrapper type implementing <a href="../trait.RngCore.html" title="RngCore"><code>RngCore</code></a> for some type implementing |
| <a href="trait.BlockRngCore.html" title="BlockRngCore"><code>BlockRngCore</code></a> with <code>u32</code> array buffer; i.e. this can be used to implement |
| a full RNG from just a <code>generate</code> function.</div></div><div class="item-row"><div class="item-left module-item"><a class="struct" href="struct.BlockRng64.html" title="rand_core::block::BlockRng64 struct">BlockRng64</a></div><div class="item-right docblock-short">A wrapper type implementing <a href="../trait.RngCore.html" title="RngCore"><code>RngCore</code></a> for some type implementing |
| <a href="trait.BlockRngCore.html" title="BlockRngCore"><code>BlockRngCore</code></a> with <code>u64</code> array buffer; i.e. this can be used to implement |
| a full RNG from just a <code>generate</code> function.</div></div></div><h2 id="traits" class="small-section-header"><a href="#traits">Traits</a></h2><div class="item-table"><div class="item-row"><div class="item-left module-item"><a class="trait" href="trait.BlockRngCore.html" title="rand_core::block::BlockRngCore trait">BlockRngCore</a></div><div class="item-right docblock-short">A trait for RNGs which do not generate random numbers individually, but in |
| blocks (typically <code>[u32; N]</code>). This technique is commonly used by |
| cryptographic RNGs to improve performance.</div></div></div></section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="rand_core" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
