| <!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/git/checkouts/incubator-teaclave-crates-c8106113f74feefc/ede1f68/rand/src/rngs/small.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>small.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="icon" href="https://www.rust-lang.org/favicon.ico"></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="../../../rand/index.html"><div class="logo-container"> |
| <img src="https://www.rust-lang.org/logos/rust-logo-128x128-blk.png" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../rand/index.html"> |
| <img src="https://www.rust-lang.org/logos/rust-logo-128x128-blk.png" 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> |
| <span id="2">2</span> |
| <span id="3">3</span> |
| <span id="4">4</span> |
| <span id="5">5</span> |
| <span id="6">6</span> |
| <span id="7">7</span> |
| <span id="8">8</span> |
| <span id="9">9</span> |
| <span id="10">10</span> |
| <span id="11">11</span> |
| <span id="12">12</span> |
| <span id="13">13</span> |
| <span id="14">14</span> |
| <span id="15">15</span> |
| <span id="16">16</span> |
| <span id="17">17</span> |
| <span id="18">18</span> |
| <span id="19">19</span> |
| <span id="20">20</span> |
| <span id="21">21</span> |
| <span id="22">22</span> |
| <span id="23">23</span> |
| <span id="24">24</span> |
| <span id="25">25</span> |
| <span id="26">26</span> |
| <span id="27">27</span> |
| <span id="28">28</span> |
| <span id="29">29</span> |
| <span id="30">30</span> |
| <span id="31">31</span> |
| <span id="32">32</span> |
| <span id="33">33</span> |
| <span id="34">34</span> |
| <span id="35">35</span> |
| <span id="36">36</span> |
| <span id="37">37</span> |
| <span id="38">38</span> |
| <span id="39">39</span> |
| <span id="40">40</span> |
| <span id="41">41</span> |
| <span id="42">42</span> |
| <span id="43">43</span> |
| <span id="44">44</span> |
| <span id="45">45</span> |
| <span id="46">46</span> |
| <span id="47">47</span> |
| <span id="48">48</span> |
| <span id="49">49</span> |
| <span id="50">50</span> |
| <span id="51">51</span> |
| <span id="52">52</span> |
| <span id="53">53</span> |
| <span id="54">54</span> |
| <span id="55">55</span> |
| <span id="56">56</span> |
| <span id="57">57</span> |
| <span id="58">58</span> |
| <span id="59">59</span> |
| <span id="60">60</span> |
| <span id="61">61</span> |
| <span id="62">62</span> |
| <span id="63">63</span> |
| <span id="64">64</span> |
| <span id="65">65</span> |
| <span id="66">66</span> |
| <span id="67">67</span> |
| <span id="68">68</span> |
| <span id="69">69</span> |
| <span id="70">70</span> |
| <span id="71">71</span> |
| <span id="72">72</span> |
| <span id="73">73</span> |
| <span id="74">74</span> |
| <span id="75">75</span> |
| <span id="76">76</span> |
| <span id="77">77</span> |
| <span id="78">78</span> |
| <span id="79">79</span> |
| <span id="80">80</span> |
| <span id="81">81</span> |
| <span id="82">82</span> |
| <span id="83">83</span> |
| <span id="84">84</span> |
| <span id="85">85</span> |
| <span id="86">86</span> |
| <span id="87">87</span> |
| <span id="88">88</span> |
| <span id="89">89</span> |
| <span id="90">90</span> |
| <span id="91">91</span> |
| <span id="92">92</span> |
| <span id="93">93</span> |
| <span id="94">94</span> |
| <span id="95">95</span> |
| <span id="96">96</span> |
| <span id="97">97</span> |
| <span id="98">98</span> |
| <span id="99">99</span> |
| <span id="100">100</span> |
| <span id="101">101</span> |
| <span id="102">102</span> |
| <span id="103">103</span> |
| <span id="104">104</span> |
| <span id="105">105</span> |
| <span id="106">106</span> |
| <span id="107">107</span> |
| <span id="108">108</span> |
| <span id="109">109</span> |
| <span id="110">110</span> |
| <span id="111">111</span> |
| <span id="112">112</span> |
| <span id="113">113</span> |
| <span id="114">114</span> |
| <span id="115">115</span> |
| <span id="116">116</span> |
| <span id="117">117</span> |
| </pre><pre class="rust"><code><span class="comment">// Copyright 2018 Developers of the Rand project. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // https://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| </span><span class="doccomment">//! A small fast RNG |
| |
| </span><span class="kw">use </span>rand_core::{Error, RngCore, SeedableRng}; |
| |
| <span class="attribute">#[cfg(target_pointer_width = <span class="string">"64"</span>)] |
| </span><span class="kw">type </span>Rng = <span class="kw">super</span>::xoshiro256plusplus::Xoshiro256PlusPlus; |
| <span class="attribute">#[cfg(not(target_pointer_width = <span class="string">"64"</span>))] |
| </span><span class="kw">type </span>Rng = <span class="kw">super</span>::xoshiro128plusplus::Xoshiro128PlusPlus; |
| |
| <span class="doccomment">/// A small-state, fast non-crypto PRNG |
| /// |
| /// `SmallRng` may be a good choice when a PRNG with small state, cheap |
| /// initialization, good statistical quality and good performance are required. |
| /// Note that depending on the application, [`StdRng`] may be faster on many |
| /// modern platforms while providing higher-quality randomness. Furthermore, |
| /// `SmallRng` is **not** a good choice when: |
| /// - Security against prediction is important. Use [`StdRng`] instead. |
| /// - Seeds with many zeros are provided. In such cases, it takes `SmallRng` |
| /// about 10 samples to produce 0 and 1 bits with equal probability. Either |
| /// provide seeds with an approximately equal number of 0 and 1 (for example |
| /// by using [`SeedableRng::from_entropy`] or [`SeedableRng::seed_from_u64`]), |
| /// or use [`StdRng`] instead. |
| /// |
| /// The algorithm is deterministic but should not be considered reproducible |
| /// due to dependence on platform and possible replacement in future |
| /// library versions. For a reproducible generator, use a named PRNG from an |
| /// external crate, e.g. [rand_xoshiro] or [rand_chacha]. |
| /// Refer also to [The Book](https://rust-random.github.io/book/guide-rngs.html). |
| /// |
| /// The PRNG algorithm in `SmallRng` is chosen to be efficient on the current |
| /// platform, without consideration for cryptography or security. The size of |
| /// its state is much smaller than [`StdRng`]. The current algorithm is |
| /// `Xoshiro256PlusPlus` on 64-bit platforms and `Xoshiro128PlusPlus` on 32-bit |
| /// platforms. Both are also implemented by the [rand_xoshiro] crate. |
| /// |
| /// # Examples |
| /// |
| /// Initializing `SmallRng` with a random seed can be done using [`SeedableRng::from_entropy`]: |
| /// |
| /// ``` |
| /// use rand::{Rng, SeedableRng}; |
| /// use rand::rngs::SmallRng; |
| /// |
| /// // Create small, cheap to initialize and fast RNG with a random seed. |
| /// // The randomness is supplied by the operating system. |
| /// let mut small_rng = SmallRng::from_entropy(); |
| /// # let v: u32 = small_rng.gen(); |
| /// ``` |
| /// |
| /// When initializing a lot of `SmallRng`'s, using [`thread_rng`] can be more |
| /// efficient: |
| /// |
| /// ``` |
| /// use rand::{SeedableRng, thread_rng}; |
| /// use rand::rngs::SmallRng; |
| /// |
| /// // Create a big, expensive to initialize and slower, but unpredictable RNG. |
| /// // This is cached and done only once per thread. |
| /// let mut thread_rng = thread_rng(); |
| /// // Create small, cheap to initialize and fast RNGs with random seeds. |
| /// // One can generally assume this won't fail. |
| /// let rngs: Vec<SmallRng> = (0..10) |
| /// .map(|_| SmallRng::from_rng(&mut thread_rng).unwrap()) |
| /// .collect(); |
| /// ``` |
| /// |
| /// [`StdRng`]: crate::rngs::StdRng |
| /// [`thread_rng`]: crate::thread_rng |
| /// [rand_chacha]: https://crates.io/crates/rand_chacha |
| /// [rand_xoshiro]: https://crates.io/crates/rand_xoshiro |
| </span><span class="attribute">#[cfg_attr(doc_cfg, doc(cfg(feature = <span class="string">"small_rng"</span>)))] |
| #[derive(Clone, Debug, PartialEq, Eq)] |
| </span><span class="kw">pub struct </span>SmallRng(Rng); |
| |
| <span class="kw">impl </span>RngCore <span class="kw">for </span>SmallRng { |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>next_u32(<span class="kw-2">&mut </span><span class="self">self</span>) -> u32 { |
| <span class="self">self</span>.<span class="number">0</span>.next_u32() |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>next_u64(<span class="kw-2">&mut </span><span class="self">self</span>) -> u64 { |
| <span class="self">self</span>.<span class="number">0</span>.next_u64() |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>fill_bytes(<span class="kw-2">&mut </span><span class="self">self</span>, dest: <span class="kw-2">&mut </span>[u8]) { |
| <span class="self">self</span>.<span class="number">0</span>.fill_bytes(dest); |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>try_fill_bytes(<span class="kw-2">&mut </span><span class="self">self</span>, dest: <span class="kw-2">&mut </span>[u8]) -> <span class="prelude-ty">Result</span><(), Error> { |
| <span class="self">self</span>.<span class="number">0</span>.try_fill_bytes(dest) |
| } |
| } |
| |
| <span class="kw">impl </span>SeedableRng <span class="kw">for </span>SmallRng { |
| <span class="kw">type </span>Seed = <Rng <span class="kw">as </span>SeedableRng>::Seed; |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>from_seed(seed: <span class="self">Self</span>::Seed) -> <span class="self">Self </span>{ |
| SmallRng(Rng::from_seed(seed)) |
| } |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>from_rng<R: RngCore>(rng: R) -> <span class="prelude-ty">Result</span><<span class="self">Self</span>, Error> { |
| Rng::from_rng(rng).map(SmallRng) |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="rand" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |