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| </pre><pre class="rust"><code><span class="comment">// Copyright 2018 Developers of the Rand project.</span> |
| <span class="comment">//</span> |
| <span class="comment">// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or</span> |
| <span class="comment">// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license</span> |
| <span class="comment">// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your</span> |
| <span class="comment">// option. This file may not be copied, modified, or distributed</span> |
| <span class="comment">// except according to those terms.</span> |
| |
| <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"serde1"</span>)]</span> <span class="kw">use</span> <span class="ident">serde</span>::{<span class="ident">Serialize</span>, <span class="ident">Deserialize</span>}; |
| <span class="kw">use</span> <span class="ident">rand_core::impls::fill_bytes_via_next</span>; |
| <span class="kw">use</span> <span class="ident">rand_core::le::read_u64_into</span>; |
| <span class="kw">use</span> <span class="ident">rand_core</span>::{<span class="ident">SeedableRng</span>, <span class="ident">RngCore</span>, <span class="ident">Error</span>}; |
| |
| <span class="doccomment">/// A xoshiro256++ random number generator.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// The xoshiro256++ algorithm is not suitable for cryptographic purposes, but</span> |
| <span class="doccomment">/// is very fast and has excellent statistical properties.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// The algorithm used here is translated from [the `xoshiro256plusplus.c`</span> |
| <span class="doccomment">/// reference source code](http://xoshiro.di.unimi.it/xoshiro256plusplus.c) by</span> |
| <span class="doccomment">/// David Blackman and Sebastiano Vigna.</span> |
| <span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>, <span class="ident">Clone</span>, <span class="ident">PartialEq</span>, <span class="ident">Eq</span>)]</span> |
| <span class="attribute">#[<span class="ident">cfg_attr</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"serde1"</span>, <span class="ident">derive</span>(<span class="ident">Serialize</span>, <span class="ident">Deserialize</span>))]</span> |
| <span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Xoshiro256PlusPlus</span> { |
| <span class="ident">s</span>: [<span class="ident">u64</span>; <span class="number">4</span>], |
| } |
| |
| <span class="kw">impl</span> <span class="ident">SeedableRng</span> <span class="kw">for</span> <span class="ident">Xoshiro256PlusPlus</span> { |
| <span class="kw">type</span> <span class="ident">Seed</span> <span class="op">=</span> [<span class="ident">u8</span>; <span class="number">32</span>]; |
| |
| <span class="doccomment">/// Create a new `Xoshiro256PlusPlus`. If `seed` is entirely 0, it will be</span> |
| <span class="doccomment">/// mapped to a different seed.</span> |
| <span class="attribute">#[<span class="ident">inline</span>]</span> |
| <span class="kw">fn</span> <span class="ident">from_seed</span>(<span class="ident">seed</span>: [<span class="ident">u8</span>; <span class="number">32</span>]) -> <span class="ident">Xoshiro256PlusPlus</span> { |
| <span class="kw">if</span> <span class="ident">seed</span>.<span class="ident">iter</span>().<span class="ident">all</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">x</span><span class="op">|</span> <span class="ident">x</span> <span class="op">==</span> <span class="number">0</span>) { |
| <span class="kw">return</span> <span class="ident"><span class="self">Self</span>::seed_from_u64</span>(<span class="number">0</span>); |
| } |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">state</span> <span class="op">=</span> [<span class="number">0</span>; <span class="number">4</span>]; |
| <span class="ident">read_u64_into</span>(<span class="kw-2">&</span><span class="ident">seed</span>, <span class="kw-2">&mut</span> <span class="ident">state</span>); |
| <span class="ident">Xoshiro256PlusPlus</span> { <span class="ident">s</span>: <span class="ident">state</span> } |
| } |
| |
| <span class="doccomment">/// Create a new `Xoshiro256PlusPlus` from a `u64` seed.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// This uses the SplitMix64 generator internally.</span> |
| <span class="kw">fn</span> <span class="ident">seed_from_u64</span>(<span class="kw-2">mut</span> <span class="ident">state</span>: <span class="ident">u64</span>) -> <span class="self">Self</span> { |
| <span class="kw">const</span> <span class="ident">PHI</span>: <span class="ident">u64</span> <span class="op">=</span> <span class="number">0x9e3779b97f4a7c15</span>; |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">seed</span> <span class="op">=</span> <span class="ident"><span class="self">Self</span>::Seed::default</span>(); |
| <span class="kw">for</span> <span class="ident">chunk</span> <span class="kw">in</span> <span class="ident">seed</span>.<span class="ident">as_mut</span>().<span class="ident">chunks_mut</span>(<span class="number">8</span>) { |
| <span class="ident">state</span> <span class="op">=</span> <span class="ident">state</span>.<span class="ident">wrapping_add</span>(<span class="ident">PHI</span>); |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">z</span> <span class="op">=</span> <span class="ident">state</span>; |
| <span class="ident">z</span> <span class="op">=</span> (<span class="ident">z</span> <span class="op">^</span> (<span class="ident">z</span> <span class="op">></span><span class="op">></span> <span class="number">30</span>)).<span class="ident">wrapping_mul</span>(<span class="number">0xbf58476d1ce4e5b9</span>); |
| <span class="ident">z</span> <span class="op">=</span> (<span class="ident">z</span> <span class="op">^</span> (<span class="ident">z</span> <span class="op">></span><span class="op">></span> <span class="number">27</span>)).<span class="ident">wrapping_mul</span>(<span class="number">0x94d049bb133111eb</span>); |
| <span class="ident">z</span> <span class="op">=</span> <span class="ident">z</span> <span class="op">^</span> (<span class="ident">z</span> <span class="op">></span><span class="op">></span> <span class="number">31</span>); |
| <span class="ident">chunk</span>.<span class="ident">copy_from_slice</span>(<span class="kw-2">&</span><span class="ident">z</span>.<span class="ident">to_le_bytes</span>()); |
| } |
| <span class="ident"><span class="self">Self</span>::from_seed</span>(<span class="ident">seed</span>) |
| } |
| } |
| |
| <span class="kw">impl</span> <span class="ident">RngCore</span> <span class="kw">for</span> <span class="ident">Xoshiro256PlusPlus</span> { |
| <span class="attribute">#[<span class="ident">inline</span>]</span> |
| <span class="kw">fn</span> <span class="ident">next_u32</span>(<span class="kw-2">&mut</span> <span class="self">self</span>) -> <span class="ident">u32</span> { |
| <span class="comment">// The lowest bits have some linear dependencies, so we use the</span> |
| <span class="comment">// upper bits instead.</span> |
| (<span class="self">self</span>.<span class="ident">next_u64</span>() <span class="op">></span><span class="op">></span> <span class="number">32</span>) <span class="kw">as</span> <span class="ident">u32</span> |
| } |
| |
| <span class="attribute">#[<span class="ident">inline</span>]</span> |
| <span class="kw">fn</span> <span class="ident">next_u64</span>(<span class="kw-2">&mut</span> <span class="self">self</span>) -> <span class="ident">u64</span> { |
| <span class="kw">let</span> <span class="ident">result_plusplus</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">s</span>[<span class="number">0</span>] |
| .<span class="ident">wrapping_add</span>(<span class="self">self</span>.<span class="ident">s</span>[<span class="number">3</span>]) |
| .<span class="ident">rotate_left</span>(<span class="number">23</span>) |
| .<span class="ident">wrapping_add</span>(<span class="self">self</span>.<span class="ident">s</span>[<span class="number">0</span>]); |
| |
| <span class="kw">let</span> <span class="ident">t</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">s</span>[<span class="number">1</span>] <span class="op"><</span><span class="op"><</span> <span class="number">17</span>; |
| |
| <span class="self">self</span>.<span class="ident">s</span>[<span class="number">2</span>] <span class="op">^</span><span class="op">=</span> <span class="self">self</span>.<span class="ident">s</span>[<span class="number">0</span>]; |
| <span class="self">self</span>.<span class="ident">s</span>[<span class="number">3</span>] <span class="op">^</span><span class="op">=</span> <span class="self">self</span>.<span class="ident">s</span>[<span class="number">1</span>]; |
| <span class="self">self</span>.<span class="ident">s</span>[<span class="number">1</span>] <span class="op">^</span><span class="op">=</span> <span class="self">self</span>.<span class="ident">s</span>[<span class="number">2</span>]; |
| <span class="self">self</span>.<span class="ident">s</span>[<span class="number">0</span>] <span class="op">^</span><span class="op">=</span> <span class="self">self</span>.<span class="ident">s</span>[<span class="number">3</span>]; |
| |
| <span class="self">self</span>.<span class="ident">s</span>[<span class="number">2</span>] <span class="op">^</span><span class="op">=</span> <span class="ident">t</span>; |
| |
| <span class="self">self</span>.<span class="ident">s</span>[<span class="number">3</span>] <span class="op">=</span> <span class="self">self</span>.<span class="ident">s</span>[<span class="number">3</span>].<span class="ident">rotate_left</span>(<span class="number">45</span>); |
| |
| <span class="ident">result_plusplus</span> |
| } |
| |
| <span class="attribute">#[<span class="ident">inline</span>]</span> |
| <span class="kw">fn</span> <span class="ident">fill_bytes</span>(<span class="kw-2">&mut</span> <span class="self">self</span>, <span class="ident">dest</span>: <span class="kw-2">&mut</span> [<span class="ident">u8</span>]) { |
| <span class="ident">fill_bytes_via_next</span>(<span class="self">self</span>, <span class="ident">dest</span>); |
| } |
| |
| <span class="attribute">#[<span class="ident">inline</span>]</span> |
| <span class="kw">fn</span> <span class="ident">try_fill_bytes</span>(<span class="kw-2">&mut</span> <span class="self">self</span>, <span class="ident">dest</span>: <span class="kw-2">&mut</span> [<span class="ident">u8</span>]) -> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">Error</span><span class="op">></span> { |
| <span class="self">self</span>.<span class="ident">fill_bytes</span>(<span class="ident">dest</span>); |
| <span class="prelude-val">Ok</span>(()) |
| } |
| } |
| |
| <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span> |
| <span class="kw">mod</span> <span class="ident">tests</span> { |
| <span class="kw">use</span> <span class="kw">super</span>::<span class="kw-2">*</span>; |
| |
| <span class="attribute">#[<span class="ident">test</span>]</span> |
| <span class="kw">fn</span> <span class="ident">reference</span>() { |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">rng</span> <span class="op">=</span> <span class="ident">Xoshiro256PlusPlus::from_seed</span>( |
| [<span class="number">1</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">2</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, |
| <span class="number">3</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">4</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>]); |
| <span class="comment">// These values were produced with the reference implementation:</span> |
| <span class="comment">// http://xoshiro.di.unimi.it/xoshiro256plusplus.c</span> |
| <span class="kw">let</span> <span class="ident">expected</span> <span class="op">=</span> [ |
| <span class="number">41943041</span>, <span class="number">58720359</span>, <span class="number">3588806011781223</span>, <span class="number">3591011842654386</span>, |
| <span class="number">9228616714210784205</span>, <span class="number">9973669472204895162</span>, <span class="number">14011001112246962877</span>, |
| <span class="number">12406186145184390807</span>, <span class="number">15849039046786891736</span>, <span class="number">10450023813501588000</span>, |
| ]; |
| <span class="kw">for</span> <span class="kw-2">&</span><span class="ident">e</span> <span class="kw">in</span> <span class="kw-2">&</span><span class="ident">expected</span> { |
| <span class="macro">assert_eq!</span>(<span class="ident">rng</span>.<span class="ident">next_u64</span>(), <span class="ident">e</span>); |
| } |
| } |
| } |
| </code></pre></div> |
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