<!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 to the Rust file `/Users/travis/.cargo/registry/src/github.com-1ecc6299db9ec823/rand_core-0.2.1/src/block.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>block.rs.html -- source</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><link rel="shortcut icon" href="https://www.rust-lang.org/favicon.ico"></head><body class="rustdoc source"><!--[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='../../rand_core/index.html'><img src='https://www.rust-lang.org/logos/rust-logo-128x128-blk.png' alt='logo' width='100'></a></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"><input class="search-input" name="search" autocomplete="off" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><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"><pre class="line-numbers"><span id="1"> 1</span>
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</pre><pre class="rust ">
<span class="comment">// Copyright 2018 The Rust Project Developers. See the COPYRIGHT</span>
<span class="comment">// file at the top-level directory of this distribution and at</span>
<span class="comment">// https://rust-lang.org/COPYRIGHT.</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="doccomment">//! The `BlockRngCore` trait and implementation helpers</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! The [`BlockRngCore`] trait exists to assist in the implementation of RNGs</span>
<span class="doccomment">//! which generate a block of data in a cache instead of returning generated</span>
<span class="doccomment">//! values directly.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Usage of this trait is optional, but provides two advantages:</span>
<span class="doccomment">//! implementations only need to concern themselves with generation of the</span>
<span class="doccomment">//! block, not the various [`RngCore`] methods (especially [`fill_bytes`], where</span>
<span class="doccomment">//! the optimal implementations are not trivial), and this allows</span>
<span class="doccomment">//! [`ReseedingRng`] perform periodic reseeding with very low overhead.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! # Example</span>
<span class="doccomment">//! </span>
<span class="doccomment">//! ```norun</span>
<span class="doccomment">//! use rand_core::block::{BlockRngCore, BlockRng};</span>
<span class="doccomment">//! </span>
<span class="doccomment">//! struct MyRngCore;</span>
<span class="doccomment">//! </span>
<span class="doccomment">//! impl BlockRngCore for MyRngCore {</span>
<span class="doccomment">//! type Results = [u32; 16];</span>
<span class="doccomment">//! </span>
<span class="doccomment">//! fn generate(&mut self, results: &mut Self::Results) {</span>
<span class="doccomment">//! unimplemented!()</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! </span>
<span class="doccomment">//! impl SeedableRng for MyRngCore {</span>
<span class="doccomment">//! type Seed = unimplemented!();</span>
<span class="doccomment">//! fn from_seed(seed: Self::Seed) -> Self {</span>
<span class="doccomment">//! unimplemented!()</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! </span>
<span class="doccomment">//! // optionally, also implement CryptoRng for MyRngCore</span>
<span class="doccomment">//! </span>
<span class="doccomment">//! // Final RNG.</span>
<span class="doccomment">//! type MyRng = BlockRng<u32, MyRngCore>;</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//! </span>
<span class="doccomment">//! [`BlockRngCore`]: trait.BlockRngCore.html</span>
<span class="doccomment">//! [`RngCore`]: ../trait.RngCore.html</span>
<span class="doccomment">//! [`fill_bytes`]: ../trait.RngCore.html#tymethod.fill_bytes</span>
<span class="doccomment">//! [`ReseedingRng`]: ../../rand/rngs/adapter/struct.ReseedingRng.html</span>
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">convert</span>::<span class="ident">AsRef</span>;
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">fmt</span>;
<span class="kw">use</span> {<span class="ident">RngCore</span>, <span class="ident">CryptoRng</span>, <span class="ident">SeedableRng</span>, <span class="ident">Error</span>};
<span class="kw">use</span> <span class="ident">impls</span>::{<span class="ident">fill_via_u32_chunks</span>, <span class="ident">fill_via_u64_chunks</span>};
<span class="doccomment">/// A trait for RNGs which do not generate random numbers individually, but in</span>
<span class="doccomment">/// blocks (typically `[u32; N]`). This technique is commonly used by</span>
<span class="doccomment">/// cryptographic RNGs to improve performance.</span>
<span class="doccomment">/// </span>
<span class="doccomment">/// See the [module documentation](index.html) for details.</span>
<span class="kw">pub</span> <span class="kw">trait</span> <span class="ident">BlockRngCore</span> {
<span class="doccomment">/// Results element type, e.g. `u32`.</span>
<span class="kw">type</span> <span class="ident">Item</span>;
<span class="doccomment">/// Results type. This is the 'block' an RNG implementing `BlockRngCore`</span>
<span class="doccomment">/// generates, which will usually be an array like `[u32; 16]`.</span>
<span class="kw">type</span> <span class="ident">Results</span>: <span class="ident">AsRef</span><span class="op"><</span>[<span class="self">Self</span>::<span class="ident">Item</span>]<span class="op">></span> <span class="op">+</span> <span class="ident">AsMut</span><span class="op"><</span>[<span class="self">Self</span>::<span class="ident">Item</span>]<span class="op">></span> <span class="op">+</span> <span class="ident">Default</span>;
<span class="doccomment">/// Generate a new block of results.</span>
<span class="kw">fn</span> <span class="ident">generate</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">results</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">Self</span>::<span class="ident">Results</span>);
}
<span class="doccomment">/// A wrapper type implementing [`RngCore`] for some type implementing</span>
<span class="doccomment">/// [`BlockRngCore`] with `u32` array buffer; i.e. this can be used to implement</span>
<span class="doccomment">/// a full RNG from just a `generate` function.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The `core` field may be accessed directly but the results buffer may not.</span>
<span class="doccomment">/// PRNG implementations can simply use a type alias</span>
<span class="doccomment">/// (`pub type MyRng = BlockRng<MyRngCore>;`) but might prefer to use a</span>
<span class="doccomment">/// wrapper type (`pub struct MyRng(BlockRng<MyRngCore>);`); the latter must</span>
<span class="doccomment">/// re-implement `RngCore` but hides the implementation details and allows</span>
<span class="doccomment">/// extra functionality to be defined on the RNG</span>
<span class="doccomment">/// (e.g. `impl MyRng { fn set_stream(...){...} }`).</span>
<span class="doccomment">///</span>
<span class="doccomment">/// `BlockRng` has heavily optimized implementations of the [`RngCore`] methods</span>
<span class="doccomment">/// reading values from the results buffer, as well as</span>
<span class="doccomment">/// calling [`BlockRngCore::generate`] directly on the output array when</span>
<span class="doccomment">/// [`fill_bytes`] / [`try_fill_bytes`] is called on a large array. These methods</span>
<span class="doccomment">/// also handle the bookkeeping of when to generate a new batch of values.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// No whole generated `u32` values are thown away and all values are consumed</span>
<span class="doccomment">/// in-order. [`next_u32`] simply takes the next available `u32` value.</span>
<span class="doccomment">/// [`next_u64`] is implemented by combining two `u32` values, least</span>
<span class="doccomment">/// significant first. [`fill_bytes`] and [`try_fill_bytes`] consume a whole</span>
<span class="doccomment">/// number of `u32` values, converting each `u32` to a byte slice in</span>
<span class="doccomment">/// little-endian order. If the requested byte length is not a multiple of 4,</span>
<span class="doccomment">/// some bytes will be discarded.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// See also [`BlockRng64`] which uses `u64` array buffers. Currently there is</span>
<span class="doccomment">/// no direct support for other buffer types.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// For easy initialization `BlockRng` also implements [`SeedableRng`].</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`BlockRngCore`]: BlockRngCore.t.html</span>
<span class="doccomment">/// [`BlockRngCore::generate`]: trait.BlockRngCore.html#tymethod.generate</span>
<span class="doccomment">/// [`BlockRng64`]: struct.BlockRng64.html</span>
<span class="doccomment">/// [`RngCore`]: ../RngCore.t.html</span>
<span class="doccomment">/// [`next_u32`]: ../trait.RngCore.html#tymethod.next_u32</span>
<span class="doccomment">/// [`next_u64`]: ../trait.RngCore.html#tymethod.next_u64</span>
<span class="doccomment">/// [`fill_bytes`]: ../trait.RngCore.html#tymethod.fill_bytes</span>
<span class="doccomment">/// [`try_fill_bytes`]: ../trait.RngCore.html#tymethod.try_fill_bytes</span>
<span class="doccomment">/// [`SeedableRng`]: ../SeedableRng.t.html</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</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">BlockRng</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">BlockRngCore</span> <span class="op">+</span> <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> {
<span class="ident">results</span>: <span class="ident">R</span>::<span class="ident">Results</span>,
<span class="ident">index</span>: <span class="ident">usize</span>,
<span class="doccomment">/// The *core* part of the RNG, implementing the `generate` function.</span>
<span class="kw">pub</span> <span class="ident">core</span>: <span class="ident">R</span>,
}
<span class="comment">// Custom Debug implementation that does not expose the contents of `results`.</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">BlockRngCore</span> <span class="op">+</span> <span class="ident">fmt</span>::<span class="ident">Debug</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">BlockRng</span><span class="op"><</span><span class="ident">R</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">fmt</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">fmt</span>.<span class="ident">debug_struct</span>(<span class="string">"BlockRng"</span>)
.<span class="ident">field</span>(<span class="string">"core"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">core</span>)
.<span class="ident">field</span>(<span class="string">"result_len"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>())
.<span class="ident">field</span>(<span class="string">"index"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">index</span>)
.<span class="ident">finish</span>()
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">BlockRngCore</span><span class="op">></span> <span class="ident">BlockRng</span><span class="op"><</span><span class="ident">R</span><span class="op">></span> {
<span class="doccomment">/// Create a new `BlockRng` from an existing RNG implementing</span>
<span class="doccomment">/// `BlockRngCore`. Results will be generated on first use.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">core</span>: <span class="ident">R</span>) <span class="op">-></span> <span class="ident">BlockRng</span><span class="op"><</span><span class="ident">R</span><span class="op">></span>{
<span class="kw">let</span> <span class="ident">results_empty</span> <span class="op">=</span> <span class="ident">R</span>::<span class="ident">Results</span>::<span class="ident">default</span>();
<span class="ident">BlockRng</span> {
<span class="ident">core</span>,
<span class="ident">index</span>: <span class="ident">results_empty</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>(),
<span class="ident">results</span>: <span class="ident">results_empty</span>,
}
}
<span class="doccomment">/// Get the index into the result buffer.</span>
<span class="doccomment">/// </span>
<span class="doccomment">/// If this is equal to or larger than the size of the result buffer then</span>
<span class="doccomment">/// the buffer is "empty" and `generate()` must be called to produce new</span>
<span class="doccomment">/// results.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">index</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="self">self</span>.<span class="ident">index</span>
}
<span class="doccomment">/// Reset the number of available results.</span>
<span class="doccomment">/// This will force a new set of results to be generated on next use.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">reset</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="self">self</span>.<span class="ident">index</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>();
}
<span class="doccomment">/// Generate a new set of results immediately, setting the index to the</span>
<span class="doccomment">/// given value.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">generate_and_set</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">index</span>: <span class="ident">usize</span>) {
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">index</span> <span class="op"><</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>());
<span class="self">self</span>.<span class="ident">core</span>.<span class="ident">generate</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">results</span>);
<span class="self">self</span>.<span class="ident">index</span> <span class="op">=</span> <span class="ident">index</span>;
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">BlockRngCore</span><span class="op"><</span><span class="ident">Item</span><span class="op">=</span><span class="ident">u32</span><span class="op">>></span> <span class="ident">RngCore</span> <span class="kw">for</span> <span class="ident">BlockRng</span><span class="op"><</span><span class="ident">R</span><span class="op">></span>
<span class="kw">where</span> <span class="op"><</span><span class="ident">R</span> <span class="kw">as</span> <span class="ident">BlockRngCore</span><span class="op">></span>::<span class="ident">Results</span>: <span class="ident">AsRef</span><span class="op"><</span>[<span class="ident">u32</span>]<span class="op">></span> <span class="op">+</span> <span class="ident">AsMut</span><span class="op"><</span>[<span class="ident">u32</span>]<span class="op">></span>
{
<span class="attribute">#[<span class="ident">inline</span>(<span class="ident">always</span>)]</span>
<span class="kw">fn</span> <span class="ident">next_u32</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">u32</span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">index</span> <span class="op">>=</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>() {
<span class="self">self</span>.<span class="ident">generate_and_set</span>(<span class="number">0</span>);
}
<span class="kw">let</span> <span class="ident">value</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>()[<span class="self">self</span>.<span class="ident">index</span>];
<span class="self">self</span>.<span class="ident">index</span> <span class="op">+=</span> <span class="number">1</span>;
<span class="ident">value</span>
}
<span class="attribute">#[<span class="ident">inline</span>(<span class="ident">always</span>)]</span>
<span class="kw">fn</span> <span class="ident">next_u64</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">u64</span> {
<span class="kw">let</span> <span class="ident">read_u64</span> <span class="op">=</span> <span class="op">|</span><span class="ident">results</span>: <span class="kw-2">&</span>[<span class="ident">u32</span>], <span class="ident">index</span><span class="op">|</span> {
<span class="kw">if</span> <span class="macro">cfg</span><span class="macro">!</span>(<span class="ident">any</span>(<span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"x86"</span>, <span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"x86_64"</span>)) {
<span class="comment">// requires little-endian CPU supporting unaligned reads:</span>
<span class="kw">unsafe</span> { <span class="kw-2">*</span>(<span class="kw-2">&</span><span class="ident">results</span>[<span class="ident">index</span>] <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">u32</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">u64</span>) }
} <span class="kw">else</span> {
<span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="ident">u64</span>::<span class="ident">from</span>(<span class="ident">results</span>[<span class="ident">index</span>]);
<span class="kw">let</span> <span class="ident">y</span> <span class="op">=</span> <span class="ident">u64</span>::<span class="ident">from</span>(<span class="ident">results</span>[<span class="ident">index</span> <span class="op">+</span> <span class="number">1</span>]);
(<span class="ident">y</span> <span class="op"><<</span> <span class="number">32</span>) <span class="op">|</span> <span class="ident">x</span>
}
};
<span class="kw">let</span> <span class="ident">len</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>();
<span class="kw">let</span> <span class="ident">index</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">index</span>;
<span class="kw">if</span> <span class="ident">index</span> <span class="op"><</span> <span class="ident">len</span><span class="op">-</span><span class="number">1</span> {
<span class="self">self</span>.<span class="ident">index</span> <span class="op">+=</span> <span class="number">2</span>;
<span class="comment">// Read an u64 from the current index</span>
<span class="ident">read_u64</span>(<span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>(), <span class="ident">index</span>)
} <span class="kw">else</span> <span class="kw">if</span> <span class="ident">index</span> <span class="op">>=</span> <span class="ident">len</span> {
<span class="self">self</span>.<span class="ident">generate_and_set</span>(<span class="number">2</span>);
<span class="ident">read_u64</span>(<span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>(), <span class="number">0</span>)
} <span class="kw">else</span> {
<span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="ident">u64</span>::<span class="ident">from</span>(<span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>()[<span class="ident">len</span><span class="op">-</span><span class="number">1</span>]);
<span class="self">self</span>.<span class="ident">generate_and_set</span>(<span class="number">1</span>);
<span class="kw">let</span> <span class="ident">y</span> <span class="op">=</span> <span class="ident">u64</span>::<span class="ident">from</span>(<span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>()[<span class="number">0</span>]);
(<span class="ident">y</span> <span class="op"><<</span> <span class="number">32</span>) <span class="op">|</span> <span class="ident">x</span>
}
}
<span class="comment">// As an optimization we try to write directly into the output buffer.</span>
<span class="comment">// This is only enabled for little-endian platforms where unaligned writes</span>
<span class="comment">// are known to be safe and fast.</span>
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">any</span>(<span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"x86"</span>, <span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"x86_64"</span>))]</span>
<span class="kw">fn</span> <span class="ident">fill_bytes</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">dest</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">u8</span>]) {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">filled</span> <span class="op">=</span> <span class="number">0</span>;
<span class="comment">// Continue filling from the current set of results</span>
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">index</span> <span class="op"><</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>() {
<span class="kw">let</span> (<span class="ident">consumed_u32</span>, <span class="ident">filled_u8</span>) <span class="op">=</span>
<span class="ident">fill_via_u32_chunks</span>(<span class="kw-2">&</span><span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>()[<span class="self">self</span>.<span class="ident">index</span>..],
<span class="ident">dest</span>);
<span class="self">self</span>.<span class="ident">index</span> <span class="op">+=</span> <span class="ident">consumed_u32</span>;
<span class="ident">filled</span> <span class="op">+=</span> <span class="ident">filled_u8</span>;
}
<span class="kw">let</span> <span class="ident">len_remainder</span> <span class="op">=</span>
(<span class="ident">dest</span>.<span class="ident">len</span>() <span class="op">-</span> <span class="ident">filled</span>) <span class="op">%</span> (<span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>() <span class="op">*</span> <span class="number">4</span>);
<span class="kw">let</span> <span class="ident">end_direct</span> <span class="op">=</span> <span class="ident">dest</span>.<span class="ident">len</span>() <span class="op">-</span> <span class="ident">len_remainder</span>;
<span class="kw">while</span> <span class="ident">filled</span> <span class="op"><</span> <span class="ident">end_direct</span> {
<span class="kw">let</span> <span class="ident">dest_u32</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">R</span>::<span class="ident">Results</span> <span class="op">=</span> <span class="kw">unsafe</span> {
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="kw-2">*</span>(<span class="ident">dest</span>[<span class="ident">filled</span>..].<span class="ident">as_mut_ptr</span>() <span class="kw">as</span>
<span class="kw-2">*</span><span class="kw-2">mut</span> <span class="op"><</span><span class="ident">R</span> <span class="kw">as</span> <span class="ident">BlockRngCore</span><span class="op">></span>::<span class="ident">Results</span>)
};
<span class="self">self</span>.<span class="ident">core</span>.<span class="ident">generate</span>(<span class="ident">dest_u32</span>);
<span class="ident">filled</span> <span class="op">+=</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>() <span class="op">*</span> <span class="number">4</span>;
<span class="self">self</span>.<span class="ident">index</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>();
}
<span class="kw">if</span> <span class="ident">len_remainder</span> <span class="op">></span> <span class="number">0</span> {
<span class="self">self</span>.<span class="ident">core</span>.<span class="ident">generate</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">results</span>);
<span class="kw">let</span> (<span class="ident">consumed_u32</span>, <span class="kw">_</span>) <span class="op">=</span>
<span class="ident">fill_via_u32_chunks</span>(<span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>(),
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">dest</span>[<span class="ident">filled</span>..]);
<span class="self">self</span>.<span class="ident">index</span> <span class="op">=</span> <span class="ident">consumed_u32</span>;
}
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">not</span>(<span class="ident">any</span>(<span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"x86"</span>, <span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"x86_64"</span>)))]</span>
<span class="kw">fn</span> <span class="ident">fill_bytes</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">dest</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">u8</span>]) {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">read_len</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">while</span> <span class="ident">read_len</span> <span class="op"><</span> <span class="ident">dest</span>.<span class="ident">len</span>() {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">index</span> <span class="op">>=</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>() {
<span class="self">self</span>.<span class="ident">generate_and_set</span>(<span class="number">0</span>);
}
<span class="kw">let</span> (<span class="ident">consumed_u32</span>, <span class="ident">filled_u8</span>) <span class="op">=</span>
<span class="ident">fill_via_u32_chunks</span>(<span class="kw-2">&</span><span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>()[<span class="self">self</span>.<span class="ident">index</span>..],
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">dest</span>[<span class="ident">read_len</span>..]);
<span class="self">self</span>.<span class="ident">index</span> <span class="op">+=</span> <span class="ident">consumed_u32</span>;
<span class="ident">read_len</span> <span class="op">+=</span> <span class="ident">filled_u8</span>;
}
}
<span class="kw">fn</span> <span class="ident">try_fill_bytes</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">dest</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">u8</span>]) <span class="op">-></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="kw">impl</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">BlockRngCore</span> <span class="op">+</span> <span class="ident">SeedableRng</span><span class="op">></span> <span class="ident">SeedableRng</span> <span class="kw">for</span> <span class="ident">BlockRng</span><span class="op"><</span><span class="ident">R</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">Seed</span> <span class="op">=</span> <span class="ident">R</span>::<span class="ident">Seed</span>;
<span class="kw">fn</span> <span class="ident">from_seed</span>(<span class="ident">seed</span>: <span class="self">Self</span>::<span class="ident">Seed</span>) <span class="op">-></span> <span class="self">Self</span> {
<span class="self">Self</span>::<span class="ident">new</span>(<span class="ident">R</span>::<span class="ident">from_seed</span>(<span class="ident">seed</span>))
}
<span class="kw">fn</span> <span class="ident">from_rng</span><span class="op"><</span><span class="ident">S</span>: <span class="ident">RngCore</span><span class="op">></span>(<span class="ident">rng</span>: <span class="ident">S</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="self">Self</span>, <span class="ident">Error</span><span class="op">></span> {
<span class="prelude-val">Ok</span>(<span class="self">Self</span>::<span class="ident">new</span>(<span class="ident">R</span>::<span class="ident">from_rng</span>(<span class="ident">rng</span>)<span class="question-mark">?</span>))
}
}
<span class="doccomment">/// A wrapper type implementing [`RngCore`] for some type implementing</span>
<span class="doccomment">/// [`BlockRngCore`] with `u64` array buffer; i.e. this can be used to implement</span>
<span class="doccomment">/// a full RNG from just a `generate` function.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This is similar to [`BlockRng`], but specialized for algorithms that operate</span>
<span class="doccomment">/// on `u64` values.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// No whole generated `u64` values are thrown away and all values are consumed</span>
<span class="doccomment">/// in-order. [`next_u64`] simply takes the next available `u64` value.</span>
<span class="doccomment">/// [`next_u32`] is however a bit special: half of a `u64` is consumed, leaving</span>
<span class="doccomment">/// the other half in the buffer. If the next function called is [`next_u32`]</span>
<span class="doccomment">/// then the other half is then consumed, however both [`next_u64`] and</span>
<span class="doccomment">/// [`fill_bytes`] discard the rest of any half-consumed `u64`s when called.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`fill_bytes`] and [`try_fill_bytes`] consume a whole number of `u64`</span>
<span class="doccomment">/// values. If the requested length is not a multiple of 8, some bytes will be</span>
<span class="doccomment">/// discarded.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`BlockRngCore`]: BlockRngCore.t.html</span>
<span class="doccomment">/// [`RngCore`]: ../RngCore.t.html</span>
<span class="doccomment">/// [`next_u32`]: ../trait.RngCore.html#tymethod.next_u32</span>
<span class="doccomment">/// [`next_u64`]: ../trait.RngCore.html#tymethod.next_u64</span>
<span class="doccomment">/// [`fill_bytes`]: ../trait.RngCore.html#tymethod.fill_bytes</span>
<span class="doccomment">/// [`try_fill_bytes`]: ../trait.RngCore.html#tymethod.try_fill_bytes</span>
<span class="doccomment">/// [`BlockRng`]: struct.BlockRng.html</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</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">BlockRng64</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">BlockRngCore</span> <span class="op">+</span> <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> {
<span class="ident">results</span>: <span class="ident">R</span>::<span class="ident">Results</span>,
<span class="ident">index</span>: <span class="ident">usize</span>,
<span class="ident">half_used</span>: <span class="ident">bool</span>, <span class="comment">// true if only half of the previous result is used</span>
<span class="doccomment">/// The *core* part of the RNG, implementing the `generate` function.</span>
<span class="kw">pub</span> <span class="ident">core</span>: <span class="ident">R</span>,
}
<span class="comment">// Custom Debug implementation that does not expose the contents of `results`.</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">BlockRngCore</span> <span class="op">+</span> <span class="ident">fmt</span>::<span class="ident">Debug</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">BlockRng64</span><span class="op"><</span><span class="ident">R</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">fmt</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">fmt</span>.<span class="ident">debug_struct</span>(<span class="string">"BlockRng64"</span>)
.<span class="ident">field</span>(<span class="string">"core"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">core</span>)
.<span class="ident">field</span>(<span class="string">"result_len"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>())
.<span class="ident">field</span>(<span class="string">"index"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">index</span>)
.<span class="ident">field</span>(<span class="string">"half_used"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">half_used</span>)
.<span class="ident">finish</span>()
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">BlockRngCore</span><span class="op">></span> <span class="ident">BlockRng64</span><span class="op"><</span><span class="ident">R</span><span class="op">></span> {
<span class="doccomment">/// Create a new `BlockRng` from an existing RNG implementing</span>
<span class="doccomment">/// `BlockRngCore`. Results will be generated on first use.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">core</span>: <span class="ident">R</span>) <span class="op">-></span> <span class="ident">BlockRng64</span><span class="op"><</span><span class="ident">R</span><span class="op">></span>{
<span class="kw">let</span> <span class="ident">results_empty</span> <span class="op">=</span> <span class="ident">R</span>::<span class="ident">Results</span>::<span class="ident">default</span>();
<span class="ident">BlockRng64</span> {
<span class="ident">core</span>,
<span class="ident">index</span>: <span class="ident">results_empty</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>(),
<span class="ident">half_used</span>: <span class="bool-val">false</span>,
<span class="ident">results</span>: <span class="ident">results_empty</span>,
}
}
<span class="doccomment">/// Get the index into the result buffer.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// If this is equal to or larger than the size of the result buffer then</span>
<span class="doccomment">/// the buffer is "empty" and `generate()` must be called to produce new</span>
<span class="doccomment">/// results.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">index</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="self">self</span>.<span class="ident">index</span>
}
<span class="doccomment">/// Reset the number of available results.</span>
<span class="doccomment">/// This will force a new set of results to be generated on next use.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">reset</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="self">self</span>.<span class="ident">index</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>();
<span class="self">self</span>.<span class="ident">half_used</span> <span class="op">=</span> <span class="bool-val">false</span>;
}
<span class="doccomment">/// Generate a new set of results immediately, setting the index to the</span>
<span class="doccomment">/// given value.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">generate_and_set</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">index</span>: <span class="ident">usize</span>) {
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">index</span> <span class="op"><</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>());
<span class="self">self</span>.<span class="ident">core</span>.<span class="ident">generate</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">results</span>);
<span class="self">self</span>.<span class="ident">index</span> <span class="op">=</span> <span class="ident">index</span>;
<span class="self">self</span>.<span class="ident">half_used</span> <span class="op">=</span> <span class="bool-val">false</span>;
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">BlockRngCore</span><span class="op"><</span><span class="ident">Item</span><span class="op">=</span><span class="ident">u64</span><span class="op">>></span> <span class="ident">RngCore</span> <span class="kw">for</span> <span class="ident">BlockRng64</span><span class="op"><</span><span class="ident">R</span><span class="op">></span>
<span class="kw">where</span> <span class="op"><</span><span class="ident">R</span> <span class="kw">as</span> <span class="ident">BlockRngCore</span><span class="op">></span>::<span class="ident">Results</span>: <span class="ident">AsRef</span><span class="op"><</span>[<span class="ident">u64</span>]<span class="op">></span> <span class="op">+</span> <span class="ident">AsMut</span><span class="op"><</span>[<span class="ident">u64</span>]<span class="op">></span>
{
<span class="attribute">#[<span class="ident">inline</span>(<span class="ident">always</span>)]</span>
<span class="kw">fn</span> <span class="ident">next_u32</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">u32</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">index</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">index</span> <span class="op">*</span> <span class="number">2</span> <span class="op">-</span> <span class="self">self</span>.<span class="ident">half_used</span> <span class="kw">as</span> <span class="ident">usize</span>;
<span class="kw">if</span> <span class="ident">index</span> <span class="op">>=</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>() <span class="op">*</span> <span class="number">2</span> {
<span class="self">self</span>.<span class="ident">core</span>.<span class="ident">generate</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">results</span>);
<span class="self">self</span>.<span class="ident">index</span> <span class="op">=</span> <span class="number">0</span>;
<span class="comment">// `self.half_used` is by definition `false`</span>
<span class="self">self</span>.<span class="ident">half_used</span> <span class="op">=</span> <span class="bool-val">false</span>;
<span class="ident">index</span> <span class="op">=</span> <span class="number">0</span>;
}
<span class="self">self</span>.<span class="ident">half_used</span> <span class="op">=</span> <span class="op">!</span><span class="self">self</span>.<span class="ident">half_used</span>;
<span class="self">self</span>.<span class="ident">index</span> <span class="op">+=</span> <span class="self">self</span>.<span class="ident">half_used</span> <span class="kw">as</span> <span class="ident">usize</span>;
<span class="comment">// Index as if this is a u32 slice.</span>
<span class="kw">unsafe</span> {
<span class="kw">let</span> <span class="ident">results</span> <span class="op">=</span>
<span class="kw-2">&</span><span class="kw-2">*</span>(<span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>() <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> [<span class="ident">u64</span>] <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> [<span class="ident">u32</span>]);
<span class="kw">if</span> <span class="macro">cfg</span><span class="macro">!</span>(<span class="ident">target_endian</span> <span class="op">=</span> <span class="string">"little"</span>) {
<span class="kw-2">*</span><span class="ident">results</span>.<span class="ident">get_unchecked</span>(<span class="ident">index</span>)
} <span class="kw">else</span> {
<span class="kw-2">*</span><span class="ident">results</span>.<span class="ident">get_unchecked</span>(<span class="ident">index</span> <span class="op">^</span> <span class="number">1</span>)
}
}
}
<span class="attribute">#[<span class="ident">inline</span>(<span class="ident">always</span>)]</span>
<span class="kw">fn</span> <span class="ident">next_u64</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">u64</span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">index</span> <span class="op">>=</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>() {
<span class="self">self</span>.<span class="ident">core</span>.<span class="ident">generate</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">results</span>);
<span class="self">self</span>.<span class="ident">index</span> <span class="op">=</span> <span class="number">0</span>;
}
<span class="kw">let</span> <span class="ident">value</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>()[<span class="self">self</span>.<span class="ident">index</span>];
<span class="self">self</span>.<span class="ident">index</span> <span class="op">+=</span> <span class="number">1</span>;
<span class="self">self</span>.<span class="ident">half_used</span> <span class="op">=</span> <span class="bool-val">false</span>;
<span class="ident">value</span>
}
<span class="comment">// As an optimization we try to write directly into the output buffer.</span>
<span class="comment">// This is only enabled for little-endian platforms where unaligned writes</span>
<span class="comment">// are known to be safe and fast.</span>
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">any</span>(<span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"x86"</span>, <span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"x86_64"</span>))]</span>
<span class="kw">fn</span> <span class="ident">fill_bytes</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">dest</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">u8</span>]) {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">filled</span> <span class="op">=</span> <span class="number">0</span>;
<span class="self">self</span>.<span class="ident">half_used</span> <span class="op">=</span> <span class="bool-val">false</span>;
<span class="comment">// Continue filling from the current set of results</span>
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">index</span> <span class="op"><</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>() {
<span class="kw">let</span> (<span class="ident">consumed_u64</span>, <span class="ident">filled_u8</span>) <span class="op">=</span>
<span class="ident">fill_via_u64_chunks</span>(<span class="kw-2">&</span><span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>()[<span class="self">self</span>.<span class="ident">index</span>..],
<span class="ident">dest</span>);
<span class="self">self</span>.<span class="ident">index</span> <span class="op">+=</span> <span class="ident">consumed_u64</span>;
<span class="ident">filled</span> <span class="op">+=</span> <span class="ident">filled_u8</span>;
}
<span class="kw">let</span> <span class="ident">len_remainder</span> <span class="op">=</span>
(<span class="ident">dest</span>.<span class="ident">len</span>() <span class="op">-</span> <span class="ident">filled</span>) <span class="op">%</span> (<span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>() <span class="op">*</span> <span class="number">8</span>);
<span class="kw">let</span> <span class="ident">end_direct</span> <span class="op">=</span> <span class="ident">dest</span>.<span class="ident">len</span>() <span class="op">-</span> <span class="ident">len_remainder</span>;
<span class="kw">while</span> <span class="ident">filled</span> <span class="op"><</span> <span class="ident">end_direct</span> {
<span class="kw">let</span> <span class="ident">dest_u64</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">R</span>::<span class="ident">Results</span> <span class="op">=</span> <span class="kw">unsafe</span> {
::<span class="ident">core</span>::<span class="ident">mem</span>::<span class="ident">transmute</span>(<span class="ident">dest</span>[<span class="ident">filled</span>..].<span class="ident">as_mut_ptr</span>())
};
<span class="self">self</span>.<span class="ident">core</span>.<span class="ident">generate</span>(<span class="ident">dest_u64</span>);
<span class="ident">filled</span> <span class="op">+=</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>() <span class="op">*</span> <span class="number">8</span>;
<span class="self">self</span>.<span class="ident">index</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>();
}
<span class="kw">if</span> <span class="ident">len_remainder</span> <span class="op">></span> <span class="number">0</span> {
<span class="self">self</span>.<span class="ident">core</span>.<span class="ident">generate</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">results</span>);
<span class="kw">let</span> (<span class="ident">consumed_u64</span>, <span class="kw">_</span>) <span class="op">=</span>
<span class="ident">fill_via_u64_chunks</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>(),
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">dest</span>[<span class="ident">filled</span>..]);
<span class="self">self</span>.<span class="ident">index</span> <span class="op">=</span> <span class="ident">consumed_u64</span>;
}
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">not</span>(<span class="ident">any</span>(<span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"x86"</span>, <span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"x86_64"</span>)))]</span>
<span class="kw">fn</span> <span class="ident">fill_bytes</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">dest</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">u8</span>]) {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">read_len</span> <span class="op">=</span> <span class="number">0</span>;
<span class="self">self</span>.<span class="ident">half_used</span> <span class="op">=</span> <span class="bool-val">false</span>;
<span class="kw">while</span> <span class="ident">read_len</span> <span class="op"><</span> <span class="ident">dest</span>.<span class="ident">len</span>() {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">index</span> <span class="kw">as</span> <span class="ident">usize</span> <span class="op">>=</span> <span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>().<span class="ident">len</span>() {
<span class="self">self</span>.<span class="ident">core</span>.<span class="ident">generate</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">results</span>);
<span class="self">self</span>.<span class="ident">index</span> <span class="op">=</span> <span class="number">0</span>;
}
<span class="kw">let</span> (<span class="ident">consumed_u64</span>, <span class="ident">filled_u8</span>) <span class="op">=</span>
<span class="ident">fill_via_u64_chunks</span>(<span class="kw-2">&</span><span class="self">self</span>.<span class="ident">results</span>.<span class="ident">as_ref</span>()[<span class="self">self</span>.<span class="ident">index</span> <span class="kw">as</span> <span class="ident">usize</span>..],
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">dest</span>[<span class="ident">read_len</span>..]);
<span class="self">self</span>.<span class="ident">index</span> <span class="op">+=</span> <span class="ident">consumed_u64</span>;
<span class="ident">read_len</span> <span class="op">+=</span> <span class="ident">filled_u8</span>;
}
}
<span class="kw">fn</span> <span class="ident">try_fill_bytes</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">dest</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">u8</span>]) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">Error</span><span class="op">></span> {
<span class="prelude-val">Ok</span>(<span class="self">self</span>.<span class="ident">fill_bytes</span>(<span class="ident">dest</span>))
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">BlockRngCore</span> <span class="op">+</span> <span class="ident">SeedableRng</span><span class="op">></span> <span class="ident">SeedableRng</span> <span class="kw">for</span> <span class="ident">BlockRng64</span><span class="op"><</span><span class="ident">R</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">Seed</span> <span class="op">=</span> <span class="ident">R</span>::<span class="ident">Seed</span>;
<span class="kw">fn</span> <span class="ident">from_seed</span>(<span class="ident">seed</span>: <span class="self">Self</span>::<span class="ident">Seed</span>) <span class="op">-></span> <span class="self">Self</span> {
<span class="self">Self</span>::<span class="ident">new</span>(<span class="ident">R</span>::<span class="ident">from_seed</span>(<span class="ident">seed</span>))
}
<span class="kw">fn</span> <span class="ident">from_rng</span><span class="op"><</span><span class="ident">S</span>: <span class="ident">RngCore</span><span class="op">></span>(<span class="ident">rng</span>: <span class="ident">S</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="self">Self</span>, <span class="ident">Error</span><span class="op">></span> {
<span class="prelude-val">Ok</span>(<span class="self">Self</span>::<span class="ident">new</span>(<span class="ident">R</span>::<span class="ident">from_rng</span>(<span class="ident">rng</span>)<span class="question-mark">?</span>))
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">BlockRngCore</span> <span class="op">+</span> <span class="ident">CryptoRng</span><span class="op">></span> <span class="ident">CryptoRng</span> <span class="kw">for</span> <span class="ident">BlockRng</span><span class="op"><</span><span class="ident">R</span><span class="op">></span> {}
</pre>
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