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| <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" class="section-header"><a href="#example">Example</a></h2> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use</span> <span class="ident">rand_core</span>::{<span class="ident">RngCore</span>, <span class="ident">SeedableRng</span>}; |
| <span class="kw">use</span> <span class="ident">rand_core::block</span>::{<span class="ident">BlockRngCore</span>, <span class="ident">BlockRng</span>}; |
| |
| <span class="kw">struct</span> <span class="ident">MyRngCore</span>; |
| |
| <span class="kw">impl</span> <span class="ident">BlockRngCore</span> <span class="kw">for</span> <span class="ident">MyRngCore</span> { |
| <span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">u32</span>; |
| <span class="kw">type</span> <span class="ident">Results</span> <span class="op">=</span> [<span class="ident">u32</span>; <span class="number">16</span>]; |
| |
| <span class="kw">fn</span> <span class="ident">generate</span>(<span class="kw-2">&mut</span> <span class="self">self</span>, <span class="ident">results</span>: <span class="kw-2">&mut</span> <span class="ident"><span class="self">Self</span>::Results</span>) { |
| <span class="macro">unimplemented!</span>() |
| } |
| } |
| |
| <span class="kw">impl</span> <span class="ident">SeedableRng</span> <span class="kw">for</span> <span class="ident">MyRngCore</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="kw">fn</span> <span class="ident">from_seed</span>(<span class="ident">seed</span>: <span class="ident"><span class="self">Self</span>::Seed</span>) -> <span class="self">Self</span> { |
| <span class="macro">unimplemented!</span>() |
| } |
| } |
| |
| <span class="comment">// optionally, also implement CryptoRng for MyRngCore</span> |
| |
| <span class="comment">// Final RNG.</span> |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">rng</span> <span class="op">=</span> <span class="ident">BlockRng</span>::<span class="op"><</span><span class="ident">MyRngCore</span><span class="op">></span><span class="ident">::seed_from_u64</span>(<span class="number">0</span>); |
| <span class="macro">println!</span>(<span class="string">"First value: {}"</span>, <span class="ident">rng</span>.<span class="ident">next_u32</span>());</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"><p>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.</p> |
| </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"><p>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.</p> |
| </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"><p>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.</p> |
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