<!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 `/home/sangenya/.cargo/registry/src/github.com-1ecc6299db9ec823/deflate-0.7.20/src/bit_reverse.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>bit_reverse.rs - 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="../../light.css" id="themeStyle"><link rel="stylesheet" type="text/css" href="../../dark.css" disabled ><link rel="stylesheet" type="text/css" href="../../ayu.css" disabled ><script id="default-settings"></script><script src="../../storage.js"></script><script src="../../crates.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="icon" type="image/svg+xml" href="../../favicon.svg">
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</pre><pre class="rust">
<span class="doccomment">/// Reverse the first length bits of n.</span>
<span class="doccomment">/// (Passing more than 16 as length will produce garbage.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">reverse_bits</span>(<span class="kw-2">mut</span> <span class="ident">n</span>: <span class="ident">u16</span>, <span class="ident">length</span>: <span class="ident">u8</span>) <span class="op">-</span><span class="op">></span> <span class="ident">u16</span> {
<span class="macro">debug_assert!</span>(<span class="ident">length</span> <span class="op"><</span><span class="op">=</span> <span class="number">16</span>);
<span class="comment">// Borrowed from http://aggregate.org/MAGIC/#Bit%20Reversal</span>
<span class="ident">n</span> <span class="op">=</span> ((<span class="ident">n</span> <span class="op">&</span> <span class="number">0xaaaa</span>) <span class="op">></span><span class="op">></span> <span class="number">1</span>) <span class="op">|</span> ((<span class="ident">n</span> <span class="op">&</span> <span class="number">0x5555</span>) <span class="op"><</span><span class="op"><</span> <span class="number">1</span>);
<span class="ident">n</span> <span class="op">=</span> ((<span class="ident">n</span> <span class="op">&</span> <span class="number">0xcccc</span>) <span class="op">></span><span class="op">></span> <span class="number">2</span>) <span class="op">|</span> ((<span class="ident">n</span> <span class="op">&</span> <span class="number">0x3333</span>) <span class="op"><</span><span class="op"><</span> <span class="number">2</span>);
<span class="ident">n</span> <span class="op">=</span> ((<span class="ident">n</span> <span class="op">&</span> <span class="number">0xf0f0</span>) <span class="op">></span><span class="op">></span> <span class="number">4</span>) <span class="op">|</span> ((<span class="ident">n</span> <span class="op">&</span> <span class="number">0x0f0f</span>) <span class="op"><</span><span class="op"><</span> <span class="number">4</span>);
<span class="ident">n</span> <span class="op">=</span> ((<span class="ident">n</span> <span class="op">&</span> <span class="number">0xff00</span>) <span class="op">></span><span class="op">></span> <span class="number">8</span>) <span class="op">|</span> ((<span class="ident">n</span> <span class="op">&</span> <span class="number">0x00ff</span>) <span class="op"><</span><span class="op"><</span> <span class="number">8</span>);
<span class="ident">n</span> <span class="op">></span><span class="op">></span> (<span class="number">16</span> <span class="op">-</span> <span class="ident">length</span>)
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span>
<span class="kw">mod</span> <span class="ident">test</span> {
<span class="kw">use</span> <span class="kw">super</span><span class="ident">::reverse_bits</span>;
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_bit_reverse</span>() {
<span class="macro">assert_eq!</span>(<span class="ident">reverse_bits</span>(<span class="number">0b0111_0100</span>, <span class="number">8</span>), <span class="number">0b0010_1110</span>);
<span class="macro">assert_eq!</span>(
<span class="ident">reverse_bits</span>(<span class="number">0b1100_1100_1100_1100</span>, <span class="number">16</span>),
<span class="number">0b0011_0011_0011_0011</span>
);
<span class="comment">// Check that we ignore >16 length</span>
<span class="comment">// We no longer check for this.</span>
<span class="comment">// assert_eq!(reverse_bits(0b11001100_11001100, 32), 0b0011001100110011);</span>
}
}
</pre></div>
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