<!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/stored_block.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>stored_block.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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<span class="kw">use</span> <span class="ident">std::io::Write</span>;
<span class="kw">use</span> <span class="ident">std::io</span>;
<span class="kw">use</span> <span class="ident">std::u16</span>;
<span class="kw">use</span> <span class="ident">bitstream::LsbWriter</span>;
<span class="kw">use</span> <span class="ident">byteorder</span>::{<span class="ident">LittleEndian</span>, <span class="ident">WriteBytesExt</span>};
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span>
<span class="kw">const</span> <span class="ident">BLOCK_SIZE</span>: <span class="ident">u16</span> <span class="op">=</span> <span class="number">32000</span>;
<span class="kw">const</span> <span class="ident">STORED_FIRST_BYTE</span>: <span class="ident">u8</span> <span class="op">=</span> <span class="number">0b0000_0000</span>;
<span class="kw">pub</span> <span class="kw">const</span> <span class="ident">STORED_FIRST_BYTE_FINAL</span>: <span class="ident">u8</span> <span class="op">=</span> <span class="number">0b0000_0001</span>;
<span class="kw">pub</span> <span class="kw">const</span> <span class="ident">MAX_STORED_BLOCK_LENGTH</span>: <span class="ident">usize</span> <span class="op">=</span> (<span class="ident">u16::MAX</span> <span class="kw">as</span> <span class="ident">usize</span>) <span class="op">/</span> <span class="number">2</span>;
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">write_stored_header</span>(<span class="ident">writer</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">LsbWriter</span>, <span class="ident">final_block</span>: <span class="ident">bool</span>) {
<span class="kw">let</span> <span class="ident">header</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">final_block</span> {
<span class="ident">STORED_FIRST_BYTE_FINAL</span>
} <span class="kw">else</span> {
<span class="ident">STORED_FIRST_BYTE</span>
};
<span class="comment">// Write the block header</span>
<span class="ident">writer</span>.<span class="ident">write_bits</span>(<span class="ident">header</span>.<span class="ident">into</span>(), <span class="number">3</span>);
<span class="comment">// Flush the writer to make sure we are aligned to the byte boundary.</span>
<span class="ident">writer</span>.<span class="ident">flush_raw</span>();
}
<span class="comment">// Compress one stored block (excluding the header)</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">compress_block_stored</span><span class="op"><</span><span class="ident">W</span>: <span class="ident">Write</span><span class="op">></span>(<span class="ident">input</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>], <span class="ident">writer</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">W</span>) <span class="op">-</span><span class="op">></span> <span class="ident">io::Result</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span> {
<span class="kw">if</span> <span class="ident">input</span>.<span class="ident">len</span>() <span class="op">></span> <span class="ident">u16::max_value</span>() <span class="kw">as</span> <span class="ident">usize</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">io::Error::new</span>(
<span class="ident">io::ErrorKind::InvalidInput</span>,
<span class="string">"Stored block too long!"</span>,
));
};
<span class="comment">// The header is written before this function.</span>
<span class="comment">// The next two bytes indicates the length</span>
<span class="ident">writer</span>.<span class="ident">write_u16</span>::<span class="op"><</span><span class="ident">LittleEndian</span><span class="op">></span>(<span class="ident">input</span>.<span class="ident">len</span>() <span class="kw">as</span> <span class="ident">u16</span>)<span class="question-mark">?</span>;
<span class="comment">// the next two after the length is the ones complement of the length</span>
<span class="ident">writer</span>.<span class="ident">write_u16</span>::<span class="op"><</span><span class="ident">LittleEndian</span><span class="op">></span>(<span class="op">!</span><span class="ident">input</span>.<span class="ident">len</span>() <span class="kw">as</span> <span class="ident">u16</span>)<span class="question-mark">?</span>;
<span class="comment">// After this the data is written directly with no compression</span>
<span class="ident">writer</span>.<span class="ident">write</span>(<span class="ident">input</span>)
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">compress_data_stored</span>(<span class="ident">input</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>]) <span class="op">-</span><span class="op">></span> <span class="ident">Vec</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">block_length</span> <span class="op">=</span> <span class="ident">BLOCK_SIZE</span> <span class="kw">as</span> <span class="ident">usize</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">output</span> <span class="op">=</span> <span class="ident">Vec::with_capacity</span>(<span class="ident">input</span>.<span class="ident">len</span>() <span class="op">+</span> <span class="number">2</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">i</span> <span class="op">=</span> <span class="ident">input</span>.<span class="ident">chunks</span>(<span class="ident">block_length</span>).<span class="ident">peekable</span>();
<span class="kw">while</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">chunk</span>) <span class="op">=</span> <span class="ident">i</span>.<span class="ident">next</span>() {
<span class="kw">let</span> <span class="ident">last_chunk</span> <span class="op">=</span> <span class="ident">i</span>.<span class="ident">peek</span>().<span class="ident">is_none</span>();
<span class="comment">// First bit tells us if this is the final chunk</span>
<span class="comment">// the next two details compression type (none in this case)</span>
<span class="kw">let</span> <span class="ident">first_byte</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">last_chunk</span> {
<span class="ident">STORED_FIRST_BYTE_FINAL</span>
} <span class="kw">else</span> {
<span class="ident">STORED_FIRST_BYTE</span>
};
<span class="ident">output</span>.<span class="ident">write</span>(<span class="kw-2">&</span>[<span class="ident">first_byte</span>]).<span class="ident">unwrap</span>();
<span class="ident">compress_block_stored</span>(<span class="ident">chunk</span>, <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">output</span>).<span class="ident">unwrap</span>();
}
<span class="ident">output</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="kw-2">*</span>;
<span class="kw">use</span> <span class="ident">test_utils::decompress_to_end</span>;
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">no_compression_one_chunk</span>() {
<span class="kw">let</span> <span class="ident">test_data</span> <span class="op">=</span> <span class="macro">vec!</span>[<span class="number">1u8</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>, <span class="number">6</span>, <span class="number">7</span>, <span class="number">8</span>];
<span class="kw">let</span> <span class="ident">compressed</span> <span class="op">=</span> <span class="ident">compress_data_stored</span>(<span class="kw-2">&</span><span class="ident">test_data</span>);
<span class="kw">let</span> <span class="ident">result</span> <span class="op">=</span> <span class="ident">decompress_to_end</span>(<span class="kw-2">&</span><span class="ident">compressed</span>);
<span class="macro">assert_eq!</span>(<span class="ident">test_data</span>, <span class="ident">result</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">no_compression_multiple_chunks</span>() {
<span class="kw">let</span> <span class="ident">test_data</span> <span class="op">=</span> <span class="macro">vec!</span>[<span class="number">32u8</span>; <span class="number">40000</span>];
<span class="kw">let</span> <span class="ident">compressed</span> <span class="op">=</span> <span class="ident">compress_data_stored</span>(<span class="kw-2">&</span><span class="ident">test_data</span>);
<span class="kw">let</span> <span class="ident">result</span> <span class="op">=</span> <span class="ident">decompress_to_end</span>(<span class="kw-2">&</span><span class="ident">compressed</span>);
<span class="macro">assert_eq!</span>(<span class="ident">test_data</span>, <span class="ident">result</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">no_compression_string</span>() {
<span class="kw">let</span> <span class="ident">test_data</span> <span class="op">=</span> <span class="ident">String::from</span>(
<span class="string">"This is some text, this is some more text, this is even \
more text, lots of text here."</span>,
).<span class="ident">into_bytes</span>();
<span class="kw">let</span> <span class="ident">compressed</span> <span class="op">=</span> <span class="ident">compress_data_stored</span>(<span class="kw-2">&</span><span class="ident">test_data</span>);
<span class="kw">let</span> <span class="ident">result</span> <span class="op">=</span> <span class="ident">decompress_to_end</span>(<span class="kw-2">&</span><span class="ident">compressed</span>);
<span class="macro">assert_eq!</span>(<span class="ident">test_data</span>, <span class="ident">result</span>);
}
}
</pre></div>
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