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</pre><pre class="rust">
<span class="doccomment">//! This module contains functionality for doing lz77 compression of data.</span>
<span class="attribute">#![<span class="ident">macro_use</span>]</span>
<span class="kw">use</span> <span class="ident">std::cmp</span>;
<span class="kw">use</span> <span class="ident">std::ops</span>::{<span class="ident">Range</span>, <span class="ident">RangeFrom</span>};
<span class="kw">use</span> <span class="ident">std::iter</span>::{<span class="self">self</span>, <span class="ident">Iterator</span>};
<span class="kw">use</span> <span class="ident">std::slice::Iter</span>;
<span class="kw">use</span> <span class="ident">std::fmt</span>;
<span class="kw">use</span> <span class="ident">input_buffer::InputBuffer</span>;
<span class="kw">use</span> <span class="ident">matching::longest_match</span>;
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span>
<span class="kw">use</span> <span class="ident">lzvalue</span>::{<span class="ident">LZValue</span>, <span class="ident">LZType</span>};
<span class="kw">use</span> <span class="ident">huffman_table</span>;
<span class="kw">use</span> <span class="ident">chained_hash_table</span>::{<span class="ident">ChainedHashTable</span>, <span class="ident">update_hash</span>};
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span>
<span class="kw">use</span> <span class="ident">compression_options</span>::{<span class="ident">HIGH_MAX_HASH_CHECKS</span>, <span class="ident">HIGH_LAZY_IF_LESS_THAN</span>};
<span class="kw">use</span> <span class="ident">output_writer</span>::{<span class="ident">BufferStatus</span>, <span class="ident">DynamicWriter</span>};
<span class="kw">use</span> <span class="ident">compress::Flush</span>;
<span class="kw">use</span> <span class="ident">rle::process_chunk_greedy_rle</span>;
<span class="kw">const</span> <span class="ident">MAX_MATCH</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="ident">huffman_table::MAX_MATCH</span> <span class="kw">as</span> <span class="ident">usize</span>;
<span class="kw">const</span> <span class="ident">MIN_MATCH</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="ident">huffman_table::MIN_MATCH</span> <span class="kw">as</span> <span class="ident">usize</span>;
<span class="kw">const</span> <span class="ident">NO_RLE</span>: <span class="ident">u16</span> <span class="op">=</span> <span class="number">43212</span>;
<span class="doccomment">/// An enum describing whether we use lazy or greedy matching.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Copy</span>, <span class="ident">Debug</span>, <span class="ident">Eq</span>, <span class="ident">PartialEq</span>, <span class="ident">Ord</span>, <span class="ident">PartialOrd</span>, <span class="ident">Hash</span>)]</span>
<span class="kw">pub</span> <span class="kw">enum</span> <span class="ident">MatchingType</span> {
<span class="doccomment">/// Use greedy matching: the matching algorithm simply uses a match right away</span>
<span class="doccomment">/// if found.</span>
<span class="ident">Greedy</span>,
<span class="doccomment">/// Use lazy matching: after finding a match, the next input byte is checked, to see</span>
<span class="doccomment">/// if there is a better match starting at that byte.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// As a special case, if max_hash_checks is set to 0, compression using only run-length</span>
<span class="doccomment">/// (i.e maximum match distance of 1) is performed instead.</span>
<span class="ident">Lazy</span>,
}
<span class="kw">impl</span> <span class="ident">fmt::Display</span> <span class="kw">for</span> <span class="ident">MatchingType</span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt::Formatter</span>) <span class="op">-</span><span class="op">></span> <span class="ident">fmt::Result</span> {
<span class="kw">match</span> <span class="kw-2">*</span><span class="self">self</span> {
<span class="ident">MatchingType::Greedy</span> <span class="op">=</span><span class="op">></span> <span class="macro">write!</span>(<span class="ident">f</span>, <span class="string">"Greedy matching"</span>),
<span class="ident">MatchingType::Lazy</span> <span class="op">=</span><span class="op">></span> <span class="macro">write!</span>(<span class="ident">f</span>, <span class="string">"Lazy matching"</span>),
}
}
}
<span class="doccomment">/// A struct that contains the hash table, and keeps track of where we are in the input data</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">LZ77State</span> {
<span class="doccomment">/// Struct containing hash chains that will be used to find matches.</span>
<span class="ident">hash_table</span>: <span class="ident">ChainedHashTable</span>,
<span class="doccomment">/// True if this is the first window that is being processed.</span>
<span class="ident">is_first_window</span>: <span class="ident">bool</span>,
<span class="doccomment">/// Set to true when the last block has been processed.</span>
<span class="ident">is_last_block</span>: <span class="ident">bool</span>,
<span class="doccomment">/// How many bytes the last match in the previous window extended into the current one.</span>
<span class="ident">overlap</span>: <span class="ident">usize</span>,
<span class="doccomment">/// How many bytes of input the current block contains.</span>
<span class="ident">current_block_input_bytes</span>: <span class="ident">u64</span>,
<span class="doccomment">/// The maximum number of hash entries to search.</span>
<span class="ident">max_hash_checks</span>: <span class="ident">u16</span>,
<span class="doccomment">/// Only lazy match if we have a match length less than this.</span>
<span class="ident">lazy_if_less_than</span>: <span class="ident">u16</span>,
<span class="doccomment">/// Whether to use greedy or lazy parsing</span>
<span class="ident">matching_type</span>: <span class="ident">MatchingType</span>,
<span class="doccomment">/// Keep track of the previous match and byte in case the buffer is full when lazy matching.</span>
<span class="ident">match_state</span>: <span class="ident">ChunkState</span>,
<span class="doccomment">/// Keep track of how many bytes in the lookahead that was part of a match, but has not been</span>
<span class="doccomment">/// added to the hash chain yet.</span>
<span class="ident">bytes_to_hash</span>: <span class="ident">usize</span>,
<span class="doccomment">/// Keep track of if sync flush was used. If this is the case, the two first bytes needs to be</span>
<span class="doccomment">/// hashed.</span>
<span class="ident">was_synced</span>: <span class="ident">bool</span>,
}
<span class="kw">impl</span> <span class="ident">LZ77State</span> {
<span class="doccomment">/// Creates a new LZ77 state</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>(
<span class="ident">max_hash_checks</span>: <span class="ident">u16</span>,
<span class="ident">lazy_if_less_than</span>: <span class="ident">u16</span>,
<span class="ident">matching_type</span>: <span class="ident">MatchingType</span>,
) <span class="op">-</span><span class="op">></span> <span class="ident">LZ77State</span> {
<span class="ident">LZ77State</span> {
<span class="ident">hash_table</span>: <span class="ident">ChainedHashTable::new</span>(),
<span class="ident">is_first_window</span>: <span class="bool-val">true</span>,
<span class="ident">is_last_block</span>: <span class="bool-val">false</span>,
<span class="ident">overlap</span>: <span class="number">0</span>,
<span class="ident">current_block_input_bytes</span>: <span class="number">0</span>,
<span class="ident">max_hash_checks</span>: <span class="ident">max_hash_checks</span>,
<span class="ident">lazy_if_less_than</span>: <span class="ident">lazy_if_less_than</span>,
<span class="ident">matching_type</span>: <span class="ident">matching_type</span>,
<span class="ident">match_state</span>: <span class="ident">ChunkState::new</span>(),
<span class="ident">bytes_to_hash</span>: <span class="number">0</span>,
<span class="ident">was_synced</span>: <span class="bool-val">false</span>,
}
}
<span class="doccomment">/// Resets the state excluding max_hash_checks and lazy_if_less_than</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">hash_table</span>.<span class="ident">reset</span>();
<span class="self">self</span>.<span class="ident">is_first_window</span> <span class="op">=</span> <span class="bool-val">true</span>;
<span class="self">self</span>.<span class="ident">is_last_block</span> <span class="op">=</span> <span class="bool-val">false</span>;
<span class="self">self</span>.<span class="ident">overlap</span> <span class="op">=</span> <span class="number">0</span>;
<span class="self">self</span>.<span class="ident">current_block_input_bytes</span> <span class="op">=</span> <span class="number">0</span>;
<span class="self">self</span>.<span class="ident">match_state</span> <span class="op">=</span> <span class="ident">ChunkState::new</span>();
<span class="self">self</span>.<span class="ident">bytes_to_hash</span> <span class="op">=</span> <span class="number">0</span>
}
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">set_last</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">is_last_block</span> <span class="op">=</span> <span class="bool-val">true</span>;
}
<span class="doccomment">/// Is this the last block we are outputting?</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">is_last_block</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">bool</span> {
<span class="self">self</span>.<span class="ident">is_last_block</span>
}
<span class="doccomment">/// How many bytes of input the current block contains.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">current_block_input_bytes</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">u64</span> {
<span class="self">self</span>.<span class="ident">current_block_input_bytes</span>
}
<span class="doccomment">/// Sets the number of input bytes for the current block to 0.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">reset_input_bytes</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">current_block_input_bytes</span> <span class="op">=</span> <span class="number">0</span>;
}
<span class="doccomment">/// Is there a buffered byte that has not been output yet?</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">pending_byte</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">bool</span> {
<span class="self">self</span>.<span class="ident">match_state</span>.<span class="ident">add</span>
}
<span class="doccomment">/// Returns 1 if pending_byte is true, 0 otherwise.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">pending_byte_as_num</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">usize</span> {
<span class="comment">// This could be implemented by using `as usize` as the documentation states this would give</span>
<span class="comment">// the same result, but not sure if that should be relied upon.</span>
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">match_state</span>.<span class="ident">add</span> {
<span class="number">1</span>
} <span class="kw">else</span> {
<span class="number">0</span>
}
}
}
<span class="kw">const</span> <span class="ident">DEFAULT_WINDOW_SIZE</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="number">32768</span>;
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="doccomment">/// Status after calling `process_chunk`.</span>
<span class="kw">pub</span> <span class="kw">enum</span> <span class="ident">ProcessStatus</span> {
<span class="doccomment">/// All the input data was processed.</span>
<span class="prelude-val">Ok</span>,
<span class="doccomment">/// The output buffer was full.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The argument is the position of the next byte to be checked by `process_chunk`.</span>
<span class="ident">BufferFull</span>(<span class="ident">usize</span>),
}
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="doccomment">/// A struct to keep track of status between calls of `process_chunk_lazy`</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This is needed as the output buffer might become full before having output all pending data.</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">ChunkState</span> {
<span class="doccomment">/// Length of the last match that was found, if any.</span>
<span class="ident">current_length</span>: <span class="ident">u16</span>,
<span class="doccomment">/// Distance of the last match that was found, if any.</span>
<span class="ident">current_distance</span>: <span class="ident">u16</span>,
<span class="doccomment">/// The previous byte checked in process_chunk.</span>
<span class="ident">prev_byte</span>: <span class="ident">u8</span>,
<span class="doccomment">/// The current byte being checked in process_chunk.</span>
<span class="ident">cur_byte</span>: <span class="ident">u8</span>,
<span class="doccomment">/// Whether prev_byte still needs to be output.</span>
<span class="ident">add</span>: <span class="ident">bool</span>,
}
<span class="kw">impl</span> <span class="ident">ChunkState</span> {
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>() <span class="op">-</span><span class="op">></span> <span class="ident">ChunkState</span> {
<span class="ident">ChunkState</span> {
<span class="ident">current_length</span>: <span class="number">0</span>,
<span class="ident">current_distance</span>: <span class="number">0</span>,
<span class="ident">prev_byte</span>: <span class="number">0</span>,
<span class="ident">cur_byte</span>: <span class="number">0</span>,
<span class="ident">add</span>: <span class="bool-val">false</span>,
}
}
}
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">buffer_full</span>(<span class="ident">position</span>: <span class="ident">usize</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ProcessStatus</span> {
<span class="ident">ProcessStatus::BufferFull</span>(<span class="ident">position</span>)
}
<span class="kw">fn</span> <span class="ident">process_chunk</span>(
<span class="ident">data</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>],
<span class="ident">iterated_data</span>: <span class="kw-2">&</span><span class="ident">Range</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>,
<span class="kw-2">mut</span> <span class="ident">match_state</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">ChunkState</span>,
<span class="ident">hash_table</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">ChainedHashTable</span>,
<span class="ident">writer</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">DynamicWriter</span>,
<span class="ident">max_hash_checks</span>: <span class="ident">u16</span>,
<span class="ident">lazy_if_less_than</span>: <span class="ident">usize</span>,
<span class="ident">matching_type</span>: <span class="ident">MatchingType</span>,
) <span class="op">-</span><span class="op">></span> (<span class="ident">usize</span>, <span class="ident">ProcessStatus</span>) {
<span class="kw">let</span> <span class="ident">avoid_rle</span> <span class="op">=</span> <span class="kw">if</span> <span class="macro">cfg!</span>(<span class="ident">test</span>) {
<span class="comment">// Avoid RLE if lazy_if_less than is a specific value.</span>
<span class="comment">// This is used in some tests, ideally we should probably do this in a less clunky way,</span>
<span class="comment">// but we use a value here that is higher than the maximum sensible one anyhow, and will</span>
<span class="comment">// be truncated by deflate_state for calls from outside the library.</span>
<span class="ident">lazy_if_less_than</span> <span class="op">=</span><span class="op">=</span> <span class="ident">NO_RLE</span> <span class="kw">as</span> <span class="ident">usize</span>
} <span class="kw">else</span> {
<span class="bool-val">false</span>
};
<span class="kw">match</span> <span class="ident">matching_type</span> {
<span class="ident">MatchingType::Greedy</span> <span class="op">=</span><span class="op">></span> {
<span class="ident">process_chunk_greedy</span>(<span class="ident">data</span>, <span class="ident">iterated_data</span>, <span class="ident">hash_table</span>, <span class="ident">writer</span>, <span class="ident">max_hash_checks</span>)
}
<span class="ident">MatchingType::Lazy</span> <span class="op">=</span><span class="op">></span> {
<span class="kw">if</span> <span class="ident">max_hash_checks</span> <span class="op">></span> <span class="number">0</span> <span class="op">|</span><span class="op">|</span> <span class="ident">avoid_rle</span> {
<span class="ident">process_chunk_lazy</span>(
<span class="ident">data</span>,
<span class="ident">iterated_data</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">match_state</span>,
<span class="ident">hash_table</span>,
<span class="ident">writer</span>,
<span class="ident">max_hash_checks</span>,
<span class="ident">lazy_if_less_than</span>,
)
} <span class="kw">else</span> {
<span class="comment">// Use the RLE method if max_hash_checks is set to 0.</span>
<span class="ident">process_chunk_greedy_rle</span>(<span class="ident">data</span>, <span class="ident">iterated_data</span>, <span class="ident">writer</span>)
}
}
}
}
<span class="doccomment">/// Add the specified number of bytes to the hash table from the iterators</span>
<span class="doccomment">/// adding `start` to the position supplied to the hash table.</span>
<span class="kw">fn</span> <span class="ident">add_to_hash_table</span>(
<span class="ident">bytes_to_add</span>: <span class="ident">usize</span>,
<span class="ident">insert_it</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">iter::Zip</span><span class="op"><</span><span class="ident">RangeFrom</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>, <span class="ident">Iter</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span><span class="op">></span>,
<span class="ident">hash_it</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">Iter</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span>,
<span class="ident">hash_table</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">ChainedHashTable</span>,
) {
<span class="kw">let</span> <span class="ident">taker</span> <span class="op">=</span> <span class="ident">insert_it</span>.<span class="ident">by_ref</span>().<span class="ident">take</span>(<span class="ident">bytes_to_add</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">hash_taker</span> <span class="op">=</span> <span class="ident">hash_it</span>.<span class="ident">by_ref</span>().<span class="ident">take</span>(<span class="ident">bytes_to_add</span>);
<span class="comment">// Update the hash manually here to keep it in a register.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">hash</span> <span class="op">=</span> <span class="ident">hash_table</span>.<span class="ident">current_hash</span>();
<span class="comment">// Advance the iterators and add the bytes we jump over to the hash table and</span>
<span class="comment">// checksum</span>
<span class="kw">for</span> (<span class="ident">ipos</span>, <span class="kw">_</span>) <span class="kw">in</span> <span class="ident">taker</span> {
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="ident">i_hash_byte</span>) <span class="op">=</span> <span class="ident">hash_taker</span>.<span class="ident">next</span>() {
<span class="ident">hash</span> <span class="op">=</span> <span class="ident">update_hash</span>(<span class="ident">hash</span>, <span class="ident">i_hash_byte</span>);
<span class="ident">hash_table</span>.<span class="ident">add_with_hash</span>(<span class="ident">ipos</span>, <span class="ident">hash</span>);
}
}
<span class="comment">// Write the hash back once we are done.</span>
<span class="ident">hash_table</span>.<span class="ident">set_hash</span>(<span class="ident">hash</span>);
}
<span class="doccomment">/// Write the specified literal `byte` to the writer `w`, and return</span>
<span class="doccomment">/// `ProcessStatus::BufferFull($pos)` if the buffer is full after writing.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// `pos` should indicate the byte to start at in the next call to `process_chunk`,</span>
<span class="doccomment">/// `is_hashed` should be set to true of the byte at pos has been added to the hash chain.</span>
<span class="macro">macro_rules!</span> <span class="ident">write_literal</span>{
(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">w</span>:<span class="ident">ident</span>, <span class="macro-nonterminal">$</span><span class="macro-nonterminal">byte</span>:<span class="ident">expr</span>, <span class="macro-nonterminal">$</span><span class="macro-nonterminal">pos</span>:<span class="ident">expr</span>) <span class="op">=</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">b_status</span> <span class="op">=</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">w</span>.<span class="ident">write_literal</span>(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">byte</span>);
<span class="kw">if</span> <span class="kw">let</span> <span class="ident">BufferStatus::Full</span> <span class="op">=</span> <span class="ident">b_status</span> {
<span class="kw">return</span> (<span class="number">0</span>, <span class="ident">buffer_full</span>(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">pos</span>));
}
};
}
<span class="doccomment">/// If the match is only 3 bytes long and the distance is more than 8 * 1024, it's likely to take</span>
<span class="doccomment">/// up more space than it would save.</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">match_too_far</span>(<span class="ident">match_len</span>: <span class="ident">usize</span>, <span class="ident">match_dist</span>: <span class="ident">usize</span>) <span class="op">-</span><span class="op">></span> <span class="ident">bool</span> {
<span class="kw">const</span> <span class="ident">TOO_FAR</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="number">8</span> <span class="op">*</span> <span class="number">1024</span>;
<span class="ident">match_len</span> <span class="op">=</span><span class="op">=</span> <span class="ident">MIN_MATCH</span> <span class="op">&&</span> <span class="ident">match_dist</span> <span class="op">></span> <span class="ident">TOO_FAR</span>
}
<span class="doccomment">///Create the iterators used when processing through a chunk of data.</span>
<span class="kw">fn</span> <span class="ident">create_iterators</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span>(
<span class="ident">data</span>: <span class="kw-2">&</span><span class="lifetime">'a</span> [<span class="ident">u8</span>],
<span class="ident">iterated_data</span>: <span class="kw-2">&</span><span class="ident">Range</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>,
) <span class="op">-</span><span class="op">></span> (
<span class="ident">usize</span>,
<span class="ident">iter::Zip</span><span class="op"><</span><span class="ident">RangeFrom</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>, <span class="ident">Iter</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">u8</span><span class="op">></span><span class="op">></span>,
<span class="ident">Iter</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">u8</span><span class="op">></span>,
) {
<span class="kw">let</span> <span class="ident">end</span> <span class="op">=</span> <span class="ident">cmp::min</span>(<span class="ident">data</span>.<span class="ident">len</span>(), <span class="ident">iterated_data</span>.<span class="ident">end</span>);
<span class="kw">let</span> <span class="ident">start</span> <span class="op">=</span> <span class="ident">iterated_data</span>.<span class="ident">start</span>;
<span class="kw">let</span> <span class="ident">current_chunk</span> <span class="op">=</span> <span class="kw-2">&</span><span class="ident">data</span>[<span class="ident">start</span>..<span class="ident">end</span>];
<span class="kw">let</span> <span class="ident">insert_it</span> <span class="op">=</span> (<span class="ident">start</span>..).<span class="ident">zip</span>(<span class="ident">current_chunk</span>.<span class="ident">iter</span>());
<span class="kw">let</span> <span class="ident">hash_it</span> <span class="op">=</span> {
<span class="kw">let</span> <span class="ident">hash_start</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">data</span>.<span class="ident">len</span>() <span class="op">-</span> <span class="ident">start</span> <span class="op">></span> <span class="number">2</span> {
<span class="ident">start</span> <span class="op">+</span> <span class="number">2</span>
} <span class="kw">else</span> {
<span class="ident">data</span>.<span class="ident">len</span>()
};
(<span class="kw-2">&</span><span class="ident">data</span>[<span class="ident">hash_start</span>..]).<span class="ident">iter</span>()
};
(<span class="ident">end</span>, <span class="ident">insert_it</span>, <span class="ident">hash_it</span>)
}
<span class="kw">fn</span> <span class="ident">process_chunk_lazy</span>(
<span class="ident">data</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>],
<span class="ident">iterated_data</span>: <span class="kw-2">&</span><span class="ident">Range</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>,
<span class="ident">state</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">ChunkState</span>,
<span class="kw-2">mut</span> <span class="ident">hash_table</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">ChainedHashTable</span>,
<span class="ident">writer</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">DynamicWriter</span>,
<span class="ident">max_hash_checks</span>: <span class="ident">u16</span>,
<span class="ident">lazy_if_less_than</span>: <span class="ident">usize</span>,
) <span class="op">-</span><span class="op">></span> (<span class="ident">usize</span>, <span class="ident">ProcessStatus</span>) {
<span class="kw">let</span> (<span class="ident">end</span>, <span class="kw-2">mut</span> <span class="ident">insert_it</span>, <span class="kw-2">mut</span> <span class="ident">hash_it</span>) <span class="op">=</span> <span class="ident">create_iterators</span>(<span class="ident">data</span>, <span class="ident">iterated_data</span>);
<span class="kw">const</span> <span class="ident">NO_LENGTH</span>: <span class="ident">u16</span> <span class="op">=</span> <span class="number">0</span>;
<span class="comment">// The previous match length, if any.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">prev_length</span> <span class="op">=</span> <span class="ident">state</span>.<span class="ident">current_length</span>;
<span class="comment">// The distance of the previous match if any.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">prev_distance</span> <span class="op">=</span> <span class="ident">state</span>.<span class="ident">current_distance</span>;
<span class="ident">state</span>.<span class="ident">current_length</span> <span class="op">=</span> <span class="number">0</span>;
<span class="ident">state</span>.<span class="ident">current_distance</span> <span class="op">=</span> <span class="number">0</span>;
<span class="comment">// The number of bytes past end that was added due to finding a match that extends into</span>
<span class="comment">// the lookahead window.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">overlap</span> <span class="op">=</span> <span class="number">0</span>;
<span class="comment">// Set to true if we found a match that is equal to or longer than `lazy_if_less_than`,</span>
<span class="comment">// indicating that we won't lazy match (check for a better match at the next byte).</span>
<span class="comment">// If we had a good match, carry this over from the previous call.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">ignore_next</span> <span class="op">=</span> <span class="ident">prev_length</span> <span class="kw">as</span> <span class="ident">usize</span> <span class="op">></span><span class="op">=</span> <span class="ident">lazy_if_less_than</span>;
<span class="comment">// This is to output the correct byte in case there is one pending to be output</span>
<span class="comment">// from the previous call.</span>
<span class="ident">state</span>.<span class="ident">prev_byte</span> <span class="op">=</span> <span class="ident">state</span>.<span class="ident">cur_byte</span>;
<span class="comment">// Iterate through the slice, adding literals or length/distance pairs</span>
<span class="kw">while</span> <span class="kw">let</span> <span class="prelude-val">Some</span>((<span class="ident">position</span>, <span class="kw-2">&</span><span class="ident">b</span>)) <span class="op">=</span> <span class="ident">insert_it</span>.<span class="ident">next</span>() {
<span class="ident">state</span>.<span class="ident">cur_byte</span> <span class="op">=</span> <span class="ident">b</span>;
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="ident">hash_byte</span>) <span class="op">=</span> <span class="ident">hash_it</span>.<span class="ident">next</span>() {
<span class="ident">hash_table</span>.<span class="ident">add_hash_value</span>(<span class="ident">position</span>, <span class="ident">hash_byte</span>);
<span class="comment">// Only lazy match if we have a match shorter than a set value</span>
<span class="comment">// TODO: This should be cleaned up a bit</span>
<span class="kw">if</span> <span class="op">!</span><span class="ident">ignore_next</span> {
<span class="kw">let</span> (<span class="kw-2">mut</span> <span class="ident">match_len</span>, <span class="ident">match_dist</span>) <span class="op">=</span> {
<span class="comment">// If there already was a decent match at the previous byte</span>
<span class="comment">// and we are lazy matching, do less match checks in this step.</span>
<span class="kw">let</span> <span class="ident">max_hash_checks</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">prev_length</span> <span class="op">></span><span class="op">=</span> <span class="number">32</span> {
<span class="ident">max_hash_checks</span> <span class="op">></span><span class="op">></span> <span class="number">2</span>
} <span class="kw">else</span> {
<span class="ident">max_hash_checks</span>
};
<span class="comment">// Check if we can find a better match here than the one we had at</span>
<span class="comment">// the previous byte.</span>
<span class="ident">longest_match</span>(
<span class="ident">data</span>,
<span class="ident">hash_table</span>,
<span class="ident">position</span>,
<span class="ident">prev_length</span> <span class="kw">as</span> <span class="ident">usize</span>,
<span class="ident">max_hash_checks</span>,
)
};
<span class="comment">// If the match is only 3 bytes long and very far back, it's probably not worth</span>
<span class="comment">// outputting.</span>
<span class="kw">if</span> <span class="ident">match_too_far</span>(<span class="ident">match_len</span>, <span class="ident">match_dist</span>) {
<span class="ident">match_len</span> <span class="op">=</span> <span class="ident">NO_LENGTH</span> <span class="kw">as</span> <span class="ident">usize</span>;
};
<span class="kw">if</span> <span class="ident">match_len</span> <span class="op">></span><span class="op">=</span> <span class="ident">lazy_if_less_than</span> {
<span class="comment">// We found a decent match, so we won't check for a better one at the next byte.</span>
<span class="ident">ignore_next</span> <span class="op">=</span> <span class="bool-val">true</span>;
}
<span class="ident">state</span>.<span class="ident">current_length</span> <span class="op">=</span> <span class="ident">match_len</span> <span class="kw">as</span> <span class="ident">u16</span>;
<span class="ident">state</span>.<span class="ident">current_distance</span> <span class="op">=</span> <span class="ident">match_dist</span> <span class="kw">as</span> <span class="ident">u16</span>;
} <span class="kw">else</span> {
<span class="comment">// We already had a decent match, so we don't bother checking for another one.</span>
<span class="ident">state</span>.<span class="ident">current_length</span> <span class="op">=</span> <span class="ident">NO_LENGTH</span>;
<span class="ident">state</span>.<span class="ident">current_distance</span> <span class="op">=</span> <span class="number">0</span>;
<span class="comment">// Make sure we check again next time.</span>
<span class="ident">ignore_next</span> <span class="op">=</span> <span class="bool-val">false</span>;
};
<span class="kw">if</span> <span class="ident">prev_length</span> <span class="op">></span><span class="op">=</span> <span class="ident">state</span>.<span class="ident">current_length</span> <span class="op">&&</span> <span class="ident">prev_length</span> <span class="op">></span><span class="op">=</span> <span class="ident">MIN_MATCH</span> <span class="kw">as</span> <span class="ident">u16</span> {
<span class="comment">// The previous match was better so we add it.</span>
<span class="comment">// Casting note: length and distance is already bounded by the longest match</span>
<span class="comment">// function. Usize is just used for convenience.</span>
<span class="kw">let</span> <span class="ident">b_status</span> <span class="op">=</span>
<span class="ident">writer</span>.<span class="ident">write_length_distance</span>(<span class="ident">prev_length</span> <span class="kw">as</span> <span class="ident">u16</span>, <span class="ident">prev_distance</span> <span class="kw">as</span> <span class="ident">u16</span>);
<span class="comment">// We add the bytes to the hash table and checksum.</span>
<span class="comment">// Since we've already added two of them, we need to add two less than</span>
<span class="comment">// the length.</span>
<span class="kw">let</span> <span class="ident">bytes_to_add</span> <span class="op">=</span> <span class="ident">prev_length</span> <span class="op">-</span> <span class="number">2</span>;
<span class="ident">add_to_hash_table</span>(
<span class="ident">bytes_to_add</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">insert_it</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">hash_it</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">hash_table</span>,
);
<span class="comment">// If the match is longer than the current window, we have note how many</span>
<span class="comment">// bytes we overlap, since we don't need to do any matching on these bytes</span>
<span class="comment">// in the next call of this function.</span>
<span class="comment">// We don't have to worry about setting overlap to 0 if this is false, as the</span>
<span class="comment">// function will stop after this condition is true, and overlap is not altered</span>
<span class="comment">// elsewhere.</span>
<span class="kw">if</span> <span class="ident">position</span> <span class="op">+</span> <span class="ident">prev_length</span> <span class="kw">as</span> <span class="ident">usize</span> <span class="op">></span> <span class="ident">end</span> {
<span class="comment">// We need to subtract 1 since the byte at pos is also included.</span>
<span class="ident">overlap</span> <span class="op">=</span> <span class="ident">position</span> <span class="op">+</span> <span class="ident">prev_length</span> <span class="kw">as</span> <span class="ident">usize</span> <span class="op">-</span> <span class="ident">end</span> <span class="op">-</span> <span class="number">1</span>;
};
<span class="ident">state</span>.<span class="ident">add</span> <span class="op">=</span> <span class="bool-val">false</span>;
<span class="comment">// Note that there is no current match.</span>
<span class="ident">state</span>.<span class="ident">current_length</span> <span class="op">=</span> <span class="number">0</span>;
<span class="ident">state</span>.<span class="ident">current_distance</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">if</span> <span class="kw">let</span> <span class="ident">BufferStatus::Full</span> <span class="op">=</span> <span class="ident">b_status</span> {
<span class="comment">// MATCH(lazy)</span>
<span class="kw">return</span> (<span class="ident">overlap</span>, <span class="ident">buffer_full</span>(<span class="ident">position</span> <span class="op">+</span> <span class="ident">prev_length</span> <span class="kw">as</span> <span class="ident">usize</span> <span class="op">-</span> <span class="number">1</span>));
}
<span class="ident">ignore_next</span> <span class="op">=</span> <span class="bool-val">false</span>;
} <span class="kw">else</span> <span class="kw">if</span> <span class="ident">state</span>.<span class="ident">add</span> {
<span class="comment">// We found a better match (or there was no previous match)</span>
<span class="comment">// so output the previous byte.</span>
<span class="comment">// BETTER OR NO MATCH</span>
<span class="macro">write_literal!</span>(<span class="ident">writer</span>, <span class="ident">state</span>.<span class="ident">prev_byte</span>, <span class="ident">position</span> <span class="op">+</span> <span class="number">1</span>);
} <span class="kw">else</span> {
<span class="ident">state</span>.<span class="ident">add</span> <span class="op">=</span> <span class="bool-val">true</span>
}
<span class="ident">prev_length</span> <span class="op">=</span> <span class="ident">state</span>.<span class="ident">current_length</span>;
<span class="ident">prev_distance</span> <span class="op">=</span> <span class="ident">state</span>.<span class="ident">current_distance</span>;
<span class="ident">state</span>.<span class="ident">prev_byte</span> <span class="op">=</span> <span class="ident">b</span>;
} <span class="kw">else</span> {
<span class="comment">// If there is a match at this point, it will not have been added, so we need to add it.</span>
<span class="kw">if</span> <span class="ident">prev_length</span> <span class="op">></span><span class="op">=</span> <span class="ident">MIN_MATCH</span> <span class="kw">as</span> <span class="ident">u16</span> {
<span class="kw">let</span> <span class="ident">b_status</span> <span class="op">=</span>
<span class="ident">writer</span>.<span class="ident">write_length_distance</span>(<span class="ident">prev_length</span> <span class="kw">as</span> <span class="ident">u16</span>, <span class="ident">prev_distance</span> <span class="kw">as</span> <span class="ident">u16</span>);
<span class="ident">state</span>.<span class="ident">current_length</span> <span class="op">=</span> <span class="number">0</span>;
<span class="ident">state</span>.<span class="ident">current_distance</span> <span class="op">=</span> <span class="number">0</span>;
<span class="ident">state</span>.<span class="ident">add</span> <span class="op">=</span> <span class="bool-val">false</span>;
<span class="comment">// As this will be a 3-length match at the end of the input data, there can't be any</span>
<span class="comment">// overlap.</span>
<span class="comment">// TODO: Not sure if we need to signal that the buffer is full here.</span>
<span class="comment">// It's only needed in the case of syncing.</span>
<span class="kw">if</span> <span class="kw">let</span> <span class="ident">BufferStatus::Full</span> <span class="op">=</span> <span class="ident">b_status</span> {
<span class="comment">// TODO: These bytes should be hashed when doing a sync flush.</span>
<span class="comment">// This can't be done here as the new input data does not exist yet.</span>
<span class="kw">return</span> (<span class="number">0</span>, <span class="ident">buffer_full</span>(<span class="ident">end</span>));
} <span class="kw">else</span> {
<span class="kw">return</span> (<span class="number">0</span>, <span class="ident">ProcessStatus::Ok</span>);
}
};
<span class="kw">if</span> <span class="ident">state</span>.<span class="ident">add</span> {
<span class="comment">// We may still have a leftover byte at this point, so we add it here if needed.</span>
<span class="ident">state</span>.<span class="ident">add</span> <span class="op">=</span> <span class="bool-val">false</span>;
<span class="comment">// ADD</span>
<span class="macro">write_literal!</span>(<span class="ident">writer</span>, <span class="ident">state</span>.<span class="ident">prev_byte</span>, <span class="ident">position</span> <span class="op">+</span> <span class="number">1</span>);
};
<span class="comment">// We are at the last two bytes we want to add, so there is no point</span>
<span class="comment">// searching for matches here.</span>
<span class="comment">// AFTER ADD</span>
<span class="macro">write_literal!</span>(<span class="ident">writer</span>, <span class="ident">b</span>, <span class="ident">position</span> <span class="op">+</span> <span class="number">1</span>);
}
}
(<span class="ident">overlap</span>, <span class="ident">ProcessStatus::Ok</span>)
}
<span class="kw">fn</span> <span class="ident">process_chunk_greedy</span>(
<span class="ident">data</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>],
<span class="ident">iterated_data</span>: <span class="kw-2">&</span><span class="ident">Range</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>,
<span class="kw-2">mut</span> <span class="ident">hash_table</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">ChainedHashTable</span>,
<span class="ident">writer</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">DynamicWriter</span>,
<span class="ident">max_hash_checks</span>: <span class="ident">u16</span>,
) <span class="op">-</span><span class="op">></span> (<span class="ident">usize</span>, <span class="ident">ProcessStatus</span>) {
<span class="kw">let</span> (<span class="ident">end</span>, <span class="kw-2">mut</span> <span class="ident">insert_it</span>, <span class="kw-2">mut</span> <span class="ident">hash_it</span>) <span class="op">=</span> <span class="ident">create_iterators</span>(<span class="ident">data</span>, <span class="ident">iterated_data</span>);
<span class="kw">const</span> <span class="ident">NO_LENGTH</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="number">0</span>;
<span class="comment">// The number of bytes past end that was added due to finding a match that extends into</span>
<span class="comment">// the lookahead window.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">overlap</span> <span class="op">=</span> <span class="number">0</span>;
<span class="comment">// Iterate through the slice, adding literals or length/distance pairs.</span>
<span class="kw">while</span> <span class="kw">let</span> <span class="prelude-val">Some</span>((<span class="ident">position</span>, <span class="kw-2">&</span><span class="ident">b</span>)) <span class="op">=</span> <span class="ident">insert_it</span>.<span class="ident">next</span>() {
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="ident">hash_byte</span>) <span class="op">=</span> <span class="ident">hash_it</span>.<span class="ident">next</span>() {
<span class="ident">hash_table</span>.<span class="ident">add_hash_value</span>(<span class="ident">position</span>, <span class="ident">hash_byte</span>);
<span class="comment">// TODO: This should be cleaned up a bit.</span>
<span class="kw">let</span> (<span class="ident">match_len</span>, <span class="ident">match_dist</span>) <span class="op">=</span>
{ <span class="ident">longest_match</span>(<span class="ident">data</span>, <span class="ident">hash_table</span>, <span class="ident">position</span>, <span class="ident">NO_LENGTH</span>, <span class="ident">max_hash_checks</span>) };
<span class="kw">if</span> <span class="ident">match_len</span> <span class="op">></span><span class="op">=</span> <span class="ident">MIN_MATCH</span> <span class="kw">as</span> <span class="ident">usize</span> <span class="op">&&</span> <span class="op">!</span><span class="ident">match_too_far</span>(<span class="ident">match_len</span>, <span class="ident">match_dist</span>) {
<span class="comment">// Casting note: length and distance is already bounded by the longest match</span>
<span class="comment">// function. Usize is just used for convenience.</span>
<span class="kw">let</span> <span class="ident">b_status</span> <span class="op">=</span> <span class="ident">writer</span>.<span class="ident">write_length_distance</span>(<span class="ident">match_len</span> <span class="kw">as</span> <span class="ident">u16</span>, <span class="ident">match_dist</span> <span class="kw">as</span> <span class="ident">u16</span>);
<span class="comment">// We add the bytes to the hash table and checksum.</span>
<span class="comment">// Since we've already added one of them, we need to add one less than</span>
<span class="comment">// the length.</span>
<span class="kw">let</span> <span class="ident">bytes_to_add</span> <span class="op">=</span> <span class="ident">match_len</span> <span class="op">-</span> <span class="number">1</span>;
<span class="ident">add_to_hash_table</span>(
<span class="ident">bytes_to_add</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">insert_it</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">hash_it</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">hash_table</span>,
);
<span class="comment">// If the match is longer than the current window, we have note how many</span>
<span class="comment">// bytes we overlap, since we don't need to do any matching on these bytes</span>
<span class="comment">// in the next call of this function.</span>
<span class="kw">if</span> <span class="ident">position</span> <span class="op">+</span> <span class="ident">match_len</span> <span class="op">></span> <span class="ident">end</span> {
<span class="comment">// We need to subtract 1 since the byte at pos is also included.</span>
<span class="ident">overlap</span> <span class="op">=</span> <span class="ident">position</span> <span class="op">+</span> <span class="ident">match_len</span> <span class="op">-</span> <span class="ident">end</span>;
};
<span class="kw">if</span> <span class="kw">let</span> <span class="ident">BufferStatus::Full</span> <span class="op">=</span> <span class="ident">b_status</span> {
<span class="comment">// MATCH</span>
<span class="kw">return</span> (<span class="ident">overlap</span>, <span class="ident">buffer_full</span>(<span class="ident">position</span> <span class="op">+</span> <span class="ident">match_len</span>));
}
} <span class="kw">else</span> {
<span class="comment">// NO MATCH</span>
<span class="macro">write_literal!</span>(<span class="ident">writer</span>, <span class="ident">b</span>, <span class="ident">position</span> <span class="op">+</span> <span class="number">1</span>);
}
} <span class="kw">else</span> {
<span class="comment">// We are at the last two bytes we want to add, so there is no point</span>
<span class="comment">// searching for matches here.</span>
<span class="comment">// END</span>
<span class="macro">write_literal!</span>(<span class="ident">writer</span>, <span class="ident">b</span>, <span class="ident">position</span> <span class="op">+</span> <span class="number">1</span>);
}
}
(<span class="ident">overlap</span>, <span class="ident">ProcessStatus::Ok</span>)
}
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Eq</span>, <span class="ident">PartialEq</span>, <span class="ident">Clone</span>, <span class="ident">Copy</span>, <span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">enum</span> <span class="ident">LZ77Status</span> {
<span class="doccomment">/// Waiting for more input before doing any processing</span>
<span class="ident">NeedInput</span>,
<span class="doccomment">/// The output buffer is full, so the current block needs to be ended so the</span>
<span class="doccomment">/// buffer can be flushed.</span>
<span class="ident">EndBlock</span>,
<span class="doccomment">/// All pending data has been processed.</span>
<span class="ident">Finished</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">lz77_compress_block_finish</span>(
<span class="ident">data</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>],
<span class="ident">state</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">LZ77State</span>,
<span class="ident">buffer</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">InputBuffer</span>,
<span class="kw-2">mut</span> <span class="ident">writer</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">DynamicWriter</span>,
) <span class="op">-</span><span class="op">></span> (<span class="ident">usize</span>, <span class="ident">LZ77Status</span>) {
<span class="kw">let</span> (<span class="ident">consumed</span>, <span class="ident">status</span>, <span class="kw">_</span>) <span class="op">=</span>
<span class="ident">lz77_compress_block</span>(<span class="ident">data</span>, <span class="ident">state</span>, <span class="ident">buffer</span>, <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">writer</span>, <span class="ident">Flush::Finish</span>);
(<span class="ident">consumed</span>, <span class="ident">status</span>)
}
<span class="doccomment">/// Compress a slice with lz77 compression.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This function processes one window at a time, and returns when there is no input left,</span>
<span class="doccomment">/// or it determines it's time to end a block.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Returns the number of bytes of the input that were consumed, a status describing</span>
<span class="doccomment">/// whether there is no input, it's time to finish, or it's time to end the block, and the position</span>
<span class="doccomment">/// of the first byte in the input buffer that has not been output (but may have been checked for</span>
<span class="doccomment">/// matches).</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">lz77_compress_block</span>(
<span class="ident">data</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>],
<span class="ident">state</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">LZ77State</span>,
<span class="ident">buffer</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">InputBuffer</span>,
<span class="kw-2">mut</span> <span class="ident">writer</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">DynamicWriter</span>,
<span class="ident">flush</span>: <span class="ident">Flush</span>,
) <span class="op">-</span><span class="op">></span> (<span class="ident">usize</span>, <span class="ident">LZ77Status</span>, <span class="ident">usize</span>) {
<span class="comment">// Currently we only support the maximum window size</span>
<span class="kw">let</span> <span class="ident">window_size</span> <span class="op">=</span> <span class="ident">DEFAULT_WINDOW_SIZE</span>;
<span class="comment">// Indicates whether we should try to process all the data including the lookahead, or if we</span>
<span class="comment">// should wait until we have at least one window size of data before doing anything.</span>
<span class="kw">let</span> <span class="ident">finish</span> <span class="op">=</span> <span class="ident">flush</span> <span class="op">=</span><span class="op">=</span> <span class="ident">Flush::Finish</span> <span class="op">|</span><span class="op">|</span> <span class="ident">flush</span> <span class="op">=</span><span class="op">=</span> <span class="ident">Flush::Sync</span>;
<span class="kw">let</span> <span class="ident">sync</span> <span class="op">=</span> <span class="ident">flush</span> <span class="op">=</span><span class="op">=</span> <span class="ident">Flush::Sync</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">current_position</span> <span class="op">=</span> <span class="number">0</span>;
<span class="comment">// The current status of the encoding.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">status</span> <span class="op">=</span> <span class="ident">LZ77Status::EndBlock</span>;
<span class="comment">// Whether warm up the hash chain with the two first values.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">add_initial</span> <span class="op">=</span> <span class="bool-val">true</span>;
<span class="comment">// If we have synced, add the two first bytes to the hash as they couldn't be added before.</span>
<span class="kw">if</span> <span class="ident">state</span>.<span class="ident">was_synced</span> {
<span class="kw">if</span> <span class="ident">buffer</span>.<span class="ident">current_end</span>() <span class="op">></span> <span class="number">2</span> {
<span class="kw">let</span> <span class="ident">pos_add</span> <span class="op">=</span> <span class="ident">buffer</span>.<span class="ident">current_end</span>() <span class="op">-</span> <span class="number">2</span>;
<span class="kw">for</span> (<span class="ident">n</span>, <span class="kw-2">&</span><span class="ident">b</span>) <span class="kw">in</span> <span class="ident">data</span>.<span class="ident">iter</span>().<span class="ident">take</span>(<span class="number">2</span>).<span class="ident">enumerate</span>() {
<span class="ident">state</span>.<span class="ident">hash_table</span>.<span class="ident">add_hash_value</span>(<span class="ident">n</span> <span class="op">+</span> <span class="ident">pos_add</span>, <span class="ident">b</span>);
}
<span class="ident">add_initial</span> <span class="op">=</span> <span class="bool-val">false</span>;
}
<span class="ident">state</span>.<span class="ident">was_synced</span> <span class="op">=</span> <span class="bool-val">false</span>;
}
<span class="comment">// Add data to the input buffer and keep a reference to the slice of data not added yet.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">remaining_data</span> <span class="op">=</span> <span class="ident">buffer</span>.<span class="ident">add_data</span>(<span class="ident">data</span>);
<span class="kw">loop</span> {
<span class="comment">// Note if there is a pending byte from the previous call to process_chunk,</span>
<span class="comment">// so we get the block input size right.</span>
<span class="kw">let</span> <span class="ident">pending_previous</span> <span class="op">=</span> <span class="ident">state</span>.<span class="ident">pending_byte_as_num</span>();
<span class="macro">assert!</span>(<span class="ident">writer</span>.<span class="ident">buffer_length</span>() <span class="op"><</span><span class="op">=</span> (<span class="ident">window_size</span> <span class="op">*</span> <span class="number">2</span>));
<span class="comment">// The process is a bit different for the first 32k bytes.</span>
<span class="comment">// TODO: There is a lot of duplicate code between the two branches here, we should be able</span>
<span class="comment">// to simplify this.</span>
<span class="kw">if</span> <span class="ident">state</span>.<span class="ident">is_first_window</span> {
<span class="comment">// Don't do anything until we are either flushing, or we have at least one window of</span>
<span class="comment">// data.</span>
<span class="kw">if</span> <span class="ident">buffer</span>.<span class="ident">current_end</span>() <span class="op">></span><span class="op">=</span> (<span class="ident">window_size</span> <span class="op">*</span> <span class="number">2</span>) <span class="op">+</span> <span class="ident">MAX_MATCH</span> <span class="op">|</span><span class="op">|</span> <span class="ident">finish</span> {
<span class="kw">if</span> <span class="ident">buffer</span>.<span class="ident">get_buffer</span>().<span class="ident">len</span>() <span class="op">></span><span class="op">=</span> <span class="number">2</span> <span class="op">&&</span> <span class="ident">add_initial</span> <span class="op">&&</span>
<span class="ident">state</span>.<span class="ident">current_block_input_bytes</span> <span class="op">=</span><span class="op">=</span> <span class="number">0</span>
{
<span class="kw">let</span> <span class="ident">b</span> <span class="op">=</span> <span class="ident">buffer</span>.<span class="ident">get_buffer</span>();
<span class="comment">// Warm up the hash with the two first values, so we can find matches at</span>
<span class="comment">// index 0.</span>
<span class="ident">state</span>.<span class="ident">hash_table</span>.<span class="ident">add_initial_hash_values</span>(<span class="ident">b</span>[<span class="number">0</span>], <span class="ident">b</span>[<span class="number">1</span>]);
<span class="ident">add_initial</span> <span class="op">=</span> <span class="bool-val">false</span>;
}
<span class="kw">let</span> <span class="ident">first_chunk_end</span> <span class="op">=</span> <span class="ident">cmp::min</span>(<span class="ident">window_size</span>, <span class="ident">buffer</span>.<span class="ident">current_end</span>());
<span class="kw">let</span> <span class="ident">start</span> <span class="op">=</span> <span class="ident">state</span>.<span class="ident">overlap</span>;
<span class="kw">let</span> (<span class="ident">overlap</span>, <span class="ident">p_status</span>) <span class="op">=</span> <span class="ident">process_chunk</span>(
<span class="ident">buffer</span>.<span class="ident">get_buffer</span>(),
<span class="kw-2">&</span>(<span class="ident">start</span>..<span class="ident">first_chunk_end</span>),
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">state</span>.<span class="ident">match_state</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">state</span>.<span class="ident">hash_table</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">writer</span>,
<span class="ident">state</span>.<span class="ident">max_hash_checks</span>,
<span class="ident">state</span>.<span class="ident">lazy_if_less_than</span> <span class="kw">as</span> <span class="ident">usize</span>,
<span class="ident">state</span>.<span class="ident">matching_type</span>,
);
<span class="ident">state</span>.<span class="ident">overlap</span> <span class="op">=</span> <span class="ident">overlap</span>;
<span class="ident">state</span>.<span class="ident">bytes_to_hash</span> <span class="op">=</span> <span class="ident">overlap</span>;
<span class="comment">// If the buffer is full, we want to end the block.</span>
<span class="kw">if</span> <span class="kw">let</span> <span class="ident">ProcessStatus::BufferFull</span>(<span class="ident">written</span>) <span class="op">=</span> <span class="ident">p_status</span> {
<span class="ident">state</span>.<span class="ident">overlap</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">overlap</span> <span class="op">></span> <span class="number">0</span> { <span class="ident">overlap</span> } <span class="kw">else</span> { <span class="ident">written</span> };
<span class="ident">status</span> <span class="op">=</span> <span class="ident">LZ77Status::EndBlock</span>;
<span class="ident">current_position</span> <span class="op">=</span> <span class="ident">written</span> <span class="op">-</span> <span class="ident">state</span>.<span class="ident">pending_byte_as_num</span>();
<span class="ident">state</span>.<span class="ident">current_block_input_bytes</span> <span class="op">+</span><span class="op">=</span>
(<span class="ident">written</span> <span class="op">-</span> <span class="ident">start</span> <span class="op">+</span> <span class="ident">overlap</span> <span class="op">+</span> <span class="ident">pending_previous</span> <span class="op">-</span>
<span class="ident">state</span>.<span class="ident">pending_byte_as_num</span>()) <span class="kw">as</span> <span class="ident">u64</span>;
<span class="kw">break</span>;
}
<span class="comment">// Update the length of how many input bytes the current block is representing,</span>
<span class="comment">// taking into account pending bytes.</span>
<span class="ident">state</span>.<span class="ident">current_block_input_bytes</span> <span class="op">+</span><span class="op">=</span>
(<span class="ident">first_chunk_end</span> <span class="op">-</span> <span class="ident">start</span> <span class="op">+</span> <span class="ident">overlap</span> <span class="op">+</span> <span class="ident">pending_previous</span> <span class="op">-</span>
<span class="ident">state</span>.<span class="ident">pending_byte_as_num</span>()) <span class="kw">as</span> <span class="ident">u64</span>;
<span class="comment">// We are at the first window so we don't need to slide the hash table yet.</span>
<span class="comment">// If finishing or syncing, we stop here.</span>
<span class="kw">if</span> <span class="ident">first_chunk_end</span> <span class="op">></span><span class="op">=</span> <span class="ident">buffer</span>.<span class="ident">current_end</span>() <span class="op">&&</span> <span class="ident">finish</span> {
<span class="ident">current_position</span> <span class="op">=</span> <span class="ident">first_chunk_end</span> <span class="op">-</span> <span class="ident">state</span>.<span class="ident">pending_byte_as_num</span>();
<span class="kw">if</span> <span class="op">!</span><span class="ident">sync</span> {
<span class="ident">state</span>.<span class="ident">set_last</span>();
<span class="ident">state</span>.<span class="ident">is_first_window</span> <span class="op">=</span> <span class="bool-val">false</span>;
} <span class="kw">else</span> {
<span class="ident">state</span>.<span class="ident">overlap</span> <span class="op">=</span> <span class="ident">first_chunk_end</span>;
<span class="ident">state</span>.<span class="ident">was_synced</span> <span class="op">=</span> <span class="bool-val">true</span>;
}
<span class="macro">debug_assert!</span>(
<span class="op">!</span><span class="ident">state</span>.<span class="ident">pending_byte</span>(),
<span class="string">"Bug! Ended compression wit a pending byte!"</span>
);
<span class="ident">status</span> <span class="op">=</span> <span class="ident">LZ77Status::Finished</span>;
<span class="kw">break</span>;
}
<span class="comment">// Otherwise, continue.</span>
<span class="ident">state</span>.<span class="ident">is_first_window</span> <span class="op">=</span> <span class="bool-val">false</span>;
} <span class="kw">else</span> {
<span class="ident">status</span> <span class="op">=</span> <span class="ident">LZ77Status::NeedInput</span>;
<span class="kw">break</span>;
}
} <span class="kw">else</span> <span class="kw">if</span> <span class="ident">buffer</span>.<span class="ident">current_end</span>() <span class="op">></span><span class="op">=</span> (<span class="ident">window_size</span> <span class="op">*</span> <span class="number">2</span>) <span class="op">+</span> <span class="ident">MAX_MATCH</span> <span class="op">|</span><span class="op">|</span> <span class="ident">finish</span> {
<span class="kw">if</span> <span class="ident">buffer</span>.<span class="ident">current_end</span>() <span class="op">></span><span class="op">=</span> <span class="ident">window_size</span> <span class="op">+</span> <span class="number">2</span> {
<span class="kw">for</span> (<span class="ident">n</span>, <span class="kw-2">&</span><span class="ident">h</span>) <span class="kw">in</span> <span class="ident">buffer</span>.<span class="ident">get_buffer</span>()[<span class="ident">window_size</span> <span class="op">+</span> <span class="number">2</span>..]
.<span class="ident">iter</span>()
.<span class="ident">enumerate</span>()
.<span class="ident">take</span>(<span class="ident">state</span>.<span class="ident">bytes_to_hash</span>)
{
<span class="ident">state</span>.<span class="ident">hash_table</span>.<span class="ident">add_hash_value</span>(<span class="ident">window_size</span> <span class="op">+</span> <span class="ident">n</span>, <span class="ident">h</span>);
}
<span class="ident">state</span>.<span class="ident">bytes_to_hash</span> <span class="op">=</span> <span class="number">0</span>;
}
<span class="comment">// This isn't the first chunk, so we start reading at one window in in the</span>
<span class="comment">// buffer plus any additional overlap from earlier.</span>
<span class="kw">let</span> <span class="ident">start</span> <span class="op">=</span> <span class="ident">window_size</span> <span class="op">+</span> <span class="ident">state</span>.<span class="ident">overlap</span>;
<span class="comment">// Determine where we have to stop iterating to slide the buffer and hash,</span>
<span class="comment">// or stop because we are at the end of the input data.</span>
<span class="kw">let</span> <span class="ident">end</span> <span class="op">=</span> <span class="ident">cmp::min</span>(<span class="ident">window_size</span> <span class="op">*</span> <span class="number">2</span>, <span class="ident">buffer</span>.<span class="ident">current_end</span>());
<span class="kw">let</span> (<span class="ident">overlap</span>, <span class="ident">p_status</span>) <span class="op">=</span> <span class="ident">process_chunk</span>(
<span class="ident">buffer</span>.<span class="ident">get_buffer</span>(),
<span class="kw-2">&</span>(<span class="ident">start</span>..<span class="ident">end</span>),
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">state</span>.<span class="ident">match_state</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">state</span>.<span class="ident">hash_table</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">writer</span>,
<span class="ident">state</span>.<span class="ident">max_hash_checks</span>,
<span class="ident">state</span>.<span class="ident">lazy_if_less_than</span> <span class="kw">as</span> <span class="ident">usize</span>,
<span class="ident">state</span>.<span class="ident">matching_type</span>,
);
<span class="ident">state</span>.<span class="ident">bytes_to_hash</span> <span class="op">=</span> <span class="ident">overlap</span>;
<span class="kw">if</span> <span class="kw">let</span> <span class="ident">ProcessStatus::BufferFull</span>(<span class="ident">written</span>) <span class="op">=</span> <span class="ident">p_status</span> {
<span class="ident">state</span>.<span class="ident">current_block_input_bytes</span> <span class="op">+</span><span class="op">=</span>
(<span class="ident">written</span> <span class="op">-</span> <span class="ident">start</span> <span class="op">+</span> <span class="ident">pending_previous</span> <span class="op">-</span> <span class="ident">state</span>.<span class="ident">pending_byte_as_num</span>()) <span class="kw">as</span> <span class="ident">u64</span>;
<span class="comment">// If the buffer is full, return and end the block.</span>
<span class="comment">// If overlap is non-zero, the buffer was full after outputting the last byte,</span>
<span class="comment">// otherwise we have to skip to the point in the buffer where we stopped in the</span>
<span class="comment">// next call.</span>
<span class="ident">state</span>.<span class="ident">overlap</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">overlap</span> <span class="op">></span> <span class="number">0</span> {
<span class="comment">// If we are at the end of the window, make sure we slide the buffer and the</span>
<span class="comment">// hash table.</span>
<span class="kw">if</span> <span class="ident">state</span>.<span class="ident">max_hash_checks</span> <span class="op">></span> <span class="number">0</span> {
<span class="ident">state</span>.<span class="ident">hash_table</span>.<span class="ident">slide</span>(<span class="ident">window_size</span>);
}
<span class="ident">remaining_data</span> <span class="op">=</span> <span class="ident">buffer</span>.<span class="ident">slide</span>(<span class="ident">remaining_data</span>.<span class="ident">unwrap_or</span>(<span class="kw-2">&</span>[]));
<span class="ident">overlap</span>
} <span class="kw">else</span> {
<span class="ident">written</span> <span class="op">-</span> <span class="ident">window_size</span>
};
<span class="ident">current_position</span> <span class="op">=</span> <span class="ident">written</span> <span class="op">-</span> <span class="ident">state</span>.<span class="ident">pending_byte_as_num</span>();
<span class="comment">// Status is already EndBlock at this point.</span>
<span class="comment">// status = LZ77Status::EndBlock;</span>
<span class="kw">break</span>;
}
<span class="ident">state</span>.<span class="ident">current_block_input_bytes</span> <span class="op">+</span><span class="op">=</span>
(<span class="ident">end</span> <span class="op">-</span> <span class="ident">start</span> <span class="op">+</span> <span class="ident">overlap</span> <span class="op">+</span> <span class="ident">pending_previous</span> <span class="op">-</span> <span class="ident">state</span>.<span class="ident">pending_byte_as_num</span>()) <span class="kw">as</span> <span class="ident">u64</span>;
<span class="comment">// The buffer is not full, but we still need to note if there is any overlap into the</span>
<span class="comment">// next window.</span>
<span class="ident">state</span>.<span class="ident">overlap</span> <span class="op">=</span> <span class="ident">overlap</span>;
<span class="kw">if</span> <span class="ident">remaining_data</span>.<span class="ident">is_none</span>() <span class="op">&&</span> <span class="ident">finish</span> <span class="op">&&</span> <span class="ident">end</span> <span class="op">=</span><span class="op">=</span> <span class="ident">buffer</span>.<span class="ident">current_end</span>() {
<span class="ident">current_position</span> <span class="op">=</span> <span class="ident">buffer</span>.<span class="ident">current_end</span>();
<span class="macro">debug_assert!</span>(
<span class="op">!</span><span class="ident">state</span>.<span class="ident">pending_byte</span>(),
<span class="string">"Bug! Ended compression wit a pending byte!"</span>
);
<span class="comment">// We stopped before or at the window size, so we are at the end.</span>
<span class="kw">if</span> <span class="op">!</span><span class="ident">sync</span> {
<span class="comment">// If we are finishing and not syncing, we simply indicate that we are done.</span>
<span class="ident">state</span>.<span class="ident">set_last</span>();
} <span class="kw">else</span> {
<span class="comment">// For sync flushing we need to slide the buffer and the hash chains so that the</span>
<span class="comment">// next call to this function starts at the right place.</span>
<span class="comment">// There won't be any overlap, since when syncing, we process to the end of the.</span>
<span class="comment">// pending data.</span>
<span class="ident">state</span>.<span class="ident">overlap</span> <span class="op">=</span> <span class="ident">buffer</span>.<span class="ident">current_end</span>() <span class="op">-</span> <span class="ident">window_size</span>;
<span class="ident">state</span>.<span class="ident">was_synced</span> <span class="op">=</span> <span class="bool-val">true</span>;
}
<span class="ident">status</span> <span class="op">=</span> <span class="ident">LZ77Status::Finished</span>;
<span class="kw">break</span>;
} <span class="kw">else</span> {
<span class="comment">// We are not at the end, so slide and continue.</span>
<span class="comment">// We slide the hash table back to make space for new hash values</span>
<span class="comment">// We only need to remember 2^15 bytes back (the maximum distance allowed by the</span>
<span class="comment">// deflate spec).</span>
<span class="kw">if</span> <span class="ident">state</span>.<span class="ident">max_hash_checks</span> <span class="op">></span> <span class="number">0</span> {
<span class="ident">state</span>.<span class="ident">hash_table</span>.<span class="ident">slide</span>(<span class="ident">window_size</span>);
}
<span class="comment">// Also slide the buffer, discarding data we no longer need and adding new data.</span>
<span class="ident">remaining_data</span> <span class="op">=</span> <span class="ident">buffer</span>.<span class="ident">slide</span>(<span class="ident">remaining_data</span>.<span class="ident">unwrap_or</span>(<span class="kw-2">&</span>[]));
}
} <span class="kw">else</span> {
<span class="comment">// The caller has not indicated that they want to finish or flush, and there is less</span>
<span class="comment">// than a window + lookahead of new data, so we wait for more.</span>
<span class="ident">status</span> <span class="op">=</span> <span class="ident">LZ77Status::NeedInput</span>;
<span class="kw">break</span>;
}
}
(
<span class="ident">data</span>.<span class="ident">len</span>() <span class="op">-</span> <span class="ident">remaining_data</span>.<span class="ident">unwrap_or</span>(<span class="kw-2">&</span>[]).<span class="ident">len</span>(),
<span class="ident">status</span>,
<span class="ident">current_position</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">decompress_lz77</span>(<span class="ident">input</span>: <span class="kw-2">&</span>[<span class="ident">LZValue</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="ident">decompress_lz77_with_backbuffer</span>(<span class="ident">input</span>, <span class="kw-2">&</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">decompress_lz77_with_backbuffer</span>(<span class="ident">input</span>: <span class="kw-2">&</span>[<span class="ident">LZValue</span>], <span class="ident">back_buffer</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="kw-2">mut</span> <span class="ident">output</span> <span class="op">=</span> <span class="ident">Vec::new</span>();
<span class="kw">for</span> <span class="ident">p</span> <span class="kw">in</span> <span class="ident">input</span> {
<span class="kw">match</span> <span class="ident">p</span>.<span class="ident">value</span>() {
<span class="ident">LZType::Literal</span>(<span class="ident">l</span>) <span class="op">=</span><span class="op">></span> <span class="ident">output</span>.<span class="ident">push</span>(<span class="ident">l</span>),
<span class="ident">LZType::StoredLengthDistance</span>(<span class="ident">l</span>, <span class="ident">d</span>) <span class="op">=</span><span class="op">></span> {
<span class="comment">// We found a match, so we have to get the data that the match refers to.</span>
<span class="kw">let</span> <span class="ident">d</span> <span class="op">=</span> <span class="ident">d</span> <span class="kw">as</span> <span class="ident">usize</span>;
<span class="kw">let</span> <span class="ident">prev_output_len</span> <span class="op">=</span> <span class="ident">output</span>.<span class="ident">len</span>();
<span class="comment">// Get match data from the back buffer if the match extends that far.</span>
<span class="kw">let</span> <span class="ident">consumed</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">d</span> <span class="op">></span> <span class="ident">output</span>.<span class="ident">len</span>() {
<span class="kw">let</span> <span class="ident">into_back_buffer</span> <span class="op">=</span> <span class="ident">d</span> <span class="op">-</span> <span class="ident">output</span>.<span class="ident">len</span>();
<span class="macro">assert!</span>(
<span class="ident">into_back_buffer</span> <span class="op"><</span><span class="op">=</span> <span class="ident">back_buffer</span>.<span class="ident">len</span>(),
<span class="string">"ERROR: Attempted to refer to a match in non-existing data!\
into_back_buffer: {}, back_buffer len {}, d {}, l {:?}"</span>,
<span class="ident">into_back_buffer</span>,
<span class="ident">back_buffer</span>.<span class="ident">len</span>(),
<span class="ident">d</span>,
<span class="ident">l</span>
);
<span class="kw">let</span> <span class="ident">start</span> <span class="op">=</span> <span class="ident">back_buffer</span>.<span class="ident">len</span>() <span class="op">-</span> <span class="ident">into_back_buffer</span>;
<span class="kw">let</span> <span class="ident">end</span> <span class="op">=</span> <span class="ident">cmp::min</span>(<span class="ident">back_buffer</span>.<span class="ident">len</span>(), <span class="ident">start</span> <span class="op">+</span> <span class="ident">l</span>.<span class="ident">actual_length</span>() <span class="kw">as</span> <span class="ident">usize</span>);
<span class="ident">output</span>.<span class="ident">extend_from_slice</span>(<span class="kw-2">&</span><span class="ident">back_buffer</span>[<span class="ident">start</span>..<span class="ident">end</span>]);
<span class="ident">end</span> <span class="op">-</span> <span class="ident">start</span>
} <span class="kw">else</span> {
<span class="number">0</span>
};
<span class="comment">// Get match data from the currently decompressed data.</span>
<span class="kw">let</span> <span class="ident">start</span> <span class="op">=</span> <span class="ident">prev_output_len</span>.<span class="ident">saturating_sub</span>(<span class="ident">d</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">n</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">while</span> <span class="ident">n</span> <span class="op"><</span> (<span class="ident">l</span>.<span class="ident">actual_length</span>() <span class="kw">as</span> <span class="ident">usize</span>).<span class="ident">saturating_sub</span>(<span class="ident">consumed</span>) {
<span class="kw">let</span> <span class="ident">b</span> <span class="op">=</span> <span class="ident">output</span>[<span class="ident">start</span> <span class="op">+</span> <span class="ident">n</span>];
<span class="ident">output</span>.<span class="ident">push</span>(<span class="ident">b</span>);
<span class="ident">n</span> <span class="op">+</span><span class="op">=</span> <span class="number">1</span>;
}
}
}
}
<span class="ident">output</span>
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">TestStruct</span> {
<span class="ident">state</span>: <span class="ident">LZ77State</span>,
<span class="ident">buffer</span>: <span class="ident">InputBuffer</span>,
<span class="ident">writer</span>: <span class="ident">DynamicWriter</span>,
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span>
<span class="kw">impl</span> <span class="ident">TestStruct</span> {
<span class="kw">fn</span> <span class="ident">new</span>() <span class="op">-</span><span class="op">></span> <span class="ident">TestStruct</span> {
<span class="ident">TestStruct::with_config</span>(
<span class="ident">HIGH_MAX_HASH_CHECKS</span>,
<span class="ident">HIGH_LAZY_IF_LESS_THAN</span>,
<span class="ident">MatchingType::Lazy</span>,
)
}
<span class="kw">fn</span> <span class="ident">with_config</span>(
<span class="ident">max_hash_checks</span>: <span class="ident">u16</span>,
<span class="ident">lazy_if_less_than</span>: <span class="ident">u16</span>,
<span class="ident">matching_type</span>: <span class="ident">MatchingType</span>,
) <span class="op">-</span><span class="op">></span> <span class="ident">TestStruct</span> {
<span class="ident">TestStruct</span> {
<span class="ident">state</span>: <span class="ident">LZ77State::new</span>(<span class="ident">max_hash_checks</span>, <span class="ident">lazy_if_less_than</span>, <span class="ident">matching_type</span>),
<span class="ident">buffer</span>: <span class="ident">InputBuffer::empty</span>(),
<span class="ident">writer</span>: <span class="ident">DynamicWriter::new</span>(),
}
}
<span class="kw">fn</span> <span class="ident">compress_block</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">data</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>], <span class="ident">flush</span>: <span class="ident">bool</span>) <span class="op">-</span><span class="op">></span> (<span class="ident">usize</span>, <span class="ident">LZ77Status</span>, <span class="ident">usize</span>) {
<span class="ident">lz77_compress_block</span>(
<span class="ident">data</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">state</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">buffer</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">writer</span>,
<span class="kw">if</span> <span class="ident">flush</span> { <span class="ident">Flush::Finish</span> } <span class="kw">else</span> { <span class="ident">Flush::None</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">lz77_compress</span>(<span class="ident">data</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>]) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">LZValue</span><span class="op">></span><span class="op">></span> {
<span class="ident">lz77_compress_conf</span>(
<span class="ident">data</span>,
<span class="ident">HIGH_MAX_HASH_CHECKS</span>,
<span class="ident">HIGH_LAZY_IF_LESS_THAN</span>,
<span class="ident">MatchingType::Lazy</span>,
)
}
<span class="doccomment">/// Compress a slice, not storing frequency information</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This is a convenience function for compression with fixed huffman values</span>
<span class="doccomment">/// Only used in tests for now</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">lz77_compress_conf</span>(
<span class="ident">data</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>],
<span class="ident">max_hash_checks</span>: <span class="ident">u16</span>,
<span class="ident">lazy_if_less_than</span>: <span class="ident">u16</span>,
<span class="ident">matching_type</span>: <span class="ident">MatchingType</span>,
) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">LZValue</span><span class="op">></span><span class="op">></span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">test_boxed</span> <span class="op">=</span> <span class="ident">Box::new</span>(<span class="ident">TestStruct::with_config</span>(
<span class="ident">max_hash_checks</span>,
<span class="ident">lazy_if_less_than</span>,
<span class="ident">matching_type</span>,
));
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">out</span> <span class="op">=</span> <span class="ident">Vec</span>::<span class="op"><</span><span class="ident">LZValue</span><span class="op">></span><span class="ident">::with_capacity</span>(<span class="ident">data</span>.<span class="ident">len</span>() <span class="op">/</span> <span class="number">3</span>);
{
<span class="kw">let</span> <span class="ident">test</span> <span class="op">=</span> <span class="ident">test_boxed</span>.<span class="ident">as_mut</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">slice</span> <span class="op">=</span> <span class="ident">data</span>;
<span class="kw">while</span> <span class="op">!</span><span class="ident">test</span>.<span class="ident">state</span>.<span class="ident">is_last_block</span> {
<span class="kw">let</span> <span class="ident">bytes_written</span> <span class="op">=</span> <span class="ident">lz77_compress_block_finish</span>(
<span class="ident">slice</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">test</span>.<span class="ident">state</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">test</span>.<span class="ident">buffer</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">test</span>.<span class="ident">writer</span>,
).<span class="number">0</span>;
<span class="ident">slice</span> <span class="op">=</span> <span class="kw-2">&</span><span class="ident">slice</span>[<span class="ident">bytes_written</span>..];
<span class="ident">out</span>.<span class="ident">extend</span>(<span class="ident">test</span>.<span class="ident">writer</span>.<span class="ident">get_buffer</span>());
<span class="ident">test</span>.<span class="ident">writer</span>.<span class="ident">clear</span>();
}
}
<span class="prelude-val">Some</span>(<span class="ident">out</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">lzvalue</span>::{<span class="ident">LZValue</span>, <span class="ident">LZType</span>, <span class="ident">lit</span>, <span class="ident">ld</span>};
<span class="kw">use</span> <span class="ident">chained_hash_table::WINDOW_SIZE</span>;
<span class="kw">use</span> <span class="ident">compression_options::DEFAULT_LAZY_IF_LESS_THAN</span>;
<span class="kw">use</span> <span class="ident">test_utils::get_test_data</span>;
<span class="kw">use</span> <span class="ident">output_writer::MAX_BUFFER_LENGTH</span>;
<span class="doccomment">/// Helper function to print the output from the lz77 compression function</span>
<span class="kw">fn</span> <span class="ident">print_output</span>(<span class="ident">input</span>: <span class="kw-2">&</span>[<span class="ident">LZValue</span>]) {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">output</span> <span class="op">=</span> <span class="macro">vec!</span>[];
<span class="kw">for</span> <span class="ident">l</span> <span class="kw">in</span> <span class="ident">input</span> {
<span class="kw">match</span> <span class="ident">l</span>.<span class="ident">value</span>() {
<span class="ident">LZType::Literal</span>(<span class="ident">l</span>) <span class="op">=</span><span class="op">></span> <span class="ident">output</span>.<span class="ident">push</span>(<span class="ident">l</span>),
<span class="ident">LZType::StoredLengthDistance</span>(<span class="ident">l</span>, <span class="ident">d</span>) <span class="op">=</span><span class="op">></span> {
<span class="ident">output</span>.<span class="ident">extend</span>(<span class="macro">format!</span>(<span class="string">"<L {}>"</span>, <span class="ident">l</span>.<span class="ident">actual_length</span>()).<span class="ident">into_bytes</span>());
<span class="ident">output</span>.<span class="ident">extend</span>(<span class="macro">format!</span>(<span class="string">"<D {}>"</span>, <span class="ident">d</span>).<span class="ident">into_bytes</span>())
}
}
}
<span class="macro">println!</span>(<span class="string">"\"{}\""</span>, <span class="ident">String::from_utf8</span>(<span class="ident">output</span>).<span class="ident">unwrap</span>());
}
<span class="doccomment">/// Test that a short string from an example on SO compresses correctly</span>
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">compress_short</span>() {
<span class="kw">let</span> <span class="ident">test_bytes</span> <span class="op">=</span> <span class="ident">String::from</span>(<span class="string">"Deflate late"</span>).<span class="ident">into_bytes</span>();
<span class="kw">let</span> <span class="ident">res</span> <span class="op">=</span> <span class="ident">lz77_compress</span>(<span class="kw-2">&</span><span class="ident">test_bytes</span>).<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">decompressed</span> <span class="op">=</span> <span class="ident">decompress_lz77</span>(<span class="kw-2">&</span><span class="ident">res</span>);
<span class="macro">assert_eq!</span>(<span class="ident">test_bytes</span>, <span class="ident">decompressed</span>);
<span class="macro">assert_eq!</span>(<span class="kw-2">*</span><span class="ident">res</span>.<span class="ident">last</span>().<span class="ident">unwrap</span>(), <span class="ident">LZValue::length_distance</span>(<span class="number">4</span>, <span class="number">5</span>));
}
<span class="doccomment">/// Test that compression is working for a longer file</span>
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">compress_long</span>() {
<span class="kw">let</span> <span class="ident">input</span> <span class="op">=</span> <span class="ident">get_test_data</span>();
<span class="kw">let</span> <span class="ident">compressed</span> <span class="op">=</span> <span class="ident">lz77_compress</span>(<span class="kw-2">&</span><span class="ident">input</span>).<span class="ident">unwrap</span>();
<span class="macro">assert!</span>(<span class="ident">compressed</span>.<span class="ident">len</span>() <span class="op"><</span> <span class="ident">input</span>.<span class="ident">len</span>());
<span class="kw">let</span> <span class="ident">decompressed</span> <span class="op">=</span> <span class="ident">decompress_lz77</span>(<span class="kw-2">&</span><span class="ident">compressed</span>);
<span class="macro">println!</span>(<span class="string">"compress_long length: {}"</span>, <span class="ident">input</span>.<span class="ident">len</span>());
<span class="comment">// This is to check where the compression fails, if it were to</span>
<span class="kw">for</span> (<span class="ident">n</span>, (<span class="kw-2">&</span><span class="ident">a</span>, <span class="kw-2">&</span><span class="ident">b</span>)) <span class="kw">in</span> <span class="ident">input</span>.<span class="ident">iter</span>().<span class="ident">zip</span>(<span class="ident">decompressed</span>.<span class="ident">iter</span>()).<span class="ident">enumerate</span>() {
<span class="kw">if</span> <span class="ident">a</span> <span class="op">!</span><span class="op">=</span> <span class="ident">b</span> {
<span class="macro">println!</span>(<span class="string">"First difference at {}, input: {}, output: {}"</span>, <span class="ident">n</span>, <span class="ident">a</span>, <span class="ident">b</span>);
<span class="kw">break</span>;
}
}
<span class="macro">assert_eq!</span>(<span class="ident">input</span>.<span class="ident">len</span>(), <span class="ident">decompressed</span>.<span class="ident">len</span>());
<span class="macro">assert!</span>(<span class="kw-2">&</span><span class="ident">decompressed</span> <span class="op">=</span><span class="op">=</span> <span class="kw-2">&</span><span class="ident">input</span>);
}
<span class="doccomment">/// Check that lazy matching is working as intended</span>
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">lazy</span>() {
<span class="comment">// We want to match on `badger` rather than `nba` as it is longer</span>
<span class="comment">// let data = b" nba nbadg badger nbadger";</span>
<span class="kw">let</span> <span class="ident">data</span> <span class="op">=</span> <span class="string">b"nba badger nbadger"</span>;
<span class="kw">let</span> <span class="ident">compressed</span> <span class="op">=</span> <span class="ident">lz77_compress</span>(<span class="ident">data</span>).<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">test</span> <span class="op">=</span> <span class="ident">compressed</span>[<span class="ident">compressed</span>.<span class="ident">len</span>() <span class="op">-</span> <span class="number">1</span>];
<span class="kw">if</span> <span class="kw">let</span> <span class="ident">LZType::StoredLengthDistance</span>(<span class="ident">l</span>, <span class="kw">_</span>) <span class="op">=</span> <span class="ident">test</span>.<span class="ident">value</span>() {
<span class="macro">assert_eq!</span>(<span class="ident">l</span>.<span class="ident">actual_length</span>(), <span class="number">6</span>);
} <span class="kw">else</span> {
<span class="ident">print_output</span>(<span class="kw-2">&</span><span class="ident">compressed</span>);
<span class="macro">panic!</span>();
}
}
<span class="kw">fn</span> <span class="ident">roundtrip</span>(<span class="ident">data</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>]) {
<span class="kw">let</span> <span class="ident">compressed</span> <span class="op">=</span> <span class="kw">super</span><span class="ident">::lz77_compress</span>(<span class="kw-2">&</span><span class="ident">data</span>).<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">decompressed</span> <span class="op">=</span> <span class="ident">decompress_lz77</span>(<span class="kw-2">&</span><span class="ident">compressed</span>);
<span class="macro">assert!</span>(<span class="ident">decompressed</span> <span class="op">=</span><span class="op">=</span> <span class="ident">data</span>);
}
<span class="comment">// Check that data with the exact window size is working properly</span>
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="attribute">#[<span class="ident">allow</span>(<span class="ident">unused</span>)]</span>
<span class="kw">fn</span> <span class="ident">exact_window_size</span>() {
<span class="kw">use</span> <span class="ident">std::io::Write</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">data</span> <span class="op">=</span> <span class="macro">vec!</span>[<span class="number">0</span>; <span class="ident">WINDOW_SIZE</span>];
<span class="ident">roundtrip</span>(<span class="kw-2">&</span><span class="ident">data</span>);
{
<span class="ident">data</span>.<span class="ident">write</span>(<span class="kw-2">&</span>[<span class="number">22</span>; <span class="ident">WINDOW_SIZE</span>]);
}
<span class="ident">roundtrip</span>(<span class="kw-2">&</span><span class="ident">data</span>);
{
<span class="ident">data</span>.<span class="ident">write</span>(<span class="kw-2">&</span>[<span class="number">55</span>; <span class="ident">WINDOW_SIZE</span>]);
}
<span class="ident">roundtrip</span>(<span class="kw-2">&</span><span class="ident">data</span>);
}
<span class="doccomment">/// Test that matches at the window border are working correctly</span>
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">border</span>() {
<span class="kw">use</span> <span class="ident">chained_hash_table::WINDOW_SIZE</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">data</span> <span class="op">=</span> <span class="macro">vec!</span>[<span class="number">35</span>; <span class="ident">WINDOW_SIZE</span>];
<span class="ident">data</span>.<span class="ident">extend</span>(<span class="string">b"Test"</span>);
<span class="kw">let</span> <span class="ident">compressed</span> <span class="op">=</span> <span class="kw">super</span><span class="ident">::lz77_compress</span>(<span class="kw-2">&</span><span class="ident">data</span>).<span class="ident">unwrap</span>();
<span class="macro">assert!</span>(<span class="ident">compressed</span>.<span class="ident">len</span>() <span class="op"><</span> <span class="ident">data</span>.<span class="ident">len</span>());
<span class="kw">let</span> <span class="ident">decompressed</span> <span class="op">=</span> <span class="ident">decompress_lz77</span>(<span class="kw-2">&</span><span class="ident">compressed</span>);
<span class="macro">assert_eq!</span>(<span class="ident">decompressed</span>.<span class="ident">len</span>(), <span class="ident">data</span>.<span class="ident">len</span>());
<span class="macro">assert!</span>(<span class="ident">decompressed</span> <span class="op">=</span><span class="op">=</span> <span class="ident">data</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">border_multiple_blocks</span>() {
<span class="kw">use</span> <span class="ident">chained_hash_table::WINDOW_SIZE</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">data</span> <span class="op">=</span> <span class="macro">vec!</span>[<span class="number">0</span>; (<span class="ident">WINDOW_SIZE</span> <span class="op">*</span> <span class="number">2</span>) <span class="op">+</span> <span class="number">50</span>];
<span class="ident">data</span>.<span class="ident">push</span>(<span class="number">1</span>);
<span class="kw">let</span> <span class="ident">compressed</span> <span class="op">=</span> <span class="kw">super</span><span class="ident">::lz77_compress</span>(<span class="kw-2">&</span><span class="ident">data</span>).<span class="ident">unwrap</span>();
<span class="macro">assert!</span>(<span class="ident">compressed</span>.<span class="ident">len</span>() <span class="op"><</span> <span class="ident">data</span>.<span class="ident">len</span>());
<span class="kw">let</span> <span class="ident">decompressed</span> <span class="op">=</span> <span class="ident">decompress_lz77</span>(<span class="kw-2">&</span><span class="ident">compressed</span>);
<span class="macro">assert_eq!</span>(<span class="ident">decompressed</span>.<span class="ident">len</span>(), <span class="ident">data</span>.<span class="ident">len</span>());
<span class="macro">assert!</span>(<span class="ident">decompressed</span> <span class="op">=</span><span class="op">=</span> <span class="ident">data</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">compress_block_status</span>() {
<span class="kw">use</span> <span class="ident">input_buffer::InputBuffer</span>;
<span class="kw">let</span> <span class="ident">data</span> <span class="op">=</span> <span class="string">b"Test data data"</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">writer</span> <span class="op">=</span> <span class="ident">DynamicWriter::new</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">buffer</span> <span class="op">=</span> <span class="ident">InputBuffer::empty</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">state</span> <span class="op">=</span> <span class="ident">LZ77State::new</span>(<span class="number">4096</span>, <span class="ident">DEFAULT_LAZY_IF_LESS_THAN</span>, <span class="ident">MatchingType::Lazy</span>);
<span class="kw">let</span> <span class="ident">status</span> <span class="op">=</span> <span class="ident">lz77_compress_block_finish</span>(<span class="ident">data</span>, <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">state</span>, <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">buffer</span>, <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">writer</span>);
<span class="macro">assert_eq!</span>(<span class="ident">status</span>.<span class="number">1</span>, <span class="ident">LZ77Status::Finished</span>);
<span class="macro">assert!</span>(<span class="kw-2">&</span><span class="ident">buffer</span>.<span class="ident">get_buffer</span>()[..<span class="ident">data</span>.<span class="ident">len</span>()] <span class="op">=</span><span class="op">=</span> <span class="ident">data</span>);
<span class="macro">assert_eq!</span>(<span class="ident">buffer</span>.<span class="ident">current_end</span>(), <span class="ident">data</span>.<span class="ident">len</span>());
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">compress_block_multiple_windows</span>() {
<span class="kw">use</span> <span class="ident">input_buffer::InputBuffer</span>;
<span class="kw">use</span> <span class="ident">output_writer::DynamicWriter</span>;
<span class="kw">let</span> <span class="ident">data</span> <span class="op">=</span> <span class="ident">get_test_data</span>();
<span class="macro">assert!</span>(<span class="ident">data</span>.<span class="ident">len</span>() <span class="op">></span> (<span class="ident">WINDOW_SIZE</span> <span class="op">*</span> <span class="number">2</span>) <span class="op">+</span> <span class="kw">super</span><span class="ident">::MAX_MATCH</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">writer</span> <span class="op">=</span> <span class="ident">DynamicWriter::new</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">buffer</span> <span class="op">=</span> <span class="ident">InputBuffer::empty</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">state</span> <span class="op">=</span> <span class="ident">LZ77State::new</span>(<span class="number">0</span>, <span class="ident">DEFAULT_LAZY_IF_LESS_THAN</span>, <span class="ident">MatchingType::Lazy</span>);
<span class="kw">let</span> (<span class="ident">bytes_consumed</span>, <span class="ident">status</span>) <span class="op">=</span>
<span class="ident">lz77_compress_block_finish</span>(<span class="kw-2">&</span><span class="ident">data</span>, <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">state</span>, <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">buffer</span>, <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">writer</span>);
<span class="macro">assert_eq!</span>(
<span class="ident">buffer</span>.<span class="ident">get_buffer</span>().<span class="ident">len</span>(),
(<span class="ident">WINDOW_SIZE</span> <span class="op">*</span> <span class="number">2</span>) <span class="op">+</span> <span class="kw">super</span><span class="ident">::MAX_MATCH</span>
);
<span class="macro">assert_eq!</span>(<span class="ident">status</span>, <span class="ident">LZ77Status::EndBlock</span>);
<span class="kw">let</span> <span class="ident">buf_len</span> <span class="op">=</span> <span class="ident">buffer</span>.<span class="ident">get_buffer</span>().<span class="ident">len</span>();
<span class="macro">assert!</span>(<span class="ident">buffer</span>.<span class="ident">get_buffer</span>()[..] <span class="op">=</span><span class="op">=</span> <span class="ident">data</span>[..<span class="ident">buf_len</span>]);
<span class="ident">writer</span>.<span class="ident">clear</span>();
<span class="kw">let</span> (<span class="kw">_</span>, <span class="ident">status</span>) <span class="op">=</span> <span class="ident">lz77_compress_block_finish</span>(
<span class="kw-2">&</span><span class="ident">data</span>[<span class="ident">bytes_consumed</span>..],
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">state</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">buffer</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">writer</span>,
);
<span class="macro">assert_eq!</span>(<span class="ident">status</span>, <span class="ident">LZ77Status::EndBlock</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">multiple_inputs</span>() {
<span class="kw">let</span> <span class="ident">data</span> <span class="op">=</span> <span class="string">b"Badger badger bababa test data 25 asfgestghresjkgh"</span>;
<span class="kw">let</span> <span class="ident">comp1</span> <span class="op">=</span> <span class="ident">lz77_compress</span>(<span class="ident">data</span>).<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">comp2</span> <span class="op">=</span> {
<span class="kw">const</span> <span class="ident">SPLIT</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="number">25</span>;
<span class="kw">let</span> <span class="ident">first_part</span> <span class="op">=</span> <span class="kw-2">&</span><span class="ident">data</span>[..<span class="ident">SPLIT</span>];
<span class="kw">let</span> <span class="ident">second_part</span> <span class="op">=</span> <span class="kw-2">&</span><span class="ident">data</span>[<span class="ident">SPLIT</span>..];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">state</span> <span class="op">=</span> <span class="ident">TestStruct::new</span>();
<span class="kw">let</span> (<span class="ident">bytes_written</span>, <span class="ident">status</span>, <span class="kw">_</span>) <span class="op">=</span> <span class="ident">state</span>.<span class="ident">compress_block</span>(<span class="ident">first_part</span>, <span class="bool-val">false</span>);
<span class="macro">assert_eq!</span>(<span class="ident">bytes_written</span>, <span class="ident">first_part</span>.<span class="ident">len</span>());
<span class="macro">assert_eq!</span>(<span class="ident">status</span>, <span class="ident">LZ77Status::NeedInput</span>);
<span class="kw">let</span> (<span class="ident">bytes_written</span>, <span class="ident">status</span>, <span class="kw">_</span>) <span class="op">=</span> <span class="ident">state</span>.<span class="ident">compress_block</span>(<span class="ident">second_part</span>, <span class="bool-val">true</span>);
<span class="macro">assert_eq!</span>(<span class="ident">bytes_written</span>, <span class="ident">second_part</span>.<span class="ident">len</span>());
<span class="macro">assert_eq!</span>(<span class="ident">status</span>, <span class="ident">LZ77Status::Finished</span>);
<span class="ident">Vec::from</span>(<span class="ident">state</span>.<span class="ident">writer</span>.<span class="ident">get_buffer</span>())
};
<span class="macro">assert!</span>(<span class="ident">comp1</span> <span class="op">=</span><span class="op">=</span> <span class="ident">comp2</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="doccomment">/// Test that the exit from process_chunk when buffer is full is working correctly.</span>
<span class="kw">fn</span> <span class="ident">buffer_fill</span>() {
<span class="kw">let</span> <span class="ident">data</span> <span class="op">=</span> <span class="ident">get_test_data</span>();
<span class="comment">// The comments above these calls refers the positions with the</span>
<span class="comment">// corersponding comments in process_chunk_{greedy/lazy}.</span>
<span class="comment">// POS BETTER OR NO MATCH</span>
<span class="ident">buffer_test_literals</span>(<span class="kw-2">&</span><span class="ident">data</span>);
<span class="comment">// POS END</span>
<span class="comment">// POS NO MATCH</span>
<span class="ident">buffer_test_last_bytes</span>(<span class="ident">MatchingType::Greedy</span>, <span class="kw-2">&</span><span class="ident">data</span>);
<span class="comment">// POS ADD</span>
<span class="comment">// POS AFTER ADD</span>
<span class="ident">buffer_test_last_bytes</span>(<span class="ident">MatchingType::Lazy</span>, <span class="kw-2">&</span><span class="ident">data</span>);
<span class="comment">// POS MATCH</span>
<span class="ident">buffer_test_match</span>(<span class="ident">MatchingType::Greedy</span>);
<span class="comment">// POS MATCH(lazy)</span>
<span class="ident">buffer_test_match</span>(<span class="ident">MatchingType::Lazy</span>);
<span class="comment">// POS END</span>
<span class="ident">buffer_test_add_end</span>(<span class="kw-2">&</span><span class="ident">data</span>);
}
<span class="doccomment">/// Test buffer fill when a byte is added due to no match being found.</span>
<span class="kw">fn</span> <span class="ident">buffer_test_literals</span>(<span class="ident">data</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>]) {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">state</span> <span class="op">=</span> <span class="ident">TestStruct::with_config</span>(<span class="number">0</span>, <span class="ident">NO_RLE</span>, <span class="ident">MatchingType::Lazy</span>);
<span class="kw">let</span> (<span class="ident">bytes_consumed</span>, <span class="ident">status</span>, <span class="ident">position</span>) <span class="op">=</span> <span class="ident">state</span>.<span class="ident">compress_block</span>(<span class="kw-2">&</span><span class="ident">data</span>, <span class="bool-val">false</span>);
<span class="comment">// There should be enough data for the block to have ended.</span>
<span class="macro">assert_eq!</span>(<span class="ident">status</span>, <span class="ident">LZ77Status::EndBlock</span>);
<span class="macro">assert!</span>(<span class="ident">bytes_consumed</span> <span class="op"><</span><span class="op">=</span> (<span class="ident">WINDOW_SIZE</span> <span class="op">*</span> <span class="number">2</span>) <span class="op">+</span> <span class="ident">MAX_MATCH</span>);
<span class="comment">// The buffer should be full.</span>
<span class="macro">assert_eq!</span>(<span class="ident">state</span>.<span class="ident">writer</span>.<span class="ident">get_buffer</span>().<span class="ident">len</span>(), <span class="ident">MAX_BUFFER_LENGTH</span>);
<span class="macro">assert_eq!</span>(<span class="ident">position</span>, <span class="ident">state</span>.<span class="ident">writer</span>.<span class="ident">get_buffer</span>().<span class="ident">len</span>());
<span class="comment">// Since all literals have been input, the block should have the exact number of litlens</span>
<span class="comment">// as there were input bytes.</span>
<span class="macro">assert_eq!</span>(
<span class="ident">state</span>.<span class="ident">state</span>.<span class="ident">current_block_input_bytes</span>() <span class="kw">as</span> <span class="ident">usize</span>,
<span class="ident">MAX_BUFFER_LENGTH</span>
);
<span class="ident">state</span>.<span class="ident">state</span>.<span class="ident">reset_input_bytes</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">out</span> <span class="op">=</span> <span class="ident">decompress_lz77</span>(<span class="ident">state</span>.<span class="ident">writer</span>.<span class="ident">get_buffer</span>());
<span class="ident">state</span>.<span class="ident">writer</span>.<span class="ident">clear</span>();
<span class="comment">// The buffer should now be cleared.</span>
<span class="macro">assert_eq!</span>(<span class="ident">state</span>.<span class="ident">writer</span>.<span class="ident">get_buffer</span>().<span class="ident">len</span>(), <span class="number">0</span>);
<span class="macro">assert!</span>(<span class="ident">data</span>[..<span class="ident">out</span>.<span class="ident">len</span>()] <span class="op">=</span><span class="op">=</span> <span class="ident">out</span>[..]);
<span class="kw">let</span> <span class="kw">_</span> <span class="op">=</span> <span class="ident">state</span>.<span class="ident">compress_block</span>(<span class="kw-2">&</span><span class="ident">data</span>[<span class="ident">bytes_consumed</span>..], <span class="bool-val">false</span>);
<span class="comment">// We should have some new data in the buffer at this point.</span>
<span class="macro">assert!</span>(<span class="ident">state</span>.<span class="ident">writer</span>.<span class="ident">get_buffer</span>().<span class="ident">len</span>() <span class="op">></span> <span class="number">0</span>);
<span class="macro">assert_eq!</span>(
<span class="ident">state</span>.<span class="ident">state</span>.<span class="ident">current_block_input_bytes</span>() <span class="kw">as</span> <span class="ident">usize</span>,
<span class="ident">MAX_BUFFER_LENGTH</span>
);
<span class="ident">out</span>.<span class="ident">extend_from_slice</span>(<span class="kw-2">&</span><span class="ident">decompress_lz77</span>(<span class="ident">state</span>.<span class="ident">writer</span>.<span class="ident">get_buffer</span>()));
<span class="macro">assert!</span>(<span class="ident">data</span>[..<span class="ident">out</span>.<span class="ident">len</span>()] <span class="op">=</span><span class="op">=</span> <span class="ident">out</span>[..]);
}
<span class="doccomment">/// Test buffer fill at the last two bytes that are not hashed.</span>
<span class="kw">fn</span> <span class="ident">buffer_test_last_bytes</span>(<span class="ident">matching_type</span>: <span class="ident">MatchingType</span>, <span class="ident">data</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>]) {
<span class="kw">const</span> <span class="ident">BYTES_USED</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="ident">MAX_BUFFER_LENGTH</span>;
<span class="macro">assert!</span>(
<span class="kw-2">&</span><span class="ident">data</span>[..<span class="ident">BYTES_USED</span>] <span class="op">=</span><span class="op">=</span>
<span class="kw-2">&</span><span class="ident">decompress_lz77</span>(<span class="kw-2">&</span><span class="ident">lz77_compress_conf</span>(
<span class="kw-2">&</span><span class="ident">data</span>[..<span class="ident">BYTES_USED</span>],
<span class="number">0</span>,
<span class="ident">NO_RLE</span>,
<span class="ident">matching_type</span>,
).<span class="ident">unwrap</span>())
[..]
);
<span class="macro">assert!</span>(
<span class="kw-2">&</span><span class="ident">data</span>[..<span class="ident">BYTES_USED</span> <span class="op">+</span> <span class="number">1</span>] <span class="op">=</span><span class="op">=</span>
<span class="kw-2">&</span><span class="ident">decompress_lz77</span>(<span class="kw-2">&</span><span class="ident">lz77_compress_conf</span>(
<span class="kw-2">&</span><span class="ident">data</span>[..<span class="ident">BYTES_USED</span> <span class="op">+</span> <span class="number">1</span>],
<span class="number">0</span>,
<span class="ident">NO_RLE</span>,
<span class="ident">matching_type</span>,
).<span class="ident">unwrap</span>())
[..]
);
}
<span class="doccomment">/// Test buffer fill when buffer is full at a match.</span>
<span class="kw">fn</span> <span class="ident">buffer_test_match</span>(<span class="ident">matching_type</span>: <span class="ident">MatchingType</span>) {
<span class="comment">// TODO: Also test this for the second block to make sure</span>
<span class="comment">// buffer is slid.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">state</span> <span class="op">=</span> <span class="ident">TestStruct::with_config</span>(<span class="number">1</span>, <span class="number">0</span>, <span class="ident">matching_type</span>);
<span class="kw">for</span> <span class="kw">_</span> <span class="kw">in</span> <span class="number">0</span>..<span class="ident">MAX_BUFFER_LENGTH</span> <span class="op">-</span> <span class="number">4</span> {
<span class="macro">assert!</span>(<span class="ident">state</span>.<span class="ident">writer</span>.<span class="ident">write_literal</span>(<span class="number">0</span>) <span class="op">=</span><span class="op">=</span> <span class="ident">BufferStatus::NotFull</span>);
}
<span class="ident">state</span>.<span class="ident">compress_block</span>(<span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>], <span class="bool-val">true</span>);
<span class="macro">assert!</span>(<span class="kw-2">*</span><span class="ident">state</span>.<span class="ident">writer</span>.<span class="ident">get_buffer</span>().<span class="ident">last</span>().<span class="ident">unwrap</span>() <span class="op">=</span><span class="op">=</span> <span class="ident">LZValue::length_distance</span>(<span class="number">3</span>, <span class="number">3</span>));
}
<span class="doccomment">/// Test buffer fill for the lazy match algorithm when adding a pending byte at the end.</span>
<span class="kw">fn</span> <span class="ident">buffer_test_add_end</span>(<span class="ident">_data</span>: <span class="kw-2">&</span>[<span class="ident">u8</span>]) {
<span class="comment">// This is disabled while the buffer size has not been stabilized.</span>
<span class="comment">/*
let mut state = TestStruct::with_config(DEFAULT_MAX_HASH_CHECKS,
DEFAULT_LAZY_IF_LESS_THAN,
MatchingType::Lazy);
// For the test file, this is how much data needs to be added to get the buffer
// full at the right spot to test that this buffer full exit is workong correctly.
for i in 0..31743 {
assert!(state.writer.write_literal(0) == BufferStatus::NotFull, "Buffer pos: {}", i);
}
let dec = decompress_lz77(&state.writer.get_buffer()[pos..]);
assert!(dec.len() > 0);
assert!(dec[..] == data[..dec.len()]);
*/</span>
}
<span class="doccomment">/// Check that decompressing lz77-data that refers to the back-buffer works.</span>
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_decompress_with_backbuffer</span>() {
<span class="kw">let</span> <span class="ident">bb</span> <span class="op">=</span> <span class="macro">vec!</span>[<span class="number">5</span>; <span class="ident">WINDOW_SIZE</span>];
<span class="kw">let</span> <span class="ident">lz_compressed</span> <span class="op">=</span> [<span class="ident">lit</span>(<span class="number">2</span>), <span class="ident">lit</span>(<span class="number">4</span>), <span class="ident">ld</span>(<span class="number">4</span>, <span class="number">20</span>), <span class="ident">lit</span>(<span class="number">1</span>), <span class="ident">lit</span>(<span class="number">1</span>), <span class="ident">ld</span>(<span class="number">5</span>, <span class="number">10</span>)];
<span class="kw">let</span> <span class="ident">dec</span> <span class="op">=</span> <span class="ident">decompress_lz77_with_backbuffer</span>(<span class="kw-2">&</span><span class="ident">lz_compressed</span>, <span class="kw-2">&</span><span class="ident">bb</span>);
<span class="comment">// ------------l2 l4 <-ld4,20-> l1 l1 <---ld5,10--></span>
<span class="macro">assert!</span>(<span class="ident">dec</span> <span class="op">=</span><span class="op">=</span> [<span class="number">2</span>, <span class="number">4</span>, <span class="number">5</span>, <span class="number">5</span>, <span class="number">5</span>, <span class="number">5</span>, <span class="number">1</span>, <span class="number">1</span>, <span class="number">5</span>, <span class="number">5</span>, <span class="number">2</span>, <span class="number">4</span>, <span class="number">5</span>]);
}
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">all</span>(<span class="ident">test</span>, <span class="ident">feature</span> <span class="op">=</span> <span class="string">"benchmarks"</span>))]</span>
<span class="kw">mod</span> <span class="ident">bench</span> {
<span class="kw">use</span> <span class="ident">test_std::Bencher</span>;
<span class="kw">use</span> <span class="ident">test_utils::get_test_data</span>;
<span class="kw">use</span> <span class="kw">super</span><span class="ident">::lz77_compress</span>;
<span class="attribute">#[<span class="ident">bench</span>]</span>
<span class="kw">fn</span> <span class="ident">test_file_zlib_lz77_only</span>(<span class="ident">b</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">Bencher</span>) {
<span class="kw">let</span> <span class="ident">test_data</span> <span class="op">=</span> <span class="ident">get_test_data</span>();
<span class="ident">b</span>.<span class="ident">iter</span>(<span class="op">|</span><span class="op">|</span> <span class="ident">lz77_compress</span>(<span class="kw-2">&</span><span class="ident">test_data</span>));
}
}
</pre></div>
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