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81 lines
2.8 KiB
C++
81 lines
2.8 KiB
C++
/* Copyright 2015 Google Inc. All Rights Reserved.
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Distributed under MIT license.
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See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
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*/
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// Algorithms for distributing the literals and commands of a metablock between
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// block types and contexts.
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#ifndef BROTLI_ENC_METABLOCK_H_
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#define BROTLI_ENC_METABLOCK_H_
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#include <vector>
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#include "./command.h"
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#include "./histogram.h"
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namespace brotli {
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struct BlockSplit {
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BlockSplit() : num_types(0) {}
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size_t num_types;
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std::vector<uint8_t> types;
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std::vector<uint32_t> lengths;
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};
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struct MetaBlockSplit {
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BlockSplit literal_split;
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BlockSplit command_split;
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BlockSplit distance_split;
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std::vector<uint32_t> literal_context_map;
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std::vector<uint32_t> distance_context_map;
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std::vector<HistogramLiteral> literal_histograms;
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std::vector<HistogramCommand> command_histograms;
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std::vector<HistogramDistance> distance_histograms;
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};
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// Uses the slow shortest-path block splitter and does context clustering.
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void BuildMetaBlock(const uint8_t* ringbuffer,
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const size_t pos,
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const size_t mask,
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uint8_t prev_byte,
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uint8_t prev_byte2,
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const Command* cmds,
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size_t num_commands,
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ContextType literal_context_mode,
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MetaBlockSplit* mb);
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// Uses a fast greedy block splitter that tries to merge current block with the
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// last or the second last block and does not do any context modeling.
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void BuildMetaBlockGreedy(const uint8_t* ringbuffer,
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size_t pos,
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size_t mask,
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const Command *commands,
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size_t n_commands,
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MetaBlockSplit* mb);
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// Uses a fast greedy block splitter that tries to merge current block with the
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// last or the second last block and uses a static context clustering which
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// is the same for all block types.
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void BuildMetaBlockGreedyWithContexts(const uint8_t* ringbuffer,
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size_t pos,
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size_t mask,
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uint8_t prev_byte,
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uint8_t prev_byte2,
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ContextType literal_context_mode,
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size_t num_contexts,
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const uint32_t* static_context_map,
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const Command *commands,
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size_t n_commands,
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MetaBlockSplit* mb);
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void OptimizeHistograms(size_t num_direct_distance_codes,
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size_t distance_postfix_bits,
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MetaBlockSplit* mb);
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} // namespace brotli
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#endif // BROTLI_ENC_METABLOCK_H_
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