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