c/enc/metablock.h

/* 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 "../common/context.h"
#include "../common/platform.h"
#include <brotli/types.h>
#include "./block_splitter.h"
#include "./command.h"
#include "./histogram.h"
#include "./memory.h"
#include "./quality.h"

#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif

typedef struct MetaBlockSplit {
  BlockSplit literal_split;
  BlockSplit command_split;
  BlockSplit distance_split;
  uint32_t* literal_context_map;
  size_t literal_context_map_size;
  uint32_t* distance_context_map;
  size_t distance_context_map_size;
  HistogramLiteral* literal_histograms;
  size_t literal_histograms_size;
  HistogramCommand* command_histograms;
  size_t command_histograms_size;
  HistogramDistance* distance_histograms;
  size_t distance_histograms_size;
} MetaBlockSplit;

static BROTLI_INLINE void InitMetaBlockSplit(MetaBlockSplit* mb) {
  BrotliInitBlockSplit(&mb->literal_split);
  BrotliInitBlockSplit(&mb->command_split);
  BrotliInitBlockSplit(&mb->distance_split);
  mb->literal_context_map = 0;
  mb->literal_context_map_size = 0;
  mb->distance_context_map = 0;
  mb->distance_context_map_size = 0;
  mb->literal_histograms = 0;
  mb->literal_histograms_size = 0;
  mb->command_histograms = 0;
  mb->command_histograms_size = 0;
  mb->distance_histograms = 0;
  mb->distance_histograms_size = 0;
}

static BROTLI_INLINE void DestroyMetaBlockSplit(
    MemoryManager* m, MetaBlockSplit* mb) {
  BrotliDestroyBlockSplit(m, &mb->literal_split);
  BrotliDestroyBlockSplit(m, &mb->command_split);
  BrotliDestroyBlockSplit(m, &mb->distance_split);
  BROTLI_FREE(m, mb->literal_context_map);
  BROTLI_FREE(m, mb->distance_context_map);
  BROTLI_FREE(m, mb->literal_histograms);
  BROTLI_FREE(m, mb->command_histograms);
  BROTLI_FREE(m, mb->distance_histograms);
}

/* Uses the slow shortest-path block splitter and does context clustering. */
BROTLI_INTERNAL void BrotliBuildMetaBlock(MemoryManager* m,
                                          const uint8_t* ringbuffer,
                                          const size_t pos,
                                          const size_t mask,
                                          const BrotliEncoderParams* params,
                                          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 uses a static context clustering which
   is the same for all block types. */
BROTLI_INTERNAL void BrotliBuildMetaBlockGreedy(
    MemoryManager* m, const uint8_t* ringbuffer, size_t pos, size_t mask,
    uint8_t prev_byte, uint8_t prev_byte2, ContextLut literal_context_lut,
    size_t num_contexts, const uint32_t* static_context_map,
    const Command* commands, size_t n_commands, MetaBlockSplit* mb);

BROTLI_INTERNAL void BrotliOptimizeHistograms(uint32_t num_distance_codes,
                                              MetaBlockSplit* mb);

#if defined(__cplusplus) || defined(c_plusplus)
}  /* extern "C" */
#endif

#endif  /* BROTLI_ENC_METABLOCK_H_ */