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https://github.com/google/brotli.git
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Update encoder (#492)
* fix comment position in `context.h` * fix typo in internal quality constant name * deduplicate `BuildMetaBlockGreedy` code * simplify aggregation in `ChooseContextMap`
This commit is contained in:
parent
27d94590a2
commit
7e347a7c84
@ -127,9 +127,9 @@ static const uint8_t kUTF8ContextLookup[512] = {
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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/* UTF8 lead byte range. */
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
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2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
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};
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32
enc/encode.c
32
enc/encode.c
@ -330,18 +330,13 @@ static void ChooseContextMap(int quality,
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uint32_t monogram_histo[3] = { 0 };
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uint32_t two_prefix_histo[6] = { 0 };
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size_t total = 0;
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size_t total;
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size_t i;
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size_t dummy;
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double entropy[4];
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for (i = 0; i < 9; ++i) {
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size_t j = i;
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total += bigram_histo[i];
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monogram_histo[i % 3] += bigram_histo[i];
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if (j >= 6) {
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j -= 6;
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}
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two_prefix_histo[j] += bigram_histo[i];
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two_prefix_histo[i % 6] += bigram_histo[i];
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}
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entropy[1] = ShannonEntropy(monogram_histo, 3, &dummy);
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entropy[2] = (ShannonEntropy(two_prefix_histo, 3, &dummy) +
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@ -351,6 +346,7 @@ static void ChooseContextMap(int quality,
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entropy[3] += ShannonEntropy(bigram_histo + 3 * i, 3, &dummy);
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}
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total = monogram_histo[0] + monogram_histo[1] + monogram_histo[2];
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assert(total != 0);
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entropy[0] = 1.0 / (double)total;
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entropy[1] *= entropy[0];
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@ -480,7 +476,7 @@ static void WriteMetaBlockInternal(MemoryManager* m,
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num_direct_distance_codes,
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distance_postfix_bits);
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}
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if (params->quality <= MAX_QUALITY_FOR_STATIC_ENRTOPY_CODES) {
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if (params->quality <= MAX_QUALITY_FOR_STATIC_ENTROPY_CODES) {
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BrotliStoreMetaBlockFast(m, data, wrapped_last_flush_pos,
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bytes, mask, is_last,
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commands, num_commands,
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@ -505,22 +501,10 @@ static void WriteMetaBlockInternal(MemoryManager* m,
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&literal_context_mode,
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&num_literal_contexts,
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&literal_context_map);
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if (literal_context_map == NULL) {
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BrotliBuildMetaBlockGreedy(m, data, wrapped_last_flush_pos, mask,
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commands, num_commands, &mb);
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if (BROTLI_IS_OOM(m)) return;
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} else {
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BrotliBuildMetaBlockGreedyWithContexts(m, data,
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wrapped_last_flush_pos,
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mask,
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prev_byte, prev_byte2,
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literal_context_mode,
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num_literal_contexts,
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literal_context_map,
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commands, num_commands,
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&mb);
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if (BROTLI_IS_OOM(m)) return;
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}
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BrotliBuildMetaBlockGreedy(m, data, wrapped_last_flush_pos, mask,
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prev_byte, prev_byte2, literal_context_mode, num_literal_contexts,
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literal_context_map, commands, num_commands, &mb);
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if (BROTLI_IS_OOM(m)) return;
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} else {
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if (!BrotliIsMostlyUTF8(data, wrapped_last_flush_pos, mask, bytes,
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kMinUTF8Ratio)) {
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187
enc/metablock.c
187
enc/metablock.c
@ -136,53 +136,7 @@ void BrotliBuildMetaBlock(MemoryManager* m,
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#include "./metablock_inc.h" /* NOLINT(build/include) */
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#undef FN
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void BrotliBuildMetaBlockGreedy(MemoryManager* m,
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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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BlockSplitterLiteral lit_blocks;
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BlockSplitterCommand cmd_blocks;
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BlockSplitterDistance dist_blocks;
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size_t num_literals = 0;
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size_t i;
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for (i = 0; i < n_commands; ++i) {
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num_literals += commands[i].insert_len_;
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}
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InitBlockSplitterLiteral(m, &lit_blocks, 256, 512, 400.0, num_literals,
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&mb->literal_split, &mb->literal_histograms,
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&mb->literal_histograms_size);
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if (BROTLI_IS_OOM(m)) return;
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InitBlockSplitterCommand(m, &cmd_blocks, BROTLI_NUM_COMMAND_SYMBOLS, 1024,
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500.0, n_commands, &mb->command_split, &mb->command_histograms,
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&mb->command_histograms_size);
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if (BROTLI_IS_OOM(m)) return;
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InitBlockSplitterDistance(m, &dist_blocks, 64, 512, 100.0, n_commands,
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&mb->distance_split, &mb->distance_histograms,
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&mb->distance_histograms_size);
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if (BROTLI_IS_OOM(m)) return;
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for (i = 0; i < n_commands; ++i) {
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const Command cmd = commands[i];
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size_t j;
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BlockSplitterAddSymbolCommand(&cmd_blocks, cmd.cmd_prefix_);
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for (j = cmd.insert_len_; j != 0; --j) {
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BlockSplitterAddSymbolLiteral(&lit_blocks, ringbuffer[pos & mask]);
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++pos;
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}
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pos += CommandCopyLen(&cmd);
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if (CommandCopyLen(&cmd) && cmd.cmd_prefix_ >= 128) {
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BlockSplitterAddSymbolDistance(&dist_blocks, cmd.dist_prefix_);
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}
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}
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BlockSplitterFinishBlockLiteral(&lit_blocks, /* is_final = */ BROTLI_TRUE);
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BlockSplitterFinishBlockCommand(&cmd_blocks, /* is_final = */ BROTLI_TRUE);
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BlockSplitterFinishBlockDistance(&dist_blocks, /* is_final = */ BROTLI_TRUE);
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}
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#define BROTLI_MAX_STATIC_CONTEXTS 3
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/* Greedy block splitter for one block category (literal, command or distance).
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Gathers histograms for all context buckets. */
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@ -214,7 +168,7 @@ typedef struct ContextBlockSplitter {
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/* Offset of the histograms of the previous two block types. */
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size_t last_histogram_ix_[2];
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/* Entropy of the previous two block types. */
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double* last_entropy_;
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double last_entropy_[2 * BROTLI_MAX_STATIC_CONTEXTS];
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/* The number of times we merged the current block with the last one. */
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size_t merge_last_count_;
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} ContextBlockSplitter;
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@ -226,6 +180,7 @@ static void InitContextBlockSplitter(
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size_t* histograms_size) {
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size_t max_num_blocks = num_symbols / min_block_size + 1;
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size_t max_num_types;
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assert(num_contexts <= BROTLI_MAX_STATIC_CONTEXTS);
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self->alphabet_size_ = alphabet_size;
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self->num_contexts_ = num_contexts;
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@ -250,7 +205,6 @@ static void InitContextBlockSplitter(
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split->lengths, split->lengths_alloc_size, max_num_blocks);
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if (BROTLI_IS_OOM(m)) return;
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split->num_blocks = max_num_blocks;
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self->last_entropy_ = BROTLI_ALLOC(m, double, 2 * num_contexts);
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if (BROTLI_IS_OOM(m)) return;
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assert(*histograms == 0);
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*histograms_size = max_num_types * num_contexts;
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@ -262,17 +216,12 @@ static void InitContextBlockSplitter(
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self->last_histogram_ix_[0] = self->last_histogram_ix_[1] = 0;
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}
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static void CleanupContextBlockSplitter(
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MemoryManager* m, ContextBlockSplitter* self) {
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BROTLI_FREE(m, self->last_entropy_);
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}
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/* Does either of three things:
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(1) emits the current block with a new block type;
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(2) emits the current block with the type of the second last block;
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(3) merges the current block with the last block. */
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static void ContextBlockSplitterFinishBlock(
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MemoryManager* m, ContextBlockSplitter* self, BROTLI_BOOL is_final) {
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ContextBlockSplitter* self, BROTLI_BOOL is_final) {
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BlockSplit* split = self->split_;
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const size_t num_contexts = self->num_contexts_;
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double* last_entropy = self->last_entropy_;
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@ -305,13 +254,11 @@ static void ContextBlockSplitterFinishBlock(
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respective set of histograms for the last and second last block types.
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Decide over the split based on the total reduction of entropy across
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all contexts. */
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double* entropy = BROTLI_ALLOC(m, double, num_contexts);
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HistogramLiteral* combined_histo =
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BROTLI_ALLOC(m, HistogramLiteral, 2 * num_contexts);
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double* combined_entropy = BROTLI_ALLOC(m, double, 2 * num_contexts);
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double entropy[BROTLI_MAX_STATIC_CONTEXTS];
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HistogramLiteral combined_histo[2 * BROTLI_MAX_STATIC_CONTEXTS]; /* 6KiB */
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double combined_entropy[2 * BROTLI_MAX_STATIC_CONTEXTS];
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double diff[2] = { 0.0 };
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size_t i;
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if (BROTLI_IS_OOM(m)) return;
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for (i = 0; i < num_contexts; ++i) {
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size_t curr_histo_ix = self->curr_histogram_ix_ + i;
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size_t j;
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@ -383,9 +330,6 @@ static void ContextBlockSplitterFinishBlock(
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self->target_block_size_ += self->min_block_size_;
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}
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}
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BROTLI_FREE(m, combined_entropy);
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BROTLI_FREE(m, combined_histo);
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BROTLI_FREE(m, entropy);
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}
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if (is_final) {
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*self->histograms_size_ = split->num_types * num_contexts;
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@ -395,30 +339,47 @@ static void ContextBlockSplitterFinishBlock(
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/* Adds the next symbol to the current block type and context. When the
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current block reaches the target size, decides on merging the block. */
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static void ContextBlockSplitterAddSymbol(MemoryManager* m,
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static void ContextBlockSplitterAddSymbol(
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ContextBlockSplitter* self, size_t symbol, size_t context) {
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HistogramAddLiteral(&self->histograms_[self->curr_histogram_ix_ + context],
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symbol);
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++self->block_size_;
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if (self->block_size_ == self->target_block_size_) {
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ContextBlockSplitterFinishBlock(m, self, /* is_final = */ BROTLI_FALSE);
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if (BROTLI_IS_OOM(m)) return;
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ContextBlockSplitterFinishBlock(self, /* is_final = */ BROTLI_FALSE);
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}
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}
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void BrotliBuildMetaBlockGreedyWithContexts(MemoryManager* m,
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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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ContextBlockSplitter lit_blocks;
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static void MapStaticContexts(MemoryManager* m,
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size_t num_contexts,
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const uint32_t* static_context_map,
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MetaBlockSplit* mb) {
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size_t i;
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assert(mb->literal_context_map == 0);
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mb->literal_context_map_size =
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mb->literal_split.num_types << BROTLI_LITERAL_CONTEXT_BITS;
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mb->literal_context_map =
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BROTLI_ALLOC(m, uint32_t, mb->literal_context_map_size);
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if (BROTLI_IS_OOM(m)) return;
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for (i = 0; i < mb->literal_split.num_types; ++i) {
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uint32_t offset = (uint32_t)(i * num_contexts);
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size_t j;
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for (j = 0; j < (1u << BROTLI_LITERAL_CONTEXT_BITS); ++j) {
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mb->literal_context_map[(i << BROTLI_LITERAL_CONTEXT_BITS) + j] =
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offset + static_context_map[j];
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}
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}
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}
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static BROTLI_INLINE void BrotliBuildMetaBlockGreedyInternal(
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MemoryManager* m, const uint8_t* ringbuffer, size_t pos, size_t mask,
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uint8_t prev_byte, uint8_t prev_byte2, ContextType literal_context_mode,
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const size_t num_contexts, const uint32_t* static_context_map,
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const Command *commands, size_t n_commands, MetaBlockSplit* mb) {
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union {
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BlockSplitterLiteral plain;
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ContextBlockSplitter ctx;
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} lit_blocks;
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BlockSplitterCommand cmd_blocks;
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BlockSplitterDistance dist_blocks;
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size_t num_literals = 0;
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@ -427,9 +388,15 @@ void BrotliBuildMetaBlockGreedyWithContexts(MemoryManager* m,
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num_literals += commands[i].insert_len_;
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}
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InitContextBlockSplitter(m, &lit_blocks, 256, num_contexts, 512, 400.0,
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num_literals, &mb->literal_split, &mb->literal_histograms,
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&mb->literal_histograms_size);
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if (num_contexts == 1) {
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InitBlockSplitterLiteral(m, &lit_blocks.plain, 256, 512, 400.0,
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num_literals, &mb->literal_split, &mb->literal_histograms,
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&mb->literal_histograms_size);
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} else {
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InitContextBlockSplitter(m, &lit_blocks.ctx, 256, num_contexts, 512, 400.0,
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num_literals, &mb->literal_split, &mb->literal_histograms,
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&mb->literal_histograms_size);
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}
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if (BROTLI_IS_OOM(m)) return;
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InitBlockSplitterCommand(m, &cmd_blocks, BROTLI_NUM_COMMAND_SYMBOLS, 1024,
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500.0, n_commands, &mb->command_split, &mb->command_histograms,
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@ -445,12 +412,15 @@ void BrotliBuildMetaBlockGreedyWithContexts(MemoryManager* m,
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size_t j;
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BlockSplitterAddSymbolCommand(&cmd_blocks, cmd.cmd_prefix_);
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for (j = cmd.insert_len_; j != 0; --j) {
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size_t context = Context(prev_byte, prev_byte2, literal_context_mode);
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uint8_t literal = ringbuffer[pos & mask];
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ContextBlockSplitterAddSymbol(
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m, &lit_blocks, literal, static_context_map[context]);
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if (num_contexts == 1) {
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BlockSplitterAddSymbolLiteral(&lit_blocks.plain, literal);
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} else {
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size_t context = Context(prev_byte, prev_byte2, literal_context_mode);
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ContextBlockSplitterAddSymbol(&lit_blocks.ctx, literal,
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static_context_map[context]);
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}
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prev_byte2 = prev_byte;
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if (BROTLI_IS_OOM(m)) return;
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prev_byte = literal;
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++pos;
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}
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@ -464,25 +434,40 @@ void BrotliBuildMetaBlockGreedyWithContexts(MemoryManager* m,
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}
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}
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ContextBlockSplitterFinishBlock(m, &lit_blocks, /* is_final = */ BROTLI_TRUE);
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if (BROTLI_IS_OOM(m)) return;
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CleanupContextBlockSplitter(m, &lit_blocks);
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if (num_contexts == 1) {
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BlockSplitterFinishBlockLiteral(
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&lit_blocks.plain, /* is_final = */ BROTLI_TRUE);
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} else {
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ContextBlockSplitterFinishBlock(
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&lit_blocks.ctx, /* is_final = */ BROTLI_TRUE);
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}
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BlockSplitterFinishBlockCommand(&cmd_blocks, /* is_final = */ BROTLI_TRUE);
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BlockSplitterFinishBlockDistance(&dist_blocks, /* is_final = */ BROTLI_TRUE);
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assert(mb->literal_context_map == 0);
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mb->literal_context_map_size =
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mb->literal_split.num_types << BROTLI_LITERAL_CONTEXT_BITS;
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mb->literal_context_map =
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BROTLI_ALLOC(m, uint32_t, mb->literal_context_map_size);
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if (BROTLI_IS_OOM(m)) return;
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if (num_contexts > 1) {
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MapStaticContexts(m, num_contexts, static_context_map, mb);
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}
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}
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for (i = 0; i < mb->literal_split.num_types; ++i) {
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size_t j;
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for (j = 0; j < (1u << BROTLI_LITERAL_CONTEXT_BITS); ++j) {
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mb->literal_context_map[(i << BROTLI_LITERAL_CONTEXT_BITS) + j] =
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(uint32_t)(i * num_contexts) + static_context_map[j];
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}
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void BrotliBuildMetaBlockGreedy(MemoryManager* m,
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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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if (num_contexts == 1) {
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BrotliBuildMetaBlockGreedyInternal(m, ringbuffer, pos, mask, prev_byte,
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prev_byte2, literal_context_mode, 1, NULL, commands, n_commands, mb);
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} else {
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BrotliBuildMetaBlockGreedyInternal(m, ringbuffer, pos, mask, prev_byte,
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prev_byte2, literal_context_mode, num_contexts, static_context_map,
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commands, n_commands, mb);
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}
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}
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@ -80,20 +80,10 @@ BROTLI_INTERNAL void BrotliBuildMetaBlock(MemoryManager* m,
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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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BROTLI_INTERNAL void BrotliBuildMetaBlockGreedy(MemoryManager* m,
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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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BROTLI_INTERNAL void BrotliBuildMetaBlockGreedyWithContexts(
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BROTLI_INTERNAL void BrotliBuildMetaBlockGreedy(
|
||||
MemoryManager* m, 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,
|
||||
|
@ -17,7 +17,7 @@
|
||||
#define ZOPFLIFICATION_QUALITY 10
|
||||
#define HQ_ZOPFLIFICATION_QUALITY 11
|
||||
|
||||
#define MAX_QUALITY_FOR_STATIC_ENRTOPY_CODES 2
|
||||
#define MAX_QUALITY_FOR_STATIC_ENTROPY_CODES 2
|
||||
#define MIN_QUALITY_FOR_BLOCK_SPLIT 4
|
||||
#define MIN_QUALITY_FOR_OPTIMIZE_HISTOGRAMS 4
|
||||
#define MIN_QUALITY_FOR_EXTENSIVE_REFERENCE_SEARCH 5
|
||||
|
Loading…
Reference in New Issue
Block a user