11b7501adc
- Copy Brotli algorithm 3rd party source code for tool Cc: Liming Gao <liming.gao@intel.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Bell Song <binx.song@intel.com> Reviewed-by: Liming Gao <liming.gao@intel.com>
131 lines
4.7 KiB
C
131 lines
4.7 KiB
C
/* Copyright 2016 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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/* Constants and formulas that affect speed-ratio trade-offs and thus define
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quality levels. */
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#ifndef BROTLI_ENC_QUALITY_H_
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#define BROTLI_ENC_QUALITY_H_
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#include "./encode.h"
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#define FAST_ONE_PASS_COMPRESSION_QUALITY 0
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#define FAST_TWO_PASS_COMPRESSION_QUALITY 1
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#define ZOPFLIFICATION_QUALITY 10
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#define HQ_ZOPFLIFICATION_QUALITY 11
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#define MAX_QUALITY_FOR_STATIC_ENRTOPY_CODES 2
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#define MIN_QUALITY_FOR_BLOCK_SPLIT 4
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#define MIN_QUALITY_FOR_OPTIMIZE_HISTOGRAMS 4
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#define MIN_QUALITY_FOR_EXTENSIVE_REFERENCE_SEARCH 5
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#define MIN_QUALITY_FOR_CONTEXT_MODELING 5
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#define MIN_QUALITY_FOR_HQ_CONTEXT_MODELING 7
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#define MIN_QUALITY_FOR_HQ_BLOCK_SPLITTING 10
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/* Only for "font" mode. */
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#define MIN_QUALITY_FOR_RECOMPUTE_DISTANCE_PREFIXES 10
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/* For quality below MIN_QUALITY_FOR_BLOCK_SPLIT there is no block splitting,
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so we buffer at most this much literals and commands. */
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#define MAX_NUM_DELAYED_SYMBOLS 0x2fff
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/* Encoding parameters */
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typedef struct BrotliEncoderParams {
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BrotliEncoderMode mode;
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int quality;
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int lgwin;
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int lgblock;
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} BrotliEncoderParams;
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/* Returns hashtable size for quality levels 0 and 1. */
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static BROTLI_INLINE size_t MaxHashTableSize(int quality) {
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return quality == FAST_ONE_PASS_COMPRESSION_QUALITY ? 1 << 15 : 1 << 17;
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}
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/* The maximum length for which the zopflification uses distinct distances. */
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#define MAX_ZOPFLI_LEN_QUALITY_10 150
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#define MAX_ZOPFLI_LEN_QUALITY_11 325
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static BROTLI_INLINE size_t MaxZopfliLen(const BrotliEncoderParams* params) {
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return params->quality <= 10 ?
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MAX_ZOPFLI_LEN_QUALITY_10 :
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MAX_ZOPFLI_LEN_QUALITY_11;
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}
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/* Number of best candidates to evaluate to expand zopfli chain. */
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static BROTLI_INLINE size_t MaxZopfliCandidates(
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const BrotliEncoderParams* params) {
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return params->quality <= 10 ? 1 : 5;
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}
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static BROTLI_INLINE void SanitizeParams(BrotliEncoderParams* params) {
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params->quality = BROTLI_MIN(int, BROTLI_MAX_QUALITY,
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BROTLI_MAX(int, BROTLI_MIN_QUALITY, params->quality));
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if (params->lgwin < kBrotliMinWindowBits) {
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params->lgwin = kBrotliMinWindowBits;
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} else if (params->lgwin > kBrotliMaxWindowBits) {
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params->lgwin = kBrotliMaxWindowBits;
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}
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}
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/* Returns optimized lg_block value. */
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static BROTLI_INLINE int ComputeLgBlock(const BrotliEncoderParams* params) {
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int lgblock = params->lgblock;
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if (params->quality == FAST_ONE_PASS_COMPRESSION_QUALITY ||
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params->quality == FAST_TWO_PASS_COMPRESSION_QUALITY) {
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lgblock = params->lgwin;
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} else if (params->quality < MIN_QUALITY_FOR_BLOCK_SPLIT) {
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lgblock = 14;
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} else if (lgblock == 0) {
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lgblock = 16;
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if (params->quality >= 9 && params->lgwin > lgblock) {
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lgblock = BROTLI_MIN(int, 18, params->lgwin);
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}
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} else {
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lgblock = BROTLI_MIN(int, kBrotliMaxInputBlockBits,
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BROTLI_MAX(int, kBrotliMinInputBlockBits, lgblock));
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}
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return lgblock;
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}
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/* Returns log2 of the size of main ring buffer area.
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Allocate at least lgwin + 1 bits for the ring buffer so that the newly
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added block fits there completely and we still get lgwin bits and at least
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read_block_size_bits + 1 bits because the copy tail length needs to be
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smaller than ringbuffer size. */
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static BROTLI_INLINE int ComputeRbBits(const BrotliEncoderParams* params) {
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return 1 + BROTLI_MAX(int, params->lgwin, params->lgblock);
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}
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static BROTLI_INLINE size_t MaxMetablockSize(
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const BrotliEncoderParams* params) {
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int bits = BROTLI_MIN(int, ComputeRbBits(params), kBrotliMaxInputBlockBits);
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return (size_t)1 << bits;
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}
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/* When searching for backward references and have not seen matches for a long
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time, we can skip some match lookups. Unsuccessful match lookups are very
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expensive and this kind of a heuristic speeds up compression quite a lot.
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At first 8 byte strides are taken and every second byte is put to hasher.
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After 4x more literals stride by 16 bytes, every put 4-th byte to hasher.
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Applied only to qualities 2 to 9. */
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static BROTLI_INLINE size_t LiteralSpreeLengthForSparseSearch(
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const BrotliEncoderParams* params) {
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return params->quality < 9 ? 64 : 512;
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}
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static BROTLI_INLINE int ChooseHasher(const BrotliEncoderParams* params) {
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if (params->quality > 9) {
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return 10;
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} else if (params->quality < 5) {
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return params->quality;
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} else if (params->lgwin <= 16) {
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return params->quality < 7 ? 40 : params->quality < 9 ? 41 : 42;
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}
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return params->quality;
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}
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#endif /* BROTLI_ENC_QUALITY_H_ */
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