/* Copyright 2016 Google Inc. All Rights Reserved. Distributed under MIT license. See file LICENSE for detail or copy at https://opensource.org/licenses/MIT */ /* Constants and formulas that affect speed-ratio trade-offs and thus define quality levels. */ #ifndef BROTLI_ENC_QUALITY_H_ #define BROTLI_ENC_QUALITY_H_ #include "../common/platform.h" #include <brotli/encode.h> #include "params.h" #define FAST_ONE_PASS_COMPRESSION_QUALITY … #define FAST_TWO_PASS_COMPRESSION_QUALITY … #define ZOPFLIFICATION_QUALITY … #define HQ_ZOPFLIFICATION_QUALITY … #define MAX_QUALITY_FOR_STATIC_ENTROPY_CODES … #define MIN_QUALITY_FOR_BLOCK_SPLIT … #define MIN_QUALITY_FOR_NONZERO_DISTANCE_PARAMS … #define MIN_QUALITY_FOR_OPTIMIZE_HISTOGRAMS … #define MIN_QUALITY_FOR_EXTENSIVE_REFERENCE_SEARCH … #define MIN_QUALITY_FOR_CONTEXT_MODELING … #define MIN_QUALITY_FOR_HQ_CONTEXT_MODELING … #define MIN_QUALITY_FOR_HQ_BLOCK_SPLITTING … /* For quality below MIN_QUALITY_FOR_BLOCK_SPLIT there is no block splitting, so we buffer at most this much literals and commands. */ #define MAX_NUM_DELAYED_SYMBOLS … /* Returns hash-table size for quality levels 0 and 1. */ static BROTLI_INLINE size_t MaxHashTableSize(int quality) { … } /* The maximum length for which the zopflification uses distinct distances. */ #define MAX_ZOPFLI_LEN_QUALITY_10 … #define MAX_ZOPFLI_LEN_QUALITY_11 … /* Do not thoroughly search when a long copy is found. */ #define BROTLI_LONG_COPY_QUICK_STEP … static BROTLI_INLINE size_t MaxZopfliLen(const BrotliEncoderParams* params) { … } /* Number of best candidates to evaluate to expand Zopfli chain. */ static BROTLI_INLINE size_t MaxZopfliCandidates( const BrotliEncoderParams* params) { … } static BROTLI_INLINE void SanitizeParams(BrotliEncoderParams* params) { … } /* Returns optimized lg_block value. */ static BROTLI_INLINE int ComputeLgBlock(const BrotliEncoderParams* params) { … } /* Returns log2 of the size of main ring buffer area. Allocate at least lgwin + 1 bits for the ring buffer so that the newly added block fits there completely and we still get lgwin bits and at least read_block_size_bits + 1 bits because the copy tail length needs to be smaller than ring-buffer size. */ static BROTLI_INLINE int ComputeRbBits(const BrotliEncoderParams* params) { … } static BROTLI_INLINE size_t MaxMetablockSize( const BrotliEncoderParams* params) { … } /* When searching for backward references and have not seen matches for a long time, we can skip some match lookups. Unsuccessful match lookups are very expensive and this kind of a heuristic speeds up compression quite a lot. At first 8 byte strides are taken and every second byte is put to hasher. After 4x more literals stride by 16 bytes, every put 4-th byte to hasher. Applied only to qualities 2 to 9. */ static BROTLI_INLINE size_t LiteralSpreeLengthForSparseSearch( const BrotliEncoderParams* params) { … } static BROTLI_INLINE void ChooseHasher(const BrotliEncoderParams* params, BrotliHasherParams* hparams) { … } #endif /* BROTLI_ENC_QUALITY_H_ */
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