+++ /dev/null
-/* Copyright 2016 Google Inc. All Rights Reserved.\r
-\r
- Distributed under MIT license.\r
- See file LICENSE for detail or copy at https://opensource.org/licenses/MIT\r
-*/\r
-\r
-/* Constants and formulas that affect speed-ratio trade-offs and thus define\r
- quality levels. */\r
-\r
-#ifndef BROTLI_ENC_QUALITY_H_\r
-#define BROTLI_ENC_QUALITY_H_\r
-\r
-#include "../common/platform.h"\r
-#include <brotli/encode.h>\r
-#include "./params.h"\r
-\r
-#define FAST_ONE_PASS_COMPRESSION_QUALITY 0\r
-#define FAST_TWO_PASS_COMPRESSION_QUALITY 1\r
-#define ZOPFLIFICATION_QUALITY 10\r
-#define HQ_ZOPFLIFICATION_QUALITY 11\r
-\r
-#define MAX_QUALITY_FOR_STATIC_ENTROPY_CODES 2\r
-#define MIN_QUALITY_FOR_BLOCK_SPLIT 4\r
-#define MIN_QUALITY_FOR_NONZERO_DISTANCE_PARAMS 4\r
-#define MIN_QUALITY_FOR_OPTIMIZE_HISTOGRAMS 4\r
-#define MIN_QUALITY_FOR_EXTENSIVE_REFERENCE_SEARCH 5\r
-#define MIN_QUALITY_FOR_CONTEXT_MODELING 5\r
-#define MIN_QUALITY_FOR_HQ_CONTEXT_MODELING 7\r
-#define MIN_QUALITY_FOR_HQ_BLOCK_SPLITTING 10\r
-\r
-/* For quality below MIN_QUALITY_FOR_BLOCK_SPLIT there is no block splitting,\r
- so we buffer at most this much literals and commands. */\r
-#define MAX_NUM_DELAYED_SYMBOLS 0x2FFF\r
-\r
-/* Returns hash-table size for quality levels 0 and 1. */\r
-static BROTLI_INLINE size_t MaxHashTableSize(int quality) {\r
- return quality == FAST_ONE_PASS_COMPRESSION_QUALITY ? 1 << 15 : 1 << 17;\r
-}\r
-\r
-/* The maximum length for which the zopflification uses distinct distances. */\r
-#define MAX_ZOPFLI_LEN_QUALITY_10 150\r
-#define MAX_ZOPFLI_LEN_QUALITY_11 325\r
-\r
-/* Do not thoroughly search when a long copy is found. */\r
-#define BROTLI_LONG_COPY_QUICK_STEP 16384\r
-\r
-static BROTLI_INLINE size_t MaxZopfliLen(const BrotliEncoderParams* params) {\r
- return params->quality <= 10 ?\r
- MAX_ZOPFLI_LEN_QUALITY_10 :\r
- MAX_ZOPFLI_LEN_QUALITY_11;\r
-}\r
-\r
-/* Number of best candidates to evaluate to expand Zopfli chain. */\r
-static BROTLI_INLINE size_t MaxZopfliCandidates(\r
- const BrotliEncoderParams* params) {\r
- return params->quality <= 10 ? 1 : 5;\r
-}\r
-\r
-static BROTLI_INLINE void SanitizeParams(BrotliEncoderParams* params) {\r
- params->quality = BROTLI_MIN(int, BROTLI_MAX_QUALITY,\r
- BROTLI_MAX(int, BROTLI_MIN_QUALITY, params->quality));\r
- if (params->quality <= MAX_QUALITY_FOR_STATIC_ENTROPY_CODES) {\r
- params->large_window = BROTLI_FALSE;\r
- }\r
- if (params->lgwin < BROTLI_MIN_WINDOW_BITS) {\r
- params->lgwin = BROTLI_MIN_WINDOW_BITS;\r
- } else {\r
- int max_lgwin = params->large_window ? BROTLI_LARGE_MAX_WINDOW_BITS :\r
- BROTLI_MAX_WINDOW_BITS;\r
- if (params->lgwin > max_lgwin) params->lgwin = max_lgwin;\r
- }\r
-}\r
-\r
-/* Returns optimized lg_block value. */\r
-static BROTLI_INLINE int ComputeLgBlock(const BrotliEncoderParams* params) {\r
- int lgblock = params->lgblock;\r
- if (params->quality == FAST_ONE_PASS_COMPRESSION_QUALITY ||\r
- params->quality == FAST_TWO_PASS_COMPRESSION_QUALITY) {\r
- lgblock = params->lgwin;\r
- } else if (params->quality < MIN_QUALITY_FOR_BLOCK_SPLIT) {\r
- lgblock = 14;\r
- } else if (lgblock == 0) {\r
- lgblock = 16;\r
- if (params->quality >= 9 && params->lgwin > lgblock) {\r
- lgblock = BROTLI_MIN(int, 18, params->lgwin);\r
- }\r
- } else {\r
- lgblock = BROTLI_MIN(int, BROTLI_MAX_INPUT_BLOCK_BITS,\r
- BROTLI_MAX(int, BROTLI_MIN_INPUT_BLOCK_BITS, lgblock));\r
- }\r
- return lgblock;\r
-}\r
-\r
-/* Returns log2 of the size of main ring buffer area.\r
- Allocate at least lgwin + 1 bits for the ring buffer so that the newly\r
- added block fits there completely and we still get lgwin bits and at least\r
- read_block_size_bits + 1 bits because the copy tail length needs to be\r
- smaller than ring-buffer size. */\r
-static BROTLI_INLINE int ComputeRbBits(const BrotliEncoderParams* params) {\r
- return 1 + BROTLI_MAX(int, params->lgwin, params->lgblock);\r
-}\r
-\r
-static BROTLI_INLINE size_t MaxMetablockSize(\r
- const BrotliEncoderParams* params) {\r
- int bits =\r
- BROTLI_MIN(int, ComputeRbBits(params), BROTLI_MAX_INPUT_BLOCK_BITS);\r
- return (size_t)1 << bits;\r
-}\r
-\r
-/* When searching for backward references and have not seen matches for a long\r
- time, we can skip some match lookups. Unsuccessful match lookups are very\r
- expensive and this kind of a heuristic speeds up compression quite a lot.\r
- At first 8 byte strides are taken and every second byte is put to hasher.\r
- After 4x more literals stride by 16 bytes, every put 4-th byte to hasher.\r
- Applied only to qualities 2 to 9. */\r
-static BROTLI_INLINE size_t LiteralSpreeLengthForSparseSearch(\r
- const BrotliEncoderParams* params) {\r
- return params->quality < 9 ? 64 : 512;\r
-}\r
-\r
-static BROTLI_INLINE void ChooseHasher(const BrotliEncoderParams* params,\r
- BrotliHasherParams* hparams) {\r
- if (params->quality > 9) {\r
- hparams->type = 10;\r
- } else if (params->quality == 4 && params->size_hint >= (1 << 20)) {\r
- hparams->type = 54;\r
- } else if (params->quality < 5) {\r
- hparams->type = params->quality;\r
- } else if (params->lgwin <= 16) {\r
- hparams->type = params->quality < 7 ? 40 : params->quality < 9 ? 41 : 42;\r
- } else if (params->size_hint >= (1 << 20) && params->lgwin >= 19) {\r
- hparams->type = 6;\r
- hparams->block_bits = params->quality - 1;\r
- hparams->bucket_bits = 15;\r
- hparams->hash_len = 5;\r
- hparams->num_last_distances_to_check =\r
- params->quality < 7 ? 4 : params->quality < 9 ? 10 : 16;\r
- } else {\r
- hparams->type = 5;\r
- hparams->block_bits = params->quality - 1;\r
- hparams->bucket_bits = params->quality < 7 ? 14 : 15;\r
- hparams->num_last_distances_to_check =\r
- params->quality < 7 ? 4 : params->quality < 9 ? 10 : 16;\r
- }\r
-\r
- if (params->lgwin > 24) {\r
- /* Different hashers for large window brotli: not for qualities <= 2,\r
- these are too fast for large window. Not for qualities >= 10: their\r
- hasher already works well with large window. So the changes are:\r
- H3 --> H35: for quality 3.\r
- H54 --> H55: for quality 4 with size hint > 1MB\r
- H6 --> H65: for qualities 5, 6, 7, 8, 9. */\r
- if (hparams->type == 3) {\r
- hparams->type = 35;\r
- }\r
- if (hparams->type == 54) {\r
- hparams->type = 55;\r
- }\r
- if (hparams->type == 6) {\r
- hparams->type = 65;\r
- }\r
- }\r
-}\r
-\r
-#endif /* BROTLI_ENC_QUALITY_H_ */\r
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