/src/libjxl/third_party/brotli/c/enc/quality.h

Source (jump to first uncovered line)
/* 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 <brotli/encode.h>

#include "../common/platform.h"
#include "params.h"

#define FAST_ONE_PASS_COMPRESSION_QUALITY 0
#define FAST_TWO_PASS_COMPRESSION_QUALITY 1
#define ZOPFLIFICATION_QUALITY 10
#define HQ_ZOPFLIFICATION_QUALITY 11

#define MAX_QUALITY_FOR_STATIC_ENTROPY_CODES 2
#define MIN_QUALITY_FOR_BLOCK_SPLIT 4
#define MIN_QUALITY_FOR_NONZERO_DISTANCE_PARAMS 4
#define MIN_QUALITY_FOR_OPTIMIZE_HISTOGRAMS 4
#define MIN_QUALITY_FOR_EXTENSIVE_REFERENCE_SEARCH 5
#define MIN_QUALITY_FOR_CONTEXT_MODELING 5
#define MIN_QUALITY_FOR_HQ_CONTEXT_MODELING 7
#define MIN_QUALITY_FOR_HQ_BLOCK_SPLITTING 10

/* 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 0x2FFF

/* Returns hash-table size for quality levels 0 and 1. */
static BROTLI_INLINE size_t MaxHashTableSize(int quality) {
  return quality == FAST_ONE_PASS_COMPRESSION_QUALITY ? 1 << 15 : 1 << 17;
}

/* The maximum length for which the zopflification uses distinct distances. */
#define MAX_ZOPFLI_LEN_QUALITY_10 150
#define MAX_ZOPFLI_LEN_QUALITY_11 325

/* Do not thoroughly search when a long copy is found. */
#define BROTLI_LONG_COPY_QUICK_STEP 16384

static BROTLI_INLINE size_t MaxZopfliLen(const BrotliEncoderParams* params) {
  return params->quality <= 10 ?
      MAX_ZOPFLI_LEN_QUALITY_10 :
      MAX_ZOPFLI_LEN_QUALITY_11;
}

/* Number of best candidates to evaluate to expand Zopfli chain. */
static BROTLI_INLINE size_t MaxZopfliCandidates(
  const BrotliEncoderParams* params) {
  return params->quality <= 10 ? 1 : 5;
}

static BROTLI_INLINE void SanitizeParams(BrotliEncoderParams* params) {
  params->quality = BROTLI_MIN(int, BROTLI_MAX_QUALITY,
      BROTLI_MAX(int, BROTLI_MIN_QUALITY, params->quality));
  if (params->quality <= MAX_QUALITY_FOR_STATIC_ENTROPY_CODES) {
    params->large_window = BROTLI_FALSE;
  }
  if (params->lgwin < BROTLI_MIN_WINDOW_BITS) {
    params->lgwin = BROTLI_MIN_WINDOW_BITS;
  } else {
    int max_lgwin = params->large_window ? BROTLI_LARGE_MAX_WINDOW_BITS :
                                           BROTLI_MAX_WINDOW_BITS;
    if (params->lgwin > max_lgwin) params->lgwin = max_lgwin;
  }
}

/* Returns optimized lg_block value. */
static BROTLI_INLINE int ComputeLgBlock(const BrotliEncoderParams* params) {
  int lgblock = params->lgblock;
  if (params->quality == FAST_ONE_PASS_COMPRESSION_QUALITY ||
      params->quality == FAST_TWO_PASS_COMPRESSION_QUALITY) {
    lgblock = params->lgwin;
  } else if (params->quality < MIN_QUALITY_FOR_BLOCK_SPLIT) {
    lgblock = 14;
  } else if (lgblock == 0) {
    lgblock = 16;
    if (params->quality >= 9 && params->lgwin > lgblock) {
      lgblock = BROTLI_MIN(int, 18, params->lgwin);
    }
  } else {
    lgblock = BROTLI_MIN(int, BROTLI_MAX_INPUT_BLOCK_BITS,
        BROTLI_MAX(int, BROTLI_MIN_INPUT_BLOCK_BITS, lgblock));
  }
  return lgblock;
}

/* 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) {
  return 1 + BROTLI_MAX(int, params->lgwin, params->lgblock);
}

static BROTLI_INLINE size_t MaxMetablockSize(
    const BrotliEncoderParams* params) {
  int bits =
      BROTLI_MIN(int, ComputeRbBits(params), BROTLI_MAX_INPUT_BLOCK_BITS);
  return (size_t)1 << bits;
}

/* 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) {
  return params->quality < 9 ? 64 : 512;
}

static BROTLI_INLINE void ChooseHasher(const BrotliEncoderParams* params,
                                       BrotliHasherParams* hparams) {
  if (params->quality > 9) {
    hparams->type = 10;
  } else if (params->quality == 4 && params->size_hint >= (1 << 20)) {
    hparams->type = 54;
  } else if (params->quality < 5) {
    hparams->type = params->quality;
  } else if (params->lgwin <= 16) {
    hparams->type = params->quality < 7 ? 40 : params->quality < 9 ? 41 : 42;
  } else if (params->size_hint >= (1 << 20) && params->lgwin >= 19) {
    hparams->type = 6;
    hparams->block_bits = params->quality - 1;
    hparams->bucket_bits = 15;
    hparams->hash_len = 5;
    hparams->num_last_distances_to_check =
        params->quality < 7 ? 4 : params->quality < 9 ? 10 : 16;
  } else {
    hparams->type = 5;
    hparams->block_bits = params->quality - 1;
    hparams->bucket_bits = params->quality < 7 ? 14 : 15;
    hparams->num_last_distances_to_check =
        params->quality < 7 ? 4 : params->quality < 9 ? 10 : 16;
  }

  if (params->lgwin > 24) {
    /* Different hashers for large window brotli: not for qualities <= 2,
       these are too fast for large window. Not for qualities >= 10: their
       hasher already works well with large window. So the changes are:
       H3 --> H35: for quality 3.
       H54 --> H55: for quality 4 with size hint > 1MB
       H6 --> H65: for qualities 5, 6, 7, 8, 9. */
    if (hparams->type == 3) {
      hparams->type = 35;
    }
    if (hparams->type == 54) {
      hparams->type = 55;
    }
    if (hparams->type == 6) {
      hparams->type = 65;
    }
  }
}

#endif  /* BROTLI_ENC_QUALITY_H_ */

Coverage Report

Created: 2025-06-16 07:00

Line	Count	Source (jump to first uncovered line)
1		/* Copyright 2016 Google Inc. All Rights Reserved.
2
3		Distributed under MIT license.
4		See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
5		*/
6
7		/* Constants and formulas that affect speed-ratio trade-offs and thus define
8		quality levels. */
9
10		#ifndef BROTLI_ENC_QUALITY_H_
11		#define BROTLI_ENC_QUALITY_H_
12
13		#include <brotli/encode.h>
14
15		#include "../common/platform.h"
16		#include "params.h"
17
18	0	#define FAST_ONE_PASS_COMPRESSION_QUALITY 0
19	0	#define FAST_TWO_PASS_COMPRESSION_QUALITY 1
20	0	#define ZOPFLIFICATION_QUALITY 10
21	0	#define HQ_ZOPFLIFICATION_QUALITY 11
22
23	0	#define MAX_QUALITY_FOR_STATIC_ENTROPY_CODES 2
24	0	#define MIN_QUALITY_FOR_BLOCK_SPLIT 4
25	0	#define MIN_QUALITY_FOR_NONZERO_DISTANCE_PARAMS 4
26	0	#define MIN_QUALITY_FOR_OPTIMIZE_HISTOGRAMS 4
27	0	#define MIN_QUALITY_FOR_EXTENSIVE_REFERENCE_SEARCH 5
28	0	#define MIN_QUALITY_FOR_CONTEXT_MODELING 5
29	0	#define MIN_QUALITY_FOR_HQ_CONTEXT_MODELING 7
30	0	#define MIN_QUALITY_FOR_HQ_BLOCK_SPLITTING 10
31
32		/* For quality below MIN_QUALITY_FOR_BLOCK_SPLIT there is no block splitting,
33		so we buffer at most this much literals and commands. */
34		#define MAX_NUM_DELAYED_SYMBOLS 0x2FFF
35
36		/* Returns hash-table size for quality levels 0 and 1. */
37	0	static BROTLI_INLINE size_t MaxHashTableSize(int quality) {
38	0	return quality == FAST_ONE_PASS_COMPRESSION_QUALITY ? 1 << 15 : 1 << 17;
39	0	} Unexecuted instantiation: encode.c:MaxHashTableSize Unexecuted instantiation: encoder_dict.c:MaxHashTableSize Unexecuted instantiation: compound_dictionary.c:MaxHashTableSize Unexecuted instantiation: metablock.c:MaxHashTableSize Unexecuted instantiation: block_splitter.c:MaxHashTableSize Unexecuted instantiation: bit_cost.c:MaxHashTableSize Unexecuted instantiation: cluster.c:MaxHashTableSize Unexecuted instantiation: histogram.c:MaxHashTableSize Unexecuted instantiation: compress_fragment_two_pass.c:MaxHashTableSize Unexecuted instantiation: brotli_bit_stream.c:MaxHashTableSize Unexecuted instantiation: compress_fragment.c:MaxHashTableSize Unexecuted instantiation: backward_references_hq.c:MaxHashTableSize Unexecuted instantiation: backward_references.c:MaxHashTableSize
40
41		/* The maximum length for which the zopflification uses distinct distances. */
42	0	#define MAX_ZOPFLI_LEN_QUALITY_10 150
43	0	#define MAX_ZOPFLI_LEN_QUALITY_11 325
44
45		/* Do not thoroughly search when a long copy is found. */
46	0	#define BROTLI_LONG_COPY_QUICK_STEP 16384
47
48	0	static BROTLI_INLINE size_t MaxZopfliLen(const BrotliEncoderParams* params) {
49	0	return params->quality <= 10 ?
50	0	MAX_ZOPFLI_LEN_QUALITY_10 :
51	0	MAX_ZOPFLI_LEN_QUALITY_11;
52	0	} Unexecuted instantiation: encode.c:MaxZopfliLen Unexecuted instantiation: encoder_dict.c:MaxZopfliLen Unexecuted instantiation: compound_dictionary.c:MaxZopfliLen Unexecuted instantiation: metablock.c:MaxZopfliLen Unexecuted instantiation: block_splitter.c:MaxZopfliLen Unexecuted instantiation: bit_cost.c:MaxZopfliLen Unexecuted instantiation: cluster.c:MaxZopfliLen Unexecuted instantiation: histogram.c:MaxZopfliLen Unexecuted instantiation: compress_fragment_two_pass.c:MaxZopfliLen Unexecuted instantiation: brotli_bit_stream.c:MaxZopfliLen Unexecuted instantiation: compress_fragment.c:MaxZopfliLen Unexecuted instantiation: backward_references_hq.c:MaxZopfliLen Unexecuted instantiation: backward_references.c:MaxZopfliLen
53
54		/* Number of best candidates to evaluate to expand Zopfli chain. */
55		static BROTLI_INLINE size_t MaxZopfliCandidates(
56	0	const BrotliEncoderParams* params) {
57	0	return params->quality <= 10 ? 1 : 5;
58	0	} Unexecuted instantiation: encode.c:MaxZopfliCandidates Unexecuted instantiation: encoder_dict.c:MaxZopfliCandidates Unexecuted instantiation: compound_dictionary.c:MaxZopfliCandidates Unexecuted instantiation: metablock.c:MaxZopfliCandidates Unexecuted instantiation: block_splitter.c:MaxZopfliCandidates Unexecuted instantiation: bit_cost.c:MaxZopfliCandidates Unexecuted instantiation: cluster.c:MaxZopfliCandidates Unexecuted instantiation: histogram.c:MaxZopfliCandidates Unexecuted instantiation: compress_fragment_two_pass.c:MaxZopfliCandidates Unexecuted instantiation: brotli_bit_stream.c:MaxZopfliCandidates Unexecuted instantiation: compress_fragment.c:MaxZopfliCandidates Unexecuted instantiation: backward_references_hq.c:MaxZopfliCandidates Unexecuted instantiation: backward_references.c:MaxZopfliCandidates
59
60	0	static BROTLI_INLINE void SanitizeParams(BrotliEncoderParams* params) {
61	0	params->quality = BROTLI_MIN(int, BROTLI_MAX_QUALITY,
62	0	BROTLI_MAX(int, BROTLI_MIN_QUALITY, params->quality));
63	0	if (params->quality <= MAX_QUALITY_FOR_STATIC_ENTROPY_CODES) {
64	0	params->large_window = BROTLI_FALSE;
65	0	}
66	0	if (params->lgwin < BROTLI_MIN_WINDOW_BITS) {
67	0	params->lgwin = BROTLI_MIN_WINDOW_BITS;
68	0	} else {
69	0	int max_lgwin = params->large_window ? BROTLI_LARGE_MAX_WINDOW_BITS :
70	0	BROTLI_MAX_WINDOW_BITS;
71	0	if (params->lgwin > max_lgwin) params->lgwin = max_lgwin;
72	0	}
73	0	} Unexecuted instantiation: encode.c:SanitizeParams Unexecuted instantiation: encoder_dict.c:SanitizeParams Unexecuted instantiation: compound_dictionary.c:SanitizeParams Unexecuted instantiation: metablock.c:SanitizeParams Unexecuted instantiation: block_splitter.c:SanitizeParams Unexecuted instantiation: bit_cost.c:SanitizeParams Unexecuted instantiation: cluster.c:SanitizeParams Unexecuted instantiation: histogram.c:SanitizeParams Unexecuted instantiation: compress_fragment_two_pass.c:SanitizeParams Unexecuted instantiation: brotli_bit_stream.c:SanitizeParams Unexecuted instantiation: compress_fragment.c:SanitizeParams Unexecuted instantiation: backward_references_hq.c:SanitizeParams Unexecuted instantiation: backward_references.c:SanitizeParams
74
75		/* Returns optimized lg_block value. */
76	0	static BROTLI_INLINE int ComputeLgBlock(const BrotliEncoderParams* params) {
77	0	int lgblock = params->lgblock;
78	0	if (params->quality == FAST_ONE_PASS_COMPRESSION_QUALITY \|\|
79	0	params->quality == FAST_TWO_PASS_COMPRESSION_QUALITY) {
80	0	lgblock = params->lgwin;
81	0	} else if (params->quality < MIN_QUALITY_FOR_BLOCK_SPLIT) {
82	0	lgblock = 14;
83	0	} else if (lgblock == 0) {
84	0	lgblock = 16;
85	0	if (params->quality >= 9 && params->lgwin > lgblock) {
86	0	lgblock = BROTLI_MIN(int, 18, params->lgwin);
87	0	}
88	0	} else {
89	0	lgblock = BROTLI_MIN(int, BROTLI_MAX_INPUT_BLOCK_BITS,
90	0	BROTLI_MAX(int, BROTLI_MIN_INPUT_BLOCK_BITS, lgblock));
91	0	}
92	0	return lgblock;
93	0	} Unexecuted instantiation: encode.c:ComputeLgBlock Unexecuted instantiation: encoder_dict.c:ComputeLgBlock Unexecuted instantiation: compound_dictionary.c:ComputeLgBlock Unexecuted instantiation: metablock.c:ComputeLgBlock Unexecuted instantiation: block_splitter.c:ComputeLgBlock Unexecuted instantiation: bit_cost.c:ComputeLgBlock Unexecuted instantiation: cluster.c:ComputeLgBlock Unexecuted instantiation: histogram.c:ComputeLgBlock Unexecuted instantiation: compress_fragment_two_pass.c:ComputeLgBlock Unexecuted instantiation: brotli_bit_stream.c:ComputeLgBlock Unexecuted instantiation: compress_fragment.c:ComputeLgBlock Unexecuted instantiation: backward_references_hq.c:ComputeLgBlock Unexecuted instantiation: backward_references.c:ComputeLgBlock
94
95		/* Returns log2 of the size of main ring buffer area.
96		Allocate at least lgwin + 1 bits for the ring buffer so that the newly
97		added block fits there completely and we still get lgwin bits and at least
98		read_block_size_bits + 1 bits because the copy tail length needs to be
99		smaller than ring-buffer size. */
100	0	static BROTLI_INLINE int ComputeRbBits(const BrotliEncoderParams* params) {
101	0	return 1 + BROTLI_MAX(int, params->lgwin, params->lgblock);
102	0	} Unexecuted instantiation: encode.c:ComputeRbBits Unexecuted instantiation: encoder_dict.c:ComputeRbBits Unexecuted instantiation: compound_dictionary.c:ComputeRbBits Unexecuted instantiation: metablock.c:ComputeRbBits Unexecuted instantiation: block_splitter.c:ComputeRbBits Unexecuted instantiation: bit_cost.c:ComputeRbBits Unexecuted instantiation: cluster.c:ComputeRbBits Unexecuted instantiation: histogram.c:ComputeRbBits Unexecuted instantiation: compress_fragment_two_pass.c:ComputeRbBits Unexecuted instantiation: brotli_bit_stream.c:ComputeRbBits Unexecuted instantiation: compress_fragment.c:ComputeRbBits Unexecuted instantiation: backward_references_hq.c:ComputeRbBits Unexecuted instantiation: backward_references.c:ComputeRbBits
103
104		static BROTLI_INLINE size_t MaxMetablockSize(
105	0	const BrotliEncoderParams* params) {
106	0	int bits =
107	0	BROTLI_MIN(int, ComputeRbBits(params), BROTLI_MAX_INPUT_BLOCK_BITS);
108	0	return (size_t)1 << bits;
109	0	} Unexecuted instantiation: encode.c:MaxMetablockSize Unexecuted instantiation: encoder_dict.c:MaxMetablockSize Unexecuted instantiation: compound_dictionary.c:MaxMetablockSize Unexecuted instantiation: metablock.c:MaxMetablockSize Unexecuted instantiation: block_splitter.c:MaxMetablockSize Unexecuted instantiation: bit_cost.c:MaxMetablockSize Unexecuted instantiation: cluster.c:MaxMetablockSize Unexecuted instantiation: histogram.c:MaxMetablockSize Unexecuted instantiation: compress_fragment_two_pass.c:MaxMetablockSize Unexecuted instantiation: brotli_bit_stream.c:MaxMetablockSize Unexecuted instantiation: compress_fragment.c:MaxMetablockSize Unexecuted instantiation: backward_references_hq.c:MaxMetablockSize Unexecuted instantiation: backward_references.c:MaxMetablockSize
110
111		/* When searching for backward references and have not seen matches for a long
112		time, we can skip some match lookups. Unsuccessful match lookups are very
113		expensive and this kind of a heuristic speeds up compression quite a lot.
114		At first 8 byte strides are taken and every second byte is put to hasher.
115		After 4x more literals stride by 16 bytes, every put 4-th byte to hasher.
116		Applied only to qualities 2 to 9. */
117		static BROTLI_INLINE size_t LiteralSpreeLengthForSparseSearch(
118	0	const BrotliEncoderParams* params) {
119	0	return params->quality < 9 ? 64 : 512;
120	0	} Unexecuted instantiation: encode.c:LiteralSpreeLengthForSparseSearch Unexecuted instantiation: encoder_dict.c:LiteralSpreeLengthForSparseSearch Unexecuted instantiation: compound_dictionary.c:LiteralSpreeLengthForSparseSearch Unexecuted instantiation: metablock.c:LiteralSpreeLengthForSparseSearch Unexecuted instantiation: block_splitter.c:LiteralSpreeLengthForSparseSearch Unexecuted instantiation: bit_cost.c:LiteralSpreeLengthForSparseSearch Unexecuted instantiation: cluster.c:LiteralSpreeLengthForSparseSearch Unexecuted instantiation: histogram.c:LiteralSpreeLengthForSparseSearch Unexecuted instantiation: compress_fragment_two_pass.c:LiteralSpreeLengthForSparseSearch Unexecuted instantiation: brotli_bit_stream.c:LiteralSpreeLengthForSparseSearch Unexecuted instantiation: compress_fragment.c:LiteralSpreeLengthForSparseSearch Unexecuted instantiation: backward_references_hq.c:LiteralSpreeLengthForSparseSearch Unexecuted instantiation: backward_references.c:LiteralSpreeLengthForSparseSearch
121
122		static BROTLI_INLINE void ChooseHasher(const BrotliEncoderParams* params,
123	0	BrotliHasherParams* hparams) {
124	0	if (params->quality > 9) {
125	0	hparams->type = 10;
126	0	} else if (params->quality == 4 && params->size_hint >= (1 << 20)) {
127	0	hparams->type = 54;
128	0	} else if (params->quality < 5) {
129	0	hparams->type = params->quality;
130	0	} else if (params->lgwin <= 16) {
131	0	hparams->type = params->quality < 7 ? 40 : params->quality < 9 ? 41 : 42;
132	0	} else if (params->size_hint >= (1 << 20) && params->lgwin >= 19) {
133	0	hparams->type = 6;
134	0	hparams->block_bits = params->quality - 1;
135	0	hparams->bucket_bits = 15;
136	0	hparams->hash_len = 5;
137	0	hparams->num_last_distances_to_check =
138	0	params->quality < 7 ? 4 : params->quality < 9 ? 10 : 16;
139	0	} else {
140	0	hparams->type = 5;
141	0	hparams->block_bits = params->quality - 1;
142	0	hparams->bucket_bits = params->quality < 7 ? 14 : 15;
143	0	hparams->num_last_distances_to_check =
144	0	params->quality < 7 ? 4 : params->quality < 9 ? 10 : 16;
145	0	}
146
147	0	if (params->lgwin > 24) {
148		/* Different hashers for large window brotli: not for qualities <= 2,
149		these are too fast for large window. Not for qualities >= 10: their
150		hasher already works well with large window. So the changes are:
151		H3 --> H35: for quality 3.
152		H54 --> H55: for quality 4 with size hint > 1MB
153		H6 --> H65: for qualities 5, 6, 7, 8, 9. */
154	0	if (hparams->type == 3) {
155	0	hparams->type = 35;
156	0	}
157	0	if (hparams->type == 54) {
158	0	hparams->type = 55;
159	0	}
160	0	if (hparams->type == 6) {
161	0	hparams->type = 65;
162	0	}
163	0	}
164	0	} Unexecuted instantiation: encode.c:ChooseHasher Unexecuted instantiation: encoder_dict.c:ChooseHasher Unexecuted instantiation: compound_dictionary.c:ChooseHasher Unexecuted instantiation: metablock.c:ChooseHasher Unexecuted instantiation: block_splitter.c:ChooseHasher Unexecuted instantiation: bit_cost.c:ChooseHasher Unexecuted instantiation: cluster.c:ChooseHasher Unexecuted instantiation: histogram.c:ChooseHasher Unexecuted instantiation: compress_fragment_two_pass.c:ChooseHasher Unexecuted instantiation: brotli_bit_stream.c:ChooseHasher Unexecuted instantiation: compress_fragment.c:ChooseHasher Unexecuted instantiation: backward_references_hq.c:ChooseHasher Unexecuted instantiation: backward_references.c:ChooseHasher
165
166		#endif /* BROTLI_ENC_QUALITY_H_ */