--- /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 "./encode.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_ENRTOPY_CODES 2\r
+#define MIN_QUALITY_FOR_BLOCK_SPLIT 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
+/* Only for "font" mode. */\r
+#define MIN_QUALITY_FOR_RECOMPUTE_DISTANCE_PREFIXES 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
+/* Encoding parameters */\r
+typedef struct BrotliEncoderParams {\r
+ BrotliEncoderMode mode;\r
+ int quality;\r
+ int lgwin;\r
+ int lgblock;\r
+} BrotliEncoderParams;\r
+\r
+/* Returns hashtable 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
+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->lgwin < kBrotliMinWindowBits) {\r
+ params->lgwin = kBrotliMinWindowBits;\r
+ } else if (params->lgwin > kBrotliMaxWindowBits) {\r
+ params->lgwin = kBrotliMaxWindowBits;\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, kBrotliMaxInputBlockBits,\r
+ BROTLI_MAX(int, kBrotliMinInputBlockBits, 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 ringbuffer 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 = BROTLI_MIN(int, ComputeRbBits(params), kBrotliMaxInputBlockBits);\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 int ChooseHasher(const BrotliEncoderParams* params) {\r
+ if (params->quality > 9) {\r
+ return 10;\r
+ } else if (params->quality < 5) {\r
+ return params->quality;\r
+ } else if (params->lgwin <= 16) {\r
+ return params->quality < 7 ? 40 : params->quality < 9 ? 41 : 42;\r
+ }\r
+ return params->quality;\r
+}\r
+\r
+#endif /* BROTLI_ENC_QUALITY_H_ */\r