| /* Copyright 2016 Google Inc. All Rights Reserved. |
| |
| Distributed under MIT license. |
| See file LICENSE for detail or copy at https://opensource.org/licenses/MIT |
| */ |
| |
| #ifndef BROTLI_COMMON_CONSTANTS_H_ |
| #define BROTLI_COMMON_CONSTANTS_H_ |
| |
| /* Specification: 7.3. Encoding of the context map */ |
| #define BROTLI_CONTEXT_MAP_MAX_RLE 16 |
| |
| /* Specification: 2. Compressed representation overview */ |
| #define BROTLI_MAX_NUMBER_OF_BLOCK_TYPES 256 |
| |
| /* Specification: 3.3. Alphabet sizes: insert-and-copy length */ |
| #define BROTLI_NUM_LITERAL_SYMBOLS 256 |
| #define BROTLI_NUM_COMMAND_SYMBOLS 704 |
| #define BROTLI_NUM_BLOCK_LEN_SYMBOLS 26 |
| #define BROTLI_MAX_CONTEXT_MAP_SYMBOLS (BROTLI_MAX_NUMBER_OF_BLOCK_TYPES + \ |
| BROTLI_CONTEXT_MAP_MAX_RLE) |
| #define BROTLI_MAX_BLOCK_TYPE_SYMBOLS (BROTLI_MAX_NUMBER_OF_BLOCK_TYPES + 2) |
| |
| /* Specification: 3.5. Complex prefix codes */ |
| #define BROTLI_REPEAT_PREVIOUS_CODE_LENGTH 16 |
| #define BROTLI_REPEAT_ZERO_CODE_LENGTH 17 |
| #define BROTLI_CODE_LENGTH_CODES (BROTLI_REPEAT_ZERO_CODE_LENGTH + 1) |
| /* "code length of 8 is repeated" */ |
| #define BROTLI_INITIAL_REPEATED_CODE_LENGTH 8 |
| |
| /* "Large Window Brotli" */ |
| #define BROTLI_LARGE_MAX_DISTANCE_BITS 62U |
| #define BROTLI_LARGE_MIN_WBITS 10 |
| #define BROTLI_LARGE_MAX_WBITS 30 |
| |
| /* Specification: 4. Encoding of distances */ |
| #define BROTLI_NUM_DISTANCE_SHORT_CODES 16 |
| #define BROTLI_MAX_NPOSTFIX 3 |
| #define BROTLI_MAX_NDIRECT 120 |
| #define BROTLI_MAX_DISTANCE_BITS 24U |
| #define BROTLI_DISTANCE_ALPHABET_SIZE(NPOSTFIX, NDIRECT, MAXNBITS) ( \ |
| BROTLI_NUM_DISTANCE_SHORT_CODES + (NDIRECT) + \ |
| ((MAXNBITS) << ((NPOSTFIX) + 1))) |
| /* BROTLI_NUM_DISTANCE_SYMBOLS == 1128 */ |
| #define BROTLI_NUM_DISTANCE_SYMBOLS \ |
| BROTLI_DISTANCE_ALPHABET_SIZE( \ |
| BROTLI_MAX_NDIRECT, BROTLI_MAX_NPOSTFIX, BROTLI_LARGE_MAX_DISTANCE_BITS) |
| #define BROTLI_MAX_DISTANCE 0x3FFFFFC |
| #define BROTLI_MAX_ALLOWED_DISTANCE 0x7FFFFFFC |
| |
| /* 7.1. Context modes and context ID lookup for literals */ |
| /* "context IDs for literals are in the range of 0..63" */ |
| #define BROTLI_LITERAL_CONTEXT_BITS 6 |
| |
| /* 7.2. Context ID for distances */ |
| #define BROTLI_DISTANCE_CONTEXT_BITS 2 |
| |
| /* 9.1. Format of the Stream Header */ |
| /* Number of slack bytes for window size. Don't confuse |
| with BROTLI_NUM_DISTANCE_SHORT_CODES. */ |
| #define BROTLI_WINDOW_GAP 16 |
| #define BROTLI_MAX_BACKWARD_LIMIT(W) (((size_t)1 << (W)) - BROTLI_WINDOW_GAP) |
| |
| #endif /* BROTLI_COMMON_CONSTANTS_H_ */ |