projects / io-compress-brotli.git / blame
| Commit | Line | Data |
|---|---|---|
| f9995f31 MG |
1 | /* Copyright 2013 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 | /* Utilities for building Huffman decoding tables. */ | |
| 8 | ||
| 9 | #ifndef BROTLI_DEC_HUFFMAN_H_ | |
| 10 | #define BROTLI_DEC_HUFFMAN_H_ | |
| 11 | ||
| 12 | #include "./types.h" | |
| 13 | ||
| 14 | #if defined(__cplusplus) || defined(c_plusplus) | |
| 15 | extern "C" { | |
| 16 | #endif | |
| 17 | ||
| 18 | #define BROTLI_HUFFMAN_MAX_CODE_LENGTH 15 | |
| 19 | ||
| 20 | /* For current format this constant equals to kNumInsertAndCopyCodes */ | |
| 21 | #define BROTLI_HUFFMAN_MAX_CODE_LENGTHS_SIZE 704 | |
| 22 | ||
| 23 | /* Maximum possible Huffman table size for an alphabet size of 704, max code | |
| 24 | * length 15 and root table bits 8. */ | |
| 25 | #define BROTLI_HUFFMAN_MAX_TABLE_SIZE 1080 | |
| 26 | ||
| 27 | #define BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH 5 | |
| 28 | ||
| 29 | typedef struct { | |
| 30 | uint8_t bits; /* number of bits used for this symbol */ | |
| 31 | uint16_t value; /* symbol value or table offset */ | |
| 32 | } HuffmanCode; | |
| 33 | ||
| 34 | ||
| 35 | /* Builds Huffman lookup table assuming code lengths are in symbol order. */ | |
| 36 | void BrotliBuildCodeLengthsHuffmanTable(HuffmanCode* root_table, | |
| 37 | const uint8_t* const code_lengths, | |
| 38 | uint16_t *count); | |
| 39 | ||
| 40 | /* Builds Huffman lookup table assuming code lengths are in symbol order. */ | |
| 41 | /* Returns size of resulting table. */ | |
| 42 | uint32_t BrotliBuildHuffmanTable(HuffmanCode* root_table, | |
| 43 | int root_bits, | |
| 44 | const uint16_t* const symbol_lists, | |
| 45 | uint16_t *count_arg); | |
| 46 | ||
| 47 | /* Builds a simple Huffman table. The num_symbols parameter is to be */ | |
| 48 | /* interpreted as follows: 0 means 1 symbol, 1 means 2 symbols, 2 means 3 */ | |
| 49 | /* symbols, 3 means 4 symbols with lengths 2,2,2,2, 4 means 4 symbols with */ | |
| 50 | /* lengths 1,2,3,3. */ | |
| 51 | uint32_t BrotliBuildSimpleHuffmanTable(HuffmanCode* table, | |
| 52 | int root_bits, | |
| 53 | uint16_t *symbols, | |
| 54 | uint32_t num_symbols); | |
| 55 | ||
| 56 | /* Contains a collection of Huffman trees with the same alphabet size. */ | |
| 57 | typedef struct { | |
| 58 | HuffmanCode** htrees; | |
| 59 | HuffmanCode* codes; | |
| 60 | uint16_t alphabet_size; | |
| 61 | uint16_t num_htrees; | |
| 62 | } HuffmanTreeGroup; | |
| 63 | ||
| 64 | #if defined(__cplusplus) || defined(c_plusplus) | |
| 65 | } /* extern "C" */ | |
| 66 | #endif | |
| 67 | ||
| 68 | #endif /* BROTLI_DEC_HUFFMAN_H_ */ |