/* Copyright 2013 Google Inc. All Rights Reserved. Distributed under MIT license. See file LICENSE for detail or copy at https://opensource.org/licenses/MIT */ /* Utilities for building Huffman decoding tables. */ #ifndef BROTLI_DEC_HUFFMAN_H_ #define BROTLI_DEC_HUFFMAN_H_ #include "./types.h" #if defined(__cplusplus) || defined(c_plusplus) extern "C" { #endif #define BROTLI_HUFFMAN_MAX_CODE_LENGTH 15 /* For current format this constant equals to kNumInsertAndCopyCodes */ #define BROTLI_HUFFMAN_MAX_CODE_LENGTHS_SIZE 704 /* Maximum possible Huffman table size for an alphabet size of (index * 32), * max code length 15 and root table bits 8. */ static const uint16_t kMaxHuffmanTableSize[] = { 256, 402, 436, 468, 500, 534, 566, 598, 630, 662, 694, 726, 758, 790, 822, 854, 886, 920, 952, 984, 1016, 1048, 1080}; #define BROTLI_HUFFMAN_MAX_SIZE_26 396 #define BROTLI_HUFFMAN_MAX_SIZE_258 632 #define BROTLI_HUFFMAN_MAX_SIZE_272 646 #define BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH 5 typedef struct { uint8_t bits; /* number of bits used for this symbol */ uint16_t value; /* symbol value or table offset */ } HuffmanCode; /* Builds Huffman lookup table assuming code lengths are in symbol order. */ void BrotliBuildCodeLengthsHuffmanTable(HuffmanCode* root_table, const uint8_t* const code_lengths, uint16_t *count); /* Builds Huffman lookup table assuming code lengths are in symbol order. */ /* Returns size of resulting table. */ uint32_t BrotliBuildHuffmanTable(HuffmanCode* root_table, int root_bits, const uint16_t* const symbol_lists, uint16_t *count_arg); /* Builds a simple Huffman table. The num_symbols parameter is to be */ /* interpreted as follows: 0 means 1 symbol, 1 means 2 symbols, 2 means 3 */ /* symbols, 3 means 4 symbols with lengths 2,2,2,2, 4 means 4 symbols with */ /* lengths 1,2,3,3. */ uint32_t BrotliBuildSimpleHuffmanTable(HuffmanCode* table, int root_bits, uint16_t *symbols, uint32_t num_symbols); /* Contains a collection of Huffman trees with the same alphabet size. */ typedef struct { HuffmanCode** htrees; HuffmanCode* codes; uint16_t alphabet_size; uint16_t num_htrees; } HuffmanTreeGroup; #if defined(__cplusplus) || defined(c_plusplus) } /* extern "C" */ #endif #endif /* BROTLI_DEC_HUFFMAN_H_ */