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1 /* Copyright 2013 Google Inc. All Rights Reserved.
3 Distributed under MIT license.
4 See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
7 /* Utilities for building Huffman decoding tables. */
9 #ifndef BROTLI_DEC_HUFFMAN_H_
10 #define BROTLI_DEC_HUFFMAN_H_
12 #include "../common/types.h"
14 #include <BrotliDecompressLibInternal.h>
16 #if defined(__cplusplus) || defined(c_plusplus)
20 #define BROTLI_HUFFMAN_MAX_CODE_LENGTH 15
22 /* Maximum possible Huffman table size for an alphabet size of (index * 32),
23 * max code length 15 and root table bits 8. */
24 static const uint16_t kMaxHuffmanTableSize
[] = {
25 256, 402, 436, 468, 500, 534, 566, 598, 630, 662, 694, 726, 758, 790, 822,
26 854, 886, 920, 952, 984, 1016, 1048, 1080};
27 /* BROTLI_NUM_BLOCK_LEN_SYMBOLS == 26 */
28 #define BROTLI_HUFFMAN_MAX_SIZE_26 396
29 /* BROTLI_MAX_BLOCK_TYPE_SYMBOLS == 258 */
30 #define BROTLI_HUFFMAN_MAX_SIZE_258 632
31 /* BROTLI_MAX_CONTEXT_MAP_SYMBOLS == 272 */
32 #define BROTLI_HUFFMAN_MAX_SIZE_272 646
34 #define BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH 5
37 uint8_t bits
; /* number of bits used for this symbol */
38 uint16_t value
; /* symbol value or table offset */
41 /* Builds Huffman lookup table assuming code lengths are in symbol order. */
42 BROTLI_INTERNAL
void BrotliBuildCodeLengthsHuffmanTable(HuffmanCode
* root_table
,
43 const uint8_t* const code_lengths
, uint16_t* count
);
45 /* Builds Huffman lookup table assuming code lengths are in symbol order. */
46 /* Returns size of resulting table. */
47 BROTLI_INTERNAL
uint32_t BrotliBuildHuffmanTable(HuffmanCode
* root_table
,
48 int root_bits
, const uint16_t* const symbol_lists
, uint16_t* count_arg
);
50 /* Builds a simple Huffman table. The num_symbols parameter is to be */
51 /* interpreted as follows: 0 means 1 symbol, 1 means 2 symbols, 2 means 3 */
52 /* symbols, 3 means 4 symbols with lengths 2,2,2,2, 4 means 4 symbols with */
53 /* lengths 1,2,3,3. */
54 BROTLI_INTERNAL
uint32_t BrotliBuildSimpleHuffmanTable(HuffmanCode
* table
,
55 int root_bits
, uint16_t* symbols
, uint32_t num_symbols
);
57 /* Contains a collection of Huffman trees with the same alphabet size. */
61 uint16_t alphabet_size
;
65 #if defined(__cplusplus) || defined(c_plusplus)
69 #endif /* BROTLI_DEC_HUFFMAN_H_ */