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Diffstat (limited to 'modules/brotli/dec/huffman.h')
| -rw-r--r-- | modules/brotli/dec/huffman.h | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/modules/brotli/dec/huffman.h b/modules/brotli/dec/huffman.h new file mode 100644 index 0000000000..a8fbc45347 --- /dev/null +++ b/modules/brotli/dec/huffman.h @@ -0,0 +1,121 @@ +/* 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 "../common/platform.h" +#include <brotli/types.h> + +#if defined(__cplusplus) || defined(c_plusplus) +extern "C" { +#endif + +#define BROTLI_HUFFMAN_MAX_CODE_LENGTH 15 + +/* BROTLI_NUM_BLOCK_LEN_SYMBOLS == 26 */ +#define BROTLI_HUFFMAN_MAX_SIZE_26 396 +/* BROTLI_MAX_BLOCK_TYPE_SYMBOLS == 258 */ +#define BROTLI_HUFFMAN_MAX_SIZE_258 632 +/* BROTLI_MAX_CONTEXT_MAP_SYMBOLS == 272 */ +#define BROTLI_HUFFMAN_MAX_SIZE_272 646 + +#define BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH 5 + +#if ((defined(BROTLI_TARGET_ARMV7) || defined(BROTLI_TARGET_ARMV8_32)) && \ + BROTLI_GNUC_HAS_ATTRIBUTE(aligned, 2, 7, 0)) +#define BROTLI_HUFFMAN_CODE_FAST_LOAD +#endif + +#if !defined(BROTLI_HUFFMAN_CODE_FAST_LOAD) +/* Do not create this struct directly - use the ConstructHuffmanCode + * constructor below! */ +typedef struct { + uint8_t bits; /* number of bits used for this symbol */ + uint16_t value; /* symbol value or table offset */ +} HuffmanCode; + +static BROTLI_INLINE HuffmanCode ConstructHuffmanCode(const uint8_t bits, + const uint16_t value) { + HuffmanCode h; + h.bits = bits; + h.value = value; + return h; +} + +/* Please use the following macros to optimize HuffmanCode accesses in hot + * paths. + * + * For example, assuming |table| contains a HuffmanCode pointer: + * + * BROTLI_HC_MARK_TABLE_FOR_FAST_LOAD(table); + * BROTLI_HC_ADJUST_TABLE_INDEX(table, index_into_table); + * *bits = BROTLI_HC_GET_BITS(table); + * *value = BROTLI_HC_GET_VALUE(table); + * BROTLI_HC_ADJUST_TABLE_INDEX(table, offset); + * *bits2 = BROTLI_HC_GET_BITS(table); + * *value2 = BROTLI_HC_GET_VALUE(table); + * + */ + +#define BROTLI_HC_MARK_TABLE_FOR_FAST_LOAD(H) +#define BROTLI_HC_ADJUST_TABLE_INDEX(H, V) H += (V) + +/* These must be given a HuffmanCode pointer! */ +#define BROTLI_HC_FAST_LOAD_BITS(H) (H->bits) +#define BROTLI_HC_FAST_LOAD_VALUE(H) (H->value) + +#else /* BROTLI_HUFFMAN_CODE_FAST_LOAD */ + +typedef BROTLI_ALIGNED(4) uint32_t HuffmanCode; + +static BROTLI_INLINE HuffmanCode ConstructHuffmanCode(const uint8_t bits, + const uint16_t value) { + return (HuffmanCode) ((value & 0xFFFF) << 16) | (bits & 0xFF); +} + +#define BROTLI_HC_MARK_TABLE_FOR_FAST_LOAD(H) uint32_t __fastload_##H = (*H) +#define BROTLI_HC_ADJUST_TABLE_INDEX(H, V) H += (V); __fastload_##H = (*H) + +/* These must be given a HuffmanCode pointer! */ +#define BROTLI_HC_FAST_LOAD_BITS(H) ((__fastload_##H) & 0xFF) +#define BROTLI_HC_FAST_LOAD_VALUE(H) ((__fastload_##H) >> 16) +#endif /* BROTLI_HUFFMAN_CODE_FAST_LOAD */ + +/* Builds Huffman lookup table assuming code lengths are in symbol order. */ +BROTLI_INTERNAL 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. */ +BROTLI_INTERNAL uint32_t BrotliBuildHuffmanTable(HuffmanCode* root_table, + int root_bits, const uint16_t* const symbol_lists, uint16_t* count); + +/* 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]. */ +BROTLI_INTERNAL 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. */ +/* alphabet_size_limit is needed due to simple codes, since + log2(alphabet_size_max) could be greater than log2(alphabet_size_limit). */ +typedef struct { + HuffmanCode** htrees; + HuffmanCode* codes; + uint16_t alphabet_size_max; + uint16_t alphabet_size_limit; + uint16_t num_htrees; +} HuffmanTreeGroup; + +#if defined(__cplusplus) || defined(c_plusplus) +} /* extern "C" */ +#endif + +#endif /* BROTLI_DEC_HUFFMAN_H_ */ |