-/* Copyright 2013 Google Inc. All Rights Reserved.\r
-\r
- Distributed under MIT license.\r
- See file LICENSE for detail or copy at https://opensource.org/licenses/MIT\r
-*/\r
-\r
-/* Utilities for building Huffman decoding tables. */\r
-\r
-#include "./huffman.h"\r
-\r
-#include <string.h> /* memcpy, memset */\r
-\r
-#include "../common/constants.h"\r
-#include "../common/platform.h"\r
-#include <brotli/types.h>\r
-\r
-#if defined(__cplusplus) || defined(c_plusplus)\r
-extern "C" {\r
-#endif\r
-\r
-#define BROTLI_REVERSE_BITS_MAX 8\r
-\r
-#if defined(BROTLI_RBIT)\r
-#define BROTLI_REVERSE_BITS_BASE \\r
- ((sizeof(brotli_reg_t) << 3) - BROTLI_REVERSE_BITS_MAX)\r
-#else\r
-#define BROTLI_REVERSE_BITS_BASE 0\r
-static uint8_t kReverseBits[1 << BROTLI_REVERSE_BITS_MAX] = {\r
- 0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0,\r
- 0x10, 0x90, 0x50, 0xD0, 0x30, 0xB0, 0x70, 0xF0,\r
- 0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8,\r
- 0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8,\r
- 0x04, 0x84, 0x44, 0xC4, 0x24, 0xA4, 0x64, 0xE4,\r
- 0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4,\r
- 0x0C, 0x8C, 0x4C, 0xCC, 0x2C, 0xAC, 0x6C, 0xEC,\r
- 0x1C, 0x9C, 0x5C, 0xDC, 0x3C, 0xBC, 0x7C, 0xFC,\r
- 0x02, 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2,\r
- 0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2, 0x72, 0xF2,\r
- 0x0A, 0x8A, 0x4A, 0xCA, 0x2A, 0xAA, 0x6A, 0xEA,\r
- 0x1A, 0x9A, 0x5A, 0xDA, 0x3A, 0xBA, 0x7A, 0xFA,\r
- 0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6,\r
- 0x16, 0x96, 0x56, 0xD6, 0x36, 0xB6, 0x76, 0xF6,\r
- 0x0E, 0x8E, 0x4E, 0xCE, 0x2E, 0xAE, 0x6E, 0xEE,\r
- 0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE,\r
- 0x01, 0x81, 0x41, 0xC1, 0x21, 0xA1, 0x61, 0xE1,\r
- 0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71, 0xF1,\r
- 0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9,\r
- 0x19, 0x99, 0x59, 0xD9, 0x39, 0xB9, 0x79, 0xF9,\r
- 0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5,\r
- 0x15, 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5,\r
- 0x0D, 0x8D, 0x4D, 0xCD, 0x2D, 0xAD, 0x6D, 0xED,\r
- 0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD,\r
- 0x03, 0x83, 0x43, 0xC3, 0x23, 0xA3, 0x63, 0xE3,\r
- 0x13, 0x93, 0x53, 0xD3, 0x33, 0xB3, 0x73, 0xF3,\r
- 0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB,\r
- 0x1B, 0x9B, 0x5B, 0xDB, 0x3B, 0xBB, 0x7B, 0xFB,\r
- 0x07, 0x87, 0x47, 0xC7, 0x27, 0xA7, 0x67, 0xE7,\r
- 0x17, 0x97, 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7,\r
- 0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F, 0xEF,\r
- 0x1F, 0x9F, 0x5F, 0xDF, 0x3F, 0xBF, 0x7F, 0xFF\r
-};\r
-#endif /* BROTLI_RBIT */\r
-\r
-#define BROTLI_REVERSE_BITS_LOWEST \\r
- ((brotli_reg_t)1 << (BROTLI_REVERSE_BITS_MAX - 1 + BROTLI_REVERSE_BITS_BASE))\r
-\r
-/* Returns reverse(num >> BROTLI_REVERSE_BITS_BASE, BROTLI_REVERSE_BITS_MAX),\r
- where reverse(value, len) is the bit-wise reversal of the len least\r
- significant bits of value. */\r
-static BROTLI_INLINE brotli_reg_t BrotliReverseBits(brotli_reg_t num) {\r
-#if defined(BROTLI_RBIT)\r
- return BROTLI_RBIT(num);\r
-#else\r
- return kReverseBits[num];\r
-#endif\r
-}\r
-\r
-/* Stores code in table[0], table[step], table[2*step], ..., table[end] */\r
-/* Assumes that end is an integer multiple of step */\r
-static BROTLI_INLINE void ReplicateValue(HuffmanCode* table,\r
- int step, int end,\r
- HuffmanCode code) {\r
- do {\r
- end -= step;\r
- table[end] = code;\r
- } while (end > 0);\r
-}\r
-\r
-/* Returns the table width of the next 2nd level table. |count| is the histogram\r
- of bit lengths for the remaining symbols, |len| is the code length of the\r
- next processed symbol. */\r
-static BROTLI_INLINE int NextTableBitSize(const uint16_t* const count,\r
- int len, int root_bits) {\r
- int left = 1 << (len - root_bits);\r
- while (len < BROTLI_HUFFMAN_MAX_CODE_LENGTH) {\r
- left -= count[len];\r
- if (left <= 0) break;\r
- ++len;\r
- left <<= 1;\r
- }\r
- return len - root_bits;\r
-}\r
-\r
-void BrotliBuildCodeLengthsHuffmanTable(HuffmanCode* table,\r
- const uint8_t* const code_lengths,\r
- uint16_t* count) {\r
- HuffmanCode code; /* current table entry */\r
- int symbol; /* symbol index in original or sorted table */\r
- brotli_reg_t key; /* prefix code */\r
- brotli_reg_t key_step; /* prefix code addend */\r
- int step; /* step size to replicate values in current table */\r
- int table_size; /* size of current table */\r
- int sorted[BROTLI_CODE_LENGTH_CODES]; /* symbols sorted by code length */\r
- /* offsets in sorted table for each length */\r
- int offset[BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH + 1];\r
- int bits;\r
- int bits_count;\r
- BROTLI_DCHECK(BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH <=\r
- BROTLI_REVERSE_BITS_MAX);\r
-\r
- /* Generate offsets into sorted symbol table by code length. */\r
- symbol = -1;\r
- bits = 1;\r
- BROTLI_REPEAT(BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH, {\r
- symbol += count[bits];\r
- offset[bits] = symbol;\r
- bits++;\r
- });\r
- /* Symbols with code length 0 are placed after all other symbols. */\r
- offset[0] = BROTLI_CODE_LENGTH_CODES - 1;\r
-\r
- /* Sort symbols by length, by symbol order within each length. */\r
- symbol = BROTLI_CODE_LENGTH_CODES;\r
- do {\r
- BROTLI_REPEAT(6, {\r
- symbol--;\r
- sorted[offset[code_lengths[symbol]]--] = symbol;\r
- });\r
- } while (symbol != 0);\r
-\r
- table_size = 1 << BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH;\r
-\r
- /* Special case: all symbols but one have 0 code length. */\r
- if (offset[0] == 0) {\r
- code.bits = 0;\r
- code.value = (uint16_t)sorted[0];\r
- for (key = 0; key < (brotli_reg_t)table_size; ++key) {\r
- table[key] = code;\r
- }\r
- return;\r
- }\r
-\r
- /* Fill in table. */\r
- key = 0;\r
- key_step = BROTLI_REVERSE_BITS_LOWEST;\r
- symbol = 0;\r
- bits = 1;\r
- step = 2;\r
- do {\r
- code.bits = (uint8_t)bits;\r
- for (bits_count = count[bits]; bits_count != 0; --bits_count) {\r
- code.value = (uint16_t)sorted[symbol++];\r
- ReplicateValue(&table[BrotliReverseBits(key)], step, table_size, code);\r
- key += key_step;\r
- }\r
- step <<= 1;\r
- key_step >>= 1;\r
- } while (++bits <= BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH);\r
-}\r
-\r
-uint32_t BrotliBuildHuffmanTable(HuffmanCode* root_table,\r
- int root_bits,\r
- const uint16_t* const symbol_lists,\r
- uint16_t* count) {\r
- HuffmanCode code; /* current table entry */\r
- HuffmanCode* table; /* next available space in table */\r
- int len; /* current code length */\r
- int symbol; /* symbol index in original or sorted table */\r
- brotli_reg_t key; /* prefix code */\r
- brotli_reg_t key_step; /* prefix code addend */\r
- brotli_reg_t sub_key; /* 2nd level table prefix code */\r
- brotli_reg_t sub_key_step; /* 2nd level table prefix code addend */\r
- int step; /* step size to replicate values in current table */\r
- int table_bits; /* key length of current table */\r
- int table_size; /* size of current table */\r
- int total_size; /* sum of root table size and 2nd level table sizes */\r
- int max_length = -1;\r
- int bits;\r
- int bits_count;\r
-\r
- BROTLI_DCHECK(root_bits <= BROTLI_REVERSE_BITS_MAX);\r
- BROTLI_DCHECK(BROTLI_HUFFMAN_MAX_CODE_LENGTH - root_bits <=\r
- BROTLI_REVERSE_BITS_MAX);\r
-\r
- while (symbol_lists[max_length] == 0xFFFF) max_length--;\r
- max_length += BROTLI_HUFFMAN_MAX_CODE_LENGTH + 1;\r
-\r
- table = root_table;\r
- table_bits = root_bits;\r
- table_size = 1 << table_bits;\r
- total_size = table_size;\r
-\r
- /* Fill in the root table. Reduce the table size to if possible,\r
- and create the repetitions by memcpy. */\r
- if (table_bits > max_length) {\r
- table_bits = max_length;\r
- table_size = 1 << table_bits;\r
- }\r
- key = 0;\r
- key_step = BROTLI_REVERSE_BITS_LOWEST;\r
- bits = 1;\r
- step = 2;\r
- do {\r
- code.bits = (uint8_t)bits;\r
- symbol = bits - (BROTLI_HUFFMAN_MAX_CODE_LENGTH + 1);\r
- for (bits_count = count[bits]; bits_count != 0; --bits_count) {\r
- symbol = symbol_lists[symbol];\r
- code.value = (uint16_t)symbol;\r
- ReplicateValue(&table[BrotliReverseBits(key)], step, table_size, code);\r
- key += key_step;\r
- }\r
- step <<= 1;\r
- key_step >>= 1;\r
- } while (++bits <= table_bits);\r
-\r
- /* If root_bits != table_bits then replicate to fill the remaining slots. */\r
- while (total_size != table_size) {\r
- memcpy(&table[table_size], &table[0],\r
- (size_t)table_size * sizeof(table[0]));\r
- table_size <<= 1;\r
- }\r
-\r
- /* Fill in 2nd level tables and add pointers to root table. */\r
- key_step = BROTLI_REVERSE_BITS_LOWEST >> (root_bits - 1);\r
- sub_key = (BROTLI_REVERSE_BITS_LOWEST << 1);\r
- sub_key_step = BROTLI_REVERSE_BITS_LOWEST;\r
- for (len = root_bits + 1, step = 2; len <= max_length; ++len) {\r
- symbol = len - (BROTLI_HUFFMAN_MAX_CODE_LENGTH + 1);\r
- for (; count[len] != 0; --count[len]) {\r
- if (sub_key == (BROTLI_REVERSE_BITS_LOWEST << 1U)) {\r
- table += table_size;\r
- table_bits = NextTableBitSize(count, len, root_bits);\r
- table_size = 1 << table_bits;\r
- total_size += table_size;\r
- sub_key = BrotliReverseBits(key);\r
- key += key_step;\r
- root_table[sub_key].bits = (uint8_t)(table_bits + root_bits);\r
- root_table[sub_key].value =\r
- (uint16_t)(((size_t)(table - root_table)) - sub_key);\r
- sub_key = 0;\r
- }\r
- code.bits = (uint8_t)(len - root_bits);\r
- symbol = symbol_lists[symbol];\r
- code.value = (uint16_t)symbol;\r
- ReplicateValue(\r
- &table[BrotliReverseBits(sub_key)], step, table_size, code);\r
- sub_key += sub_key_step;\r
- }\r
- step <<= 1;\r
- sub_key_step >>= 1;\r
- }\r
- return (uint32_t)total_size;\r
-}\r
-\r
-uint32_t BrotliBuildSimpleHuffmanTable(HuffmanCode* table,\r
- int root_bits,\r
- uint16_t* val,\r
- uint32_t num_symbols) {\r
- uint32_t table_size = 1;\r
- const uint32_t goal_size = 1U << root_bits;\r
- switch (num_symbols) {\r
- case 0:\r
- table[0].bits = 0;\r
- table[0].value = val[0];\r
- break;\r
- case 1:\r
- table[0].bits = 1;\r
- table[1].bits = 1;\r
- if (val[1] > val[0]) {\r
- table[0].value = val[0];\r
- table[1].value = val[1];\r
- } else {\r
- table[0].value = val[1];\r
- table[1].value = val[0];\r
- }\r
- table_size = 2;\r
- break;\r
- case 2:\r
- table[0].bits = 1;\r
- table[0].value = val[0];\r
- table[2].bits = 1;\r
- table[2].value = val[0];\r
- if (val[2] > val[1]) {\r
- table[1].value = val[1];\r
- table[3].value = val[2];\r
- } else {\r
- table[1].value = val[2];\r
- table[3].value = val[1];\r
- }\r
- table[1].bits = 2;\r
- table[3].bits = 2;\r
- table_size = 4;\r
- break;\r
- case 3: {\r
- int i, k;\r
- for (i = 0; i < 3; ++i) {\r
- for (k = i + 1; k < 4; ++k) {\r
- if (val[k] < val[i]) {\r
- uint16_t t = val[k];\r
- val[k] = val[i];\r
- val[i] = t;\r
- }\r
- }\r
- }\r
- for (i = 0; i < 4; ++i) {\r
- table[i].bits = 2;\r
- }\r
- table[0].value = val[0];\r
- table[2].value = val[1];\r
- table[1].value = val[2];\r
- table[3].value = val[3];\r
- table_size = 4;\r
- break;\r
- }\r
- case 4: {\r
- int i;\r
- if (val[3] < val[2]) {\r
- uint16_t t = val[3];\r
- val[3] = val[2];\r
- val[2] = t;\r
- }\r
- for (i = 0; i < 7; ++i) {\r
- table[i].value = val[0];\r
- table[i].bits = (uint8_t)(1 + (i & 1));\r
- }\r
- table[1].value = val[1];\r
- table[3].value = val[2];\r
- table[5].value = val[1];\r
- table[7].value = val[3];\r
- table[3].bits = 3;\r
- table[7].bits = 3;\r
- table_size = 8;\r
- break;\r
- }\r
- }\r
- while (table_size != goal_size) {\r
- memcpy(&table[table_size], &table[0],\r
- (size_t)table_size * sizeof(table[0]));\r
- table_size <<= 1;\r
- }\r
- return goal_size;\r
-}\r
-\r
-#if defined(__cplusplus) || defined(c_plusplus)\r
-} /* extern "C" */\r
-#endif\r
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