--- /dev/null
+/* 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/types.h"\r
+#include "./port.h"\r
+\r
+#if defined(__cplusplus) || defined(c_plusplus)\r
+extern "C" {\r
+#endif\r
+\r
+#define BROTLI_REVERSE_BITS_MAX 8\r
+\r
+#ifdef BROTLI_RBIT\r
+#define BROTLI_REVERSE_BITS_BASE (32 - 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
+ (1U << (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 uint32_t BrotliReverseBits(uint32_t num) {\r
+#ifdef 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 next\r
+ 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
+ uint32_t key; /* prefix code */\r
+ uint32_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 < (uint32_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
+ uint32_t key; /* prefix code */\r
+ uint32_t key_step; /* prefix code addend */\r
+ uint32_t sub_key; /* 2nd level table prefix code */\r
+ uint32_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 root table */\r
+ /* let's reduce the table size to a smaller size if possible, and */\r
+ /* create the repetitions by memcpy if possible in the coming loop */\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 we only created one fraction of the */\r
+ /* table, and we need to replicate it now. */\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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