/* 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. */ | |
#include "./huffman.h" | |
//#include <string.h> /* memcpy, memset */ | |
#include "../common/constants.h" | |
#include "../common/types.h" | |
#include "./port.h" | |
#if defined(__cplusplus) || defined(c_plusplus) | |
extern "C" { | |
#endif | |
#define BROTLI_REVERSE_BITS_MAX 8 | |
#ifdef BROTLI_RBIT | |
#define BROTLI_REVERSE_BITS_BASE (32 - BROTLI_REVERSE_BITS_MAX) | |
#else | |
#define BROTLI_REVERSE_BITS_BASE 0 | |
static uint8_t kReverseBits[1 << BROTLI_REVERSE_BITS_MAX] = { | |
0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0, | |
0x10, 0x90, 0x50, 0xD0, 0x30, 0xB0, 0x70, 0xF0, | |
0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8, | |
0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8, | |
0x04, 0x84, 0x44, 0xC4, 0x24, 0xA4, 0x64, 0xE4, | |
0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4, | |
0x0C, 0x8C, 0x4C, 0xCC, 0x2C, 0xAC, 0x6C, 0xEC, | |
0x1C, 0x9C, 0x5C, 0xDC, 0x3C, 0xBC, 0x7C, 0xFC, | |
0x02, 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2, | |
0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2, 0x72, 0xF2, | |
0x0A, 0x8A, 0x4A, 0xCA, 0x2A, 0xAA, 0x6A, 0xEA, | |
0x1A, 0x9A, 0x5A, 0xDA, 0x3A, 0xBA, 0x7A, 0xFA, | |
0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6, | |
0x16, 0x96, 0x56, 0xD6, 0x36, 0xB6, 0x76, 0xF6, | |
0x0E, 0x8E, 0x4E, 0xCE, 0x2E, 0xAE, 0x6E, 0xEE, | |
0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE, | |
0x01, 0x81, 0x41, 0xC1, 0x21, 0xA1, 0x61, 0xE1, | |
0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71, 0xF1, | |
0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9, | |
0x19, 0x99, 0x59, 0xD9, 0x39, 0xB9, 0x79, 0xF9, | |
0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5, | |
0x15, 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5, | |
0x0D, 0x8D, 0x4D, 0xCD, 0x2D, 0xAD, 0x6D, 0xED, | |
0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD, | |
0x03, 0x83, 0x43, 0xC3, 0x23, 0xA3, 0x63, 0xE3, | |
0x13, 0x93, 0x53, 0xD3, 0x33, 0xB3, 0x73, 0xF3, | |
0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB, | |
0x1B, 0x9B, 0x5B, 0xDB, 0x3B, 0xBB, 0x7B, 0xFB, | |
0x07, 0x87, 0x47, 0xC7, 0x27, 0xA7, 0x67, 0xE7, | |
0x17, 0x97, 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7, | |
0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F, 0xEF, | |
0x1F, 0x9F, 0x5F, 0xDF, 0x3F, 0xBF, 0x7F, 0xFF | |
}; | |
#endif /* BROTLI_RBIT */ | |
#define BROTLI_REVERSE_BITS_LOWEST \ | |
(1U << (BROTLI_REVERSE_BITS_MAX - 1 + BROTLI_REVERSE_BITS_BASE)) | |
/* Returns reverse(num >> BROTLI_REVERSE_BITS_BASE, BROTLI_REVERSE_BITS_MAX), | |
where reverse(value, len) is the bit-wise reversal of the len least | |
significant bits of value. */ | |
static BROTLI_INLINE uint32_t BrotliReverseBits(uint32_t num) { | |
#ifdef BROTLI_RBIT | |
return BROTLI_RBIT(num); | |
#else | |
return kReverseBits[num]; | |
#endif | |
} | |
/* Stores code in table[0], table[step], table[2*step], ..., table[end] */ | |
/* Assumes that end is an integer multiple of step */ | |
static BROTLI_INLINE void ReplicateValue(HuffmanCode* table, | |
int step, int end, | |
HuffmanCode code) { | |
do { | |
end -= step; | |
table[end] = code; | |
} while (end > 0); | |
} | |
/* Returns the table width of the next 2nd level table. count is the histogram | |
of bit lengths for the remaining symbols, len is the code length of the next | |
processed symbol */ | |
static BROTLI_INLINE int NextTableBitSize(const uint16_t* const count, | |
int len, int root_bits) { | |
int left = 1 << (len - root_bits); | |
while (len < BROTLI_HUFFMAN_MAX_CODE_LENGTH) { | |
left -= count[len]; | |
if (left <= 0) break; | |
++len; | |
left <<= 1; | |
} | |
return len - root_bits; | |
} | |
void BrotliBuildCodeLengthsHuffmanTable(HuffmanCode* table, | |
const uint8_t* const code_lengths, | |
uint16_t* count) { | |
HuffmanCode code; /* current table entry */ | |
int symbol; /* symbol index in original or sorted table */ | |
uint32_t key; /* prefix code */ | |
uint32_t key_step; /* prefix code addend */ | |
int step; /* step size to replicate values in current table */ | |
int table_size; /* size of current table */ | |
int sorted[BROTLI_CODE_LENGTH_CODES]; /* symbols sorted by code length */ | |
/* offsets in sorted table for each length */ | |
int offset[BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH + 1]; | |
int bits; | |
int bits_count; | |
BROTLI_DCHECK(BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH <= | |
BROTLI_REVERSE_BITS_MAX); | |
/* generate offsets into sorted symbol table by code length */ | |
symbol = -1; | |
bits = 1; | |
BROTLI_REPEAT(BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH, { | |
symbol += count[bits]; | |
offset[bits] = symbol; | |
bits++; | |
}); | |
/* Symbols with code length 0 are placed after all other symbols. */ | |
offset[0] = BROTLI_CODE_LENGTH_CODES - 1; | |
/* sort symbols by length, by symbol order within each length */ | |
symbol = BROTLI_CODE_LENGTH_CODES; | |
do { | |
BROTLI_REPEAT(6, { | |
symbol--; | |
sorted[offset[code_lengths[symbol]]--] = symbol; | |
}); | |
} while (symbol != 0); | |
table_size = 1 << BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH; | |
/* Special case: all symbols but one have 0 code length. */ | |
if (offset[0] == 0) { | |
code.bits = 0; | |
code.value = (uint16_t)sorted[0]; | |
for (key = 0; key < (uint32_t)table_size; ++key) { | |
table[key] = code; | |
} | |
return; | |
} | |
/* fill in table */ | |
key = 0; | |
key_step = BROTLI_REVERSE_BITS_LOWEST; | |
symbol = 0; | |
bits = 1; | |
step = 2; | |
do { | |
code.bits = (uint8_t)bits; | |
for (bits_count = count[bits]; bits_count != 0; --bits_count) { | |
code.value = (uint16_t)sorted[symbol++]; | |
ReplicateValue(&table[BrotliReverseBits(key)], step, table_size, code); | |
key += key_step; | |
} | |
step <<= 1; | |
key_step >>= 1; | |
} while (++bits <= BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH); | |
} | |
uint32_t BrotliBuildHuffmanTable(HuffmanCode* root_table, | |
int root_bits, | |
const uint16_t* const symbol_lists, | |
uint16_t* count) { | |
HuffmanCode code; /* current table entry */ | |
HuffmanCode* table; /* next available space in table */ | |
int len; /* current code length */ | |
int symbol; /* symbol index in original or sorted table */ | |
uint32_t key; /* prefix code */ | |
uint32_t key_step; /* prefix code addend */ | |
uint32_t sub_key; /* 2nd level table prefix code */ | |
uint32_t sub_key_step; /* 2nd level table prefix code addend */ | |
int step; /* step size to replicate values in current table */ | |
int table_bits; /* key length of current table */ | |
int table_size; /* size of current table */ | |
int total_size; /* sum of root table size and 2nd level table sizes */ | |
int max_length = -1; | |
int bits; | |
int bits_count; | |
BROTLI_DCHECK(root_bits <= BROTLI_REVERSE_BITS_MAX); | |
BROTLI_DCHECK(BROTLI_HUFFMAN_MAX_CODE_LENGTH - root_bits <= | |
BROTLI_REVERSE_BITS_MAX); | |
while (symbol_lists[max_length] == 0xFFFF) max_length--; | |
max_length += BROTLI_HUFFMAN_MAX_CODE_LENGTH + 1; | |
table = root_table; | |
table_bits = root_bits; | |
table_size = 1 << table_bits; | |
total_size = table_size; | |
/* fill in root table */ | |
/* let's reduce the table size to a smaller size if possible, and */ | |
/* create the repetitions by memcpy if possible in the coming loop */ | |
if (table_bits > max_length) { | |
table_bits = max_length; | |
table_size = 1 << table_bits; | |
} | |
key = 0; | |
key_step = BROTLI_REVERSE_BITS_LOWEST; | |
bits = 1; | |
step = 2; | |
do { | |
code.bits = (uint8_t)bits; | |
symbol = bits - (BROTLI_HUFFMAN_MAX_CODE_LENGTH + 1); | |
for (bits_count = count[bits]; bits_count != 0; --bits_count) { | |
symbol = symbol_lists[symbol]; | |
code.value = (uint16_t)symbol; | |
ReplicateValue(&table[BrotliReverseBits(key)], step, table_size, code); | |
key += key_step; | |
} | |
step <<= 1; | |
key_step >>= 1; | |
} while (++bits <= table_bits); | |
/* if root_bits != table_bits we only created one fraction of the */ | |
/* table, and we need to replicate it now. */ | |
while (total_size != table_size) { | |
memcpy(&table[table_size], &table[0], | |
(size_t)table_size * sizeof(table[0])); | |
table_size <<= 1; | |
} | |
/* fill in 2nd level tables and add pointers to root table */ | |
key_step = BROTLI_REVERSE_BITS_LOWEST >> (root_bits - 1); | |
sub_key = (BROTLI_REVERSE_BITS_LOWEST << 1); | |
sub_key_step = BROTLI_REVERSE_BITS_LOWEST; | |
for (len = root_bits + 1, step = 2; len <= max_length; ++len) { | |
symbol = len - (BROTLI_HUFFMAN_MAX_CODE_LENGTH + 1); | |
for (; count[len] != 0; --count[len]) { | |
if (sub_key == (BROTLI_REVERSE_BITS_LOWEST << 1U)) { | |
table += table_size; | |
table_bits = NextTableBitSize(count, len, root_bits); | |
table_size = 1 << table_bits; | |
total_size += table_size; | |
sub_key = BrotliReverseBits(key); | |
key += key_step; | |
root_table[sub_key].bits = (uint8_t)(table_bits + root_bits); | |
root_table[sub_key].value = | |
(uint16_t)(((size_t)(table - root_table)) - sub_key); | |
sub_key = 0; | |
} | |
code.bits = (uint8_t)(len - root_bits); | |
symbol = symbol_lists[symbol]; | |
code.value = (uint16_t)symbol; | |
ReplicateValue( | |
&table[BrotliReverseBits(sub_key)], step, table_size, code); | |
sub_key += sub_key_step; | |
} | |
step <<= 1; | |
sub_key_step >>= 1; | |
} | |
return (uint32_t)total_size; | |
} | |
uint32_t BrotliBuildSimpleHuffmanTable(HuffmanCode* table, | |
int root_bits, | |
uint16_t* val, | |
uint32_t num_symbols) { | |
uint32_t table_size = 1; | |
const uint32_t goal_size = 1U << root_bits; | |
switch (num_symbols) { | |
case 0: | |
table[0].bits = 0; | |
table[0].value = val[0]; | |
break; | |
case 1: | |
table[0].bits = 1; | |
table[1].bits = 1; | |
if (val[1] > val[0]) { | |
table[0].value = val[0]; | |
table[1].value = val[1]; | |
} else { | |
table[0].value = val[1]; | |
table[1].value = val[0]; | |
} | |
table_size = 2; | |
break; | |
case 2: | |
table[0].bits = 1; | |
table[0].value = val[0]; | |
table[2].bits = 1; | |
table[2].value = val[0]; | |
if (val[2] > val[1]) { | |
table[1].value = val[1]; | |
table[3].value = val[2]; | |
} else { | |
table[1].value = val[2]; | |
table[3].value = val[1]; | |
} | |
table[1].bits = 2; | |
table[3].bits = 2; | |
table_size = 4; | |
break; | |
case 3: { | |
int i, k; | |
for (i = 0; i < 3; ++i) { | |
for (k = i + 1; k < 4; ++k) { | |
if (val[k] < val[i]) { | |
uint16_t t = val[k]; | |
val[k] = val[i]; | |
val[i] = t; | |
} | |
} | |
} | |
for (i = 0; i < 4; ++i) { | |
table[i].bits = 2; | |
} | |
table[0].value = val[0]; | |
table[2].value = val[1]; | |
table[1].value = val[2]; | |
table[3].value = val[3]; | |
table_size = 4; | |
break; | |
} | |
case 4: { | |
int i; | |
if (val[3] < val[2]) { | |
uint16_t t = val[3]; | |
val[3] = val[2]; | |
val[2] = t; | |
} | |
for (i = 0; i < 7; ++i) { | |
table[i].value = val[0]; | |
table[i].bits = (uint8_t)(1 + (i & 1)); | |
} | |
table[1].value = val[1]; | |
table[3].value = val[2]; | |
table[5].value = val[1]; | |
table[7].value = val[3]; | |
table[3].bits = 3; | |
table[7].bits = 3; | |
table_size = 8; | |
break; | |
} | |
} | |
while (table_size != goal_size) { | |
memcpy(&table[table_size], &table[0], | |
(size_t)table_size * sizeof(table[0])); | |
table_size <<= 1; | |
} | |
return goal_size; | |
} | |
#if defined(__cplusplus) || defined(c_plusplus) | |
} /* extern "C" */ | |
#endif |