summaryrefslogtreecommitdiffstats
path: root/modules/brotli/dec/huffman.c
diff options
context:
space:
mode:
Diffstat (limited to 'modules/brotli/dec/huffman.c')
-rw-r--r--modules/brotli/dec/huffman.c356
1 files changed, 356 insertions, 0 deletions
diff --git a/modules/brotli/dec/huffman.c b/modules/brotli/dec/huffman.c
new file mode 100644
index 000000000..3775ffe7e
--- /dev/null
+++ b/modules/brotli/dec/huffman.c
@@ -0,0 +1,356 @@
+/* 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 "./port.h"
+#include "./types.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[18]; /* 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] = 17;
+
+ /* sort symbols by length, by symbol order within each length */
+ symbol = 18;
+ 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