/src/woff2/brotli/c/dec/huffman.c
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1 | | /* Copyright 2013 Google Inc. All Rights Reserved. |
2 | | |
3 | | Distributed under MIT license. |
4 | | See file LICENSE for detail or copy at https://opensource.org/licenses/MIT |
5 | | */ |
6 | | |
7 | | /* Utilities for building Huffman decoding tables. */ |
8 | | |
9 | | #include "./huffman.h" |
10 | | |
11 | | #include <string.h> /* memcpy, memset */ |
12 | | |
13 | | #include "../common/constants.h" |
14 | | #include "../common/platform.h" |
15 | | #include <brotli/types.h> |
16 | | |
17 | | #if defined(__cplusplus) || defined(c_plusplus) |
18 | | extern "C" { |
19 | | #endif |
20 | | |
21 | 1.70M | #define BROTLI_REVERSE_BITS_MAX 8 |
22 | | |
23 | | #ifdef BROTLI_RBIT |
24 | | #define BROTLI_REVERSE_BITS_BASE \ |
25 | | ((sizeof(brotli_reg_t) << 3) - BROTLI_REVERSE_BITS_MAX) |
26 | | #else |
27 | 1.70M | #define BROTLI_REVERSE_BITS_BASE 0 |
28 | | static uint8_t kReverseBits[1 << BROTLI_REVERSE_BITS_MAX] = { |
29 | | 0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0, |
30 | | 0x10, 0x90, 0x50, 0xD0, 0x30, 0xB0, 0x70, 0xF0, |
31 | | 0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8, |
32 | | 0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8, |
33 | | 0x04, 0x84, 0x44, 0xC4, 0x24, 0xA4, 0x64, 0xE4, |
34 | | 0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4, |
35 | | 0x0C, 0x8C, 0x4C, 0xCC, 0x2C, 0xAC, 0x6C, 0xEC, |
36 | | 0x1C, 0x9C, 0x5C, 0xDC, 0x3C, 0xBC, 0x7C, 0xFC, |
37 | | 0x02, 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2, |
38 | | 0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2, 0x72, 0xF2, |
39 | | 0x0A, 0x8A, 0x4A, 0xCA, 0x2A, 0xAA, 0x6A, 0xEA, |
40 | | 0x1A, 0x9A, 0x5A, 0xDA, 0x3A, 0xBA, 0x7A, 0xFA, |
41 | | 0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6, |
42 | | 0x16, 0x96, 0x56, 0xD6, 0x36, 0xB6, 0x76, 0xF6, |
43 | | 0x0E, 0x8E, 0x4E, 0xCE, 0x2E, 0xAE, 0x6E, 0xEE, |
44 | | 0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE, |
45 | | 0x01, 0x81, 0x41, 0xC1, 0x21, 0xA1, 0x61, 0xE1, |
46 | | 0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71, 0xF1, |
47 | | 0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9, |
48 | | 0x19, 0x99, 0x59, 0xD9, 0x39, 0xB9, 0x79, 0xF9, |
49 | | 0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5, |
50 | | 0x15, 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5, |
51 | | 0x0D, 0x8D, 0x4D, 0xCD, 0x2D, 0xAD, 0x6D, 0xED, |
52 | | 0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD, |
53 | | 0x03, 0x83, 0x43, 0xC3, 0x23, 0xA3, 0x63, 0xE3, |
54 | | 0x13, 0x93, 0x53, 0xD3, 0x33, 0xB3, 0x73, 0xF3, |
55 | | 0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB, |
56 | | 0x1B, 0x9B, 0x5B, 0xDB, 0x3B, 0xBB, 0x7B, 0xFB, |
57 | | 0x07, 0x87, 0x47, 0xC7, 0x27, 0xA7, 0x67, 0xE7, |
58 | | 0x17, 0x97, 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7, |
59 | | 0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F, 0xEF, |
60 | | 0x1F, 0x9F, 0x5F, 0xDF, 0x3F, 0xBF, 0x7F, 0xFF |
61 | | }; |
62 | | #endif /* BROTLI_RBIT */ |
63 | | |
64 | | #define BROTLI_REVERSE_BITS_LOWEST \ |
65 | 1.70M | ((brotli_reg_t)1 << (BROTLI_REVERSE_BITS_MAX - 1 + BROTLI_REVERSE_BITS_BASE)) |
66 | | |
67 | | /* Returns reverse(num >> BROTLI_REVERSE_BITS_BASE, BROTLI_REVERSE_BITS_MAX), |
68 | | where reverse(value, len) is the bit-wise reversal of the len least |
69 | | significant bits of value. */ |
70 | 4.19M | static BROTLI_INLINE brotli_reg_t BrotliReverseBits(brotli_reg_t num) { |
71 | | #ifdef BROTLI_RBIT |
72 | | return BROTLI_RBIT(num); |
73 | | #else |
74 | 4.19M | return kReverseBits[num]; |
75 | 4.19M | #endif |
76 | 4.19M | } |
77 | | |
78 | | /* Stores code in table[0], table[step], table[2*step], ..., table[end] */ |
79 | | /* Assumes that end is an integer multiple of step */ |
80 | | static BROTLI_INLINE void ReplicateValue(HuffmanCode* table, |
81 | | int step, int end, |
82 | 3.71M | HuffmanCode code) { |
83 | 9.11M | do { |
84 | 9.11M | end -= step; |
85 | 9.11M | table[end] = code; |
86 | 9.11M | } while (end > 0); |
87 | 3.71M | } |
88 | | |
89 | | /* Returns the table width of the next 2nd level table. |count| is the histogram |
90 | | of bit lengths for the remaining symbols, |len| is the code length of the |
91 | | next processed symbol. */ |
92 | | static BROTLI_INLINE int NextTableBitSize(const uint16_t* const count, |
93 | 475k | int len, int root_bits) { |
94 | 475k | int left = 1 << (len - root_bits); |
95 | 491k | while (len < BROTLI_HUFFMAN_MAX_CODE_LENGTH) { |
96 | 491k | left -= count[len]; |
97 | 491k | if (left <= 0) break; |
98 | 16.3k | ++len; |
99 | 16.3k | left <<= 1; |
100 | 16.3k | } |
101 | 475k | return len - root_bits; |
102 | 475k | } |
103 | | |
104 | | void BrotliBuildCodeLengthsHuffmanTable(HuffmanCode* table, |
105 | | const uint8_t* const code_lengths, |
106 | 44.0k | uint16_t* count) { |
107 | 44.0k | HuffmanCode code; /* current table entry */ |
108 | 44.0k | int symbol; /* symbol index in original or sorted table */ |
109 | 44.0k | brotli_reg_t key; /* prefix code */ |
110 | 44.0k | brotli_reg_t key_step; /* prefix code addend */ |
111 | 44.0k | int step; /* step size to replicate values in current table */ |
112 | 44.0k | int table_size; /* size of current table */ |
113 | 44.0k | int sorted[BROTLI_CODE_LENGTH_CODES]; /* symbols sorted by code length */ |
114 | | /* offsets in sorted table for each length */ |
115 | 44.0k | int offset[BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH + 1]; |
116 | 44.0k | int bits; |
117 | 44.0k | int bits_count; |
118 | 44.0k | BROTLI_DCHECK(BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH <= |
119 | 44.0k | BROTLI_REVERSE_BITS_MAX); |
120 | | |
121 | | /* Generate offsets into sorted symbol table by code length. */ |
122 | 44.0k | symbol = -1; |
123 | 44.0k | bits = 1; |
124 | 44.0k | BROTLI_REPEAT(BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH, { |
125 | 44.0k | symbol += count[bits]; |
126 | 44.0k | offset[bits] = symbol; |
127 | 44.0k | bits++; |
128 | 44.0k | }); |
129 | | /* Symbols with code length 0 are placed after all other symbols. */ |
130 | 44.0k | offset[0] = BROTLI_CODE_LENGTH_CODES - 1; |
131 | | |
132 | | /* Sort symbols by length, by symbol order within each length. */ |
133 | 44.0k | symbol = BROTLI_CODE_LENGTH_CODES; |
134 | 132k | do { |
135 | 132k | BROTLI_REPEAT(6, { |
136 | 132k | symbol--; |
137 | 132k | sorted[offset[code_lengths[symbol]]--] = symbol; |
138 | 132k | }); |
139 | 132k | } while (symbol != 0); |
140 | | |
141 | 44.0k | table_size = 1 << BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH; |
142 | | |
143 | | /* Special case: all symbols but one have 0 code length. */ |
144 | 44.0k | if (offset[0] == 0) { |
145 | 777 | code.bits = 0; |
146 | 777 | code.value = (uint16_t)sorted[0]; |
147 | 25.6k | for (key = 0; key < (brotli_reg_t)table_size; ++key) { |
148 | 24.8k | table[key] = code; |
149 | 24.8k | } |
150 | 777 | return; |
151 | 777 | } |
152 | | |
153 | | /* Fill in table. */ |
154 | 43.2k | key = 0; |
155 | 43.2k | key_step = BROTLI_REVERSE_BITS_LOWEST; |
156 | 43.2k | symbol = 0; |
157 | 43.2k | bits = 1; |
158 | 43.2k | step = 2; |
159 | 216k | do { |
160 | 216k | code.bits = (uint8_t)bits; |
161 | 527k | for (bits_count = count[bits]; bits_count != 0; --bits_count) { |
162 | 311k | code.value = (uint16_t)sorted[symbol++]; |
163 | 311k | ReplicateValue(&table[BrotliReverseBits(key)], step, table_size, code); |
164 | 311k | key += key_step; |
165 | 311k | } |
166 | 216k | step <<= 1; |
167 | 216k | key_step >>= 1; |
168 | 216k | } while (++bits <= BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH); |
169 | 43.2k | } |
170 | | |
171 | | uint32_t BrotliBuildHuffmanTable(HuffmanCode* root_table, |
172 | | int root_bits, |
173 | | const uint16_t* const symbol_lists, |
174 | 43.3k | uint16_t* count) { |
175 | 43.3k | HuffmanCode code; /* current table entry */ |
176 | 43.3k | HuffmanCode* table; /* next available space in table */ |
177 | 43.3k | int len; /* current code length */ |
178 | 43.3k | int symbol; /* symbol index in original or sorted table */ |
179 | 43.3k | brotli_reg_t key; /* prefix code */ |
180 | 43.3k | brotli_reg_t key_step; /* prefix code addend */ |
181 | 43.3k | brotli_reg_t sub_key; /* 2nd level table prefix code */ |
182 | 43.3k | brotli_reg_t sub_key_step; /* 2nd level table prefix code addend */ |
183 | 43.3k | int step; /* step size to replicate values in current table */ |
184 | 43.3k | int table_bits; /* key length of current table */ |
185 | 43.3k | int table_size; /* size of current table */ |
186 | 43.3k | int total_size; /* sum of root table size and 2nd level table sizes */ |
187 | 43.3k | int max_length = -1; |
188 | 43.3k | int bits; |
189 | 43.3k | int bits_count; |
190 | | |
191 | 43.3k | BROTLI_DCHECK(root_bits <= BROTLI_REVERSE_BITS_MAX); |
192 | 43.3k | BROTLI_DCHECK(BROTLI_HUFFMAN_MAX_CODE_LENGTH - root_bits <= |
193 | 43.3k | BROTLI_REVERSE_BITS_MAX); |
194 | | |
195 | 370k | while (symbol_lists[max_length] == 0xFFFF) max_length--; |
196 | 43.3k | max_length += BROTLI_HUFFMAN_MAX_CODE_LENGTH + 1; |
197 | | |
198 | 43.3k | table = root_table; |
199 | 43.3k | table_bits = root_bits; |
200 | 43.3k | table_size = 1 << table_bits; |
201 | 43.3k | total_size = table_size; |
202 | | |
203 | | /* Fill in the root table. Reduce the table size to if possible, |
204 | | and create the repetitions by memcpy. */ |
205 | 43.3k | if (table_bits > max_length) { |
206 | 21.1k | table_bits = max_length; |
207 | 21.1k | table_size = 1 << table_bits; |
208 | 21.1k | } |
209 | 43.3k | key = 0; |
210 | 43.3k | key_step = BROTLI_REVERSE_BITS_LOWEST; |
211 | 43.3k | bits = 1; |
212 | 43.3k | step = 2; |
213 | 280k | do { |
214 | 280k | code.bits = (uint8_t)bits; |
215 | 280k | symbol = bits - (BROTLI_HUFFMAN_MAX_CODE_LENGTH + 1); |
216 | 2.19M | for (bits_count = count[bits]; bits_count != 0; --bits_count) { |
217 | 1.91M | symbol = symbol_lists[symbol]; |
218 | 1.91M | code.value = (uint16_t)symbol; |
219 | 1.91M | ReplicateValue(&table[BrotliReverseBits(key)], step, table_size, code); |
220 | 1.91M | key += key_step; |
221 | 1.91M | } |
222 | 280k | step <<= 1; |
223 | 280k | key_step >>= 1; |
224 | 280k | } while (++bits <= table_bits); |
225 | | |
226 | | /* If root_bits != table_bits then replicate to fill the remaining slots. */ |
227 | 109k | while (total_size != table_size) { |
228 | 66.5k | memcpy(&table[table_size], &table[0], |
229 | 66.5k | (size_t)table_size * sizeof(table[0])); |
230 | 66.5k | table_size <<= 1; |
231 | 66.5k | } |
232 | | |
233 | | /* Fill in 2nd level tables and add pointers to root table. */ |
234 | 43.3k | key_step = BROTLI_REVERSE_BITS_LOWEST >> (root_bits - 1); |
235 | 43.3k | sub_key = (BROTLI_REVERSE_BITS_LOWEST << 1); |
236 | 43.3k | sub_key_step = BROTLI_REVERSE_BITS_LOWEST; |
237 | 86.6k | for (len = root_bits + 1, step = 2; len <= max_length; ++len) { |
238 | 43.2k | symbol = len - (BROTLI_HUFFMAN_MAX_CODE_LENGTH + 1); |
239 | 1.52M | for (; count[len] != 0; --count[len]) { |
240 | 1.48M | if (sub_key == (BROTLI_REVERSE_BITS_LOWEST << 1U)) { |
241 | 475k | table += table_size; |
242 | 475k | table_bits = NextTableBitSize(count, len, root_bits); |
243 | 475k | table_size = 1 << table_bits; |
244 | 475k | total_size += table_size; |
245 | 475k | sub_key = BrotliReverseBits(key); |
246 | 475k | key += key_step; |
247 | 475k | root_table[sub_key].bits = (uint8_t)(table_bits + root_bits); |
248 | 475k | root_table[sub_key].value = |
249 | 475k | (uint16_t)(((size_t)(table - root_table)) - sub_key); |
250 | 475k | sub_key = 0; |
251 | 475k | } |
252 | 1.48M | code.bits = (uint8_t)(len - root_bits); |
253 | 1.48M | symbol = symbol_lists[symbol]; |
254 | 1.48M | code.value = (uint16_t)symbol; |
255 | 1.48M | ReplicateValue( |
256 | 1.48M | &table[BrotliReverseBits(sub_key)], step, table_size, code); |
257 | 1.48M | sub_key += sub_key_step; |
258 | 1.48M | } |
259 | 43.2k | step <<= 1; |
260 | 43.2k | sub_key_step >>= 1; |
261 | 43.2k | } |
262 | 43.3k | return (uint32_t)total_size; |
263 | 43.3k | } |
264 | | |
265 | | uint32_t BrotliBuildSimpleHuffmanTable(HuffmanCode* table, |
266 | | int root_bits, |
267 | | uint16_t* val, |
268 | 64.1k | uint32_t num_symbols) { |
269 | 64.1k | uint32_t table_size = 1; |
270 | 64.1k | const uint32_t goal_size = 1U << root_bits; |
271 | 64.1k | switch (num_symbols) { |
272 | 37.8k | case 0: |
273 | 37.8k | table[0].bits = 0; |
274 | 37.8k | table[0].value = val[0]; |
275 | 37.8k | break; |
276 | 10.3k | case 1: |
277 | 10.3k | table[0].bits = 1; |
278 | 10.3k | table[1].bits = 1; |
279 | 10.3k | if (val[1] > val[0]) { |
280 | 7.54k | table[0].value = val[0]; |
281 | 7.54k | table[1].value = val[1]; |
282 | 7.54k | } else { |
283 | 2.82k | table[0].value = val[1]; |
284 | 2.82k | table[1].value = val[0]; |
285 | 2.82k | } |
286 | 10.3k | table_size = 2; |
287 | 10.3k | break; |
288 | 11.7k | case 2: |
289 | 11.7k | table[0].bits = 1; |
290 | 11.7k | table[0].value = val[0]; |
291 | 11.7k | table[2].bits = 1; |
292 | 11.7k | table[2].value = val[0]; |
293 | 11.7k | if (val[2] > val[1]) { |
294 | 4.43k | table[1].value = val[1]; |
295 | 4.43k | table[3].value = val[2]; |
296 | 7.31k | } else { |
297 | 7.31k | table[1].value = val[2]; |
298 | 7.31k | table[3].value = val[1]; |
299 | 7.31k | } |
300 | 11.7k | table[1].bits = 2; |
301 | 11.7k | table[3].bits = 2; |
302 | 11.7k | table_size = 4; |
303 | 11.7k | break; |
304 | 2.27k | case 3: { |
305 | 2.27k | int i, k; |
306 | 9.11k | for (i = 0; i < 3; ++i) { |
307 | 20.5k | for (k = i + 1; k < 4; ++k) { |
308 | 13.6k | if (val[k] < val[i]) { |
309 | 5.60k | uint16_t t = val[k]; |
310 | 5.60k | val[k] = val[i]; |
311 | 5.60k | val[i] = t; |
312 | 5.60k | } |
313 | 13.6k | } |
314 | 6.83k | } |
315 | 11.3k | for (i = 0; i < 4; ++i) { |
316 | 9.11k | table[i].bits = 2; |
317 | 9.11k | } |
318 | 2.27k | table[0].value = val[0]; |
319 | 2.27k | table[2].value = val[1]; |
320 | 2.27k | table[1].value = val[2]; |
321 | 2.27k | table[3].value = val[3]; |
322 | 2.27k | table_size = 4; |
323 | 2.27k | break; |
324 | 0 | } |
325 | 1.91k | case 4: { |
326 | 1.91k | int i; |
327 | 1.91k | if (val[3] < val[2]) { |
328 | 871 | uint16_t t = val[3]; |
329 | 871 | val[3] = val[2]; |
330 | 871 | val[2] = t; |
331 | 871 | } |
332 | 15.3k | for (i = 0; i < 7; ++i) { |
333 | 13.3k | table[i].value = val[0]; |
334 | 13.3k | table[i].bits = (uint8_t)(1 + (i & 1)); |
335 | 13.3k | } |
336 | 1.91k | table[1].value = val[1]; |
337 | 1.91k | table[3].value = val[2]; |
338 | 1.91k | table[5].value = val[1]; |
339 | 1.91k | table[7].value = val[3]; |
340 | 1.91k | table[3].bits = 3; |
341 | 1.91k | table[7].bits = 3; |
342 | 1.91k | table_size = 8; |
343 | 1.91k | break; |
344 | 0 | } |
345 | 64.1k | } |
346 | 533k | while (table_size != goal_size) { |
347 | 469k | memcpy(&table[table_size], &table[0], |
348 | 469k | (size_t)table_size * sizeof(table[0])); |
349 | 469k | table_size <<= 1; |
350 | 469k | } |
351 | 64.1k | return goal_size; |
352 | 64.1k | } |
353 | | |
354 | | #if defined(__cplusplus) || defined(c_plusplus) |
355 | | } /* extern "C" */ |
356 | | #endif |