1/* 2 * Common bit i/o utils 3 * Copyright (c) 2000, 2001 Fabrice Bellard 4 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> 5 * Copyright (c) 2010 Loren Merritt 6 * 7 * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at> 8 * 9 * This file is part of FFmpeg. 10 * 11 * FFmpeg is free software; you can redistribute it and/or 12 * modify it under the terms of the GNU Lesser General Public 13 * License as published by the Free Software Foundation; either 14 * version 2.1 of the License, or (at your option) any later version. 15 * 16 * FFmpeg is distributed in the hope that it will be useful, 17 * but WITHOUT ANY WARRANTY; without even the implied warranty of 18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 19 * Lesser General Public License for more details. 20 * 21 * You should have received a copy of the GNU Lesser General Public 22 * License along with FFmpeg; if not, write to the Free Software 23 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 24 */ 25 26/** 27 * @file 28 * bitstream api. 29 */ 30 31#include "libavutil/atomic.h" 32#include "libavutil/avassert.h" 33#include "avcodec.h" 34#include "mathops.h" 35#include "get_bits.h" 36#include "put_bits.h" 37 38const uint8_t ff_log2_run[41]={ 39 0, 0, 0, 0, 1, 1, 1, 1, 40 2, 2, 2, 2, 3, 3, 3, 3, 41 4, 4, 5, 5, 6, 6, 7, 7, 42 8, 9,10,11,12,13,14,15, 4316,17,18,19,20,21,22,23, 4424, 45}; 46 47void avpriv_align_put_bits(PutBitContext *s) 48{ 49 put_bits(s, s->bit_left & 7, 0); 50} 51 52void avpriv_put_string(PutBitContext *pb, const char *string, 53 int terminate_string) 54{ 55 while (*string) { 56 put_bits(pb, 8, *string); 57 string++; 58 } 59 if (terminate_string) 60 put_bits(pb, 8, 0); 61} 62 63void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length) 64{ 65 int words = length >> 4; 66 int bits = length & 15; 67 int i; 68 69 if (length == 0) 70 return; 71 72 if (CONFIG_SMALL || words < 16 || put_bits_count(pb) & 7) { 73 for (i = 0; i < words; i++) 74 put_bits(pb, 16, AV_RB16(src + 2 * i)); 75 } else { 76 for (i = 0; put_bits_count(pb) & 31; i++) 77 put_bits(pb, 8, src[i]); 78 flush_put_bits(pb); 79 memcpy(put_bits_ptr(pb), src + i, 2 * words - i); 80 skip_put_bytes(pb, 2 * words - i); 81 } 82 83 put_bits(pb, bits, AV_RB16(src + 2 * words) >> (16 - bits)); 84} 85 86/* VLC decoding */ 87 88#define GET_DATA(v, table, i, wrap, size) \ 89{ \ 90 const uint8_t *ptr = (const uint8_t *)table + i * wrap; \ 91 switch(size) { \ 92 case 1: \ 93 v = *(const uint8_t *)ptr; \ 94 break; \ 95 case 2: \ 96 v = *(const uint16_t *)ptr; \ 97 break; \ 98 default: \ 99 v = *(const uint32_t *)ptr; \ 100 break; \ 101 } \ 102} 103 104 105static int alloc_table(VLC *vlc, int size, int use_static) 106{ 107 int index = vlc->table_size; 108 109 vlc->table_size += size; 110 if (vlc->table_size > vlc->table_allocated) { 111 if (use_static) 112 abort(); // cannot do anything, init_vlc() is used with too little memory 113 vlc->table_allocated += (1 << vlc->bits); 114 vlc->table = av_realloc_f(vlc->table, vlc->table_allocated, sizeof(VLC_TYPE) * 2); 115 if (!vlc->table) { 116 vlc->table_allocated = 0; 117 vlc->table_size = 0; 118 return AVERROR(ENOMEM); 119 } 120 memset(vlc->table + vlc->table_allocated - (1 << vlc->bits), 0, sizeof(VLC_TYPE) * 2 << vlc->bits); 121 } 122 return index; 123} 124 125static av_always_inline uint32_t bitswap_32(uint32_t x) 126{ 127 return (uint32_t)ff_reverse[ x & 0xFF] << 24 | 128 (uint32_t)ff_reverse[(x >> 8) & 0xFF] << 16 | 129 (uint32_t)ff_reverse[(x >> 16) & 0xFF] << 8 | 130 (uint32_t)ff_reverse[ x >> 24]; 131} 132 133typedef struct { 134 uint8_t bits; 135 uint16_t symbol; 136 /** codeword, with the first bit-to-be-read in the msb 137 * (even if intended for a little-endian bitstream reader) */ 138 uint32_t code; 139} VLCcode; 140 141static int compare_vlcspec(const void *a, const void *b) 142{ 143 const VLCcode *sa = a, *sb = b; 144 return (sa->code >> 1) - (sb->code >> 1); 145} 146/** 147 * Build VLC decoding tables suitable for use with get_vlc(). 148 * 149 * @param vlc the context to be initted 150 * 151 * @param table_nb_bits max length of vlc codes to store directly in this table 152 * (Longer codes are delegated to subtables.) 153 * 154 * @param nb_codes number of elements in codes[] 155 * 156 * @param codes descriptions of the vlc codes 157 * These must be ordered such that codes going into the same subtable are contiguous. 158 * Sorting by VLCcode.code is sufficient, though not necessary. 159 */ 160static int build_table(VLC *vlc, int table_nb_bits, int nb_codes, 161 VLCcode *codes, int flags) 162{ 163 int table_size, table_index, index, code_prefix, symbol, subtable_bits; 164 int i, j, k, n, nb, inc; 165 uint32_t code; 166 volatile VLC_TYPE (* volatile table)[2]; // the double volatile is needed to prevent a internal compiler error in gcc 4.2 167 168 table_size = 1 << table_nb_bits; 169 if (table_nb_bits > 30) 170 return -1; 171 table_index = alloc_table(vlc, table_size, flags & INIT_VLC_USE_NEW_STATIC); 172 av_dlog(NULL, "new table index=%d size=%d\n", table_index, table_size); 173 if (table_index < 0) 174 return table_index; 175 table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index]; 176 177 /* first pass: map codes and compute auxiliary table sizes */ 178 for (i = 0; i < nb_codes; i++) { 179 n = codes[i].bits; 180 code = codes[i].code; 181 symbol = codes[i].symbol; 182 av_dlog(NULL, "i=%d n=%d code=0x%x\n", i, n, code); 183 if (n <= table_nb_bits) { 184 /* no need to add another table */ 185 j = code >> (32 - table_nb_bits); 186 nb = 1 << (table_nb_bits - n); 187 inc = 1; 188 if (flags & INIT_VLC_LE) { 189 j = bitswap_32(code); 190 inc = 1 << n; 191 } 192 for (k = 0; k < nb; k++) { 193 int bits = table[j][1]; 194 av_dlog(NULL, "%4x: code=%d n=%d\n", j, i, n); 195 if (bits != 0 && bits != n) { 196 av_log(NULL, AV_LOG_ERROR, "incorrect codes\n"); 197 return AVERROR_INVALIDDATA; 198 } 199 table[j][1] = n; //bits 200 table[j][0] = symbol; 201 j += inc; 202 } 203 } else { 204 /* fill auxiliary table recursively */ 205 n -= table_nb_bits; 206 code_prefix = code >> (32 - table_nb_bits); 207 subtable_bits = n; 208 codes[i].bits = n; 209 codes[i].code = code << table_nb_bits; 210 for (k = i+1; k < nb_codes; k++) { 211 n = codes[k].bits - table_nb_bits; 212 if (n <= 0) 213 break; 214 code = codes[k].code; 215 if (code >> (32 - table_nb_bits) != code_prefix) 216 break; 217 codes[k].bits = n; 218 codes[k].code = code << table_nb_bits; 219 subtable_bits = FFMAX(subtable_bits, n); 220 } 221 subtable_bits = FFMIN(subtable_bits, table_nb_bits); 222 j = (flags & INIT_VLC_LE) ? bitswap_32(code_prefix) >> (32 - table_nb_bits) : code_prefix; 223 table[j][1] = -subtable_bits; 224 av_dlog(NULL, "%4x: n=%d (subtable)\n", 225 j, codes[i].bits + table_nb_bits); 226 index = build_table(vlc, subtable_bits, k-i, codes+i, flags); 227 if (index < 0) 228 return index; 229 /* note: realloc has been done, so reload tables */ 230 table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index]; 231 table[j][0] = index; //code 232 i = k-1; 233 } 234 } 235 236 for (i = 0; i < table_size; i++) { 237 if (table[i][1] == 0) //bits 238 table[i][0] = -1; //codes 239 } 240 241 return table_index; 242} 243 244 245/* Build VLC decoding tables suitable for use with get_vlc(). 246 247 'nb_bits' set thee decoding table size (2^nb_bits) entries. The 248 bigger it is, the faster is the decoding. But it should not be too 249 big to save memory and L1 cache. '9' is a good compromise. 250 251 'nb_codes' : number of vlcs codes 252 253 'bits' : table which gives the size (in bits) of each vlc code. 254 255 'codes' : table which gives the bit pattern of of each vlc code. 256 257 'symbols' : table which gives the values to be returned from get_vlc(). 258 259 'xxx_wrap' : give the number of bytes between each entry of the 260 'bits' or 'codes' tables. 261 262 'xxx_size' : gives the number of bytes of each entry of the 'bits' 263 or 'codes' tables. 264 265 'wrap' and 'size' allows to use any memory configuration and types 266 (byte/word/long) to store the 'bits', 'codes', and 'symbols' tables. 267 268 'use_static' should be set to 1 for tables, which should be freed 269 with av_free_static(), 0 if ff_free_vlc() will be used. 270*/ 271int ff_init_vlc_sparse(VLC *vlc_arg, int nb_bits, int nb_codes, 272 const void *bits, int bits_wrap, int bits_size, 273 const void *codes, int codes_wrap, int codes_size, 274 const void *symbols, int symbols_wrap, int symbols_size, 275 int flags) 276{ 277 VLCcode *buf; 278 int i, j, ret; 279 VLCcode localbuf[1500]; // the maximum currently needed is 1296 by rv34 280 VLC localvlc, *vlc; 281 282 vlc = vlc_arg; 283 vlc->bits = nb_bits; 284 if (flags & INIT_VLC_USE_NEW_STATIC) { 285 av_assert0(nb_codes + 1 <= FF_ARRAY_ELEMS(localbuf)); 286 buf = localbuf; 287 localvlc = *vlc_arg; 288 vlc = &localvlc; 289 vlc->table_size = 0; 290 } else { 291 vlc->table = NULL; 292 vlc->table_allocated = 0; 293 vlc->table_size = 0; 294 295 buf = av_malloc_array((nb_codes + 1), sizeof(VLCcode)); 296 if (!buf) 297 return AVERROR(ENOMEM); 298 } 299 300 301 av_assert0(symbols_size <= 2 || !symbols); 302 j = 0; 303#define COPY(condition)\ 304 for (i = 0; i < nb_codes; i++) { \ 305 GET_DATA(buf[j].bits, bits, i, bits_wrap, bits_size); \ 306 if (!(condition)) \ 307 continue; \ 308 if (buf[j].bits > 3*nb_bits || buf[j].bits>32) { \ 309 av_log(NULL, AV_LOG_ERROR, "Too long VLC (%d) in init_vlc\n", buf[j].bits);\ 310 if (!(flags & INIT_VLC_USE_NEW_STATIC)) \ 311 av_free(buf); \ 312 return -1; \ 313 } \ 314 GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size); \ 315 if (buf[j].code >= (1LL<<buf[j].bits)) { \ 316 av_log(NULL, AV_LOG_ERROR, "Invalid code in init_vlc\n"); \ 317 if (!(flags & INIT_VLC_USE_NEW_STATIC)) \ 318 av_free(buf); \ 319 return -1; \ 320 } \ 321 if (flags & INIT_VLC_LE) \ 322 buf[j].code = bitswap_32(buf[j].code); \ 323 else \ 324 buf[j].code <<= 32 - buf[j].bits; \ 325 if (symbols) \ 326 GET_DATA(buf[j].symbol, symbols, i, symbols_wrap, symbols_size) \ 327 else \ 328 buf[j].symbol = i; \ 329 j++; \ 330 } 331 COPY(buf[j].bits > nb_bits); 332 // qsort is the slowest part of init_vlc, and could probably be improved or avoided 333 qsort(buf, j, sizeof(VLCcode), compare_vlcspec); 334 COPY(buf[j].bits && buf[j].bits <= nb_bits); 335 nb_codes = j; 336 337 ret = build_table(vlc, nb_bits, nb_codes, buf, flags); 338 339 if (flags & INIT_VLC_USE_NEW_STATIC) { 340 if(vlc->table_size != vlc->table_allocated) 341 av_log(NULL, AV_LOG_ERROR, "needed %d had %d\n", vlc->table_size, vlc->table_allocated); 342 343 av_assert0(ret >= 0); 344 *vlc_arg = *vlc; 345 } else { 346 av_free(buf); 347 if (ret < 0) { 348 av_freep(&vlc->table); 349 return ret; 350 } 351 } 352 return 0; 353} 354 355 356void ff_free_vlc(VLC *vlc) 357{ 358 av_freep(&vlc->table); 359} 360