| 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 | |
| 38 | const 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, |
| 43 | 16,17,18,19,20,21,22,23, |
| 44 | 24, |
| 45 | }; |
| 46 | |
| 47 | void avpriv_align_put_bits(PutBitContext *s) |
| 48 | { |
| 49 | put_bits(s, s->bit_left & 7, 0); |
| 50 | } |
| 51 | |
| 52 | void 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 | |
| 63 | void 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 | |
| 105 | static 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 | |
| 125 | static 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 | |
| 133 | typedef 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 | |
| 141 | static 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 | */ |
| 160 | static 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 | */ |
| 271 | int 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 | |
| 356 | void ff_free_vlc(VLC *vlc) |
| 357 | { |
| 358 | av_freep(&vlc->table); |
| 359 | } |