libavcodec/get_bits.h

   1 /*
   2  * copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
   3  *
   4  * This file is part of FFmpeg.
   5  *
   6  * FFmpeg is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * FFmpeg is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with FFmpeg; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 /**
  22  * @file libavcodec/get_bits.h
  23  * bitstream reader API header.
  24  */
  25
  26 #ifndef AVCODEC_GET_BITS_H
  27 #define AVCODEC_GET_BITS_H
  28
  29 #include <stdint.h>
  30 #include <stdlib.h>
  31 #include <assert.h>
  32 #include "libavutil/bswap.h"
  33 #include "libavutil/common.h"
  34 #include "libavutil/intreadwrite.h"
  35 #include "libavutil/log.h"
  36 #include "mathops.h"
  37
  38 #if defined(ALT_BITSTREAM_READER_LE) && !defined(ALT_BITSTREAM_READER)
  39 #   define ALT_BITSTREAM_READER
  40 #endif
  41
  42 #if !defined(LIBMPEG2_BITSTREAM_READER) && !defined(A32_BITSTREAM_READER) && !defined(ALT_BITSTREAM_READER)
  43 #   if ARCH_ARM && !HAVE_FAST_UNALIGNED
  44 #       define A32_BITSTREAM_READER
  45 #   else
  46 #       define ALT_BITSTREAM_READER
  47 //#define LIBMPEG2_BITSTREAM_READER
  48 //#define A32_BITSTREAM_READER
  49 #   endif
  50 #endif
  51
  52 /* bit input */
  53 /* buffer, buffer_end and size_in_bits must be present and used by every reader */
  54 typedef struct GetBitContext {
  55     const uint8_t *buffer, *buffer_end;
  56 #ifdef ALT_BITSTREAM_READER
  57     int index;
  58 #elif defined LIBMPEG2_BITSTREAM_READER
  59     uint8_t *buffer_ptr;
  60     uint32_t cache;
  61     int bit_count;
  62 #elif defined A32_BITSTREAM_READER
  63     uint32_t *buffer_ptr;
  64     uint32_t cache0;
  65     uint32_t cache1;
  66     int bit_count;
  67 #endif
  68     int size_in_bits;
  69 } GetBitContext;
  70
  71 #define VLC_TYPE int16_t
  72
  73 typedef struct VLC {
  74     int bits;
  75     VLC_TYPE (*table)[2]; ///< code, bits
  76     int table_size, table_allocated;
  77 } VLC;
  78
  79 typedef struct RL_VLC_ELEM {
  80     int16_t level;
  81     int8_t len;
  82     uint8_t run;
  83 } RL_VLC_ELEM;
  84
  85 /* Bitstream reader API docs:
  86 name
  87     arbitrary name which is used as prefix for the internal variables
  88
  89 gb
  90     getbitcontext
  91
  92 OPEN_READER(name, gb)
  93     loads gb into local variables
  94
  95 CLOSE_READER(name, gb)
  96     stores local vars in gb
  97
  98 UPDATE_CACHE(name, gb)
  99     refills the internal cache from the bitstream
 100     after this call at least MIN_CACHE_BITS will be available,
 101
 102 GET_CACHE(name, gb)
 103     will output the contents of the internal cache, next bit is MSB of 32 or 64 bit (FIXME 64bit)
 104
 105 SHOW_UBITS(name, gb, num)
 106     will return the next num bits
 107
 108 SHOW_SBITS(name, gb, num)
 109     will return the next num bits and do sign extension
 110
 111 SKIP_BITS(name, gb, num)
 112     will skip over the next num bits
 113     note, this is equivalent to SKIP_CACHE; SKIP_COUNTER
 114
 115 SKIP_CACHE(name, gb, num)
 116     will remove the next num bits from the cache (note SKIP_COUNTER MUST be called before UPDATE_CACHE / CLOSE_READER)
 117
 118 SKIP_COUNTER(name, gb, num)
 119     will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS)
 120
 121 LAST_SKIP_CACHE(name, gb, num)
 122     will remove the next num bits from the cache if it is needed for UPDATE_CACHE otherwise it will do nothing
 123
 124 LAST_SKIP_BITS(name, gb, num)
 125     is equivalent to LAST_SKIP_CACHE; SKIP_COUNTER
 126
 127 for examples see get_bits, show_bits, skip_bits, get_vlc
 128 */
 129
 130 #ifdef ALT_BITSTREAM_READER
 131 #   define MIN_CACHE_BITS 25
 132
 133 #   define OPEN_READER(name, gb)\
 134         unsigned int name##_index= (gb)->index;\
 135         int name##_cache= 0;\
 136
 137 #   define CLOSE_READER(name, gb)\
 138         (gb)->index= name##_index;\
 139
 140 # ifdef ALT_BITSTREAM_READER_LE
 141 #   define UPDATE_CACHE(name, gb)\
 142         name##_cache= AV_RL32( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) >> (name##_index&0x07);\
 143
 144 #   define SKIP_CACHE(name, gb, num)\
 145         name##_cache >>= (num);
 146 # else
 147 #   define UPDATE_CACHE(name, gb)\
 148         name##_cache= AV_RB32( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) << (name##_index&0x07);\
 149
 150 #   define SKIP_CACHE(name, gb, num)\
 151         name##_cache <<= (num);
 152 # endif
 153
 154 // FIXME name?
 155 #   define SKIP_COUNTER(name, gb, num)\
 156         name##_index += (num);\
 157
 158 #   define SKIP_BITS(name, gb, num)\
 159         {\
 160             SKIP_CACHE(name, gb, num)\
 161             SKIP_COUNTER(name, gb, num)\
 162         }\
 163
 164 #   define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
 165 #   define LAST_SKIP_CACHE(name, gb, num) ;
 166
 167 # ifdef ALT_BITSTREAM_READER_LE
 168 #   define SHOW_UBITS(name, gb, num)\
 169         zero_extend(name##_cache, num)
 170
 171 #   define SHOW_SBITS(name, gb, num)\
 172         sign_extend(name##_cache, num)
 173 # else
 174 #   define SHOW_UBITS(name, gb, num)\
 175         NEG_USR32(name##_cache, num)
 176
 177 #   define SHOW_SBITS(name, gb, num)\
 178         NEG_SSR32(name##_cache, num)
 179 # endif
 180
 181 #   define GET_CACHE(name, gb)\
 182         ((uint32_t)name##_cache)
 183
 184 static inline int get_bits_count(const GetBitContext *s){
 185     return s->index;
 186 }
 187
 188 static inline void skip_bits_long(GetBitContext *s, int n){
 189     s->index += n;
 190 }
 191
 192 #elif defined LIBMPEG2_BITSTREAM_READER
 193 //libmpeg2 like reader
 194
 195 #   define MIN_CACHE_BITS 17
 196
 197 #   define OPEN_READER(name, gb)\
 198         int name##_bit_count=(gb)->bit_count;\
 199         int name##_cache= (gb)->cache;\
 200         uint8_t * name##_buffer_ptr=(gb)->buffer_ptr;\
 201
 202 #   define CLOSE_READER(name, gb)\
 203         (gb)->bit_count= name##_bit_count;\
 204         (gb)->cache= name##_cache;\
 205         (gb)->buffer_ptr= name##_buffer_ptr;\
 206
 207 #   define UPDATE_CACHE(name, gb)\
 208     if(name##_bit_count >= 0){\
 209         name##_cache+= AV_RB16(name##_buffer_ptr) << name##_bit_count; \
 210         name##_buffer_ptr+=2;\
 211         name##_bit_count-= 16;\
 212     }\
 213
 214 #   define SKIP_CACHE(name, gb, num)\
 215         name##_cache <<= (num);\
 216
 217 #   define SKIP_COUNTER(name, gb, num)\
 218         name##_bit_count += (num);\
 219
 220 #   define SKIP_BITS(name, gb, num)\
 221         {\
 222             SKIP_CACHE(name, gb, num)\
 223             SKIP_COUNTER(name, gb, num)\
 224         }\
 225
 226 #   define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
 227 #   define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
 228
 229 #   define SHOW_UBITS(name, gb, num)\
 230         NEG_USR32(name##_cache, num)
 231
 232 #   define SHOW_SBITS(name, gb, num)\
 233         NEG_SSR32(name##_cache, num)
 234
 235 #   define GET_CACHE(name, gb)\
 236         ((uint32_t)name##_cache)
 237
 238 static inline int get_bits_count(const GetBitContext *s){
 239     return (s->buffer_ptr - s->buffer)*8 - 16 + s->bit_count;
 240 }
 241
 242 static inline void skip_bits_long(GetBitContext *s, int n){
 243     OPEN_READER(re, s)
 244     re_bit_count += n;
 245     re_buffer_ptr += 2*(re_bit_count>>4);
 246     re_bit_count &= 15;
 247     re_cache = ((re_buffer_ptr[-2]<<8) + re_buffer_ptr[-1]) << (16+re_bit_count);
 248     UPDATE_CACHE(re, s)
 249     CLOSE_READER(re, s)
 250 }
 251
 252 #elif defined A32_BITSTREAM_READER
 253
 254 #   define MIN_CACHE_BITS 32
 255
 256 #   define OPEN_READER(name, gb)\
 257         int name##_bit_count=(gb)->bit_count;\
 258         uint32_t name##_cache0= (gb)->cache0;\
 259         uint32_t name##_cache1= (gb)->cache1;\
 260         uint32_t * name##_buffer_ptr=(gb)->buffer_ptr;\
 261
 262 #   define CLOSE_READER(name, gb)\
 263         (gb)->bit_count= name##_bit_count;\
 264         (gb)->cache0= name##_cache0;\
 265         (gb)->cache1= name##_cache1;\
 266         (gb)->buffer_ptr= name##_buffer_ptr;\
 267
 268 #   define UPDATE_CACHE(name, gb)\
 269     if(name##_bit_count > 0){\
 270         const uint32_t next= be2me_32( *name##_buffer_ptr );\
 271         name##_cache0 |= NEG_USR32(next,name##_bit_count);\
 272         name##_cache1 |= next<<name##_bit_count;\
 273         name##_buffer_ptr++;\
 274         name##_bit_count-= 32;\
 275     }\
 276
 277 #if ARCH_X86
 278 #   define SKIP_CACHE(name, gb, num)\
 279         __asm__(\
 280             "shldl %2, %1, %0          \n\t"\
 281             "shll %2, %1               \n\t"\
 282             : "+r" (name##_cache0), "+r" (name##_cache1)\
 283             : "Ic" ((uint8_t)(num))\
 284            );
 285 #else
 286 #   define SKIP_CACHE(name, gb, num)\
 287         name##_cache0 <<= (num);\
 288         name##_cache0 |= NEG_USR32(name##_cache1,num);\
 289         name##_cache1 <<= (num);
 290 #endif
 291
 292 #   define SKIP_COUNTER(name, gb, num)\
 293         name##_bit_count += (num);\
 294
 295 #   define SKIP_BITS(name, gb, num)\
 296         {\
 297             SKIP_CACHE(name, gb, num)\
 298             SKIP_COUNTER(name, gb, num)\
 299         }\
 300
 301 #   define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
 302 #   define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
 303
 304 #   define SHOW_UBITS(name, gb, num)\
 305         NEG_USR32(name##_cache0, num)
 306
 307 #   define SHOW_SBITS(name, gb, num)\
 308         NEG_SSR32(name##_cache0, num)
 309
 310 #   define GET_CACHE(name, gb)\
 311         (name##_cache0)
 312
 313 static inline int get_bits_count(const GetBitContext *s){
 314     return ((uint8_t*)s->buffer_ptr - s->buffer)*8 - 32 + s->bit_count;
 315 }
 316
 317 static inline void skip_bits_long(GetBitContext *s, int n){
 318     OPEN_READER(re, s)
 319     re_bit_count += n;
 320     re_buffer_ptr += re_bit_count>>5;
 321     re_bit_count &= 31;
 322     re_cache0 = be2me_32( re_buffer_ptr[-1] ) << re_bit_count;
 323     re_cache1 = 0;
 324     UPDATE_CACHE(re, s)
 325     CLOSE_READER(re, s)
 326 }
 327
 328 #endif
 329
 330 /**
 331  * read mpeg1 dc style vlc (sign bit + mantisse with no MSB).
 332  * if MSB not set it is negative
 333  * @param n length in bits
 334  * @author BERO
 335  */
 336 static inline int get_xbits(GetBitContext *s, int n){
 337     register int sign;
 338     register int32_t cache;
 339     OPEN_READER(re, s)
 340     UPDATE_CACHE(re, s)
 341     cache = GET_CACHE(re,s);
 342     sign=(~cache)>>31;
 343     LAST_SKIP_BITS(re, s, n)
 344     CLOSE_READER(re, s)
 345     return (NEG_USR32(sign ^ cache, n) ^ sign) - sign;
 346 }
 347
 348 static inline int get_sbits(GetBitContext *s, int n){
 349     register int tmp;
 350     OPEN_READER(re, s)
 351     UPDATE_CACHE(re, s)
 352     tmp= SHOW_SBITS(re, s, n);
 353     LAST_SKIP_BITS(re, s, n)
 354     CLOSE_READER(re, s)
 355     return tmp;
 356 }
 357
 358 /**
 359  * reads 1-17 bits.
 360  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
 361  */
 362 static inline unsigned int get_bits(GetBitContext *s, int n){
 363     register int tmp;
 364     OPEN_READER(re, s)
 365     UPDATE_CACHE(re, s)
 366     tmp= SHOW_UBITS(re, s, n);
 367     LAST_SKIP_BITS(re, s, n)
 368     CLOSE_READER(re, s)
 369     return tmp;
 370 }
 371
 372 /**
 373  * shows 1-17 bits.
 374  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
 375  */
 376 static inline unsigned int show_bits(GetBitContext *s, int n){
 377     register int tmp;
 378     OPEN_READER(re, s)
 379     UPDATE_CACHE(re, s)
 380     tmp= SHOW_UBITS(re, s, n);
 381 //    CLOSE_READER(re, s)
 382     return tmp;
 383 }
 384
 385 static inline void skip_bits(GetBitContext *s, int n){
 386  //Note gcc seems to optimize this to s->index+=n for the ALT_READER :))
 387     OPEN_READER(re, s)
 388     UPDATE_CACHE(re, s)
 389     LAST_SKIP_BITS(re, s, n)
 390     CLOSE_READER(re, s)
 391 }
 392
 393 static inline unsigned int get_bits1(GetBitContext *s){
 394 #ifdef ALT_BITSTREAM_READER
 395     unsigned int index= s->index;
 396     uint8_t result= s->buffer[ index>>3 ];
 397 #ifdef ALT_BITSTREAM_READER_LE
 398     result>>= (index&0x07);
 399     result&= 1;
 400 #else
 401     result<<= (index&0x07);
 402     result>>= 8 - 1;
 403 #endif
 404     index++;
 405     s->index= index;
 406
 407     return result;
 408 #else
 409     return get_bits(s, 1);
 410 #endif
 411 }
 412
 413 static inline unsigned int show_bits1(GetBitContext *s){
 414     return show_bits(s, 1);
 415 }
 416
 417 static inline void skip_bits1(GetBitContext *s){
 418     skip_bits(s, 1);
 419 }
 420
 421 /**
 422  * reads 0-32 bits.
 423  */
 424 static inline unsigned int get_bits_long(GetBitContext *s, int n){
 425     if(n<=17) return get_bits(s, n);
 426     else{
 427 #ifdef ALT_BITSTREAM_READER_LE
 428         int ret= get_bits(s, 16);
 429         return ret | (get_bits(s, n-16) << 16);
 430 #else
 431         int ret= get_bits(s, 16) << (n-16);
 432         return ret | get_bits(s, n-16);
 433 #endif
 434     }
 435 }
 436
 437 /**
 438  * reads 0-32 bits as a signed integer.
 439  */
 440 static inline int get_sbits_long(GetBitContext *s, int n) {
 441     return sign_extend(get_bits_long(s, n), n);
 442 }
 443
 444 /**
 445  * shows 0-32 bits.
 446  */
 447 static inline unsigned int show_bits_long(GetBitContext *s, int n){
 448     if(n<=17) return show_bits(s, n);
 449     else{
 450         GetBitContext gb= *s;
 451         return get_bits_long(&gb, n);
 452     }
 453 }
 454
 455 static inline int check_marker(GetBitContext *s, const char *msg)
 456 {
 457     int bit= get_bits1(s);
 458     if(!bit)
 459         av_log(NULL, AV_LOG_INFO, "Marker bit missing %s\n", msg);
 460
 461     return bit;
 462 }
 463
 464 /**
 465  * init GetBitContext.
 466  * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger then the actual read bits
 467  * because some optimized bitstream readers read 32 or 64 bit at once and could read over the end
 468  * @param bit_size the size of the buffer in bits
 469  *
 470  * While GetBitContext stores the buffer size, for performance reasons you are
 471  * responsible for checking for the buffer end yourself (take advantage of the padding)!
 472  */
 473 static inline void init_get_bits(GetBitContext *s,
 474                    const uint8_t *buffer, int bit_size)
 475 {
 476     int buffer_size= (bit_size+7)>>3;
 477     if(buffer_size < 0 || bit_size < 0) {
 478         buffer_size = bit_size = 0;
 479         buffer = NULL;
 480     }
 481
 482     s->buffer= buffer;
 483     s->size_in_bits= bit_size;
 484     s->buffer_end= buffer + buffer_size;
 485 #ifdef ALT_BITSTREAM_READER
 486     s->index=0;
 487 #elif defined LIBMPEG2_BITSTREAM_READER
 488     s->buffer_ptr = (uint8_t*)((intptr_t)buffer&(~1));
 489     s->bit_count = 16 + 8*((intptr_t)buffer&1);
 490     skip_bits_long(s, 0);
 491 #elif defined A32_BITSTREAM_READER
 492     s->buffer_ptr = (uint32_t*)((intptr_t)buffer&(~3));
 493     s->bit_count = 32 + 8*((intptr_t)buffer&3);
 494     skip_bits_long(s, 0);
 495 #endif
 496 }
 497
 498 static inline void align_get_bits(GetBitContext *s)
 499 {
 500     int n= (-get_bits_count(s)) & 7;
 501     if(n) skip_bits(s, n);
 502 }
 503
 504 #define init_vlc(vlc, nb_bits, nb_codes,\
 505                  bits, bits_wrap, bits_size,\
 506                  codes, codes_wrap, codes_size,\
 507                  flags)\
 508         init_vlc_sparse(vlc, nb_bits, nb_codes,\
 509                  bits, bits_wrap, bits_size,\
 510                  codes, codes_wrap, codes_size,\
 511                  NULL, 0, 0, flags)
 512
 513 int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,
 514              const void *bits, int bits_wrap, int bits_size,
 515              const void *codes, int codes_wrap, int codes_size,
 516              const void *symbols, int symbols_wrap, int symbols_size,
 517              int flags);
 518 #define INIT_VLC_LE         2
 519 #define INIT_VLC_USE_NEW_STATIC 4
 520 void free_vlc(VLC *vlc);
 521
 522 #define INIT_VLC_STATIC(vlc, bits, a,b,c,d,e,f,g, static_size)\
 523 {\
 524     static VLC_TYPE table[static_size][2];\
 525     (vlc)->table= table;\
 526     (vlc)->table_allocated= static_size;\
 527     init_vlc(vlc, bits, a,b,c,d,e,f,g, INIT_VLC_USE_NEW_STATIC);\
 528 }
 529
 530
 531 /**
 532  *
 533  * If the vlc code is invalid and max_depth=1, then no bits will be removed.
 534  * If the vlc code is invalid and max_depth>1, then the number of bits removed
 535  * is undefined.
 536  */
 537 #define GET_VLC(code, name, gb, table, bits, max_depth)\
 538 {\
 539     int n, nb_bits;\
 540     unsigned int index;\
 541 \
 542     index= SHOW_UBITS(name, gb, bits);\
 543     code = table[index][0];\
 544     n    = table[index][1];\
 545 \
 546     if(max_depth > 1 && n < 0){\
 547         LAST_SKIP_BITS(name, gb, bits)\
 548         UPDATE_CACHE(name, gb)\
 549 \
 550         nb_bits = -n;\
 551 \
 552         index= SHOW_UBITS(name, gb, nb_bits) + code;\
 553         code = table[index][0];\
 554         n    = table[index][1];\
 555         if(max_depth > 2 && n < 0){\
 556             LAST_SKIP_BITS(name, gb, nb_bits)\
 557             UPDATE_CACHE(name, gb)\
 558 \
 559             nb_bits = -n;\
 560 \
 561             index= SHOW_UBITS(name, gb, nb_bits) + code;\
 562             code = table[index][0];\
 563             n    = table[index][1];\
 564         }\
 565     }\
 566     SKIP_BITS(name, gb, n)\
 567 }
 568
 569 #define GET_RL_VLC(level, run, name, gb, table, bits, max_depth, need_update)\
 570 {\
 571     int n, nb_bits;\
 572     unsigned int index;\
 573 \
 574     index= SHOW_UBITS(name, gb, bits);\
 575     level = table[index].level;\
 576     n     = table[index].len;\
 577 \
 578     if(max_depth > 1 && n < 0){\
 579         SKIP_BITS(name, gb, bits)\
 580         if(need_update){\
 581             UPDATE_CACHE(name, gb)\
 582         }\
 583 \
 584         nb_bits = -n;\
 585 \
 586         index= SHOW_UBITS(name, gb, nb_bits) + level;\
 587         level = table[index].level;\
 588         n     = table[index].len;\
 589     }\
 590     run= table[index].run;\
 591     SKIP_BITS(name, gb, n)\
 592 }
 593
 594
 595 /**
 596  * parses a vlc code, faster then get_vlc()
 597  * @param bits is the number of bits which will be read at once, must be
 598  *             identical to nb_bits in init_vlc()
 599  * @param max_depth is the number of times bits bits must be read to completely
 600  *                  read the longest vlc code
 601  *                  = (max_vlc_length + bits - 1) / bits
 602  */
 603 static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2],
 604                                   int bits, int max_depth)
 605 {
 606     int code;
 607
 608     OPEN_READER(re, s)
 609     UPDATE_CACHE(re, s)
 610
 611     GET_VLC(code, re, s, table, bits, max_depth)
 612
 613     CLOSE_READER(re, s)
 614     return code;
 615 }
 616
 617 //#define TRACE
 618
 619 #ifdef TRACE
 620 static inline void print_bin(int bits, int n){
 621     int i;
 622
 623     for(i=n-1; i>=0; i--){
 624         av_log(NULL, AV_LOG_DEBUG, "%d", (bits>>i)&1);
 625     }
 626     for(i=n; i<24; i++)
 627         av_log(NULL, AV_LOG_DEBUG, " ");
 628 }
 629
 630 static inline int get_bits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
 631     int r= get_bits(s, n);
 632
 633     print_bin(r, n);
 634     av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d bit @%5d in %s %s:%d\n", r, n, r, get_bits_count(s)-n, file, func, line);
 635     return r;
 636 }
 637 static inline int get_vlc_trace(GetBitContext *s, VLC_TYPE (*table)[2], int bits, int max_depth, char *file, const char *func, int line){
 638     int show= show_bits(s, 24);
 639     int pos= get_bits_count(s);
 640     int r= get_vlc2(s, table, bits, max_depth);
 641     int len= get_bits_count(s) - pos;
 642     int bits2= show>>(24-len);
 643
 644     print_bin(bits2, len);
 645
 646     av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d vlc @%5d in %s %s:%d\n", bits2, len, r, pos, file, func, line);
 647     return r;
 648 }
 649 static inline int get_xbits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
 650     int show= show_bits(s, n);
 651     int r= get_xbits(s, n);
 652
 653     print_bin(show, n);
 654     av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d xbt @%5d in %s %s:%d\n", show, n, r, get_bits_count(s)-n, file, func, line);
 655     return r;
 656 }
 657
 658 #define get_bits(s, n)  get_bits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 659 #define get_bits1(s)    get_bits_trace(s, 1, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 660 #define get_xbits(s, n) get_xbits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 661 #define get_vlc(s, vlc)            get_vlc_trace(s, (vlc)->table, (vlc)->bits, 3, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 662 #define get_vlc2(s, tab, bits, max) get_vlc_trace(s, tab, bits, max, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 663
 664 #define tprintf(p, ...) av_log(p, AV_LOG_DEBUG, __VA_ARGS__)
 665
 666 #else //TRACE
 667 #define tprintf(p, ...) {}
 668 #endif
 669
 670 static inline int decode012(GetBitContext *gb){
 671     int n;
 672     n = get_bits1(gb);
 673     if (n == 0)
 674         return 0;
 675     else
 676         return get_bits1(gb) + 1;
 677 }
 678
 679 static inline int decode210(GetBitContext *gb){
 680     if (get_bits1(gb))
 681         return 0;
 682     else
 683         return 2 - get_bits1(gb);
 684 }
 685
 686 static inline int get_bits_left(GetBitContext *gb)
 687 {
 688     return gb->size_in_bits - get_bits_count(gb);
 689 }
 690
 691 #endif /* AVCODEC_GET_BITS_H */