libavcodec/bitstream.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 bitstream.h
  23  * bitstream api header.
  24  */
  25
  26 #ifndef AVCODEC_BITSTREAM_H
  27 #define AVCODEC_BITSTREAM_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
  37 #if defined(ALT_BITSTREAM_READER_LE) && !defined(ALT_BITSTREAM_READER)
  38 #   define ALT_BITSTREAM_READER
  39 #endif
  40
  41 //#define ALT_BITSTREAM_WRITER
  42 //#define ALIGNED_BITSTREAM_WRITER
  43 #if !defined(LIBMPEG2_BITSTREAM_READER) && !defined(A32_BITSTREAM_READER) && !defined(ALT_BITSTREAM_READER)
  44 #   if ARCH_ARM
  45 #       define A32_BITSTREAM_READER
  46 #   else
  47 #       define ALT_BITSTREAM_READER
  48 //#define LIBMPEG2_BITSTREAM_READER
  49 //#define A32_BITSTREAM_READER
  50 #   endif
  51 #endif
  52
  53 extern const uint8_t ff_reverse[256];
  54
  55 #if ARCH_X86
  56 // avoid +32 for shift optimization (gcc should do that ...)
  57 static inline  int32_t NEG_SSR32( int32_t a, int8_t s){
  58     __asm__ ("sarl %1, %0\n\t"
  59          : "+r" (a)
  60          : "ic" ((uint8_t)(-s))
  61     );
  62     return a;
  63 }
  64 static inline uint32_t NEG_USR32(uint32_t a, int8_t s){
  65     __asm__ ("shrl %1, %0\n\t"
  66          : "+r" (a)
  67          : "ic" ((uint8_t)(-s))
  68     );
  69     return a;
  70 }
  71 #else
  72 #    define NEG_SSR32(a,s) ((( int32_t)(a))>>(32-(s)))
  73 #    define NEG_USR32(a,s) (((uint32_t)(a))>>(32-(s)))
  74 #endif
  75
  76 /* bit output */
  77
  78 /* buf and buf_end must be present and used by every alternative writer. */
  79 typedef struct PutBitContext {
  80 #ifdef ALT_BITSTREAM_WRITER
  81     uint8_t *buf, *buf_end;
  82     int index;
  83 #else
  84     uint32_t bit_buf;
  85     int bit_left;
  86     uint8_t *buf, *buf_ptr, *buf_end;
  87 #endif
  88 } PutBitContext;
  89
  90 static inline void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
  91 {
  92     if(buffer_size < 0) {
  93         buffer_size = 0;
  94         buffer = NULL;
  95     }
  96
  97     s->buf = buffer;
  98     s->buf_end = s->buf + buffer_size;
  99 #ifdef ALT_BITSTREAM_WRITER
 100     s->index=0;
 101     ((uint32_t*)(s->buf))[0]=0;
 102 //    memset(buffer, 0, buffer_size);
 103 #else
 104     s->buf_ptr = s->buf;
 105     s->bit_left=32;
 106     s->bit_buf=0;
 107 #endif
 108 }
 109
 110 /* return the number of bits output */
 111 static inline int put_bits_count(PutBitContext *s)
 112 {
 113 #ifdef ALT_BITSTREAM_WRITER
 114     return s->index;
 115 #else
 116     return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
 117 #endif
 118 }
 119
 120 /* pad the end of the output stream with zeros */
 121 static inline void flush_put_bits(PutBitContext *s)
 122 {
 123 #ifdef ALT_BITSTREAM_WRITER
 124     align_put_bits(s);
 125 #else
 126 #ifndef BITSTREAM_WRITER_LE
 127     s->bit_buf<<= s->bit_left;
 128 #endif
 129     while (s->bit_left < 32) {
 130         /* XXX: should test end of buffer */
 131 #ifdef BITSTREAM_WRITER_LE
 132         *s->buf_ptr++=s->bit_buf;
 133         s->bit_buf>>=8;
 134 #else
 135         *s->buf_ptr++=s->bit_buf >> 24;
 136         s->bit_buf<<=8;
 137 #endif
 138         s->bit_left+=8;
 139     }
 140     s->bit_left=32;
 141     s->bit_buf=0;
 142 #endif
 143 }
 144
 145 void align_put_bits(PutBitContext *s);
 146 void ff_put_string(PutBitContext * pbc, const char *s, int put_zero);
 147 void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
 148
 149 /* bit input */
 150 /* buffer, buffer_end and size_in_bits must be present and used by every reader */
 151 typedef struct GetBitContext {
 152     const uint8_t *buffer, *buffer_end;
 153 #ifdef ALT_BITSTREAM_READER
 154     int index;
 155 #elif defined LIBMPEG2_BITSTREAM_READER
 156     uint8_t *buffer_ptr;
 157     uint32_t cache;
 158     int bit_count;
 159 #elif defined A32_BITSTREAM_READER
 160     uint32_t *buffer_ptr;
 161     uint32_t cache0;
 162     uint32_t cache1;
 163     int bit_count;
 164 #endif
 165     int size_in_bits;
 166 } GetBitContext;
 167
 168 #define VLC_TYPE int16_t
 169
 170 typedef struct VLC {
 171     int bits;
 172     VLC_TYPE (*table)[2]; ///< code, bits
 173     int table_size, table_allocated;
 174 } VLC;
 175
 176 typedef struct RL_VLC_ELEM {
 177     int16_t level;
 178     int8_t len;
 179     uint8_t run;
 180 } RL_VLC_ELEM;
 181
 182 #ifndef ALT_BITSTREAM_WRITER
 183 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
 184 {
 185     unsigned int bit_buf;
 186     int bit_left;
 187
 188     //    printf("put_bits=%d %x\n", n, value);
 189     assert(n == 32 || value < (1U << n));
 190
 191     bit_buf = s->bit_buf;
 192     bit_left = s->bit_left;
 193
 194     //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
 195     /* XXX: optimize */
 196 #ifdef BITSTREAM_WRITER_LE
 197     bit_buf |= value << (32 - bit_left);
 198     if (n >= bit_left) {
 199 #if !HAVE_FAST_UNALIGNED
 200         if (3 & (intptr_t) s->buf_ptr) {
 201             AV_WL32(s->buf_ptr, bit_buf);
 202         } else
 203 #endif
 204         *(uint32_t *)s->buf_ptr = le2me_32(bit_buf);
 205         s->buf_ptr+=4;
 206         bit_buf = (bit_left==32)?0:value >> bit_left;
 207         bit_left+=32;
 208     }
 209     bit_left-=n;
 210 #else
 211     if (n < bit_left) {
 212         bit_buf = (bit_buf<<n) | value;
 213         bit_left-=n;
 214     } else {
 215         bit_buf<<=bit_left;
 216         bit_buf |= value >> (n - bit_left);
 217 #if !HAVE_FAST_UNALIGNED
 218         if (3 & (intptr_t) s->buf_ptr) {
 219             AV_WB32(s->buf_ptr, bit_buf);
 220         } else
 221 #endif
 222         *(uint32_t *)s->buf_ptr = be2me_32(bit_buf);
 223         //printf("bitbuf = %08x\n", bit_buf);
 224         s->buf_ptr+=4;
 225         bit_left+=32 - n;
 226         bit_buf = value;
 227     }
 228 #endif
 229
 230     s->bit_buf = bit_buf;
 231     s->bit_left = bit_left;
 232 }
 233 #endif
 234
 235
 236 #ifdef ALT_BITSTREAM_WRITER
 237 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
 238 {
 239 #    ifdef ALIGNED_BITSTREAM_WRITER
 240 #        if ARCH_X86
 241     __asm__ volatile(
 242         "movl %0, %%ecx                 \n\t"
 243         "xorl %%eax, %%eax              \n\t"
 244         "shrdl %%cl, %1, %%eax          \n\t"
 245         "shrl %%cl, %1                  \n\t"
 246         "movl %0, %%ecx                 \n\t"
 247         "shrl $3, %%ecx                 \n\t"
 248         "andl $0xFFFFFFFC, %%ecx        \n\t"
 249         "bswapl %1                      \n\t"
 250         "orl %1, (%2, %%ecx)            \n\t"
 251         "bswapl %%eax                   \n\t"
 252         "addl %3, %0                    \n\t"
 253         "movl %%eax, 4(%2, %%ecx)       \n\t"
 254         : "=&r" (s->index), "=&r" (value)
 255         : "r" (s->buf), "r" (n), "0" (s->index), "1" (value<<(-n))
 256         : "%eax", "%ecx"
 257     );
 258 #        else
 259     int index= s->index;
 260     uint32_t *ptr= ((uint32_t *)s->buf)+(index>>5);
 261
 262     value<<= 32-n;
 263
 264     ptr[0] |= be2me_32(value>>(index&31));
 265     ptr[1]  = be2me_32(value<<(32-(index&31)));
 266 //if(n>24) printf("%d %d\n", n, value);
 267     index+= n;
 268     s->index= index;
 269 #        endif
 270 #    else //ALIGNED_BITSTREAM_WRITER
 271 #        if ARCH_X86
 272     __asm__ volatile(
 273         "movl $7, %%ecx                 \n\t"
 274         "andl %0, %%ecx                 \n\t"
 275         "addl %3, %%ecx                 \n\t"
 276         "negl %%ecx                     \n\t"
 277         "shll %%cl, %1                  \n\t"
 278         "bswapl %1                      \n\t"
 279         "movl %0, %%ecx                 \n\t"
 280         "shrl $3, %%ecx                 \n\t"
 281         "orl %1, (%%ecx, %2)            \n\t"
 282         "addl %3, %0                    \n\t"
 283         "movl $0, 4(%%ecx, %2)          \n\t"
 284         : "=&r" (s->index), "=&r" (value)
 285         : "r" (s->buf), "r" (n), "0" (s->index), "1" (value)
 286         : "%ecx"
 287     );
 288 #        else
 289     int index= s->index;
 290     uint32_t *ptr= (uint32_t*)(((uint8_t *)s->buf)+(index>>3));
 291
 292     ptr[0] |= be2me_32(value<<(32-n-(index&7) ));
 293     ptr[1] = 0;
 294 //if(n>24) printf("%d %d\n", n, value);
 295     index+= n;
 296     s->index= index;
 297 #        endif
 298 #    endif //!ALIGNED_BITSTREAM_WRITER
 299 }
 300 #endif
 301
 302 static inline void put_sbits(PutBitContext *pb, int bits, int32_t val)
 303 {
 304     assert(bits >= 0 && bits <= 31);
 305
 306     put_bits(pb, bits, val & ((1<<bits)-1));
 307 }
 308
 309
 310 static inline uint8_t* pbBufPtr(PutBitContext *s)
 311 {
 312 #ifdef ALT_BITSTREAM_WRITER
 313         return s->buf + (s->index>>3);
 314 #else
 315         return s->buf_ptr;
 316 #endif
 317 }
 318
 319 /**
 320  *
 321  * PutBitContext must be flushed & aligned to a byte boundary before calling this.
 322  */
 323 static inline void skip_put_bytes(PutBitContext *s, int n){
 324         assert((put_bits_count(s)&7)==0);
 325 #ifdef ALT_BITSTREAM_WRITER
 326         FIXME may need some cleaning of the buffer
 327         s->index += n<<3;
 328 #else
 329         assert(s->bit_left==32);
 330         s->buf_ptr += n;
 331 #endif
 332 }
 333
 334 /**
 335  * Skips the given number of bits.
 336  * Must only be used if the actual values in the bitstream do not matter.
 337  */
 338 static inline void skip_put_bits(PutBitContext *s, int n){
 339 #ifdef ALT_BITSTREAM_WRITER
 340     s->index += n;
 341 #else
 342     s->bit_left -= n;
 343     s->buf_ptr-= s->bit_left>>5;
 344     s->bit_left &= 31;
 345 #endif
 346 }
 347
 348 /**
 349  * Changes the end of the buffer.
 350  */
 351 static inline void set_put_bits_buffer_size(PutBitContext *s, int size){
 352     s->buf_end= s->buf + size;
 353 }
 354
 355 /* Bitstream reader API docs:
 356 name
 357     arbitrary name which is used as prefix for the internal variables
 358
 359 gb
 360     getbitcontext
 361
 362 OPEN_READER(name, gb)
 363     loads gb into local variables
 364
 365 CLOSE_READER(name, gb)
 366     stores local vars in gb
 367
 368 UPDATE_CACHE(name, gb)
 369     refills the internal cache from the bitstream
 370     after this call at least MIN_CACHE_BITS will be available,
 371
 372 GET_CACHE(name, gb)
 373     will output the contents of the internal cache, next bit is MSB of 32 or 64 bit (FIXME 64bit)
 374
 375 SHOW_UBITS(name, gb, num)
 376     will return the next num bits
 377
 378 SHOW_SBITS(name, gb, num)
 379     will return the next num bits and do sign extension
 380
 381 SKIP_BITS(name, gb, num)
 382     will skip over the next num bits
 383     note, this is equivalent to SKIP_CACHE; SKIP_COUNTER
 384
 385 SKIP_CACHE(name, gb, num)
 386     will remove the next num bits from the cache (note SKIP_COUNTER MUST be called before UPDATE_CACHE / CLOSE_READER)
 387
 388 SKIP_COUNTER(name, gb, num)
 389     will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS)
 390
 391 LAST_SKIP_CACHE(name, gb, num)
 392     will remove the next num bits from the cache if it is needed for UPDATE_CACHE otherwise it will do nothing
 393
 394 LAST_SKIP_BITS(name, gb, num)
 395     is equivalent to SKIP_LAST_CACHE; SKIP_COUNTER
 396
 397 for examples see get_bits, show_bits, skip_bits, get_vlc
 398 */
 399
 400 #ifdef ALT_BITSTREAM_READER
 401 #   define MIN_CACHE_BITS 25
 402
 403 #   define OPEN_READER(name, gb)\
 404         int name##_index= (gb)->index;\
 405         int name##_cache= 0;\
 406
 407 #   define CLOSE_READER(name, gb)\
 408         (gb)->index= name##_index;\
 409
 410 # ifdef ALT_BITSTREAM_READER_LE
 411 #   define UPDATE_CACHE(name, gb)\
 412         name##_cache= AV_RL32( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) >> (name##_index&0x07);\
 413
 414 #   define SKIP_CACHE(name, gb, num)\
 415         name##_cache >>= (num);
 416 # else
 417 #   define UPDATE_CACHE(name, gb)\
 418         name##_cache= AV_RB32( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) << (name##_index&0x07);\
 419
 420 #   define SKIP_CACHE(name, gb, num)\
 421         name##_cache <<= (num);
 422 # endif
 423
 424 // FIXME name?
 425 #   define SKIP_COUNTER(name, gb, num)\
 426         name##_index += (num);\
 427
 428 #   define SKIP_BITS(name, gb, num)\
 429         {\
 430             SKIP_CACHE(name, gb, num)\
 431             SKIP_COUNTER(name, gb, num)\
 432         }\
 433
 434 #   define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
 435 #   define LAST_SKIP_CACHE(name, gb, num) ;
 436
 437 # ifdef ALT_BITSTREAM_READER_LE
 438 #   define SHOW_UBITS(name, gb, num)\
 439         ((name##_cache) & (NEG_USR32(0xffffffff,num)))
 440
 441 #   define SHOW_SBITS(name, gb, num)\
 442         NEG_SSR32((name##_cache)<<(32-(num)), num)
 443 # else
 444 #   define SHOW_UBITS(name, gb, num)\
 445         NEG_USR32(name##_cache, num)
 446
 447 #   define SHOW_SBITS(name, gb, num)\
 448         NEG_SSR32(name##_cache, num)
 449 # endif
 450
 451 #   define GET_CACHE(name, gb)\
 452         ((uint32_t)name##_cache)
 453
 454 static inline int get_bits_count(GetBitContext *s){
 455     return s->index;
 456 }
 457
 458 static inline void skip_bits_long(GetBitContext *s, int n){
 459     s->index += n;
 460 }
 461
 462 #elif defined LIBMPEG2_BITSTREAM_READER
 463 //libmpeg2 like reader
 464
 465 #   define MIN_CACHE_BITS 17
 466
 467 #   define OPEN_READER(name, gb)\
 468         int name##_bit_count=(gb)->bit_count;\
 469         int name##_cache= (gb)->cache;\
 470         uint8_t * name##_buffer_ptr=(gb)->buffer_ptr;\
 471
 472 #   define CLOSE_READER(name, gb)\
 473         (gb)->bit_count= name##_bit_count;\
 474         (gb)->cache= name##_cache;\
 475         (gb)->buffer_ptr= name##_buffer_ptr;\
 476
 477 #   define UPDATE_CACHE(name, gb)\
 478     if(name##_bit_count >= 0){\
 479         name##_cache+= AV_RB16(name##_buffer_ptr) << name##_bit_count; \
 480         name##_buffer_ptr+=2;\
 481         name##_bit_count-= 16;\
 482     }\
 483
 484 #   define SKIP_CACHE(name, gb, num)\
 485         name##_cache <<= (num);\
 486
 487 #   define SKIP_COUNTER(name, gb, num)\
 488         name##_bit_count += (num);\
 489
 490 #   define SKIP_BITS(name, gb, num)\
 491         {\
 492             SKIP_CACHE(name, gb, num)\
 493             SKIP_COUNTER(name, gb, num)\
 494         }\
 495
 496 #   define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
 497 #   define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
 498
 499 #   define SHOW_UBITS(name, gb, num)\
 500         NEG_USR32(name##_cache, num)
 501
 502 #   define SHOW_SBITS(name, gb, num)\
 503         NEG_SSR32(name##_cache, num)
 504
 505 #   define GET_CACHE(name, gb)\
 506         ((uint32_t)name##_cache)
 507
 508 static inline int get_bits_count(GetBitContext *s){
 509     return (s->buffer_ptr - s->buffer)*8 - 16 + s->bit_count;
 510 }
 511
 512 static inline void skip_bits_long(GetBitContext *s, int n){
 513     OPEN_READER(re, s)
 514     re_bit_count += n;
 515     re_buffer_ptr += 2*(re_bit_count>>4);
 516     re_bit_count &= 15;
 517     re_cache = ((re_buffer_ptr[-2]<<8) + re_buffer_ptr[-1]) << (16+re_bit_count);
 518     UPDATE_CACHE(re, s)
 519     CLOSE_READER(re, s)
 520 }
 521
 522 #elif defined A32_BITSTREAM_READER
 523
 524 #   define MIN_CACHE_BITS 32
 525
 526 #   define OPEN_READER(name, gb)\
 527         int name##_bit_count=(gb)->bit_count;\
 528         uint32_t name##_cache0= (gb)->cache0;\
 529         uint32_t name##_cache1= (gb)->cache1;\
 530         uint32_t * name##_buffer_ptr=(gb)->buffer_ptr;\
 531
 532 #   define CLOSE_READER(name, gb)\
 533         (gb)->bit_count= name##_bit_count;\
 534         (gb)->cache0= name##_cache0;\
 535         (gb)->cache1= name##_cache1;\
 536         (gb)->buffer_ptr= name##_buffer_ptr;\
 537
 538 #   define UPDATE_CACHE(name, gb)\
 539     if(name##_bit_count > 0){\
 540         const uint32_t next= be2me_32( *name##_buffer_ptr );\
 541         name##_cache0 |= NEG_USR32(next,name##_bit_count);\
 542         name##_cache1 |= next<<name##_bit_count;\
 543         name##_buffer_ptr++;\
 544         name##_bit_count-= 32;\
 545     }\
 546
 547 #if ARCH_X86
 548 #   define SKIP_CACHE(name, gb, num)\
 549         __asm__(\
 550             "shldl %2, %1, %0          \n\t"\
 551             "shll %2, %1               \n\t"\
 552             : "+r" (name##_cache0), "+r" (name##_cache1)\
 553             : "Ic" ((uint8_t)(num))\
 554            );
 555 #else
 556 #   define SKIP_CACHE(name, gb, num)\
 557         name##_cache0 <<= (num);\
 558         name##_cache0 |= NEG_USR32(name##_cache1,num);\
 559         name##_cache1 <<= (num);
 560 #endif
 561
 562 #   define SKIP_COUNTER(name, gb, num)\
 563         name##_bit_count += (num);\
 564
 565 #   define SKIP_BITS(name, gb, num)\
 566         {\
 567             SKIP_CACHE(name, gb, num)\
 568             SKIP_COUNTER(name, gb, num)\
 569         }\
 570
 571 #   define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
 572 #   define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
 573
 574 #   define SHOW_UBITS(name, gb, num)\
 575         NEG_USR32(name##_cache0, num)
 576
 577 #   define SHOW_SBITS(name, gb, num)\
 578         NEG_SSR32(name##_cache0, num)
 579
 580 #   define GET_CACHE(name, gb)\
 581         (name##_cache0)
 582
 583 static inline int get_bits_count(GetBitContext *s){
 584     return ((uint8_t*)s->buffer_ptr - s->buffer)*8 - 32 + s->bit_count;
 585 }
 586
 587 static inline void skip_bits_long(GetBitContext *s, int n){
 588     OPEN_READER(re, s)
 589     re_bit_count += n;
 590     re_buffer_ptr += re_bit_count>>5;
 591     re_bit_count &= 31;
 592     re_cache0 = be2me_32( re_buffer_ptr[-1] ) << re_bit_count;
 593     re_cache1 = 0;
 594     UPDATE_CACHE(re, s)
 595     CLOSE_READER(re, s)
 596 }
 597
 598 #endif
 599
 600 /**
 601  * read mpeg1 dc style vlc (sign bit + mantisse with no MSB).
 602  * if MSB not set it is negative
 603  * @param n length in bits
 604  * @author BERO
 605  */
 606 static inline int get_xbits(GetBitContext *s, int n){
 607     register int sign;
 608     register int32_t cache;
 609     OPEN_READER(re, s)
 610     UPDATE_CACHE(re, s)
 611     cache = GET_CACHE(re,s);
 612     sign=(~cache)>>31;
 613     LAST_SKIP_BITS(re, s, n)
 614     CLOSE_READER(re, s)
 615     return (NEG_USR32(sign ^ cache, n) ^ sign) - sign;
 616 }
 617
 618 static inline int get_sbits(GetBitContext *s, int n){
 619     register int tmp;
 620     OPEN_READER(re, s)
 621     UPDATE_CACHE(re, s)
 622     tmp= SHOW_SBITS(re, s, n);
 623     LAST_SKIP_BITS(re, s, n)
 624     CLOSE_READER(re, s)
 625     return tmp;
 626 }
 627
 628 /**
 629  * reads 1-17 bits.
 630  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
 631  */
 632 static inline unsigned int get_bits(GetBitContext *s, int n){
 633     register int tmp;
 634     OPEN_READER(re, s)
 635     UPDATE_CACHE(re, s)
 636     tmp= SHOW_UBITS(re, s, n);
 637     LAST_SKIP_BITS(re, s, n)
 638     CLOSE_READER(re, s)
 639     return tmp;
 640 }
 641
 642 /**
 643  * shows 1-17 bits.
 644  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
 645  */
 646 static inline unsigned int show_bits(GetBitContext *s, int n){
 647     register int tmp;
 648     OPEN_READER(re, s)
 649     UPDATE_CACHE(re, s)
 650     tmp= SHOW_UBITS(re, s, n);
 651 //    CLOSE_READER(re, s)
 652     return tmp;
 653 }
 654
 655 static inline void skip_bits(GetBitContext *s, int n){
 656  //Note gcc seems to optimize this to s->index+=n for the ALT_READER :))
 657     OPEN_READER(re, s)
 658     UPDATE_CACHE(re, s)
 659     LAST_SKIP_BITS(re, s, n)
 660     CLOSE_READER(re, s)
 661 }
 662
 663 static inline unsigned int get_bits1(GetBitContext *s){
 664 #ifdef ALT_BITSTREAM_READER
 665     int index= s->index;
 666     uint8_t result= s->buffer[ index>>3 ];
 667 #ifdef ALT_BITSTREAM_READER_LE
 668     result>>= (index&0x07);
 669     result&= 1;
 670 #else
 671     result<<= (index&0x07);
 672     result>>= 8 - 1;
 673 #endif
 674     index++;
 675     s->index= index;
 676
 677     return result;
 678 #else
 679     return get_bits(s, 1);
 680 #endif
 681 }
 682
 683 static inline unsigned int show_bits1(GetBitContext *s){
 684     return show_bits(s, 1);
 685 }
 686
 687 static inline void skip_bits1(GetBitContext *s){
 688     skip_bits(s, 1);
 689 }
 690
 691 /**
 692  * reads 0-32 bits.
 693  */
 694 static inline unsigned int get_bits_long(GetBitContext *s, int n){
 695     if(n<=17) return get_bits(s, n);
 696     else{
 697 #ifdef ALT_BITSTREAM_READER_LE
 698         int ret= get_bits(s, 16);
 699         return ret | (get_bits(s, n-16) << 16);
 700 #else
 701         int ret= get_bits(s, 16) << (n-16);
 702         return ret | get_bits(s, n-16);
 703 #endif
 704     }
 705 }
 706
 707 /**
 708  * shows 0-32 bits.
 709  */
 710 static inline unsigned int show_bits_long(GetBitContext *s, int n){
 711     if(n<=17) return show_bits(s, n);
 712     else{
 713         GetBitContext gb= *s;
 714         int ret= get_bits_long(s, n);
 715         *s= gb;
 716         return ret;
 717     }
 718 }
 719
 720 static inline int check_marker(GetBitContext *s, const char *msg)
 721 {
 722     int bit= get_bits1(s);
 723     if(!bit)
 724         av_log(NULL, AV_LOG_INFO, "Marker bit missing %s\n", msg);
 725
 726     return bit;
 727 }
 728
 729 /**
 730  * init GetBitContext.
 731  * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger then the actual read bits
 732  * because some optimized bitstream readers read 32 or 64 bit at once and could read over the end
 733  * @param bit_size the size of the buffer in bits
 734  */
 735 static inline void init_get_bits(GetBitContext *s,
 736                    const uint8_t *buffer, int bit_size)
 737 {
 738     int buffer_size= (bit_size+7)>>3;
 739     if(buffer_size < 0 || bit_size < 0) {
 740         buffer_size = bit_size = 0;
 741         buffer = NULL;
 742     }
 743
 744     s->buffer= buffer;
 745     s->size_in_bits= bit_size;
 746     s->buffer_end= buffer + buffer_size;
 747 #ifdef ALT_BITSTREAM_READER
 748     s->index=0;
 749 #elif defined LIBMPEG2_BITSTREAM_READER
 750     s->buffer_ptr = (uint8_t*)((intptr_t)buffer&(~1));
 751     s->bit_count = 16 + 8*((intptr_t)buffer&1);
 752     skip_bits_long(s, 0);
 753 #elif defined A32_BITSTREAM_READER
 754     s->buffer_ptr = (uint32_t*)((intptr_t)buffer&(~3));
 755     s->bit_count = 32 + 8*((intptr_t)buffer&3);
 756     skip_bits_long(s, 0);
 757 #endif
 758 }
 759
 760 static inline void align_get_bits(GetBitContext *s)
 761 {
 762     int n= (-get_bits_count(s)) & 7;
 763     if(n) skip_bits(s, n);
 764 }
 765
 766 #define init_vlc(vlc, nb_bits, nb_codes,\
 767                  bits, bits_wrap, bits_size,\
 768                  codes, codes_wrap, codes_size,\
 769                  flags)\
 770         init_vlc_sparse(vlc, nb_bits, nb_codes,\
 771                  bits, bits_wrap, bits_size,\
 772                  codes, codes_wrap, codes_size,\
 773                  NULL, 0, 0, flags)
 774
 775 int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,
 776              const void *bits, int bits_wrap, int bits_size,
 777              const void *codes, int codes_wrap, int codes_size,
 778              const void *symbols, int symbols_wrap, int symbols_size,
 779              int flags);
 780 #define INIT_VLC_USE_STATIC 1 ///< VERY strongly deprecated and forbidden
 781 #define INIT_VLC_LE         2
 782 #define INIT_VLC_USE_NEW_STATIC 4
 783 void free_vlc(VLC *vlc);
 784
 785 #define INIT_VLC_STATIC(vlc, bits, a,b,c,d,e,f,g, static_size)\
 786 {\
 787     static VLC_TYPE table[static_size][2];\
 788     (vlc)->table= table;\
 789     (vlc)->table_allocated= static_size;\
 790     init_vlc(vlc, bits, a,b,c,d,e,f,g, INIT_VLC_USE_NEW_STATIC);\
 791 }
 792
 793
 794 /**
 795  *
 796  * if the vlc code is invalid and max_depth=1 than no bits will be removed
 797  * if the vlc code is invalid and max_depth>1 than the number of bits removed
 798  * is undefined
 799  */
 800 #define GET_VLC(code, name, gb, table, bits, max_depth)\
 801 {\
 802     int n, index, nb_bits;\
 803 \
 804     index= SHOW_UBITS(name, gb, bits);\
 805     code = table[index][0];\
 806     n    = table[index][1];\
 807 \
 808     if(max_depth > 1 && n < 0){\
 809         LAST_SKIP_BITS(name, gb, bits)\
 810         UPDATE_CACHE(name, gb)\
 811 \
 812         nb_bits = -n;\
 813 \
 814         index= SHOW_UBITS(name, gb, nb_bits) + code;\
 815         code = table[index][0];\
 816         n    = table[index][1];\
 817         if(max_depth > 2 && n < 0){\
 818             LAST_SKIP_BITS(name, gb, nb_bits)\
 819             UPDATE_CACHE(name, gb)\
 820 \
 821             nb_bits = -n;\
 822 \
 823             index= SHOW_UBITS(name, gb, nb_bits) + code;\
 824             code = table[index][0];\
 825             n    = table[index][1];\
 826         }\
 827     }\
 828     SKIP_BITS(name, gb, n)\
 829 }
 830
 831 #define GET_RL_VLC(level, run, name, gb, table, bits, max_depth, need_update)\
 832 {\
 833     int n, index, nb_bits;\
 834 \
 835     index= SHOW_UBITS(name, gb, bits);\
 836     level = table[index].level;\
 837     n     = table[index].len;\
 838 \
 839     if(max_depth > 1 && n < 0){\
 840         SKIP_BITS(name, gb, bits)\
 841         if(need_update){\
 842             UPDATE_CACHE(name, gb)\
 843         }\
 844 \
 845         nb_bits = -n;\
 846 \
 847         index= SHOW_UBITS(name, gb, nb_bits) + level;\
 848         level = table[index].level;\
 849         n     = table[index].len;\
 850     }\
 851     run= table[index].run;\
 852     SKIP_BITS(name, gb, n)\
 853 }
 854
 855
 856 /**
 857  * parses a vlc code, faster then get_vlc()
 858  * @param bits is the number of bits which will be read at once, must be
 859  *             identical to nb_bits in init_vlc()
 860  * @param max_depth is the number of times bits bits must be read to completely
 861  *                  read the longest vlc code
 862  *                  = (max_vlc_length + bits - 1) / bits
 863  */
 864 static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2],
 865                                   int bits, int max_depth)
 866 {
 867     int code;
 868
 869     OPEN_READER(re, s)
 870     UPDATE_CACHE(re, s)
 871
 872     GET_VLC(code, re, s, table, bits, max_depth)
 873
 874     CLOSE_READER(re, s)
 875     return code;
 876 }
 877
 878 //#define TRACE
 879
 880 #ifdef TRACE
 881 static inline void print_bin(int bits, int n){
 882     int i;
 883
 884     for(i=n-1; i>=0; i--){
 885         av_log(NULL, AV_LOG_DEBUG, "%d", (bits>>i)&1);
 886     }
 887     for(i=n; i<24; i++)
 888         av_log(NULL, AV_LOG_DEBUG, " ");
 889 }
 890
 891 static inline int get_bits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
 892     int r= get_bits(s, n);
 893
 894     print_bin(r, n);
 895     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);
 896     return r;
 897 }
 898 static inline int get_vlc_trace(GetBitContext *s, VLC_TYPE (*table)[2], int bits, int max_depth, char *file, const char *func, int line){
 899     int show= show_bits(s, 24);
 900     int pos= get_bits_count(s);
 901     int r= get_vlc2(s, table, bits, max_depth);
 902     int len= get_bits_count(s) - pos;
 903     int bits2= show>>(24-len);
 904
 905     print_bin(bits2, len);
 906
 907     av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d vlc @%5d in %s %s:%d\n", bits2, len, r, pos, file, func, line);
 908     return r;
 909 }
 910 static inline int get_xbits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
 911     int show= show_bits(s, n);
 912     int r= get_xbits(s, n);
 913
 914     print_bin(show, n);
 915     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);
 916     return r;
 917 }
 918
 919 #define get_bits(s, n)  get_bits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 920 #define get_bits1(s)    get_bits_trace(s, 1, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 921 #define get_xbits(s, n) get_xbits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 922 #define get_vlc(s, vlc)            get_vlc_trace(s, (vlc)->table, (vlc)->bits, 3, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 923 #define get_vlc2(s, tab, bits, max) get_vlc_trace(s, tab, bits, max, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 924
 925 #define tprintf(p, ...) av_log(p, AV_LOG_DEBUG, __VA_ARGS__)
 926
 927 #else //TRACE
 928 #define tprintf(p, ...) {}
 929 #endif
 930
 931 static inline int decode012(GetBitContext *gb){
 932     int n;
 933     n = get_bits1(gb);
 934     if (n == 0)
 935         return 0;
 936     else
 937         return get_bits1(gb) + 1;
 938 }
 939
 940 static inline int decode210(GetBitContext *gb){
 941     if (get_bits1(gb))
 942         return 0;
 943     else
 944         return 2 - get_bits1(gb);
 945 }
 946
 947 #endif /* AVCODEC_BITSTREAM_H */