quicktime/ffmpeg/libavcodec/bitstream.h

   1 /**
   2  * @file bitstream.h
   3  * bitstream api header.
   4  */
   5
   6 #ifndef BITSTREAM_H
   7 #define BITSTREAM_H
   8
   9 //#define ALT_BITSTREAM_WRITER
  10 //#define ALIGNED_BITSTREAM_WRITER
  11
  12 #define ALT_BITSTREAM_READER
  13 //#define LIBMPEG2_BITSTREAM_READER
  14 //#define A32_BITSTREAM_READER
  15 #define LIBMPEG2_BITSTREAM_READER_HACK //add BERO
  16
  17 extern const uint8_t ff_reverse[256];
  18
  19 #if defined(ARCH_X86) || defined(ARCH_X86_64)
  20 // avoid +32 for shift optimization (gcc should do that ...)
  21 static inline  int32_t NEG_SSR32( int32_t a, int8_t s){
  22     asm ("sarl %1, %0\n\t"
  23          : "+r" (a)
  24          : "ic" ((uint8_t)(-s))
  25     );
  26     return a;
  27 }
  28 static inline uint32_t NEG_USR32(uint32_t a, int8_t s){
  29     asm ("shrl %1, %0\n\t"
  30          : "+r" (a)
  31          : "ic" ((uint8_t)(-s))
  32     );
  33     return a;
  34 }
  35 #else
  36 #    define NEG_SSR32(a,s) ((( int32_t)(a))>>(32-(s)))
  37 #    define NEG_USR32(a,s) (((uint32_t)(a))>>(32-(s)))
  38 #endif
  39
  40 /* bit output */
  41
  42 /* buf and buf_end must be present and used by every alternative writer. */
  43 typedef struct PutBitContext {
  44 #ifdef ALT_BITSTREAM_WRITER
  45     uint8_t *buf, *buf_end;
  46     int index;
  47 #else
  48     uint32_t bit_buf;
  49     int bit_left;
  50     uint8_t *buf, *buf_ptr, *buf_end;
  51 #endif
  52 } PutBitContext;
  53
  54 static inline void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
  55 {
  56     s->buf = buffer;
  57     s->buf_end = s->buf + buffer_size;
  58 #ifdef ALT_BITSTREAM_WRITER
  59     s->index=0;
  60     ((uint32_t*)(s->buf))[0]=0;
  61 //    memset(buffer, 0, buffer_size);
  62 #else
  63     s->buf_ptr = s->buf;
  64     s->bit_left=32;
  65     s->bit_buf=0;
  66 #endif
  67 }
  68
  69 /* return the number of bits output */
  70 static inline int put_bits_count(PutBitContext *s)
  71 {
  72 #ifdef ALT_BITSTREAM_WRITER
  73     return s->index;
  74 #else
  75     return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
  76 #endif
  77 }
  78
  79 /* pad the end of the output stream with zeros */
  80 static inline void flush_put_bits(PutBitContext *s)
  81 {
  82 #ifdef ALT_BITSTREAM_WRITER
  83     align_put_bits(s);
  84 #else
  85     s->bit_buf<<= s->bit_left;
  86     while (s->bit_left < 32) {
  87         /* XXX: should test end of buffer */
  88         *s->buf_ptr++=s->bit_buf >> 24;
  89         s->bit_buf<<=8;
  90         s->bit_left+=8;
  91     }
  92     s->bit_left=32;
  93     s->bit_buf=0;
  94 #endif
  95 }
  96
  97 void align_put_bits(PutBitContext *s);
  98 void put_string(PutBitContext * pbc, char *s, int put_zero);
  99
 100 /* bit input */
 101 /* buffer, buffer_end and size_in_bits must be present and used by every reader */
 102 typedef struct GetBitContext {
 103     const uint8_t *buffer, *buffer_end;
 104 #ifdef ALT_BITSTREAM_READER
 105     int index;
 106 #elif defined LIBMPEG2_BITSTREAM_READER
 107     uint8_t *buffer_ptr;
 108     uint32_t cache;
 109     int bit_count;
 110 #elif defined A32_BITSTREAM_READER
 111     uint32_t *buffer_ptr;
 112     uint32_t cache0;
 113     uint32_t cache1;
 114     int bit_count;
 115 #endif
 116     int size_in_bits;
 117 } GetBitContext;
 118
 119 #define VLC_TYPE int16_t
 120
 121 typedef struct VLC {
 122     int bits;
 123     VLC_TYPE (*table)[2]; ///< code, bits
 124     int table_size, table_allocated;
 125 } VLC;
 126
 127 typedef struct RL_VLC_ELEM {
 128     int16_t level;
 129     int8_t len;
 130     uint8_t run;
 131 } RL_VLC_ELEM;
 132
 133 #if defined(ARCH_SPARC) || defined(ARCH_ARMV4L)
 134 #define UNALIGNED_STORES_ARE_BAD
 135 #endif
 136
 137 /* used to avoid missaligned exceptions on some archs (alpha, ...) */
 138 #if defined(ARCH_X86) || defined(ARCH_X86_64)
 139 #    define unaligned32(a) (*(const uint32_t*)(a))
 140 #else
 141 #    ifdef __GNUC__
 142 static inline uint32_t unaligned32(const void *v) {
 143     struct Unaligned {
 144         uint32_t i;
 145     } __attribute__((packed));
 146
 147     return ((const struct Unaligned *) v)->i;
 148 }
 149 #    elif defined(__DECC)
 150 static inline uint32_t unaligned32(const void *v) {
 151     return *(const __unaligned uint32_t *) v;
 152 }
 153 #    else
 154 static inline uint32_t unaligned32(const void *v) {
 155     return *(const uint32_t *) v;
 156 }
 157 #    endif
 158 #endif //!ARCH_X86
 159
 160 #ifndef ALT_BITSTREAM_WRITER
 161 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
 162 {
 163     unsigned int bit_buf;
 164     int bit_left;
 165
 166 #ifdef STATS
 167     st_out_bit_counts[st_current_index] += n;
 168 #endif
 169     //    printf("put_bits=%d %x\n", n, value);
 170     assert(n == 32 || value < (1U << n));
 171
 172     bit_buf = s->bit_buf;
 173     bit_left = s->bit_left;
 174
 175     //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
 176     /* XXX: optimize */
 177     if (n < bit_left) {
 178         bit_buf = (bit_buf<<n) | value;
 179         bit_left-=n;
 180     } else {
 181         bit_buf<<=bit_left;
 182         bit_buf |= value >> (n - bit_left);
 183 #ifdef UNALIGNED_STORES_ARE_BAD
 184         if (3 & (intptr_t) s->buf_ptr) {
 185             s->buf_ptr[0] = bit_buf >> 24;
 186             s->buf_ptr[1] = bit_buf >> 16;
 187             s->buf_ptr[2] = bit_buf >>  8;
 188             s->buf_ptr[3] = bit_buf      ;
 189         } else
 190 #endif
 191         *(uint32_t *)s->buf_ptr = be2me_32(bit_buf);
 192         //printf("bitbuf = %08x\n", bit_buf);
 193         s->buf_ptr+=4;
 194         bit_left+=32 - n;
 195         bit_buf = value;
 196     }
 197
 198     s->bit_buf = bit_buf;
 199     s->bit_left = bit_left;
 200 }
 201 #endif
 202
 203
 204 #ifdef ALT_BITSTREAM_WRITER
 205 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
 206 {
 207 #    ifdef ALIGNED_BITSTREAM_WRITER
 208 #        if defined(ARCH_X86) || defined(ARCH_X86_64)
 209     asm volatile(
 210         "movl %0, %%ecx                 \n\t"
 211         "xorl %%eax, %%eax              \n\t"
 212         "shrdl %%cl, %1, %%eax          \n\t"
 213         "shrl %%cl, %1                  \n\t"
 214         "movl %0, %%ecx                 \n\t"
 215         "shrl $3, %%ecx                 \n\t"
 216         "andl $0xFFFFFFFC, %%ecx        \n\t"
 217         "bswapl %1                      \n\t"
 218         "orl %1, (%2, %%ecx)            \n\t"
 219         "bswapl %%eax                   \n\t"
 220         "addl %3, %0                    \n\t"
 221         "movl %%eax, 4(%2, %%ecx)       \n\t"
 222         : "=&r" (s->index), "=&r" (value)
 223         : "r" (s->buf), "r" (n), "0" (s->index), "1" (value<<(-n))
 224         : "%eax", "%ecx"
 225     );
 226 #        else
 227     int index= s->index;
 228     uint32_t *ptr= ((uint32_t *)s->buf)+(index>>5);
 229
 230     value<<= 32-n;
 231
 232     ptr[0] |= be2me_32(value>>(index&31));
 233     ptr[1]  = be2me_32(value<<(32-(index&31)));
 234 //if(n>24) printf("%d %d\n", n, value);
 235     index+= n;
 236     s->index= index;
 237 #        endif
 238 #    else //ALIGNED_BITSTREAM_WRITER
 239 #        if defined(ARCH_X86) || defined(ARCH_X86_64)
 240     asm volatile(
 241         "movl $7, %%ecx                 \n\t"
 242         "andl %0, %%ecx                 \n\t"
 243         "addl %3, %%ecx                 \n\t"
 244         "negl %%ecx                     \n\t"
 245         "shll %%cl, %1                  \n\t"
 246         "bswapl %1                      \n\t"
 247         "movl %0, %%ecx                 \n\t"
 248         "shrl $3, %%ecx                 \n\t"
 249         "orl %1, (%%ecx, %2)            \n\t"
 250         "addl %3, %0                    \n\t"
 251         "movl $0, 4(%%ecx, %2)          \n\t"
 252         : "=&r" (s->index), "=&r" (value)
 253         : "r" (s->buf), "r" (n), "0" (s->index), "1" (value)
 254         : "%ecx"
 255     );
 256 #        else
 257     int index= s->index;
 258     uint32_t *ptr= (uint32_t*)(((uint8_t *)s->buf)+(index>>3));
 259
 260     ptr[0] |= be2me_32(value<<(32-n-(index&7) ));
 261     ptr[1] = 0;
 262 //if(n>24) printf("%d %d\n", n, value);
 263     index+= n;
 264     s->index= index;
 265 #        endif
 266 #    endif //!ALIGNED_BITSTREAM_WRITER
 267 }
 268 #endif
 269
 270
 271 static inline uint8_t* pbBufPtr(PutBitContext *s)
 272 {
 273 #ifdef ALT_BITSTREAM_WRITER
 274         return s->buf + (s->index>>3);
 275 #else
 276         return s->buf_ptr;
 277 #endif
 278 }
 279
 280 /**
 281  *
 282  * PutBitContext must be flushed & aligned to a byte boundary before calling this.
 283  */
 284 static inline void skip_put_bytes(PutBitContext *s, int n){
 285         assert((put_bits_count(s)&7)==0);
 286 #ifdef ALT_BITSTREAM_WRITER
 287         FIXME may need some cleaning of the buffer
 288         s->index += n<<3;
 289 #else
 290         assert(s->bit_left==32);
 291         s->buf_ptr += n;
 292 #endif
 293 }
 294
 295 /**
 296  * skips the given number of bits.
 297  * must only be used if the actual values in the bitstream dont matter
 298  */
 299 static inline void skip_put_bits(PutBitContext *s, int n){
 300 #ifdef ALT_BITSTREAM_WRITER
 301     s->index += n;
 302 #else
 303     s->bit_left -= n;
 304     s->buf_ptr-= s->bit_left>>5;
 305     s->bit_left &= 31;
 306 #endif
 307 }
 308
 309 /**
 310  * Changes the end of the buffer.
 311  */
 312 static inline void set_put_bits_buffer_size(PutBitContext *s, int size){
 313     s->buf_end= s->buf + size;
 314 }
 315
 316 /* Bitstream reader API docs:
 317 name
 318     abritary name which is used as prefix for the internal variables
 319
 320 gb
 321     getbitcontext
 322
 323 OPEN_READER(name, gb)
 324     loads gb into local variables
 325
 326 CLOSE_READER(name, gb)
 327     stores local vars in gb
 328
 329 UPDATE_CACHE(name, gb)
 330     refills the internal cache from the bitstream
 331     after this call at least MIN_CACHE_BITS will be available,
 332
 333 GET_CACHE(name, gb)
 334     will output the contents of the internal cache, next bit is MSB of 32 or 64 bit (FIXME 64bit)
 335
 336 SHOW_UBITS(name, gb, num)
 337     will return the next num bits
 338
 339 SHOW_SBITS(name, gb, num)
 340     will return the next num bits and do sign extension
 341
 342 SKIP_BITS(name, gb, num)
 343     will skip over the next num bits
 344     note, this is equivalent to SKIP_CACHE; SKIP_COUNTER
 345
 346 SKIP_CACHE(name, gb, num)
 347     will remove the next num bits from the cache (note SKIP_COUNTER MUST be called before UPDATE_CACHE / CLOSE_READER)
 348
 349 SKIP_COUNTER(name, gb, num)
 350     will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS)
 351
 352 LAST_SKIP_CACHE(name, gb, num)
 353     will remove the next num bits from the cache if it is needed for UPDATE_CACHE otherwise it will do nothing
 354
 355 LAST_SKIP_BITS(name, gb, num)
 356     is equivalent to SKIP_LAST_CACHE; SKIP_COUNTER
 357
 358 for examples see get_bits, show_bits, skip_bits, get_vlc
 359 */
 360
 361 static inline int unaligned32_be(const void *v)
 362 {
 363 #ifdef CONFIG_ALIGN
 364         const uint8_t *p=v;
 365         return (((p[0]<<8) | p[1])<<16) | (p[2]<<8) | (p[3]);
 366 #else
 367         return be2me_32( unaligned32(v)); //original
 368 #endif
 369 }
 370
 371 static inline int unaligned32_le(const void *v)
 372 {
 373 #ifdef CONFIG_ALIGN
 374        const uint8_t *p=v;
 375        return (((p[3]<<8) | p[2])<<16) | (p[1]<<8) | (p[0]);
 376 #else
 377        return le2me_32( unaligned32(v)); //original
 378 #endif
 379 }
 380
 381 #ifdef ALT_BITSTREAM_READER
 382 #   define MIN_CACHE_BITS 25
 383
 384 #   define OPEN_READER(name, gb)\
 385         int name##_index= (gb)->index;\
 386         int name##_cache= 0;\
 387
 388 #   define CLOSE_READER(name, gb)\
 389         (gb)->index= name##_index;\
 390
 391 # ifdef ALT_BITSTREAM_READER_LE
 392 #   define UPDATE_CACHE(name, gb)\
 393         name##_cache= unaligned32_le( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) >> (name##_index&0x07);\
 394
 395 #   define SKIP_CACHE(name, gb, num)\
 396         name##_cache >>= (num);
 397 # else
 398 #   define UPDATE_CACHE(name, gb)\
 399         name##_cache= unaligned32_be( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) << (name##_index&0x07);\
 400
 401 #   define SKIP_CACHE(name, gb, num)\
 402         name##_cache <<= (num);
 403 # endif
 404
 405 // FIXME name?
 406 #   define SKIP_COUNTER(name, gb, num)\
 407         name##_index += (num);\
 408
 409 #   define SKIP_BITS(name, gb, num)\
 410         {\
 411             SKIP_CACHE(name, gb, num)\
 412             SKIP_COUNTER(name, gb, num)\
 413         }\
 414
 415 #   define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
 416 #   define LAST_SKIP_CACHE(name, gb, num) ;
 417
 418 # ifdef ALT_BITSTREAM_READER_LE
 419 #   define SHOW_UBITS(name, gb, num)\
 420         ((name##_cache) & (NEG_USR32(0xffffffff,num)))
 421 # else
 422 #   define SHOW_UBITS(name, gb, num)\
 423         NEG_USR32(name##_cache, num)
 424 # endif
 425
 426 #   define SHOW_SBITS(name, gb, num)\
 427         NEG_SSR32(name##_cache, num)
 428
 429 #   define GET_CACHE(name, gb)\
 430         ((uint32_t)name##_cache)
 431
 432 static inline int get_bits_count(GetBitContext *s){
 433     return s->index;
 434 }
 435 #elif defined LIBMPEG2_BITSTREAM_READER
 436 //libmpeg2 like reader
 437
 438 #   define MIN_CACHE_BITS 17
 439
 440 #   define OPEN_READER(name, gb)\
 441         int name##_bit_count=(gb)->bit_count;\
 442         int name##_cache= (gb)->cache;\
 443         uint8_t * name##_buffer_ptr=(gb)->buffer_ptr;\
 444
 445 #   define CLOSE_READER(name, gb)\
 446         (gb)->bit_count= name##_bit_count;\
 447         (gb)->cache= name##_cache;\
 448         (gb)->buffer_ptr= name##_buffer_ptr;\
 449
 450 #ifdef LIBMPEG2_BITSTREAM_READER_HACK
 451
 452 #   define UPDATE_CACHE(name, gb)\
 453     if(name##_bit_count >= 0){\
 454         name##_cache+= (int)be2me_16(*(uint16_t*)name##_buffer_ptr) << name##_bit_count;\
 455         name##_buffer_ptr += 2;\
 456         name##_bit_count-= 16;\
 457     }\
 458
 459 #else
 460
 461 #   define UPDATE_CACHE(name, gb)\
 462     if(name##_bit_count >= 0){\
 463         name##_cache+= ((name##_buffer_ptr[0]<<8) + name##_buffer_ptr[1]) << name##_bit_count;\
 464         name##_buffer_ptr+=2;\
 465         name##_bit_count-= 16;\
 466     }\
 467
 468 #endif
 469
 470 #   define SKIP_CACHE(name, gb, num)\
 471         name##_cache <<= (num);\
 472
 473 #   define SKIP_COUNTER(name, gb, num)\
 474         name##_bit_count += (num);\
 475
 476 #   define SKIP_BITS(name, gb, num)\
 477         {\
 478             SKIP_CACHE(name, gb, num)\
 479             SKIP_COUNTER(name, gb, num)\
 480         }\
 481
 482 #   define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
 483 #   define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
 484
 485 #   define SHOW_UBITS(name, gb, num)\
 486         NEG_USR32(name##_cache, num)
 487
 488 #   define SHOW_SBITS(name, gb, num)\
 489         NEG_SSR32(name##_cache, num)
 490
 491 #   define GET_CACHE(name, gb)\
 492         ((uint32_t)name##_cache)
 493
 494 static inline int get_bits_count(GetBitContext *s){
 495     return (s->buffer_ptr - s->buffer)*8 - 16 + s->bit_count;
 496 }
 497
 498 #elif defined A32_BITSTREAM_READER
 499
 500 #   define MIN_CACHE_BITS 32
 501
 502 #   define OPEN_READER(name, gb)\
 503         int name##_bit_count=(gb)->bit_count;\
 504         uint32_t name##_cache0= (gb)->cache0;\
 505         uint32_t name##_cache1= (gb)->cache1;\
 506         uint32_t * name##_buffer_ptr=(gb)->buffer_ptr;\
 507
 508 #   define CLOSE_READER(name, gb)\
 509         (gb)->bit_count= name##_bit_count;\
 510         (gb)->cache0= name##_cache0;\
 511         (gb)->cache1= name##_cache1;\
 512         (gb)->buffer_ptr= name##_buffer_ptr;\
 513
 514 #   define UPDATE_CACHE(name, gb)\
 515     if(name##_bit_count > 0){\
 516         const uint32_t next= be2me_32( *name##_buffer_ptr );\
 517         name##_cache0 |= NEG_USR32(next,name##_bit_count);\
 518         name##_cache1 |= next<<name##_bit_count;\
 519         name##_buffer_ptr++;\
 520         name##_bit_count-= 32;\
 521     }\
 522
 523 #if defined(ARCH_X86) || defined(ARCH_X86_64)
 524 #   define SKIP_CACHE(name, gb, num)\
 525         asm(\
 526             "shldl %2, %1, %0           \n\t"\
 527             "shll %2, %1                \n\t"\
 528             : "+r" (name##_cache0), "+r" (name##_cache1)\
 529             : "Ic" ((uint8_t)num)\
 530            );
 531 #else
 532 #   define SKIP_CACHE(name, gb, num)\
 533         name##_cache0 <<= (num);\
 534         name##_cache0 |= NEG_USR32(name##_cache1,num);\
 535         name##_cache1 <<= (num);
 536 #endif
 537
 538 #   define SKIP_COUNTER(name, gb, num)\
 539         name##_bit_count += (num);\
 540
 541 #   define SKIP_BITS(name, gb, num)\
 542         {\
 543             SKIP_CACHE(name, gb, num)\
 544             SKIP_COUNTER(name, gb, num)\
 545         }\
 546
 547 #   define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
 548 #   define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
 549
 550 #   define SHOW_UBITS(name, gb, num)\
 551         NEG_USR32(name##_cache0, num)
 552
 553 #   define SHOW_SBITS(name, gb, num)\
 554         NEG_SSR32(name##_cache0, num)
 555
 556 #   define GET_CACHE(name, gb)\
 557         (name##_cache0)
 558
 559 static inline int get_bits_count(GetBitContext *s){
 560     return ((uint8_t*)s->buffer_ptr - s->buffer)*8 - 32 + s->bit_count;
 561 }
 562
 563 #endif
 564
 565 /**
 566  * read mpeg1 dc style vlc (sign bit + mantisse with no MSB).
 567  * if MSB not set it is negative
 568  * @param n length in bits
 569  * @author BERO
 570  */
 571 static inline int get_xbits(GetBitContext *s, int n){
 572     register int tmp;
 573     register int32_t cache;
 574     OPEN_READER(re, s)
 575     UPDATE_CACHE(re, s)
 576     cache = GET_CACHE(re,s);
 577     if ((int32_t)cache<0) { //MSB=1
 578         tmp = NEG_USR32(cache,n);
 579     } else {
 580     //   tmp = (-1<<n) | NEG_USR32(cache,n) + 1; mpeg12.c algo
 581     //   tmp = - (NEG_USR32(cache,n) ^ ((1 << n) - 1)); h263.c algo
 582         tmp = - NEG_USR32(~cache,n);
 583     }
 584     LAST_SKIP_BITS(re, s, n)
 585     CLOSE_READER(re, s)
 586     return tmp;
 587 }
 588
 589 static inline int get_sbits(GetBitContext *s, int n){
 590     register int tmp;
 591     OPEN_READER(re, s)
 592     UPDATE_CACHE(re, s)
 593     tmp= SHOW_SBITS(re, s, n);
 594     LAST_SKIP_BITS(re, s, n)
 595     CLOSE_READER(re, s)
 596     return tmp;
 597 }
 598
 599 /**
 600  * reads 0-17 bits.
 601  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
 602  */
 603 static inline unsigned int get_bits(GetBitContext *s, int n){
 604     register int tmp;
 605     OPEN_READER(re, s)
 606     UPDATE_CACHE(re, s)
 607     tmp= SHOW_UBITS(re, s, n);
 608     LAST_SKIP_BITS(re, s, n)
 609     CLOSE_READER(re, s)
 610     return tmp;
 611 }
 612
 613 unsigned int get_bits_long(GetBitContext *s, int n);
 614
 615 /**
 616  * shows 0-17 bits.
 617  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
 618  */
 619 static inline unsigned int show_bits(GetBitContext *s, int n){
 620     register int tmp;
 621     OPEN_READER(re, s)
 622     UPDATE_CACHE(re, s)
 623     tmp= SHOW_UBITS(re, s, n);
 624 //    CLOSE_READER(re, s)
 625     return tmp;
 626 }
 627
 628 unsigned int show_bits_long(GetBitContext *s, int n);
 629
 630 static inline void skip_bits(GetBitContext *s, int n){
 631  //Note gcc seems to optimize this to s->index+=n for the ALT_READER :))
 632     OPEN_READER(re, s)
 633     UPDATE_CACHE(re, s)
 634     LAST_SKIP_BITS(re, s, n)
 635     CLOSE_READER(re, s)
 636 }
 637
 638 static inline unsigned int get_bits1(GetBitContext *s){
 639 #ifdef ALT_BITSTREAM_READER
 640     int index= s->index;
 641     uint8_t result= s->buffer[ index>>3 ];
 642 #ifdef ALT_BITSTREAM_READER_LE
 643     result>>= (index&0x07);
 644     result&= 1;
 645 #else
 646     result<<= (index&0x07);
 647     result>>= 8 - 1;
 648 #endif
 649     index++;
 650     s->index= index;
 651
 652     return result;
 653 #else
 654     return get_bits(s, 1);
 655 #endif
 656 }
 657
 658 static inline unsigned int show_bits1(GetBitContext *s){
 659     return show_bits(s, 1);
 660 }
 661
 662 static inline void skip_bits1(GetBitContext *s){
 663     skip_bits(s, 1);
 664 }
 665
 666 /**
 667  * init GetBitContext.
 668  * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger then the actual read bits
 669  * because some optimized bitstream readers read 32 or 64 bit at once and could read over the end
 670  * @param bit_size the size of the buffer in bits
 671  */
 672 static inline void init_get_bits(GetBitContext *s,
 673                    const uint8_t *buffer, int bit_size)
 674 {
 675     const int buffer_size= (bit_size+7)>>3;
 676
 677     s->buffer= buffer;
 678     s->size_in_bits= bit_size;
 679     s->buffer_end= buffer + buffer_size;
 680 #ifdef ALT_BITSTREAM_READER
 681     s->index=0;
 682 #elif defined LIBMPEG2_BITSTREAM_READER
 683 #ifdef LIBMPEG2_BITSTREAM_READER_HACK
 684   if ((int)buffer&1) {
 685      /* word alignment */
 686     s->cache = (*buffer++)<<24;
 687     s->buffer_ptr = buffer;
 688     s->bit_count = 16-8;
 689   } else
 690 #endif
 691   {
 692     s->buffer_ptr = buffer;
 693     s->bit_count = 16;
 694     s->cache = 0;
 695   }
 696 #elif defined A32_BITSTREAM_READER
 697     s->buffer_ptr = (uint32_t*)buffer;
 698     s->bit_count = 32;
 699     s->cache0 = 0;
 700     s->cache1 = 0;
 701 #endif
 702     {
 703         OPEN_READER(re, s)
 704         UPDATE_CACHE(re, s)
 705         UPDATE_CACHE(re, s)
 706         CLOSE_READER(re, s)
 707     }
 708 #ifdef A32_BITSTREAM_READER
 709     s->cache1 = 0;
 710 #endif
 711 }
 712
 713 int check_marker(GetBitContext *s, const char *msg);
 714 void align_get_bits(GetBitContext *s);
 715 int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
 716              const void *bits, int bits_wrap, int bits_size,
 717              const void *codes, int codes_wrap, int codes_size,
 718              int flags);
 719 #define INIT_VLC_USE_STATIC 1
 720 #define INIT_VLC_LE         2
 721 void free_vlc(VLC *vlc);
 722
 723 /**
 724  *
 725  * if the vlc code is invalid and max_depth=1 than no bits will be removed
 726  * if the vlc code is invalid and max_depth>1 than the number of bits removed
 727  * is undefined
 728  */
 729 #define GET_VLC(code, name, gb, table, bits, max_depth)\
 730 {\
 731     int n, index, nb_bits;\
 732 \
 733     index= SHOW_UBITS(name, gb, bits);\
 734     code = table[index][0];\
 735     n    = table[index][1];\
 736 \
 737     if(max_depth > 1 && n < 0){\
 738         LAST_SKIP_BITS(name, gb, bits)\
 739         UPDATE_CACHE(name, gb)\
 740 \
 741         nb_bits = -n;\
 742 \
 743         index= SHOW_UBITS(name, gb, nb_bits) + code;\
 744         code = table[index][0];\
 745         n    = table[index][1];\
 746         if(max_depth > 2 && n < 0){\
 747             LAST_SKIP_BITS(name, gb, nb_bits)\
 748             UPDATE_CACHE(name, gb)\
 749 \
 750             nb_bits = -n;\
 751 \
 752             index= SHOW_UBITS(name, gb, nb_bits) + code;\
 753             code = table[index][0];\
 754             n    = table[index][1];\
 755         }\
 756     }\
 757     SKIP_BITS(name, gb, n)\
 758 }
 759
 760 #define GET_RL_VLC(level, run, name, gb, table, bits, max_depth, need_update)\
 761 {\
 762     int n, index, nb_bits;\
 763 \
 764     index= SHOW_UBITS(name, gb, bits);\
 765     level = table[index].level;\
 766     n     = table[index].len;\
 767 \
 768     if(max_depth > 1 && n < 0){\
 769         SKIP_BITS(name, gb, bits)\
 770         if(need_update){\
 771             UPDATE_CACHE(name, gb)\
 772         }\
 773 \
 774         nb_bits = -n;\
 775 \
 776         index= SHOW_UBITS(name, gb, nb_bits) + level;\
 777         level = table[index].level;\
 778         n     = table[index].len;\
 779     }\
 780     run= table[index].run;\
 781     SKIP_BITS(name, gb, n)\
 782 }
 783
 784 // deprecated, dont use get_vlc for new code, use get_vlc2 instead or use GET_VLC directly
 785 static inline int get_vlc(GetBitContext *s, VLC *vlc)
 786 {
 787     int code;
 788     VLC_TYPE (*table)[2]= vlc->table;
 789
 790     OPEN_READER(re, s)
 791     UPDATE_CACHE(re, s)
 792
 793     GET_VLC(code, re, s, table, vlc->bits, 3)
 794
 795     CLOSE_READER(re, s)
 796     return code;
 797 }
 798
 799 /**
 800  * parses a vlc code, faster then get_vlc()
 801  * @param bits is the number of bits which will be read at once, must be
 802  *             identical to nb_bits in init_vlc()
 803  * @param max_depth is the number of times bits bits must be readed to completly
 804  *                  read the longest vlc code
 805  *                  = (max_vlc_length + bits - 1) / bits
 806  */
 807 static always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2],
 808                                   int bits, int max_depth)
 809 {
 810     int code;
 811
 812     OPEN_READER(re, s)
 813     UPDATE_CACHE(re, s)
 814
 815     GET_VLC(code, re, s, table, bits, max_depth)
 816
 817     CLOSE_READER(re, s)
 818     return code;
 819 }
 820
 821 //#define TRACE
 822
 823 #ifdef TRACE
 824 #include "avcodec.h"
 825 static inline void print_bin(int bits, int n){
 826     int i;
 827
 828     for(i=n-1; i>=0; i--){
 829         av_log(NULL, AV_LOG_DEBUG, "%d", (bits>>i)&1);
 830     }
 831     for(i=n; i<24; i++)
 832         av_log(NULL, AV_LOG_DEBUG, " ");
 833 }
 834
 835 static inline int get_bits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
 836     int r= get_bits(s, n);
 837
 838     print_bin(r, n);
 839     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);
 840     return r;
 841 }
 842 static inline int get_vlc_trace(GetBitContext *s, VLC_TYPE (*table)[2], int bits, int max_depth, char *file, const char *func, int line){
 843     int show= show_bits(s, 24);
 844     int pos= get_bits_count(s);
 845     int r= get_vlc2(s, table, bits, max_depth);
 846     int len= get_bits_count(s) - pos;
 847     int bits2= show>>(24-len);
 848
 849     print_bin(bits2, len);
 850
 851     av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d vlc @%5d in %s %s:%d\n", bits2, len, r, pos, file, func, line);
 852     return r;
 853 }
 854 static inline int get_xbits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
 855     int show= show_bits(s, n);
 856     int r= get_xbits(s, n);
 857
 858     print_bin(show, n);
 859     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);
 860     return r;
 861 }
 862
 863 #define get_bits(s, n)  get_bits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 864 #define get_bits1(s)    get_bits_trace(s, 1, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 865 #define get_xbits(s, n) get_xbits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 866 #define get_vlc(s, vlc)            get_vlc_trace(s, (vlc)->table, (vlc)->bits, 3, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 867 #define get_vlc2(s, tab, bits, max) get_vlc_trace(s, tab, bits, max, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 868
 869 #define tprintf(...) av_log(NULL, AV_LOG_DEBUG, __VA_ARGS__)
 870
 871 #else //TRACE
 872 #define tprintf(...) {}
 873 #endif
 874
 875 static inline int decode012(GetBitContext *gb){
 876     int n;
 877     n = get_bits1(gb);
 878     if (n == 0)
 879         return 0;
 880     else
 881         return get_bits1(gb) + 1;
 882 }
 883
 884 #endif /* BITSTREAM_H */