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 BITSTREAM_H
  27 #define BITSTREAM_H
  28
  29 #include "log.h"
  30
  31 #if defined(ALT_BITSTREAM_READER_LE) && !defined(ALT_BITSTREAM_READER)
  32 #define ALT_BITSTREAM_READER
  33 #endif
  34
  35 //#define ALT_BITSTREAM_WRITER
  36 //#define ALIGNED_BITSTREAM_WRITER
  37 #if !defined(LIBMPEG2_BITSTREAM_READER) && !defined(A32_BITSTREAM_READER) && !defined(ALT_BITSTREAM_READER)
  38 #   ifdef ARCH_ARMV4L
  39 #       define A32_BITSTREAM_READER
  40 #   else
  41 #define ALT_BITSTREAM_READER
  42 //#define LIBMPEG2_BITSTREAM_READER
  43 //#define A32_BITSTREAM_READER
  44 #   endif
  45 #endif
  46 #define LIBMPEG2_BITSTREAM_READER_HACK //add BERO
  47
  48 extern const uint8_t ff_reverse[256];
  49
  50 #if defined(ARCH_X86) || defined(ARCH_X86_64)
  51 // avoid +32 for shift optimization (gcc should do that ...)
  52 static inline  int32_t NEG_SSR32( int32_t a, int8_t s){
  53     asm ("sarl %1, %0\n\t"
  54          : "+r" (a)
  55          : "ic" ((uint8_t)(-s))
  56     );
  57     return a;
  58 }
  59 static inline uint32_t NEG_USR32(uint32_t a, int8_t s){
  60     asm ("shrl %1, %0\n\t"
  61          : "+r" (a)
  62          : "ic" ((uint8_t)(-s))
  63     );
  64     return a;
  65 }
  66 #else
  67 #    define NEG_SSR32(a,s) ((( int32_t)(a))>>(32-(s)))
  68 #    define NEG_USR32(a,s) (((uint32_t)(a))>>(32-(s)))
  69 #endif
  70
  71 /* bit output */
  72
  73 /* buf and buf_end must be present and used by every alternative writer. */
  74 typedef struct PutBitContext {
  75 #ifdef ALT_BITSTREAM_WRITER
  76     uint8_t *buf, *buf_end;
  77     int index;
  78 #else
  79     uint32_t bit_buf;
  80     int bit_left;
  81     uint8_t *buf, *buf_ptr, *buf_end;
  82 #endif
  83 } PutBitContext;
  84
  85 static inline void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
  86 {
  87     if(buffer_size < 0) {
  88         buffer_size = 0;
  89         buffer = NULL;
  90     }
  91
  92     s->buf = buffer;
  93     s->buf_end = s->buf + buffer_size;
  94 #ifdef ALT_BITSTREAM_WRITER
  95     s->index=0;
  96     ((uint32_t*)(s->buf))[0]=0;
  97 //    memset(buffer, 0, buffer_size);
  98 #else
  99     s->buf_ptr = s->buf;
 100     s->bit_left=32;
 101     s->bit_buf=0;
 102 #endif
 103 }
 104
 105 /* return the number of bits output */
 106 static inline int put_bits_count(PutBitContext *s)
 107 {
 108 #ifdef ALT_BITSTREAM_WRITER
 109     return s->index;
 110 #else
 111     return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
 112 #endif
 113 }
 114
 115 /* pad the end of the output stream with zeros */
 116 static inline void flush_put_bits(PutBitContext *s)
 117 {
 118 #ifdef ALT_BITSTREAM_WRITER
 119     align_put_bits(s);
 120 #else
 121     s->bit_buf<<= s->bit_left;
 122     while (s->bit_left < 32) {
 123         /* XXX: should test end of buffer */
 124         *s->buf_ptr++=s->bit_buf >> 24;
 125         s->bit_buf<<=8;
 126         s->bit_left+=8;
 127     }
 128     s->bit_left=32;
 129     s->bit_buf=0;
 130 #endif
 131 }
 132
 133 void align_put_bits(PutBitContext *s);
 134 void ff_put_string(PutBitContext * pbc, char *s, int put_zero);
 135
 136 /* bit input */
 137 /* buffer, buffer_end and size_in_bits must be present and used by every reader */
 138 typedef struct GetBitContext {
 139     const uint8_t *buffer, *buffer_end;
 140 #ifdef ALT_BITSTREAM_READER
 141     int index;
 142 #elif defined LIBMPEG2_BITSTREAM_READER
 143     uint8_t *buffer_ptr;
 144     uint32_t cache;
 145     int bit_count;
 146 #elif defined A32_BITSTREAM_READER
 147     uint32_t *buffer_ptr;
 148     uint32_t cache0;
 149     uint32_t cache1;
 150     int bit_count;
 151 #endif
 152     int size_in_bits;
 153 } GetBitContext;
 154
 155 #define VLC_TYPE int16_t
 156
 157 typedef struct VLC {
 158     int bits;
 159     VLC_TYPE (*table)[2]; ///< code, bits
 160     int table_size, table_allocated;
 161 } VLC;
 162
 163 typedef struct RL_VLC_ELEM {
 164     int16_t level;
 165     int8_t len;
 166     uint8_t run;
 167 } RL_VLC_ELEM;
 168
 169 #if defined(ARCH_SPARC) || defined(ARCH_ARMV4L) || defined(ARCH_MIPS)
 170 #define UNALIGNED_STORES_ARE_BAD
 171 #endif
 172
 173 /* used to avoid missaligned exceptions on some archs (alpha, ...) */
 174 #if defined(ARCH_X86) || defined(ARCH_X86_64)
 175 #    define unaligned16(a) (*(const uint16_t*)(a))
 176 #    define unaligned32(a) (*(const uint32_t*)(a))
 177 #    define unaligned64(a) (*(const uint64_t*)(a))
 178 #else
 179 #    ifdef __GNUC__
 180 #    define unaligned(x)                                \
 181 static inline uint##x##_t unaligned##x(const void *v) { \
 182     struct Unaligned {                                  \
 183         uint##x##_t i;                                  \
 184     } __attribute__((packed));                          \
 185                                                         \
 186     return ((const struct Unaligned *) v)->i;           \
 187 }
 188 #    elif defined(__DECC)
 189 #    define unaligned(x)                                        \
 190 static inline uint##x##_t unaligned##x##(const void *v) {       \
 191     return *(const __unaligned uint##x##_t *) v;                \
 192 }
 193 #    else
 194 #    define unaligned(x)                                        \
 195 static inline uint##x##_t unaligned##x##(const void *v) {       \
 196     return *(const uint##x##_t *) v;                            \
 197 }
 198 #    endif
 199 unaligned(16)
 200 unaligned(32)
 201 unaligned(64)
 202 #undef unaligned
 203 #endif /* defined(ARCH_X86) || defined(ARCH_X86_64) */
 204
 205 #ifndef ALT_BITSTREAM_WRITER
 206 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
 207 {
 208     unsigned int bit_buf;
 209     int bit_left;
 210
 211     //    printf("put_bits=%d %x\n", n, value);
 212     assert(n == 32 || value < (1U << n));
 213
 214     bit_buf = s->bit_buf;
 215     bit_left = s->bit_left;
 216
 217     //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
 218     /* XXX: optimize */
 219     if (n < bit_left) {
 220         bit_buf = (bit_buf<<n) | value;
 221         bit_left-=n;
 222     } else {
 223         bit_buf<<=bit_left;
 224         bit_buf |= value >> (n - bit_left);
 225 #ifdef UNALIGNED_STORES_ARE_BAD
 226         if (3 & (intptr_t) s->buf_ptr) {
 227             s->buf_ptr[0] = bit_buf >> 24;
 228             s->buf_ptr[1] = bit_buf >> 16;
 229             s->buf_ptr[2] = bit_buf >>  8;
 230             s->buf_ptr[3] = bit_buf      ;
 231         } else
 232 #endif
 233         *(uint32_t *)s->buf_ptr = be2me_32(bit_buf);
 234         //printf("bitbuf = %08x\n", bit_buf);
 235         s->buf_ptr+=4;
 236         bit_left+=32 - n;
 237         bit_buf = value;
 238     }
 239
 240     s->bit_buf = bit_buf;
 241     s->bit_left = bit_left;
 242 }
 243 #endif
 244
 245
 246 #ifdef ALT_BITSTREAM_WRITER
 247 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
 248 {
 249 #    ifdef ALIGNED_BITSTREAM_WRITER
 250 #        if defined(ARCH_X86) || defined(ARCH_X86_64)
 251     asm volatile(
 252         "movl %0, %%ecx                 \n\t"
 253         "xorl %%eax, %%eax              \n\t"
 254         "shrdl %%cl, %1, %%eax          \n\t"
 255         "shrl %%cl, %1                  \n\t"
 256         "movl %0, %%ecx                 \n\t"
 257         "shrl $3, %%ecx                 \n\t"
 258         "andl $0xFFFFFFFC, %%ecx        \n\t"
 259         "bswapl %1                      \n\t"
 260         "orl %1, (%2, %%ecx)            \n\t"
 261         "bswapl %%eax                   \n\t"
 262         "addl %3, %0                    \n\t"
 263         "movl %%eax, 4(%2, %%ecx)       \n\t"
 264         : "=&r" (s->index), "=&r" (value)
 265         : "r" (s->buf), "r" (n), "0" (s->index), "1" (value<<(-n))
 266         : "%eax", "%ecx"
 267     );
 268 #        else
 269     int index= s->index;
 270     uint32_t *ptr= ((uint32_t *)s->buf)+(index>>5);
 271
 272     value<<= 32-n;
 273
 274     ptr[0] |= be2me_32(value>>(index&31));
 275     ptr[1]  = be2me_32(value<<(32-(index&31)));
 276 //if(n>24) printf("%d %d\n", n, value);
 277     index+= n;
 278     s->index= index;
 279 #        endif
 280 #    else //ALIGNED_BITSTREAM_WRITER
 281 #        if defined(ARCH_X86) || defined(ARCH_X86_64)
 282     asm volatile(
 283         "movl $7, %%ecx                 \n\t"
 284         "andl %0, %%ecx                 \n\t"
 285         "addl %3, %%ecx                 \n\t"
 286         "negl %%ecx                     \n\t"
 287         "shll %%cl, %1                  \n\t"
 288         "bswapl %1                      \n\t"
 289         "movl %0, %%ecx                 \n\t"
 290         "shrl $3, %%ecx                 \n\t"
 291         "orl %1, (%%ecx, %2)            \n\t"
 292         "addl %3, %0                    \n\t"
 293         "movl $0, 4(%%ecx, %2)          \n\t"
 294         : "=&r" (s->index), "=&r" (value)
 295         : "r" (s->buf), "r" (n), "0" (s->index), "1" (value)
 296         : "%ecx"
 297     );
 298 #        else
 299     int index= s->index;
 300     uint32_t *ptr= (uint32_t*)(((uint8_t *)s->buf)+(index>>3));
 301
 302     ptr[0] |= be2me_32(value<<(32-n-(index&7) ));
 303     ptr[1] = 0;
 304 //if(n>24) printf("%d %d\n", n, value);
 305     index+= n;
 306     s->index= index;
 307 #        endif
 308 #    endif //!ALIGNED_BITSTREAM_WRITER
 309 }
 310 #endif
 311
 312
 313 static inline uint8_t* pbBufPtr(PutBitContext *s)
 314 {
 315 #ifdef ALT_BITSTREAM_WRITER
 316         return s->buf + (s->index>>3);
 317 #else
 318         return s->buf_ptr;
 319 #endif
 320 }
 321
 322 /**
 323  *
 324  * PutBitContext must be flushed & aligned to a byte boundary before calling this.
 325  */
 326 static inline void skip_put_bytes(PutBitContext *s, int n){
 327         assert((put_bits_count(s)&7)==0);
 328 #ifdef ALT_BITSTREAM_WRITER
 329         FIXME may need some cleaning of the buffer
 330         s->index += n<<3;
 331 #else
 332         assert(s->bit_left==32);
 333         s->buf_ptr += n;
 334 #endif
 335 }
 336
 337 /**
 338  * skips the given number of bits.
 339  * must only be used if the actual values in the bitstream dont matter
 340  */
 341 static inline void skip_put_bits(PutBitContext *s, int n){
 342 #ifdef ALT_BITSTREAM_WRITER
 343     s->index += n;
 344 #else
 345     s->bit_left -= n;
 346     s->buf_ptr-= s->bit_left>>5;
 347     s->bit_left &= 31;
 348 #endif
 349 }
 350
 351 /**
 352  * Changes the end of the buffer.
 353  */
 354 static inline void set_put_bits_buffer_size(PutBitContext *s, int size){
 355     s->buf_end= s->buf + size;
 356 }
 357
 358 /* Bitstream reader API docs:
 359 name
 360     abritary name which is used as prefix for the internal variables
 361
 362 gb
 363     getbitcontext
 364
 365 OPEN_READER(name, gb)
 366     loads gb into local variables
 367
 368 CLOSE_READER(name, gb)
 369     stores local vars in gb
 370
 371 UPDATE_CACHE(name, gb)
 372     refills the internal cache from the bitstream
 373     after this call at least MIN_CACHE_BITS will be available,
 374
 375 GET_CACHE(name, gb)
 376     will output the contents of the internal cache, next bit is MSB of 32 or 64 bit (FIXME 64bit)
 377
 378 SHOW_UBITS(name, gb, num)
 379     will return the next num bits
 380
 381 SHOW_SBITS(name, gb, num)
 382     will return the next num bits and do sign extension
 383
 384 SKIP_BITS(name, gb, num)
 385     will skip over the next num bits
 386     note, this is equivalent to SKIP_CACHE; SKIP_COUNTER
 387
 388 SKIP_CACHE(name, gb, num)
 389     will remove the next num bits from the cache (note SKIP_COUNTER MUST be called before UPDATE_CACHE / CLOSE_READER)
 390
 391 SKIP_COUNTER(name, gb, num)
 392     will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS)
 393
 394 LAST_SKIP_CACHE(name, gb, num)
 395     will remove the next num bits from the cache if it is needed for UPDATE_CACHE otherwise it will do nothing
 396
 397 LAST_SKIP_BITS(name, gb, num)
 398     is equivalent to SKIP_LAST_CACHE; SKIP_COUNTER
 399
 400 for examples see get_bits, show_bits, skip_bits, get_vlc
 401 */
 402
 403 static inline int unaligned32_be(const void *v)
 404 {
 405 #ifdef CONFIG_ALIGN
 406         const uint8_t *p=v;
 407         return (((p[0]<<8) | p[1])<<16) | (p[2]<<8) | (p[3]);
 408 #else
 409         return be2me_32( unaligned32(v)); //original
 410 #endif
 411 }
 412
 413 static inline int unaligned32_le(const void *v)
 414 {
 415 #ifdef CONFIG_ALIGN
 416        const uint8_t *p=v;
 417        return (((p[3]<<8) | p[2])<<16) | (p[1]<<8) | (p[0]);
 418 #else
 419        return le2me_32( unaligned32(v)); //original
 420 #endif
 421 }
 422
 423 #ifdef ALT_BITSTREAM_READER
 424 #   define MIN_CACHE_BITS 25
 425
 426 #   define OPEN_READER(name, gb)\
 427         int name##_index= (gb)->index;\
 428         int name##_cache= 0;\
 429
 430 #   define CLOSE_READER(name, gb)\
 431         (gb)->index= name##_index;\
 432
 433 # ifdef ALT_BITSTREAM_READER_LE
 434 #   define UPDATE_CACHE(name, gb)\
 435         name##_cache= unaligned32_le( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) >> (name##_index&0x07);\
 436
 437 #   define SKIP_CACHE(name, gb, num)\
 438         name##_cache >>= (num);
 439 # else
 440 #   define UPDATE_CACHE(name, gb)\
 441         name##_cache= unaligned32_be( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) << (name##_index&0x07);\
 442
 443 #   define SKIP_CACHE(name, gb, num)\
 444         name##_cache <<= (num);
 445 # endif
 446
 447 // FIXME name?
 448 #   define SKIP_COUNTER(name, gb, num)\
 449         name##_index += (num);\
 450
 451 #   define SKIP_BITS(name, gb, num)\
 452         {\
 453             SKIP_CACHE(name, gb, num)\
 454             SKIP_COUNTER(name, gb, num)\
 455         }\
 456
 457 #   define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
 458 #   define LAST_SKIP_CACHE(name, gb, num) ;
 459
 460 # ifdef ALT_BITSTREAM_READER_LE
 461 #   define SHOW_UBITS(name, gb, num)\
 462         ((name##_cache) & (NEG_USR32(0xffffffff,num)))
 463
 464 #   define SHOW_SBITS(name, gb, num)\
 465         NEG_SSR32((name##_cache)<<(32-(num)), num)
 466 # else
 467 #   define SHOW_UBITS(name, gb, num)\
 468         NEG_USR32(name##_cache, num)
 469
 470 #   define SHOW_SBITS(name, gb, num)\
 471         NEG_SSR32(name##_cache, num)
 472 # endif
 473
 474 #   define GET_CACHE(name, gb)\
 475         ((uint32_t)name##_cache)
 476
 477 static inline int get_bits_count(GetBitContext *s){
 478     return s->index;
 479 }
 480
 481 static inline void skip_bits_long(GetBitContext *s, int n){
 482     s->index += n;
 483 }
 484
 485 #elif defined LIBMPEG2_BITSTREAM_READER
 486 //libmpeg2 like reader
 487
 488 #   define MIN_CACHE_BITS 17
 489
 490 #   define OPEN_READER(name, gb)\
 491         int name##_bit_count=(gb)->bit_count;\
 492         int name##_cache= (gb)->cache;\
 493         uint8_t * name##_buffer_ptr=(gb)->buffer_ptr;\
 494
 495 #   define CLOSE_READER(name, gb)\
 496         (gb)->bit_count= name##_bit_count;\
 497         (gb)->cache= name##_cache;\
 498         (gb)->buffer_ptr= name##_buffer_ptr;\
 499
 500 #ifdef LIBMPEG2_BITSTREAM_READER_HACK
 501
 502 #   define UPDATE_CACHE(name, gb)\
 503     if(name##_bit_count >= 0){\
 504         name##_cache+= (int)be2me_16(*(uint16_t*)name##_buffer_ptr) << name##_bit_count;\
 505         name##_buffer_ptr += 2;\
 506         name##_bit_count-= 16;\
 507     }\
 508
 509 #else
 510
 511 #   define UPDATE_CACHE(name, gb)\
 512     if(name##_bit_count >= 0){\
 513         name##_cache+= ((name##_buffer_ptr[0]<<8) + name##_buffer_ptr[1]) << name##_bit_count;\
 514         name##_buffer_ptr+=2;\
 515         name##_bit_count-= 16;\
 516     }\
 517
 518 #endif
 519
 520 #   define SKIP_CACHE(name, gb, num)\
 521         name##_cache <<= (num);\
 522
 523 #   define SKIP_COUNTER(name, gb, num)\
 524         name##_bit_count += (num);\
 525
 526 #   define SKIP_BITS(name, gb, num)\
 527         {\
 528             SKIP_CACHE(name, gb, num)\
 529             SKIP_COUNTER(name, gb, num)\
 530         }\
 531
 532 #   define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
 533 #   define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
 534
 535 #   define SHOW_UBITS(name, gb, num)\
 536         NEG_USR32(name##_cache, num)
 537
 538 #   define SHOW_SBITS(name, gb, num)\
 539         NEG_SSR32(name##_cache, num)
 540
 541 #   define GET_CACHE(name, gb)\
 542         ((uint32_t)name##_cache)
 543
 544 static inline int get_bits_count(GetBitContext *s){
 545     return (s->buffer_ptr - s->buffer)*8 - 16 + s->bit_count;
 546 }
 547
 548 static inline void skip_bits_long(GetBitContext *s, int n){
 549     OPEN_READER(re, s)
 550     re_bit_count += n;
 551     re_buffer_ptr += 2*(re_bit_count>>4);
 552     re_bit_count &= 15;
 553     re_cache = ((re_buffer_ptr[-2]<<8) + re_buffer_ptr[-1]) << (16+re_bit_count);
 554     UPDATE_CACHE(re, s)
 555     CLOSE_READER(re, s)
 556 }
 557
 558 #elif defined A32_BITSTREAM_READER
 559
 560 #   define MIN_CACHE_BITS 32
 561
 562 #   define OPEN_READER(name, gb)\
 563         int name##_bit_count=(gb)->bit_count;\
 564         uint32_t name##_cache0= (gb)->cache0;\
 565         uint32_t name##_cache1= (gb)->cache1;\
 566         uint32_t * name##_buffer_ptr=(gb)->buffer_ptr;\
 567
 568 #   define CLOSE_READER(name, gb)\
 569         (gb)->bit_count= name##_bit_count;\
 570         (gb)->cache0= name##_cache0;\
 571         (gb)->cache1= name##_cache1;\
 572         (gb)->buffer_ptr= name##_buffer_ptr;\
 573
 574 #   define UPDATE_CACHE(name, gb)\
 575     if(name##_bit_count > 0){\
 576         const uint32_t next= be2me_32( *name##_buffer_ptr );\
 577         name##_cache0 |= NEG_USR32(next,name##_bit_count);\
 578         name##_cache1 |= next<<name##_bit_count;\
 579         name##_buffer_ptr++;\
 580         name##_bit_count-= 32;\
 581     }\
 582
 583 #if defined(ARCH_X86) || defined(ARCH_X86_64)
 584 #   define SKIP_CACHE(name, gb, num)\
 585         asm(\
 586             "shldl %2, %1, %0          \n\t"\
 587             "shll %2, %1               \n\t"\
 588             : "+r" (name##_cache0), "+r" (name##_cache1)\
 589             : "Ic" ((uint8_t)(num))\
 590            );
 591 #else
 592 #   define SKIP_CACHE(name, gb, num)\
 593         name##_cache0 <<= (num);\
 594         name##_cache0 |= NEG_USR32(name##_cache1,num);\
 595         name##_cache1 <<= (num);
 596 #endif
 597
 598 #   define SKIP_COUNTER(name, gb, num)\
 599         name##_bit_count += (num);\
 600
 601 #   define SKIP_BITS(name, gb, num)\
 602         {\
 603             SKIP_CACHE(name, gb, num)\
 604             SKIP_COUNTER(name, gb, num)\
 605         }\
 606
 607 #   define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
 608 #   define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
 609
 610 #   define SHOW_UBITS(name, gb, num)\
 611         NEG_USR32(name##_cache0, num)
 612
 613 #   define SHOW_SBITS(name, gb, num)\
 614         NEG_SSR32(name##_cache0, num)
 615
 616 #   define GET_CACHE(name, gb)\
 617         (name##_cache0)
 618
 619 static inline int get_bits_count(GetBitContext *s){
 620     return ((uint8_t*)s->buffer_ptr - s->buffer)*8 - 32 + s->bit_count;
 621 }
 622
 623 static inline void skip_bits_long(GetBitContext *s, int n){
 624     OPEN_READER(re, s)
 625     re_bit_count += n;
 626     re_buffer_ptr += re_bit_count>>5;
 627     re_bit_count &= 31;
 628     re_cache0 = be2me_32( re_buffer_ptr[-1] ) << re_bit_count;
 629     re_cache1 = 0;
 630     UPDATE_CACHE(re, s)
 631     CLOSE_READER(re, s)
 632 }
 633
 634 #endif
 635
 636 /**
 637  * read mpeg1 dc style vlc (sign bit + mantisse with no MSB).
 638  * if MSB not set it is negative
 639  * @param n length in bits
 640  * @author BERO
 641  */
 642 static inline int get_xbits(GetBitContext *s, int n){
 643     register int sign;
 644     register int32_t cache;
 645     OPEN_READER(re, s)
 646     UPDATE_CACHE(re, s)
 647     cache = GET_CACHE(re,s);
 648     sign=(~cache)>>31;
 649     LAST_SKIP_BITS(re, s, n)
 650     CLOSE_READER(re, s)
 651     return (NEG_USR32(sign ^ cache, n) ^ sign) - sign;
 652 }
 653
 654 static inline int get_sbits(GetBitContext *s, int n){
 655     register int tmp;
 656     OPEN_READER(re, s)
 657     UPDATE_CACHE(re, s)
 658     tmp= SHOW_SBITS(re, s, n);
 659     LAST_SKIP_BITS(re, s, n)
 660     CLOSE_READER(re, s)
 661     return tmp;
 662 }
 663
 664 /**
 665  * reads 0-17 bits.
 666  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
 667  */
 668 static inline unsigned int get_bits(GetBitContext *s, int n){
 669     register int tmp;
 670     OPEN_READER(re, s)
 671     UPDATE_CACHE(re, s)
 672     tmp= SHOW_UBITS(re, s, n);
 673     LAST_SKIP_BITS(re, s, n)
 674     CLOSE_READER(re, s)
 675     return tmp;
 676 }
 677
 678 /**
 679  * shows 0-17 bits.
 680  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
 681  */
 682 static inline unsigned int show_bits(GetBitContext *s, int n){
 683     register int tmp;
 684     OPEN_READER(re, s)
 685     UPDATE_CACHE(re, s)
 686     tmp= SHOW_UBITS(re, s, n);
 687 //    CLOSE_READER(re, s)
 688     return tmp;
 689 }
 690
 691 static inline void skip_bits(GetBitContext *s, int n){
 692  //Note gcc seems to optimize this to s->index+=n for the ALT_READER :))
 693     OPEN_READER(re, s)
 694     UPDATE_CACHE(re, s)
 695     LAST_SKIP_BITS(re, s, n)
 696     CLOSE_READER(re, s)
 697 }
 698
 699 static inline unsigned int get_bits1(GetBitContext *s){
 700 #ifdef ALT_BITSTREAM_READER
 701     int index= s->index;
 702     uint8_t result= s->buffer[ index>>3 ];
 703 #ifdef ALT_BITSTREAM_READER_LE
 704     result>>= (index&0x07);
 705     result&= 1;
 706 #else
 707     result<<= (index&0x07);
 708     result>>= 8 - 1;
 709 #endif
 710     index++;
 711     s->index= index;
 712
 713     return result;
 714 #else
 715     return get_bits(s, 1);
 716 #endif
 717 }
 718
 719 static inline unsigned int show_bits1(GetBitContext *s){
 720     return show_bits(s, 1);
 721 }
 722
 723 static inline void skip_bits1(GetBitContext *s){
 724     skip_bits(s, 1);
 725 }
 726
 727 /**
 728  * reads 0-32 bits.
 729  */
 730 static inline unsigned int get_bits_long(GetBitContext *s, int n){
 731     if(n<=17) return get_bits(s, n);
 732     else{
 733 #ifdef ALT_BITSTREAM_READER_LE
 734         int ret= get_bits(s, 16);
 735         return ret | (get_bits(s, n-16) << 16);
 736 #else
 737         int ret= get_bits(s, 16) << (n-16);
 738         return ret | get_bits(s, n-16);
 739 #endif
 740     }
 741 }
 742
 743 /**
 744  * shows 0-32 bits.
 745  */
 746 static inline unsigned int show_bits_long(GetBitContext *s, int n){
 747     if(n<=17) return show_bits(s, n);
 748     else{
 749         GetBitContext gb= *s;
 750         int ret= get_bits_long(s, n);
 751         *s= gb;
 752         return ret;
 753     }
 754 }
 755
 756 static inline int check_marker(GetBitContext *s, const char *msg)
 757 {
 758     int bit= get_bits1(s);
 759     if(!bit)
 760         av_log(NULL, AV_LOG_INFO, "Marker bit missing %s\n", msg);
 761
 762     return bit;
 763 }
 764
 765 /**
 766  * init GetBitContext.
 767  * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger then the actual read bits
 768  * because some optimized bitstream readers read 32 or 64 bit at once and could read over the end
 769  * @param bit_size the size of the buffer in bits
 770  */
 771 static inline void init_get_bits(GetBitContext *s,
 772                    const uint8_t *buffer, int bit_size)
 773 {
 774     int buffer_size= (bit_size+7)>>3;
 775     if(buffer_size < 0 || bit_size < 0) {
 776         buffer_size = bit_size = 0;
 777         buffer = NULL;
 778     }
 779
 780     s->buffer= buffer;
 781     s->size_in_bits= bit_size;
 782     s->buffer_end= buffer + buffer_size;
 783 #ifdef ALT_BITSTREAM_READER
 784     s->index=0;
 785 #elif defined LIBMPEG2_BITSTREAM_READER
 786     s->buffer_ptr = (uint8_t*)((intptr_t)buffer&(~1));
 787     s->bit_count = 16 + 8*((intptr_t)buffer&1);
 788     skip_bits_long(s, 0);
 789 #elif defined A32_BITSTREAM_READER
 790     s->buffer_ptr = (uint32_t*)((intptr_t)buffer&(~3));
 791     s->bit_count = 32 + 8*((intptr_t)buffer&3);
 792     skip_bits_long(s, 0);
 793 #endif
 794 }
 795
 796 static inline void align_get_bits(GetBitContext *s)
 797 {
 798     int n= (-get_bits_count(s)) & 7;
 799     if(n) skip_bits(s, n);
 800 }
 801
 802 int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
 803              const void *bits, int bits_wrap, int bits_size,
 804              const void *codes, int codes_wrap, int codes_size,
 805              int flags);
 806 #define INIT_VLC_USE_STATIC 1
 807 #define INIT_VLC_LE         2
 808 void free_vlc(VLC *vlc);
 809
 810 /**
 811  *
 812  * if the vlc code is invalid and max_depth=1 than no bits will be removed
 813  * if the vlc code is invalid and max_depth>1 than the number of bits removed
 814  * is undefined
 815  */
 816 #define GET_VLC(code, name, gb, table, bits, max_depth)\
 817 {\
 818     int n, index, nb_bits;\
 819 \
 820     index= SHOW_UBITS(name, gb, bits);\
 821     code = table[index][0];\
 822     n    = table[index][1];\
 823 \
 824     if(max_depth > 1 && n < 0){\
 825         LAST_SKIP_BITS(name, gb, bits)\
 826         UPDATE_CACHE(name, gb)\
 827 \
 828         nb_bits = -n;\
 829 \
 830         index= SHOW_UBITS(name, gb, nb_bits) + code;\
 831         code = table[index][0];\
 832         n    = table[index][1];\
 833         if(max_depth > 2 && n < 0){\
 834             LAST_SKIP_BITS(name, gb, nb_bits)\
 835             UPDATE_CACHE(name, gb)\
 836 \
 837             nb_bits = -n;\
 838 \
 839             index= SHOW_UBITS(name, gb, nb_bits) + code;\
 840             code = table[index][0];\
 841             n    = table[index][1];\
 842         }\
 843     }\
 844     SKIP_BITS(name, gb, n)\
 845 }
 846
 847 #define GET_RL_VLC(level, run, name, gb, table, bits, max_depth, need_update)\
 848 {\
 849     int n, index, nb_bits;\
 850 \
 851     index= SHOW_UBITS(name, gb, bits);\
 852     level = table[index].level;\
 853     n     = table[index].len;\
 854 \
 855     if(max_depth > 1 && n < 0){\
 856         SKIP_BITS(name, gb, bits)\
 857         if(need_update){\
 858             UPDATE_CACHE(name, gb)\
 859         }\
 860 \
 861         nb_bits = -n;\
 862 \
 863         index= SHOW_UBITS(name, gb, nb_bits) + level;\
 864         level = table[index].level;\
 865         n     = table[index].len;\
 866     }\
 867     run= table[index].run;\
 868     SKIP_BITS(name, gb, n)\
 869 }
 870
 871
 872 /**
 873  * parses a vlc code, faster then get_vlc()
 874  * @param bits is the number of bits which will be read at once, must be
 875  *             identical to nb_bits in init_vlc()
 876  * @param max_depth is the number of times bits bits must be readed to completly
 877  *                  read the longest vlc code
 878  *                  = (max_vlc_length + bits - 1) / bits
 879  */
 880 static always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2],
 881                                   int bits, int max_depth)
 882 {
 883     int code;
 884
 885     OPEN_READER(re, s)
 886     UPDATE_CACHE(re, s)
 887
 888     GET_VLC(code, re, s, table, bits, max_depth)
 889
 890     CLOSE_READER(re, s)
 891     return code;
 892 }
 893
 894 //#define TRACE
 895
 896 #ifdef TRACE
 897 static inline void print_bin(int bits, int n){
 898     int i;
 899
 900     for(i=n-1; i>=0; i--){
 901         av_log(NULL, AV_LOG_DEBUG, "%d", (bits>>i)&1);
 902     }
 903     for(i=n; i<24; i++)
 904         av_log(NULL, AV_LOG_DEBUG, " ");
 905 }
 906
 907 static inline int get_bits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
 908     int r= get_bits(s, n);
 909
 910     print_bin(r, n);
 911     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);
 912     return r;
 913 }
 914 static inline int get_vlc_trace(GetBitContext *s, VLC_TYPE (*table)[2], int bits, int max_depth, char *file, const char *func, int line){
 915     int show= show_bits(s, 24);
 916     int pos= get_bits_count(s);
 917     int r= get_vlc2(s, table, bits, max_depth);
 918     int len= get_bits_count(s) - pos;
 919     int bits2= show>>(24-len);
 920
 921     print_bin(bits2, len);
 922
 923     av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d vlc @%5d in %s %s:%d\n", bits2, len, r, pos, file, func, line);
 924     return r;
 925 }
 926 static inline int get_xbits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
 927     int show= show_bits(s, n);
 928     int r= get_xbits(s, n);
 929
 930     print_bin(show, n);
 931     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);
 932     return r;
 933 }
 934
 935 #define get_bits(s, n)  get_bits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 936 #define get_bits1(s)    get_bits_trace(s, 1, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 937 #define get_xbits(s, n) get_xbits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 938 #define get_vlc(s, vlc)            get_vlc_trace(s, (vlc)->table, (vlc)->bits, 3, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 939 #define get_vlc2(s, tab, bits, max) get_vlc_trace(s, tab, bits, max, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 940
 941 #define tprintf(...) av_log(NULL, AV_LOG_DEBUG, __VA_ARGS__)
 942
 943 #else //TRACE
 944 #define tprintf(...) {}
 945 #endif
 946
 947 static inline int decode012(GetBitContext *gb){
 948     int n;
 949     n = get_bits1(gb);
 950     if (n == 0)
 951         return 0;
 952     else
 953         return get_bits1(gb) + 1;
 954 }
 955
 956 #endif /* BITSTREAM_H */