apps/codecs/lib/ffmpeg_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 #ifndef BITSTREAM_H
  22 #define BITSTREAM_H
  23
  24 #include <inttypes.h>
  25 #include <stdlib.h>
  26 //#include <assert.h>
  27 #include <string.h>
  28 #include <stdio.h>
  29 #include "ffmpeg_bswap.h"
  30
  31 /* The following 2 defines are taken from libavutil/intreadwrite.h */
  32 #define AV_RB32(x)  ((((const uint8_t*)(x))[0] << 24) | \
  33                      (((const uint8_t*)(x))[1] << 16) | \
  34                      (((const uint8_t*)(x))[2] <<  8) | \
  35                       ((const uint8_t*)(x))[3])
  36 #define AV_WB32(p, d) do { \
  37                     ((uint8_t*)(p))[3] = (d); \
  38                     ((uint8_t*)(p))[2] = (d)>>8; \
  39                     ((uint8_t*)(p))[1] = (d)>>16; \
  40                     ((uint8_t*)(p))[0] = (d)>>24; } while(0)
  41
  42 #if defined(ALT_BITSTREAM_READER_LE) && !defined(ALT_BITSTREAM_READER)
  43 #   define ALT_BITSTREAM_READER
  44 #endif
  45
  46 //#define ALT_BITSTREAM_WRITER
  47 //#define ALIGNED_BITSTREAM_WRITER
  48 #if !defined(LIBMPEG2_BITSTREAM_READER) && !defined(A32_BITSTREAM_READER) && !defined(ALT_BITSTREAM_READER)
  49 #   if defined(ARCH_ARM)
  50 #       define A32_BITSTREAM_READER
  51 #   else
  52 #       define ALT_BITSTREAM_READER
  53 //#define LIBMPEG2_BITSTREAM_READER
  54 //#define A32_BITSTREAM_READER
  55 #   endif
  56 #endif
  57
  58 extern const uint8_t ff_reverse[256];
  59
  60 #if defined(ARCH_X86)
  61 // avoid +32 for shift optimization (gcc should do that ...)
  62 static inline  int32_t NEG_SSR32( int32_t a, int8_t s){
  63     __asm__ ("sarl %1, %0\n\t"
  64          : "+r" (a)
  65          : "ic" ((uint8_t)(-s))
  66     );
  67     return a;
  68 }
  69 static inline uint32_t NEG_USR32(uint32_t a, int8_t s){
  70     __asm__ ("shrl %1, %0\n\t"
  71          : "+r" (a)
  72          : "ic" ((uint8_t)(-s))
  73     );
  74     return a;
  75 }
  76 #else
  77 #    define NEG_SSR32(a,s) ((( int32_t)(a))>>(32-(s)))
  78 #    define NEG_USR32(a,s) (((uint32_t)(a))>>(32-(s)))
  79 #endif
  80
  81 /* bit output */
  82
  83 /* buf and buf_end must be present and used by every alternative writer. */
  84 typedef struct PutBitContext {
  85 #ifdef ALT_BITSTREAM_WRITER
  86     uint8_t *buf, *buf_end;
  87     int index;
  88 #else
  89     uint32_t bit_buf;
  90     int bit_left;
  91     uint8_t *buf, *buf_ptr, *buf_end;
  92 #endif
  93     int size_in_bits;
  94 } PutBitContext;
  95
  96 static inline void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
  97 {
  98     if(buffer_size < 0) {
  99         buffer_size = 0;
 100         buffer = NULL;
 101     }
 102
 103     s->size_in_bits= 8*buffer_size;
 104     s->buf = buffer;
 105     s->buf_end = s->buf + buffer_size;
 106 #ifdef ALT_BITSTREAM_WRITER
 107     s->index=0;
 108     ((uint32_t*)(s->buf))[0]=0;
 109 //    memset(buffer, 0, buffer_size);
 110 #else
 111     s->buf_ptr = s->buf;
 112     s->bit_left=32;
 113     s->bit_buf=0;
 114 #endif
 115 }
 116
 117 /* return the number of bits output */
 118 static inline int put_bits_count(PutBitContext *s)
 119 {
 120 #ifdef ALT_BITSTREAM_WRITER
 121     return s->index;
 122 #else
 123     return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
 124 #endif
 125 }
 126
 127 /* pad the end of the output stream with zeros */
 128 static inline void flush_put_bits(PutBitContext *s)
 129 {
 130 #ifdef ALT_BITSTREAM_WRITER
 131     align_put_bits(s);
 132 #else
 133 #ifndef BITSTREAM_WRITER_LE
 134     s->bit_buf<<= s->bit_left;
 135 #endif
 136     while (s->bit_left < 32) {
 137         /* XXX: should test end of buffer */
 138 #ifdef BITSTREAM_WRITER_LE
 139         *s->buf_ptr++=s->bit_buf;
 140         s->bit_buf>>=8;
 141 #else
 142         *s->buf_ptr++=s->bit_buf >> 24;
 143         s->bit_buf<<=8;
 144 #endif
 145         s->bit_left+=8;
 146     }
 147     s->bit_left=32;
 148     s->bit_buf=0;
 149 #endif
 150 }
 151
 152 void align_put_bits(PutBitContext *s);
 153 void ff_put_string(PutBitContext * pbc, const char *s, int put_zero);
 154 void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
 155
 156 /* bit input */
 157 /* buffer, buffer_end and size_in_bits must be present and used by every reader */
 158 typedef struct GetBitContext {
 159     const uint8_t *buffer, *buffer_end;
 160 #ifdef ALT_BITSTREAM_READER
 161     int index;
 162 #elif defined LIBMPEG2_BITSTREAM_READER
 163     uint8_t *buffer_ptr;
 164     uint32_t cache;
 165     int bit_count;
 166 #elif defined A32_BITSTREAM_READER
 167     uint32_t *buffer_ptr;
 168     uint32_t cache0;
 169     uint32_t cache1;
 170     int bit_count;
 171 #endif
 172     int size_in_bits;
 173 } GetBitContext;
 174
 175 #define VLC_TYPE int16_t
 176
 177 typedef struct VLC {
 178     int bits;
 179     VLC_TYPE (*table)[2]; ///< code, bits
 180     int table_size, table_allocated;
 181 } VLC;
 182
 183 typedef struct RL_VLC_ELEM {
 184     int16_t level;
 185     int8_t len;
 186     uint8_t run;
 187 } RL_VLC_ELEM;
 188
 189 #ifndef ALT_BITSTREAM_WRITER
 190 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
 191 {
 192     unsigned int bit_buf;
 193     int bit_left;
 194
 195     //    printf("put_bits=%d %x\n", n, value);
 196     //assert(n == 32 || value < (1U << n));
 197
 198     bit_buf = s->bit_buf;
 199     bit_left = s->bit_left;
 200
 201     //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
 202     /* XXX: optimize */
 203 #ifdef BITSTREAM_WRITER_LE
 204     bit_buf |= value << (32 - bit_left);
 205     if (n >= bit_left) {
 206 #if !HAVE_FAST_UNALIGNED
 207         if (3 & (intptr_t) s->buf_ptr) {
 208             AV_WL32(s->buf_ptr, bit_buf);
 209         } else
 210 #endif
 211         *(uint32_t *)s->buf_ptr = le2me_32(bit_buf);
 212         s->buf_ptr+=4;
 213         bit_buf = (bit_left==32)?0:value >> bit_left;
 214         bit_left+=32;
 215     }
 216     bit_left-=n;
 217 #else
 218     if (n < bit_left) {
 219         bit_buf = (bit_buf<<n) | value;
 220         bit_left-=n;
 221     } else {
 222         bit_buf<<=bit_left;
 223         bit_buf |= value >> (n - bit_left);
 224 #if !defined(HAVE_FAST_UNALIGNED)
 225         if (3 & (intptr_t) s->buf_ptr) {
 226             AV_WB32(s->buf_ptr, bit_buf);
 227         } else
 228 #endif
 229         *(uint32_t *)s->buf_ptr = be2me_32(bit_buf);
 230         //printf("bitbuf = %08x\n", bit_buf);
 231         s->buf_ptr+=4;
 232         bit_left+=32 - n;
 233         bit_buf = value;
 234     }
 235 #endif
 236
 237     s->bit_buf = bit_buf;
 238     s->bit_left = bit_left;
 239 }
 240 #endif
 241
 242
 243 #ifdef ALT_BITSTREAM_WRITER
 244 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
 245 {
 246 #    ifdef ALIGNED_BITSTREAM_WRITER
 247 #        if ARCH_X86
 248     __asm__ volatile(
 249         "movl %0, %%ecx                 \n\t"
 250         "xorl %%eax, %%eax              \n\t"
 251         "shrdl %%cl, %1, %%eax          \n\t"
 252         "shrl %%cl, %1                  \n\t"
 253         "movl %0, %%ecx                 \n\t"
 254         "shrl $3, %%ecx                 \n\t"
 255         "andl $0xFFFFFFFC, %%ecx        \n\t"
 256         "bswapl %1                      \n\t"
 257         "orl %1, (%2, %%ecx)            \n\t"
 258         "bswapl %%eax                   \n\t"
 259         "addl %3, %0                    \n\t"
 260         "movl %%eax, 4(%2, %%ecx)       \n\t"
 261         : "=&r" (s->index), "=&r" (value)
 262         : "r" (s->buf), "r" (n), "0" (s->index), "1" (value<<(-n))
 263         : "%eax", "%ecx"
 264     );
 265 #        else
 266     int index= s->index;
 267     uint32_t *ptr= ((uint32_t *)s->buf)+(index>>5);
 268
 269     value<<= 32-n;
 270
 271     ptr[0] |= be2me_32(value>>(index&31));
 272     ptr[1]  = be2me_32(value<<(32-(index&31)));
 273 //if(n>24) printf("%d %d\n", n, value);
 274     index+= n;
 275     s->index= index;
 276 #        endif
 277 #    else //ALIGNED_BITSTREAM_WRITER
 278 #        if ARCH_X86
 279     __asm__ volatile(
 280         "movl $7, %%ecx                 \n\t"
 281         "andl %0, %%ecx                 \n\t"
 282         "addl %3, %%ecx                 \n\t"
 283         "negl %%ecx                     \n\t"
 284         "shll %%cl, %1                  \n\t"
 285         "bswapl %1                      \n\t"
 286         "movl %0, %%ecx                 \n\t"
 287         "shrl $3, %%ecx                 \n\t"
 288         "orl %1, (%%ecx, %2)            \n\t"
 289         "addl %3, %0                    \n\t"
 290         "movl $0, 4(%%ecx, %2)          \n\t"
 291         : "=&r" (s->index), "=&r" (value)
 292         : "r" (s->buf), "r" (n), "0" (s->index), "1" (value)
 293         : "%ecx"
 294     );
 295 #        else
 296     int index= s->index;
 297     uint32_t *ptr= (uint32_t*)(((uint8_t *)s->buf)+(index>>3));
 298
 299     ptr[0] |= be2me_32(value<<(32-n-(index&7) ));
 300     ptr[1] = 0;
 301 //if(n>24) printf("%d %d\n", n, value);
 302     index+= n;
 303     s->index= index;
 304 #        endif
 305 #    endif //!ALIGNED_BITSTREAM_WRITER
 306 }
 307 #endif
 308
 309 static inline void put_sbits(PutBitContext *pb, int bits, int32_t val)
 310 {
 311     //assert(bits >= 0 && bits <= 31);
 312
 313     put_bits(pb, bits, val & ((1<<bits)-1));
 314 }
 315
 316
 317 static inline uint8_t* pbBufPtr(PutBitContext *s)
 318 {
 319 #ifdef ALT_BITSTREAM_WRITER
 320         return s->buf + (s->index>>3);
 321 #else
 322         return s->buf_ptr;
 323 #endif
 324 }
 325
 326 /**
 327  *
 328  * PutBitContext must be flushed & aligned to a byte boundary before calling this.
 329  */
 330 static inline void skip_put_bytes(PutBitContext *s, int n){
 331         //assert((put_bits_count(s)&7)==0);
 332 #ifdef ALT_BITSTREAM_WRITER
 333         FIXME may need some cleaning of the buffer
 334         s->index += n<<3;
 335 #else
 336         //assert(s->bit_left==32);
 337         s->buf_ptr += n;
 338 #endif
 339 }
 340
 341 /**
 342  * Skips the given number of bits.
 343  * Must only be used if the actual values in the bitstream do not matter.
 344  */
 345 static inline void skip_put_bits(PutBitContext *s, int n){
 346 #ifdef ALT_BITSTREAM_WRITER
 347     s->index += n;
 348 #else
 349     s->bit_left -= n;
 350     s->buf_ptr-= s->bit_left>>5;
 351     s->bit_left &= 31;
 352 #endif
 353 }
 354
 355 /**
 356  * Changes the end of the buffer.
 357  */
 358 static inline void set_put_bits_buffer_size(PutBitContext *s, int size){
 359     s->buf_end= s->buf + size;
 360 }
 361
 362 /* Bitstream reader API docs:
 363 name
 364     arbitrary name which is used as prefix for the internal variables
 365
 366 gb
 367     getbitcontext
 368
 369 OPEN_READER(name, gb)
 370     loads gb into local variables
 371
 372 CLOSE_READER(name, gb)
 373     stores local vars in gb
 374
 375 UPDATE_CACHE(name, gb)
 376     refills the internal cache from the bitstream
 377     after this call at least MIN_CACHE_BITS will be available,
 378
 379 GET_CACHE(name, gb)
 380     will output the contents of the internal cache, next bit is MSB of 32 or 64 bit (FIXME 64bit)
 381
 382 SHOW_UBITS(name, gb, num)
 383     will return the next num bits
 384
 385 SHOW_SBITS(name, gb, num)
 386     will return the next num bits and do sign extension
 387
 388 SKIP_BITS(name, gb, num)
 389     will skip over the next num bits
 390     note, this is equivalent to SKIP_CACHE; SKIP_COUNTER
 391
 392 SKIP_CACHE(name, gb, num)
 393     will remove the next num bits from the cache (note SKIP_COUNTER MUST be called before UPDATE_CACHE / CLOSE_READER)
 394
 395 SKIP_COUNTER(name, gb, num)
 396     will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS)
 397
 398 LAST_SKIP_CACHE(name, gb, num)
 399     will remove the next num bits from the cache if it is needed for UPDATE_CACHE otherwise it will do nothing
 400
 401 LAST_SKIP_BITS(name, gb, num)
 402     is equivalent to SKIP_LAST_CACHE; SKIP_COUNTER
 403
 404 for examples see get_bits, show_bits, skip_bits, get_vlc
 405 */
 406
 407 #ifdef ALT_BITSTREAM_READER
 408 #   define MIN_CACHE_BITS 25
 409
 410 #   define OPEN_READER(name, gb)\
 411         int name##_index= (gb)->index;\
 412         int name##_cache= 0;\
 413
 414 #   define CLOSE_READER(name, gb)\
 415         (gb)->index= name##_index;\
 416
 417 # ifdef ALT_BITSTREAM_READER_LE
 418 #   define UPDATE_CACHE(name, gb)\
 419         name##_cache= AV_RL32( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) >> (name##_index&0x07);\
 420
 421 #   define SKIP_CACHE(name, gb, num)\
 422         name##_cache >>= (num);
 423 # else
 424 #   define UPDATE_CACHE(name, gb)\
 425         name##_cache= AV_RB32( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) << (name##_index&0x07);\
 426
 427 #   define SKIP_CACHE(name, gb, num)\
 428         name##_cache <<= (num);
 429 # endif
 430
 431 // FIXME name?
 432 #   define SKIP_COUNTER(name, gb, num)\
 433         name##_index += (num);\
 434
 435 #   define SKIP_BITS(name, gb, num)\
 436         {\
 437             SKIP_CACHE(name, gb, num)\
 438             SKIP_COUNTER(name, gb, num)\
 439         }\
 440
 441 #   define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
 442 #   define LAST_SKIP_CACHE(name, gb, num) ;
 443
 444 # ifdef ALT_BITSTREAM_READER_LE
 445 #   define SHOW_UBITS(name, gb, num)\
 446         ((name##_cache) & (NEG_USR32(0xffffffff,num)))
 447
 448 #   define SHOW_SBITS(name, gb, num)\
 449         NEG_SSR32((name##_cache)<<(32-(num)), num)
 450 # else
 451 #   define SHOW_UBITS(name, gb, num)\
 452         NEG_USR32(name##_cache, num)
 453
 454 #   define SHOW_SBITS(name, gb, num)\
 455         NEG_SSR32(name##_cache, num)
 456 # endif
 457
 458 #   define GET_CACHE(name, gb)\
 459         ((uint32_t)name##_cache)
 460
 461 static inline int get_bits_count(GetBitContext *s){
 462     return s->index;
 463 }
 464
 465 static inline void skip_bits_long(GetBitContext *s, int n){
 466     s->index += n;
 467 }
 468
 469 #elif defined LIBMPEG2_BITSTREAM_READER
 470 //libmpeg2 like reader
 471
 472 #   define MIN_CACHE_BITS 17
 473
 474 #   define OPEN_READER(name, gb)\
 475         int name##_bit_count=(gb)->bit_count;\
 476         int name##_cache= (gb)->cache;\
 477         uint8_t * name##_buffer_ptr=(gb)->buffer_ptr;\
 478
 479 #   define CLOSE_READER(name, gb)\
 480         (gb)->bit_count= name##_bit_count;\
 481         (gb)->cache= name##_cache;\
 482         (gb)->buffer_ptr= name##_buffer_ptr;\
 483
 484 #   define UPDATE_CACHE(name, gb)\
 485     if(name##_bit_count >= 0){\
 486         name##_cache+= AV_RB16(name##_buffer_ptr) << name##_bit_count; \
 487         name##_buffer_ptr+=2;\
 488         name##_bit_count-= 16;\
 489     }\
 490
 491 #   define SKIP_CACHE(name, gb, num)\
 492         name##_cache <<= (num);\
 493
 494 #   define SKIP_COUNTER(name, gb, num)\
 495         name##_bit_count += (num);\
 496
 497 #   define SKIP_BITS(name, gb, num)\
 498         {\
 499             SKIP_CACHE(name, gb, num)\
 500             SKIP_COUNTER(name, gb, num)\
 501         }\
 502
 503 #   define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
 504 #   define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
 505
 506 #   define SHOW_UBITS(name, gb, num)\
 507         NEG_USR32(name##_cache, num)
 508
 509 #   define SHOW_SBITS(name, gb, num)\
 510         NEG_SSR32(name##_cache, num)
 511
 512 #   define GET_CACHE(name, gb)\
 513         ((uint32_t)name##_cache)
 514
 515 static inline int get_bits_count(GetBitContext *s){
 516     return (s->buffer_ptr - s->buffer)*8 - 16 + s->bit_count;
 517 }
 518
 519 static inline void skip_bits_long(GetBitContext *s, int n){
 520     OPEN_READER(re, s)
 521     re_bit_count += n;
 522     re_buffer_ptr += 2*(re_bit_count>>4);
 523     re_bit_count &= 15;
 524     re_cache = ((re_buffer_ptr[-2]<<8) + re_buffer_ptr[-1]) << (16+re_bit_count);
 525     UPDATE_CACHE(re, s)
 526     CLOSE_READER(re, s)
 527 }
 528
 529 #elif defined A32_BITSTREAM_READER
 530
 531 #   define MIN_CACHE_BITS 32
 532
 533 #   define OPEN_READER(name, gb)\
 534         int name##_bit_count=(gb)->bit_count;\
 535         uint32_t name##_cache0= (gb)->cache0;\
 536         uint32_t name##_cache1= (gb)->cache1;\
 537         uint32_t * name##_buffer_ptr=(gb)->buffer_ptr;\
 538
 539 #   define CLOSE_READER(name, gb)\
 540         (gb)->bit_count= name##_bit_count;\
 541         (gb)->cache0= name##_cache0;\
 542         (gb)->cache1= name##_cache1;\
 543         (gb)->buffer_ptr= name##_buffer_ptr;\
 544
 545 #   define UPDATE_CACHE(name, gb)\
 546     if(name##_bit_count > 0){\
 547         const uint32_t next= be2me_32( *name##_buffer_ptr );\
 548         name##_cache0 |= NEG_USR32(next,name##_bit_count);\
 549         name##_cache1 |= next<<name##_bit_count;\
 550         name##_buffer_ptr++;\
 551         name##_bit_count-= 32;\
 552     }\
 553
 554 #if ARCH_X86
 555 #   define SKIP_CACHE(name, gb, num)\
 556         __asm__(\
 557             "shldl %2, %1, %0          \n\t"\
 558             "shll %2, %1               \n\t"\
 559             : "+r" (name##_cache0), "+r" (name##_cache1)\
 560             : "Ic" ((uint8_t)(num))\
 561            );
 562 #else
 563 #   define SKIP_CACHE(name, gb, num)\
 564         name##_cache0 <<= (num);\
 565         name##_cache0 |= NEG_USR32(name##_cache1,num);\
 566         name##_cache1 <<= (num);
 567 #endif
 568
 569 #   define SKIP_COUNTER(name, gb, num)\
 570         name##_bit_count += (num);\
 571
 572 #   define SKIP_BITS(name, gb, num)\
 573         {\
 574             SKIP_CACHE(name, gb, num)\
 575             SKIP_COUNTER(name, gb, num)\
 576         }\
 577
 578 #   define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
 579 #   define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
 580
 581 #   define SHOW_UBITS(name, gb, num)\
 582         NEG_USR32(name##_cache0, num)
 583
 584 #   define SHOW_SBITS(name, gb, num)\
 585         NEG_SSR32(name##_cache0, num)
 586
 587 #   define GET_CACHE(name, gb)\
 588         (name##_cache0)
 589
 590 static inline int get_bits_count(GetBitContext *s){
 591     return ((uint8_t*)s->buffer_ptr - s->buffer)*8 - 32 + s->bit_count;
 592 }
 593
 594 static inline void skip_bits_long(GetBitContext *s, int n){
 595     OPEN_READER(re, s)
 596     re_bit_count += n;
 597     re_buffer_ptr += re_bit_count>>5;
 598     re_bit_count &= 31;
 599     re_cache0 = be2me_32( re_buffer_ptr[-1] ) << re_bit_count;
 600     re_cache1 = 0;
 601     UPDATE_CACHE(re, s)
 602     CLOSE_READER(re, s)
 603 }
 604
 605 #endif
 606
 607 /**
 608  * read mpeg1 dc style vlc (sign bit + mantisse with no MSB).
 609  * if MSB not set it is negative
 610  * @param n length in bits
 611  * @author BERO
 612  */
 613 static inline int get_xbits(GetBitContext *s, int n){
 614     register int sign;
 615     register int32_t cache;
 616     OPEN_READER(re, s)
 617     UPDATE_CACHE(re, s)
 618     cache = GET_CACHE(re,s);
 619     sign=(~cache)>>31;
 620     LAST_SKIP_BITS(re, s, n)
 621     CLOSE_READER(re, s)
 622     return (NEG_USR32(sign ^ cache, n) ^ sign) - sign;
 623 }
 624
 625 static inline int get_sbits(GetBitContext *s, int n){
 626     register int tmp;
 627     OPEN_READER(re, s)
 628     UPDATE_CACHE(re, s)
 629     tmp= SHOW_SBITS(re, s, n);
 630     LAST_SKIP_BITS(re, s, n)
 631     CLOSE_READER(re, s)
 632     return tmp;
 633 }
 634
 635 /**
 636  * reads 1-17 bits.
 637  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
 638  */
 639 static inline unsigned int get_bits(GetBitContext *s, int n){
 640     register int tmp;
 641     OPEN_READER(re, s)
 642     UPDATE_CACHE(re, s)
 643     tmp= SHOW_UBITS(re, s, n);
 644     LAST_SKIP_BITS(re, s, n)
 645     CLOSE_READER(re, s)
 646     return tmp;
 647 }
 648
 649 /**
 650  * shows 1-17 bits.
 651  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
 652  */
 653 static inline unsigned int show_bits(GetBitContext *s, int n){
 654     register int tmp;
 655     OPEN_READER(re, s)
 656     UPDATE_CACHE(re, s)
 657     tmp= SHOW_UBITS(re, s, n);
 658 //    CLOSE_READER(re, s)
 659     return tmp;
 660 }
 661
 662 static inline void skip_bits(GetBitContext *s, int n){
 663  //Note gcc seems to optimize this to s->index+=n for the ALT_READER :))
 664     OPEN_READER(re, s)
 665     UPDATE_CACHE(re, s)
 666     LAST_SKIP_BITS(re, s, n)
 667     CLOSE_READER(re, s)
 668 }
 669
 670 static inline unsigned int get_bits1(GetBitContext *s){
 671 #ifdef ALT_BITSTREAM_READER
 672     int index= s->index;
 673     uint8_t result= s->buffer[ index>>3 ];
 674 #ifdef ALT_BITSTREAM_READER_LE
 675     result>>= (index&0x07);
 676     result&= 1;
 677 #else
 678     result<<= (index&0x07);
 679     result>>= 8 - 1;
 680 #endif
 681     index++;
 682     s->index= index;
 683
 684     return result;
 685 #else
 686     return get_bits(s, 1);
 687 #endif
 688 }
 689
 690 static inline unsigned int show_bits1(GetBitContext *s){
 691     return show_bits(s, 1);
 692 }
 693
 694 static inline void skip_bits1(GetBitContext *s){
 695     skip_bits(s, 1);
 696 }
 697
 698 /**
 699  * reads 0-32 bits.
 700  */
 701 static inline unsigned int get_bits_long(GetBitContext *s, int n){
 702     if(n<=17) return get_bits(s, n);
 703     else{
 704 #ifdef ALT_BITSTREAM_READER_LE
 705         int ret= get_bits(s, 16);
 706         return ret | (get_bits(s, n-16) << 16);
 707 #else
 708         int ret= get_bits(s, 16) << (n-16);
 709         return ret | get_bits(s, n-16);
 710 #endif
 711     }
 712 }
 713
 714 #if 0
 715 /**
 716  * reads 0-32 bits as a signed integer.
 717  */
 718 static inline int get_sbits_long(GetBitContext *s, int n) {
 719     return sign_extend(get_bits_long(s, n), n);
 720 }
 721 #endif
 722
 723 /**
 724  * shows 0-32 bits.
 725  */
 726 static inline unsigned int show_bits_long(GetBitContext *s, int n){
 727     if(n<=17) return show_bits(s, n);
 728     else{
 729         GetBitContext gb= *s;
 730         return get_bits_long(&gb, n);
 731     }
 732 }
 733
 734 #if 0
 735 static inline int check_marker(GetBitContext *s, const char *msg)
 736 {
 737     int bit= get_bits1(s);
 738     if(!bit)
 739         printf("Marker bit missing %s\n", msg);
 740
 741     return bit;
 742 }
 743 #endif
 744
 745 /**
 746  * init GetBitContext.
 747  * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger then the actual read bits
 748  * because some optimized bitstream readers read 32 or 64 bit at once and could read over the end
 749  * @param bit_size the size of the buffer in bits
 750  */
 751 static inline void init_get_bits(GetBitContext *s,
 752                    const uint8_t *buffer, int bit_size)
 753 {
 754     int buffer_size= (bit_size+7)>>3;
 755     if(buffer_size < 0 || bit_size < 0) {
 756         buffer_size = bit_size = 0;
 757         buffer = NULL;
 758     }
 759
 760     s->buffer= buffer;
 761     s->size_in_bits= bit_size;
 762     s->buffer_end= buffer + buffer_size;
 763 #ifdef ALT_BITSTREAM_READER
 764     s->index=0;
 765 #elif defined LIBMPEG2_BITSTREAM_READER
 766     s->buffer_ptr = (uint8_t*)((intptr_t)buffer&(~1));
 767     s->bit_count = 16 + 8*((intptr_t)buffer&1);
 768     skip_bits_long(s, 0);
 769 #elif defined A32_BITSTREAM_READER
 770     s->buffer_ptr = (uint32_t*)((intptr_t)buffer&(~3));
 771     s->bit_count = 32 + 8*((intptr_t)buffer&3);
 772     skip_bits_long(s, 0);
 773 #endif
 774 }
 775
 776 static inline void align_get_bits(GetBitContext *s)
 777 {
 778     int n= (-get_bits_count(s)) & 7;
 779     if(n) skip_bits(s, n);
 780 }
 781
 782 #define init_vlc(vlc, nb_bits, nb_codes,\
 783                  bits, bits_wrap, bits_size,\
 784                  codes, codes_wrap, codes_size,\
 785                  flags)\
 786         init_vlc_sparse(vlc, nb_bits, nb_codes,\
 787                  bits, bits_wrap, bits_size,\
 788                  codes, codes_wrap, codes_size,\
 789                  NULL, 0, 0, flags)
 790
 791 int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,
 792              const void *bits, int bits_wrap, int bits_size,
 793              const void *codes, int codes_wrap, int codes_size,
 794              const void *symbols, int symbols_wrap, int symbols_size,
 795              int flags);
 796 #define INIT_VLC_USE_STATIC 1 ///< VERY strongly deprecated and forbidden
 797 #define INIT_VLC_LE         2
 798 #define INIT_VLC_USE_NEW_STATIC 4
 799 void free_vlc(VLC *vlc);
 800
 801 #define INIT_VLC_STATIC(vlc, bits, a,b,c,d,e,f,g, static_size)\
 802 {\
 803     static VLC_TYPE table[static_size][2];\
 804     (vlc)->table= table;\
 805     (vlc)->table_allocated= static_size;\
 806     init_vlc(vlc, bits, a,b,c,d,e,f,g, INIT_VLC_USE_NEW_STATIC);\
 807 }
 808
 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 read to completely
 877  *                  read the longest vlc code
 878  *                  = (max_vlc_length + bits - 1) / bits
 879  */
 880 static 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         printf("%d", (bits>>i)&1);
 902     }
 903     for(i=n; i<24; i++)
 904         printf(" ");
 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     printf("%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     printf("%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     printf("%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(p, ...) printf
 942
 943 #else //TRACE
 944 #define tprintf(p, ...) {}
 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 static inline int decode210(GetBitContext *gb){
 957     if (get_bits1(gb))
 958         return 0;
 959     else
 960         return 2 - get_bits1(gb);
 961 }
 962
 963 #endif /* BITSTREAM_H */