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 libavcodec/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     int size_in_bits;
  89 } PutBitContext;
  90
  91 static inline void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
  92 {
  93     if(buffer_size < 0) {
  94         buffer_size = 0;
  95         buffer = NULL;
  96     }
  97
  98     s->size_in_bits= 8*buffer_size;
  99     s->buf = buffer;
 100     s->buf_end = s->buf + buffer_size;
 101 #ifdef ALT_BITSTREAM_WRITER
 102     s->index=0;
 103     ((uint32_t*)(s->buf))[0]=0;
 104 //    memset(buffer, 0, buffer_size);
 105 #else
 106     s->buf_ptr = s->buf;
 107     s->bit_left=32;
 108     s->bit_buf=0;
 109 #endif
 110 }
 111
 112 /* return the number of bits output */
 113 static inline int put_bits_count(PutBitContext *s)
 114 {
 115 #ifdef ALT_BITSTREAM_WRITER
 116     return s->index;
 117 #else
 118     return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
 119 #endif
 120 }
 121
 122 /* pad the end of the output stream with zeros */
 123 static inline void flush_put_bits(PutBitContext *s)
 124 {
 125 #ifdef ALT_BITSTREAM_WRITER
 126     align_put_bits(s);
 127 #else
 128 #ifndef BITSTREAM_WRITER_LE
 129     s->bit_buf<<= s->bit_left;
 130 #endif
 131     while (s->bit_left < 32) {
 132         /* XXX: should test end of buffer */
 133 #ifdef BITSTREAM_WRITER_LE
 134         *s->buf_ptr++=s->bit_buf;
 135         s->bit_buf>>=8;
 136 #else
 137         *s->buf_ptr++=s->bit_buf >> 24;
 138         s->bit_buf<<=8;
 139 #endif
 140         s->bit_left+=8;
 141     }
 142     s->bit_left=32;
 143     s->bit_buf=0;
 144 #endif
 145 }
 146
 147 void align_put_bits(PutBitContext *s);
 148 void ff_put_string(PutBitContext * pbc, const char *s, int put_zero);
 149 void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
 150
 151 /* bit input */
 152 /* buffer, buffer_end and size_in_bits must be present and used by every reader */
 153 typedef struct GetBitContext {
 154     const uint8_t *buffer, *buffer_end;
 155 #ifdef ALT_BITSTREAM_READER
 156     int index;
 157 #elif defined LIBMPEG2_BITSTREAM_READER
 158     uint8_t *buffer_ptr;
 159     uint32_t cache;
 160     int bit_count;
 161 #elif defined A32_BITSTREAM_READER
 162     uint32_t *buffer_ptr;
 163     uint32_t cache0;
 164     uint32_t cache1;
 165     int bit_count;
 166 #endif
 167     int size_in_bits;
 168 } GetBitContext;
 169
 170 #define VLC_TYPE int16_t
 171
 172 typedef struct VLC {
 173     int bits;
 174     VLC_TYPE (*table)[2]; ///< code, bits
 175     int table_size, table_allocated;
 176 } VLC;
 177
 178 typedef struct RL_VLC_ELEM {
 179     int16_t level;
 180     int8_t len;
 181     uint8_t run;
 182 } RL_VLC_ELEM;
 183
 184 #ifndef ALT_BITSTREAM_WRITER
 185 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
 186 {
 187     unsigned int bit_buf;
 188     int bit_left;
 189
 190     //    printf("put_bits=%d %x\n", n, value);
 191     assert(n == 32 || value < (1U << n));
 192
 193     bit_buf = s->bit_buf;
 194     bit_left = s->bit_left;
 195
 196     //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
 197     /* XXX: optimize */
 198 #ifdef BITSTREAM_WRITER_LE
 199     bit_buf |= value << (32 - bit_left);
 200     if (n >= bit_left) {
 201 #if !HAVE_FAST_UNALIGNED
 202         if (3 & (intptr_t) s->buf_ptr) {
 203             AV_WL32(s->buf_ptr, bit_buf);
 204         } else
 205 #endif
 206         *(uint32_t *)s->buf_ptr = le2me_32(bit_buf);
 207         s->buf_ptr+=4;
 208         bit_buf = (bit_left==32)?0:value >> bit_left;
 209         bit_left+=32;
 210     }
 211     bit_left-=n;
 212 #else
 213     if (n < bit_left) {
 214         bit_buf = (bit_buf<<n) | value;
 215         bit_left-=n;
 216     } else {
 217         bit_buf<<=bit_left;
 218         bit_buf |= value >> (n - bit_left);
 219 #if !HAVE_FAST_UNALIGNED
 220         if (3 & (intptr_t) s->buf_ptr) {
 221             AV_WB32(s->buf_ptr, bit_buf);
 222         } else
 223 #endif
 224         *(uint32_t *)s->buf_ptr = be2me_32(bit_buf);
 225         //printf("bitbuf = %08x\n", bit_buf);
 226         s->buf_ptr+=4;
 227         bit_left+=32 - n;
 228         bit_buf = value;
 229     }
 230 #endif
 231
 232     s->bit_buf = bit_buf;
 233     s->bit_left = bit_left;
 234 }
 235 #endif
 236
 237
 238 #ifdef ALT_BITSTREAM_WRITER
 239 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
 240 {
 241 #    ifdef ALIGNED_BITSTREAM_WRITER
 242 #        if ARCH_X86
 243     __asm__ volatile(
 244         "movl %0, %%ecx                 \n\t"
 245         "xorl %%eax, %%eax              \n\t"
 246         "shrdl %%cl, %1, %%eax          \n\t"
 247         "shrl %%cl, %1                  \n\t"
 248         "movl %0, %%ecx                 \n\t"
 249         "shrl $3, %%ecx                 \n\t"
 250         "andl $0xFFFFFFFC, %%ecx        \n\t"
 251         "bswapl %1                      \n\t"
 252         "orl %1, (%2, %%ecx)            \n\t"
 253         "bswapl %%eax                   \n\t"
 254         "addl %3, %0                    \n\t"
 255         "movl %%eax, 4(%2, %%ecx)       \n\t"
 256         : "=&r" (s->index), "=&r" (value)
 257         : "r" (s->buf), "r" (n), "0" (s->index), "1" (value<<(-n))
 258         : "%eax", "%ecx"
 259     );
 260 #        else
 261     int index= s->index;
 262     uint32_t *ptr= ((uint32_t *)s->buf)+(index>>5);
 263
 264     value<<= 32-n;
 265
 266     ptr[0] |= be2me_32(value>>(index&31));
 267     ptr[1]  = be2me_32(value<<(32-(index&31)));
 268 //if(n>24) printf("%d %d\n", n, value);
 269     index+= n;
 270     s->index= index;
 271 #        endif
 272 #    else //ALIGNED_BITSTREAM_WRITER
 273 #        if ARCH_X86
 274     __asm__ volatile(
 275         "movl $7, %%ecx                 \n\t"
 276         "andl %0, %%ecx                 \n\t"
 277         "addl %3, %%ecx                 \n\t"
 278         "negl %%ecx                     \n\t"
 279         "shll %%cl, %1                  \n\t"
 280         "bswapl %1                      \n\t"
 281         "movl %0, %%ecx                 \n\t"
 282         "shrl $3, %%ecx                 \n\t"
 283         "orl %1, (%%ecx, %2)            \n\t"
 284         "addl %3, %0                    \n\t"
 285         "movl $0, 4(%%ecx, %2)          \n\t"
 286         : "=&r" (s->index), "=&r" (value)
 287         : "r" (s->buf), "r" (n), "0" (s->index), "1" (value)
 288         : "%ecx"
 289     );
 290 #        else
 291     int index= s->index;
 292     uint32_t *ptr= (uint32_t*)(((uint8_t *)s->buf)+(index>>3));
 293
 294     ptr[0] |= be2me_32(value<<(32-n-(index&7) ));
 295     ptr[1] = 0;
 296 //if(n>24) printf("%d %d\n", n, value);
 297     index+= n;
 298     s->index= index;
 299 #        endif
 300 #    endif //!ALIGNED_BITSTREAM_WRITER
 301 }
 302 #endif
 303
 304 static inline void put_sbits(PutBitContext *pb, int bits, int32_t val)
 305 {
 306     assert(bits >= 0 && bits <= 31);
 307
 308     put_bits(pb, bits, val & ((1<<bits)-1));
 309 }
 310
 311
 312 static inline uint8_t* pbBufPtr(PutBitContext *s)
 313 {
 314 #ifdef ALT_BITSTREAM_WRITER
 315         return s->buf + (s->index>>3);
 316 #else
 317         return s->buf_ptr;
 318 #endif
 319 }
 320
 321 /**
 322  *
 323  * PutBitContext must be flushed & aligned to a byte boundary before calling this.
 324  */
 325 static inline void skip_put_bytes(PutBitContext *s, int n){
 326         assert((put_bits_count(s)&7)==0);
 327 #ifdef ALT_BITSTREAM_WRITER
 328         FIXME may need some cleaning of the buffer
 329         s->index += n<<3;
 330 #else
 331         assert(s->bit_left==32);
 332         s->buf_ptr += n;
 333 #endif
 334 }
 335
 336 /**
 337  * Skips the given number of bits.
 338  * Must only be used if the actual values in the bitstream do not matter.
 339  */
 340 static inline void skip_put_bits(PutBitContext *s, int n){
 341 #ifdef ALT_BITSTREAM_WRITER
 342     s->index += n;
 343 #else
 344     s->bit_left -= n;
 345     s->buf_ptr-= s->bit_left>>5;
 346     s->bit_left &= 31;
 347 #endif
 348 }
 349
 350 /**
 351  * Changes the end of the buffer.
 352  */
 353 static inline void set_put_bits_buffer_size(PutBitContext *s, int size){
 354     s->buf_end= s->buf + size;
 355 }
 356
 357 /* Bitstream reader API docs:
 358 name
 359     arbitrary name which is used as prefix for the internal variables
 360
 361 gb
 362     getbitcontext
 363
 364 OPEN_READER(name, gb)
 365     loads gb into local variables
 366
 367 CLOSE_READER(name, gb)
 368     stores local vars in gb
 369
 370 UPDATE_CACHE(name, gb)
 371     refills the internal cache from the bitstream
 372     after this call at least MIN_CACHE_BITS will be available,
 373
 374 GET_CACHE(name, gb)
 375     will output the contents of the internal cache, next bit is MSB of 32 or 64 bit (FIXME 64bit)
 376
 377 SHOW_UBITS(name, gb, num)
 378     will return the next num bits
 379
 380 SHOW_SBITS(name, gb, num)
 381     will return the next num bits and do sign extension
 382
 383 SKIP_BITS(name, gb, num)
 384     will skip over the next num bits
 385     note, this is equivalent to SKIP_CACHE; SKIP_COUNTER
 386
 387 SKIP_CACHE(name, gb, num)
 388     will remove the next num bits from the cache (note SKIP_COUNTER MUST be called before UPDATE_CACHE / CLOSE_READER)
 389
 390 SKIP_COUNTER(name, gb, num)
 391     will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS)
 392
 393 LAST_SKIP_CACHE(name, gb, num)
 394     will remove the next num bits from the cache if it is needed for UPDATE_CACHE otherwise it will do nothing
 395
 396 LAST_SKIP_BITS(name, gb, num)
 397     is equivalent to SKIP_LAST_CACHE; SKIP_COUNTER
 398
 399 for examples see get_bits, show_bits, skip_bits, get_vlc
 400 */
 401
 402 #ifdef ALT_BITSTREAM_READER
 403 #   define MIN_CACHE_BITS 25
 404
 405 #   define OPEN_READER(name, gb)\
 406         int name##_index= (gb)->index;\
 407         int name##_cache= 0;\
 408
 409 #   define CLOSE_READER(name, gb)\
 410         (gb)->index= name##_index;\
 411
 412 # ifdef ALT_BITSTREAM_READER_LE
 413 #   define UPDATE_CACHE(name, gb)\
 414         name##_cache= AV_RL32( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) >> (name##_index&0x07);\
 415
 416 #   define SKIP_CACHE(name, gb, num)\
 417         name##_cache >>= (num);
 418 # else
 419 #   define UPDATE_CACHE(name, gb)\
 420         name##_cache= AV_RB32( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) << (name##_index&0x07);\
 421
 422 #   define SKIP_CACHE(name, gb, num)\
 423         name##_cache <<= (num);
 424 # endif
 425
 426 // FIXME name?
 427 #   define SKIP_COUNTER(name, gb, num)\
 428         name##_index += (num);\
 429
 430 #   define SKIP_BITS(name, gb, num)\
 431         {\
 432             SKIP_CACHE(name, gb, num)\
 433             SKIP_COUNTER(name, gb, num)\
 434         }\
 435
 436 #   define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
 437 #   define LAST_SKIP_CACHE(name, gb, num) ;
 438
 439 # ifdef ALT_BITSTREAM_READER_LE
 440 #   define SHOW_UBITS(name, gb, num)\
 441         ((name##_cache) & (NEG_USR32(0xffffffff,num)))
 442
 443 #   define SHOW_SBITS(name, gb, num)\
 444         NEG_SSR32((name##_cache)<<(32-(num)), num)
 445 # else
 446 #   define SHOW_UBITS(name, gb, num)\
 447         NEG_USR32(name##_cache, num)
 448
 449 #   define SHOW_SBITS(name, gb, num)\
 450         NEG_SSR32(name##_cache, num)
 451 # endif
 452
 453 #   define GET_CACHE(name, gb)\
 454         ((uint32_t)name##_cache)
 455
 456 static inline int get_bits_count(GetBitContext *s){
 457     return s->index;
 458 }
 459
 460 static inline void skip_bits_long(GetBitContext *s, int n){
 461     s->index += n;
 462 }
 463
 464 #elif defined LIBMPEG2_BITSTREAM_READER
 465 //libmpeg2 like reader
 466
 467 #   define MIN_CACHE_BITS 17
 468
 469 #   define OPEN_READER(name, gb)\
 470         int name##_bit_count=(gb)->bit_count;\
 471         int name##_cache= (gb)->cache;\
 472         uint8_t * name##_buffer_ptr=(gb)->buffer_ptr;\
 473
 474 #   define CLOSE_READER(name, gb)\
 475         (gb)->bit_count= name##_bit_count;\
 476         (gb)->cache= name##_cache;\
 477         (gb)->buffer_ptr= name##_buffer_ptr;\
 478
 479 #   define UPDATE_CACHE(name, gb)\
 480     if(name##_bit_count >= 0){\
 481         name##_cache+= AV_RB16(name##_buffer_ptr) << name##_bit_count; \
 482         name##_buffer_ptr+=2;\
 483         name##_bit_count-= 16;\
 484     }\
 485
 486 #   define SKIP_CACHE(name, gb, num)\
 487         name##_cache <<= (num);\
 488
 489 #   define SKIP_COUNTER(name, gb, num)\
 490         name##_bit_count += (num);\
 491
 492 #   define SKIP_BITS(name, gb, num)\
 493         {\
 494             SKIP_CACHE(name, gb, num)\
 495             SKIP_COUNTER(name, gb, num)\
 496         }\
 497
 498 #   define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
 499 #   define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
 500
 501 #   define SHOW_UBITS(name, gb, num)\
 502         NEG_USR32(name##_cache, num)
 503
 504 #   define SHOW_SBITS(name, gb, num)\
 505         NEG_SSR32(name##_cache, num)
 506
 507 #   define GET_CACHE(name, gb)\
 508         ((uint32_t)name##_cache)
 509
 510 static inline int get_bits_count(GetBitContext *s){
 511     return (s->buffer_ptr - s->buffer)*8 - 16 + s->bit_count;
 512 }
 513
 514 static inline void skip_bits_long(GetBitContext *s, int n){
 515     OPEN_READER(re, s)
 516     re_bit_count += n;
 517     re_buffer_ptr += 2*(re_bit_count>>4);
 518     re_bit_count &= 15;
 519     re_cache = ((re_buffer_ptr[-2]<<8) + re_buffer_ptr[-1]) << (16+re_bit_count);
 520     UPDATE_CACHE(re, s)
 521     CLOSE_READER(re, s)
 522 }
 523
 524 #elif defined A32_BITSTREAM_READER
 525
 526 #   define MIN_CACHE_BITS 32
 527
 528 #   define OPEN_READER(name, gb)\
 529         int name##_bit_count=(gb)->bit_count;\
 530         uint32_t name##_cache0= (gb)->cache0;\
 531         uint32_t name##_cache1= (gb)->cache1;\
 532         uint32_t * name##_buffer_ptr=(gb)->buffer_ptr;\
 533
 534 #   define CLOSE_READER(name, gb)\
 535         (gb)->bit_count= name##_bit_count;\
 536         (gb)->cache0= name##_cache0;\
 537         (gb)->cache1= name##_cache1;\
 538         (gb)->buffer_ptr= name##_buffer_ptr;\
 539
 540 #   define UPDATE_CACHE(name, gb)\
 541     if(name##_bit_count > 0){\
 542         const uint32_t next= be2me_32( *name##_buffer_ptr );\
 543         name##_cache0 |= NEG_USR32(next,name##_bit_count);\
 544         name##_cache1 |= next<<name##_bit_count;\
 545         name##_buffer_ptr++;\
 546         name##_bit_count-= 32;\
 547     }\
 548
 549 #if ARCH_X86
 550 #   define SKIP_CACHE(name, gb, num)\
 551         __asm__(\
 552             "shldl %2, %1, %0          \n\t"\
 553             "shll %2, %1               \n\t"\
 554             : "+r" (name##_cache0), "+r" (name##_cache1)\
 555             : "Ic" ((uint8_t)(num))\
 556            );
 557 #else
 558 #   define SKIP_CACHE(name, gb, num)\
 559         name##_cache0 <<= (num);\
 560         name##_cache0 |= NEG_USR32(name##_cache1,num);\
 561         name##_cache1 <<= (num);
 562 #endif
 563
 564 #   define SKIP_COUNTER(name, gb, num)\
 565         name##_bit_count += (num);\
 566
 567 #   define SKIP_BITS(name, gb, num)\
 568         {\
 569             SKIP_CACHE(name, gb, num)\
 570             SKIP_COUNTER(name, gb, num)\
 571         }\
 572
 573 #   define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
 574 #   define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
 575
 576 #   define SHOW_UBITS(name, gb, num)\
 577         NEG_USR32(name##_cache0, num)
 578
 579 #   define SHOW_SBITS(name, gb, num)\
 580         NEG_SSR32(name##_cache0, num)
 581
 582 #   define GET_CACHE(name, gb)\
 583         (name##_cache0)
 584
 585 static inline int get_bits_count(GetBitContext *s){
 586     return ((uint8_t*)s->buffer_ptr - s->buffer)*8 - 32 + s->bit_count;
 587 }
 588
 589 static inline void skip_bits_long(GetBitContext *s, int n){
 590     OPEN_READER(re, s)
 591     re_bit_count += n;
 592     re_buffer_ptr += re_bit_count>>5;
 593     re_bit_count &= 31;
 594     re_cache0 = be2me_32( re_buffer_ptr[-1] ) << re_bit_count;
 595     re_cache1 = 0;
 596     UPDATE_CACHE(re, s)
 597     CLOSE_READER(re, s)
 598 }
 599
 600 #endif
 601
 602 /**
 603  * read mpeg1 dc style vlc (sign bit + mantisse with no MSB).
 604  * if MSB not set it is negative
 605  * @param n length in bits
 606  * @author BERO
 607  */
 608 static inline int get_xbits(GetBitContext *s, int n){
 609     register int sign;
 610     register int32_t cache;
 611     OPEN_READER(re, s)
 612     UPDATE_CACHE(re, s)
 613     cache = GET_CACHE(re,s);
 614     sign=(~cache)>>31;
 615     LAST_SKIP_BITS(re, s, n)
 616     CLOSE_READER(re, s)
 617     return (NEG_USR32(sign ^ cache, n) ^ sign) - sign;
 618 }
 619
 620 static inline int get_sbits(GetBitContext *s, int n){
 621     register int tmp;
 622     OPEN_READER(re, s)
 623     UPDATE_CACHE(re, s)
 624     tmp= SHOW_SBITS(re, s, n);
 625     LAST_SKIP_BITS(re, s, n)
 626     CLOSE_READER(re, s)
 627     return tmp;
 628 }
 629
 630 /**
 631  * reads 1-17 bits.
 632  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
 633  */
 634 static inline unsigned int get_bits(GetBitContext *s, int n){
 635     register int tmp;
 636     OPEN_READER(re, s)
 637     UPDATE_CACHE(re, s)
 638     tmp= SHOW_UBITS(re, s, n);
 639     LAST_SKIP_BITS(re, s, n)
 640     CLOSE_READER(re, s)
 641     return tmp;
 642 }
 643
 644 /**
 645  * shows 1-17 bits.
 646  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
 647  */
 648 static inline unsigned int show_bits(GetBitContext *s, int n){
 649     register int tmp;
 650     OPEN_READER(re, s)
 651     UPDATE_CACHE(re, s)
 652     tmp= SHOW_UBITS(re, s, n);
 653 //    CLOSE_READER(re, s)
 654     return tmp;
 655 }
 656
 657 static inline void skip_bits(GetBitContext *s, int n){
 658  //Note gcc seems to optimize this to s->index+=n for the ALT_READER :))
 659     OPEN_READER(re, s)
 660     UPDATE_CACHE(re, s)
 661     LAST_SKIP_BITS(re, s, n)
 662     CLOSE_READER(re, s)
 663 }
 664
 665 static inline unsigned int get_bits1(GetBitContext *s){
 666 #ifdef ALT_BITSTREAM_READER
 667     int index= s->index;
 668     uint8_t result= s->buffer[ index>>3 ];
 669 #ifdef ALT_BITSTREAM_READER_LE
 670     result>>= (index&0x07);
 671     result&= 1;
 672 #else
 673     result<<= (index&0x07);
 674     result>>= 8 - 1;
 675 #endif
 676     index++;
 677     s->index= index;
 678
 679     return result;
 680 #else
 681     return get_bits(s, 1);
 682 #endif
 683 }
 684
 685 static inline unsigned int show_bits1(GetBitContext *s){
 686     return show_bits(s, 1);
 687 }
 688
 689 static inline void skip_bits1(GetBitContext *s){
 690     skip_bits(s, 1);
 691 }
 692
 693 /**
 694  * reads 0-32 bits.
 695  */
 696 static inline unsigned int get_bits_long(GetBitContext *s, int n){
 697     if(n<=17) return get_bits(s, n);
 698     else{
 699 #ifdef ALT_BITSTREAM_READER_LE
 700         int ret= get_bits(s, 16);
 701         return ret | (get_bits(s, n-16) << 16);
 702 #else
 703         int ret= get_bits(s, 16) << (n-16);
 704         return ret | get_bits(s, n-16);
 705 #endif
 706     }
 707 }
 708
 709 /**
 710  * shows 0-32 bits.
 711  */
 712 static inline unsigned int show_bits_long(GetBitContext *s, int n){
 713     if(n<=17) return show_bits(s, n);
 714     else{
 715         GetBitContext gb= *s;
 716         int ret= get_bits_long(s, n);
 717         *s= gb;
 718         return ret;
 719     }
 720 }
 721
 722 static inline int check_marker(GetBitContext *s, const char *msg)
 723 {
 724     int bit= get_bits1(s);
 725     if(!bit)
 726         av_log(NULL, AV_LOG_INFO, "Marker bit missing %s\n", msg);
 727
 728     return bit;
 729 }
 730
 731 /**
 732  * init GetBitContext.
 733  * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger then the actual read bits
 734  * because some optimized bitstream readers read 32 or 64 bit at once and could read over the end
 735  * @param bit_size the size of the buffer in bits
 736  */
 737 static inline void init_get_bits(GetBitContext *s,
 738                    const uint8_t *buffer, int bit_size)
 739 {
 740     int buffer_size= (bit_size+7)>>3;
 741     if(buffer_size < 0 || bit_size < 0) {
 742         buffer_size = bit_size = 0;
 743         buffer = NULL;
 744     }
 745
 746     s->buffer= buffer;
 747     s->size_in_bits= bit_size;
 748     s->buffer_end= buffer + buffer_size;
 749 #ifdef ALT_BITSTREAM_READER
 750     s->index=0;
 751 #elif defined LIBMPEG2_BITSTREAM_READER
 752     s->buffer_ptr = (uint8_t*)((intptr_t)buffer&(~1));
 753     s->bit_count = 16 + 8*((intptr_t)buffer&1);
 754     skip_bits_long(s, 0);
 755 #elif defined A32_BITSTREAM_READER
 756     s->buffer_ptr = (uint32_t*)((intptr_t)buffer&(~3));
 757     s->bit_count = 32 + 8*((intptr_t)buffer&3);
 758     skip_bits_long(s, 0);
 759 #endif
 760 }
 761
 762 static inline void align_get_bits(GetBitContext *s)
 763 {
 764     int n= (-get_bits_count(s)) & 7;
 765     if(n) skip_bits(s, n);
 766 }
 767
 768 #define init_vlc(vlc, nb_bits, nb_codes,\
 769                  bits, bits_wrap, bits_size,\
 770                  codes, codes_wrap, codes_size,\
 771                  flags)\
 772         init_vlc_sparse(vlc, nb_bits, nb_codes,\
 773                  bits, bits_wrap, bits_size,\
 774                  codes, codes_wrap, codes_size,\
 775                  NULL, 0, 0, flags)
 776
 777 int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,
 778              const void *bits, int bits_wrap, int bits_size,
 779              const void *codes, int codes_wrap, int codes_size,
 780              const void *symbols, int symbols_wrap, int symbols_size,
 781              int flags);
 782 #define INIT_VLC_USE_STATIC 1 ///< VERY strongly deprecated and forbidden
 783 #define INIT_VLC_LE         2
 784 #define INIT_VLC_USE_NEW_STATIC 4
 785 void free_vlc(VLC *vlc);
 786
 787 #define INIT_VLC_STATIC(vlc, bits, a,b,c,d,e,f,g, static_size)\
 788 {\
 789     static VLC_TYPE table[static_size][2];\
 790     (vlc)->table= table;\
 791     (vlc)->table_allocated= static_size;\
 792     init_vlc(vlc, bits, a,b,c,d,e,f,g, INIT_VLC_USE_NEW_STATIC);\
 793 }
 794
 795
 796 /**
 797  *
 798  * if the vlc code is invalid and max_depth=1 than no bits will be removed
 799  * if the vlc code is invalid and max_depth>1 than the number of bits removed
 800  * is undefined
 801  */
 802 #define GET_VLC(code, name, gb, table, bits, max_depth)\
 803 {\
 804     int n, index, nb_bits;\
 805 \
 806     index= SHOW_UBITS(name, gb, bits);\
 807     code = table[index][0];\
 808     n    = table[index][1];\
 809 \
 810     if(max_depth > 1 && n < 0){\
 811         LAST_SKIP_BITS(name, gb, bits)\
 812         UPDATE_CACHE(name, gb)\
 813 \
 814         nb_bits = -n;\
 815 \
 816         index= SHOW_UBITS(name, gb, nb_bits) + code;\
 817         code = table[index][0];\
 818         n    = table[index][1];\
 819         if(max_depth > 2 && n < 0){\
 820             LAST_SKIP_BITS(name, gb, nb_bits)\
 821             UPDATE_CACHE(name, gb)\
 822 \
 823             nb_bits = -n;\
 824 \
 825             index= SHOW_UBITS(name, gb, nb_bits) + code;\
 826             code = table[index][0];\
 827             n    = table[index][1];\
 828         }\
 829     }\
 830     SKIP_BITS(name, gb, n)\
 831 }
 832
 833 #define GET_RL_VLC(level, run, name, gb, table, bits, max_depth, need_update)\
 834 {\
 835     int n, index, nb_bits;\
 836 \
 837     index= SHOW_UBITS(name, gb, bits);\
 838     level = table[index].level;\
 839     n     = table[index].len;\
 840 \
 841     if(max_depth > 1 && n < 0){\
 842         SKIP_BITS(name, gb, bits)\
 843         if(need_update){\
 844             UPDATE_CACHE(name, gb)\
 845         }\
 846 \
 847         nb_bits = -n;\
 848 \
 849         index= SHOW_UBITS(name, gb, nb_bits) + level;\
 850         level = table[index].level;\
 851         n     = table[index].len;\
 852     }\
 853     run= table[index].run;\
 854     SKIP_BITS(name, gb, n)\
 855 }
 856
 857
 858 /**
 859  * parses a vlc code, faster then get_vlc()
 860  * @param bits is the number of bits which will be read at once, must be
 861  *             identical to nb_bits in init_vlc()
 862  * @param max_depth is the number of times bits bits must be read to completely
 863  *                  read the longest vlc code
 864  *                  = (max_vlc_length + bits - 1) / bits
 865  */
 866 static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2],
 867                                   int bits, int max_depth)
 868 {
 869     int code;
 870
 871     OPEN_READER(re, s)
 872     UPDATE_CACHE(re, s)
 873
 874     GET_VLC(code, re, s, table, bits, max_depth)
 875
 876     CLOSE_READER(re, s)
 877     return code;
 878 }
 879
 880 //#define TRACE
 881
 882 #ifdef TRACE
 883 static inline void print_bin(int bits, int n){
 884     int i;
 885
 886     for(i=n-1; i>=0; i--){
 887         av_log(NULL, AV_LOG_DEBUG, "%d", (bits>>i)&1);
 888     }
 889     for(i=n; i<24; i++)
 890         av_log(NULL, AV_LOG_DEBUG, " ");
 891 }
 892
 893 static inline int get_bits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
 894     int r= get_bits(s, n);
 895
 896     print_bin(r, n);
 897     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);
 898     return r;
 899 }
 900 static inline int get_vlc_trace(GetBitContext *s, VLC_TYPE (*table)[2], int bits, int max_depth, char *file, const char *func, int line){
 901     int show= show_bits(s, 24);
 902     int pos= get_bits_count(s);
 903     int r= get_vlc2(s, table, bits, max_depth);
 904     int len= get_bits_count(s) - pos;
 905     int bits2= show>>(24-len);
 906
 907     print_bin(bits2, len);
 908
 909     av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d vlc @%5d in %s %s:%d\n", bits2, len, r, pos, file, func, line);
 910     return r;
 911 }
 912 static inline int get_xbits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
 913     int show= show_bits(s, n);
 914     int r= get_xbits(s, n);
 915
 916     print_bin(show, n);
 917     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);
 918     return r;
 919 }
 920
 921 #define get_bits(s, n)  get_bits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 922 #define get_bits1(s)    get_bits_trace(s, 1, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 923 #define get_xbits(s, n) get_xbits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 924 #define get_vlc(s, vlc)            get_vlc_trace(s, (vlc)->table, (vlc)->bits, 3, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 925 #define get_vlc2(s, tab, bits, max) get_vlc_trace(s, tab, bits, max, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 926
 927 #define tprintf(p, ...) av_log(p, AV_LOG_DEBUG, __VA_ARGS__)
 928
 929 #else //TRACE
 930 #define tprintf(p, ...) {}
 931 #endif
 932
 933 static inline int decode012(GetBitContext *gb){
 934     int n;
 935     n = get_bits1(gb);
 936     if (n == 0)
 937         return 0;
 938     else
 939         return get_bits1(gb) + 1;
 940 }
 941
 942 static inline int decode210(GetBitContext *gb){
 943     if (get_bits1(gb))
 944         return 0;
 945     else
 946         return 2 - get_bits1(gb);
 947 }
 948
 949 #endif /* AVCODEC_BITSTREAM_H */