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 #include "mathops.h"
  37
  38 #if defined(ALT_BITSTREAM_READER_LE) && !defined(ALT_BITSTREAM_READER)
  39 #   define ALT_BITSTREAM_READER
  40 #endif
  41
  42 //#define ALT_BITSTREAM_WRITER
  43 //#define ALIGNED_BITSTREAM_WRITER
  44 #if !defined(LIBMPEG2_BITSTREAM_READER) && !defined(A32_BITSTREAM_READER) && !defined(ALT_BITSTREAM_READER)
  45 #   if ARCH_ARM
  46 #       define A32_BITSTREAM_READER
  47 #   else
  48 #       define ALT_BITSTREAM_READER
  49 //#define LIBMPEG2_BITSTREAM_READER
  50 //#define A32_BITSTREAM_READER
  51 #   endif
  52 #endif
  53
  54 extern const uint8_t ff_reverse[256];
  55
  56 #if ARCH_X86
  57 // avoid +32 for shift optimization (gcc should do that ...)
  58 static inline  int32_t NEG_SSR32( int32_t a, int8_t s){
  59     __asm__ ("sarl %1, %0\n\t"
  60          : "+r" (a)
  61          : "ic" ((uint8_t)(-s))
  62     );
  63     return a;
  64 }
  65 static inline uint32_t NEG_USR32(uint32_t a, int8_t s){
  66     __asm__ ("shrl %1, %0\n\t"
  67          : "+r" (a)
  68          : "ic" ((uint8_t)(-s))
  69     );
  70     return a;
  71 }
  72 #else
  73 #    define NEG_SSR32(a,s) ((( int32_t)(a))>>(32-(s)))
  74 #    define NEG_USR32(a,s) (((uint32_t)(a))>>(32-(s)))
  75 #endif
  76
  77 /* bit output */
  78
  79 /* buf and buf_end must be present and used by every alternative writer. */
  80 typedef struct PutBitContext {
  81 #ifdef ALT_BITSTREAM_WRITER
  82     uint8_t *buf, *buf_end;
  83     int index;
  84 #else
  85     uint32_t bit_buf;
  86     int bit_left;
  87     uint8_t *buf, *buf_ptr, *buf_end;
  88 #endif
  89     int size_in_bits;
  90 } PutBitContext;
  91
  92 static inline void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
  93 {
  94     if(buffer_size < 0) {
  95         buffer_size = 0;
  96         buffer = NULL;
  97     }
  98
  99     s->size_in_bits= 8*buffer_size;
 100     s->buf = buffer;
 101     s->buf_end = s->buf + buffer_size;
 102 #ifdef ALT_BITSTREAM_WRITER
 103     s->index=0;
 104     ((uint32_t*)(s->buf))[0]=0;
 105 //    memset(buffer, 0, buffer_size);
 106 #else
 107     s->buf_ptr = s->buf;
 108     s->bit_left=32;
 109     s->bit_buf=0;
 110 #endif
 111 }
 112
 113 /* return the number of bits output */
 114 static inline int put_bits_count(PutBitContext *s)
 115 {
 116 #ifdef ALT_BITSTREAM_WRITER
 117     return s->index;
 118 #else
 119     return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
 120 #endif
 121 }
 122
 123 /* pad the end of the output stream with zeros */
 124 static inline void flush_put_bits(PutBitContext *s)
 125 {
 126 #ifdef ALT_BITSTREAM_WRITER
 127     align_put_bits(s);
 128 #else
 129 #ifndef BITSTREAM_WRITER_LE
 130     s->bit_buf<<= s->bit_left;
 131 #endif
 132     while (s->bit_left < 32) {
 133         /* XXX: should test end of buffer */
 134 #ifdef BITSTREAM_WRITER_LE
 135         *s->buf_ptr++=s->bit_buf;
 136         s->bit_buf>>=8;
 137 #else
 138         *s->buf_ptr++=s->bit_buf >> 24;
 139         s->bit_buf<<=8;
 140 #endif
 141         s->bit_left+=8;
 142     }
 143     s->bit_left=32;
 144     s->bit_buf=0;
 145 #endif
 146 }
 147
 148 void align_put_bits(PutBitContext *s);
 149 void ff_put_string(PutBitContext * pbc, const char *s, int put_zero);
 150 void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
 151
 152 /* bit input */
 153 /* buffer, buffer_end and size_in_bits must be present and used by every reader */
 154 typedef struct GetBitContext {
 155     const uint8_t *buffer, *buffer_end;
 156 #ifdef ALT_BITSTREAM_READER
 157     int index;
 158 #elif defined LIBMPEG2_BITSTREAM_READER
 159     uint8_t *buffer_ptr;
 160     uint32_t cache;
 161     int bit_count;
 162 #elif defined A32_BITSTREAM_READER
 163     uint32_t *buffer_ptr;
 164     uint32_t cache0;
 165     uint32_t cache1;
 166     int bit_count;
 167 #endif
 168     int size_in_bits;
 169 } GetBitContext;
 170
 171 #define VLC_TYPE int16_t
 172
 173 typedef struct VLC {
 174     int bits;
 175     VLC_TYPE (*table)[2]; ///< code, bits
 176     int table_size, table_allocated;
 177 } VLC;
 178
 179 typedef struct RL_VLC_ELEM {
 180     int16_t level;
 181     int8_t len;
 182     uint8_t run;
 183 } RL_VLC_ELEM;
 184
 185 #ifndef ALT_BITSTREAM_WRITER
 186 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
 187 {
 188     unsigned int bit_buf;
 189     int bit_left;
 190
 191     //    printf("put_bits=%d %x\n", n, value);
 192     assert(n == 32 || value < (1U << n));
 193
 194     bit_buf = s->bit_buf;
 195     bit_left = s->bit_left;
 196
 197     //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
 198     /* XXX: optimize */
 199 #ifdef BITSTREAM_WRITER_LE
 200     bit_buf |= value << (32 - bit_left);
 201     if (n >= bit_left) {
 202 #if !HAVE_FAST_UNALIGNED
 203         if (3 & (intptr_t) s->buf_ptr) {
 204             AV_WL32(s->buf_ptr, bit_buf);
 205         } else
 206 #endif
 207         *(uint32_t *)s->buf_ptr = le2me_32(bit_buf);
 208         s->buf_ptr+=4;
 209         bit_buf = (bit_left==32)?0:value >> bit_left;
 210         bit_left+=32;
 211     }
 212     bit_left-=n;
 213 #else
 214     if (n < bit_left) {
 215         bit_buf = (bit_buf<<n) | value;
 216         bit_left-=n;
 217     } else {
 218         bit_buf<<=bit_left;
 219         bit_buf |= value >> (n - bit_left);
 220 #if !HAVE_FAST_UNALIGNED
 221         if (3 & (intptr_t) s->buf_ptr) {
 222             AV_WB32(s->buf_ptr, bit_buf);
 223         } else
 224 #endif
 225         *(uint32_t *)s->buf_ptr = be2me_32(bit_buf);
 226         //printf("bitbuf = %08x\n", bit_buf);
 227         s->buf_ptr+=4;
 228         bit_left+=32 - n;
 229         bit_buf = value;
 230     }
 231 #endif
 232
 233     s->bit_buf = bit_buf;
 234     s->bit_left = bit_left;
 235 }
 236 #endif
 237
 238
 239 #ifdef ALT_BITSTREAM_WRITER
 240 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
 241 {
 242 #    ifdef ALIGNED_BITSTREAM_WRITER
 243 #        if ARCH_X86
 244     __asm__ volatile(
 245         "movl %0, %%ecx                 \n\t"
 246         "xorl %%eax, %%eax              \n\t"
 247         "shrdl %%cl, %1, %%eax          \n\t"
 248         "shrl %%cl, %1                  \n\t"
 249         "movl %0, %%ecx                 \n\t"
 250         "shrl $3, %%ecx                 \n\t"
 251         "andl $0xFFFFFFFC, %%ecx        \n\t"
 252         "bswapl %1                      \n\t"
 253         "orl %1, (%2, %%ecx)            \n\t"
 254         "bswapl %%eax                   \n\t"
 255         "addl %3, %0                    \n\t"
 256         "movl %%eax, 4(%2, %%ecx)       \n\t"
 257         : "=&r" (s->index), "=&r" (value)
 258         : "r" (s->buf), "r" (n), "0" (s->index), "1" (value<<(-n))
 259         : "%eax", "%ecx"
 260     );
 261 #        else
 262     int index= s->index;
 263     uint32_t *ptr= ((uint32_t *)s->buf)+(index>>5);
 264
 265     value<<= 32-n;
 266
 267     ptr[0] |= be2me_32(value>>(index&31));
 268     ptr[1]  = be2me_32(value<<(32-(index&31)));
 269 //if(n>24) printf("%d %d\n", n, value);
 270     index+= n;
 271     s->index= index;
 272 #        endif
 273 #    else //ALIGNED_BITSTREAM_WRITER
 274 #        if ARCH_X86
 275     __asm__ volatile(
 276         "movl $7, %%ecx                 \n\t"
 277         "andl %0, %%ecx                 \n\t"
 278         "addl %3, %%ecx                 \n\t"
 279         "negl %%ecx                     \n\t"
 280         "shll %%cl, %1                  \n\t"
 281         "bswapl %1                      \n\t"
 282         "movl %0, %%ecx                 \n\t"
 283         "shrl $3, %%ecx                 \n\t"
 284         "orl %1, (%%ecx, %2)            \n\t"
 285         "addl %3, %0                    \n\t"
 286         "movl $0, 4(%%ecx, %2)          \n\t"
 287         : "=&r" (s->index), "=&r" (value)
 288         : "r" (s->buf), "r" (n), "0" (s->index), "1" (value)
 289         : "%ecx"
 290     );
 291 #        else
 292     int index= s->index;
 293     uint32_t *ptr= (uint32_t*)(((uint8_t *)s->buf)+(index>>3));
 294
 295     ptr[0] |= be2me_32(value<<(32-n-(index&7) ));
 296     ptr[1] = 0;
 297 //if(n>24) printf("%d %d\n", n, value);
 298     index+= n;
 299     s->index= index;
 300 #        endif
 301 #    endif //!ALIGNED_BITSTREAM_WRITER
 302 }
 303 #endif
 304
 305 static inline void put_sbits(PutBitContext *pb, int bits, int32_t val)
 306 {
 307     assert(bits >= 0 && bits <= 31);
 308
 309     put_bits(pb, bits, val & ((1<<bits)-1));
 310 }
 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 do not 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     arbitrary 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 #ifdef ALT_BITSTREAM_READER
 404 #   define MIN_CACHE_BITS 25
 405
 406 #   define OPEN_READER(name, gb)\
 407         int name##_index= (gb)->index;\
 408         int name##_cache= 0;\
 409
 410 #   define CLOSE_READER(name, gb)\
 411         (gb)->index= name##_index;\
 412
 413 # ifdef ALT_BITSTREAM_READER_LE
 414 #   define UPDATE_CACHE(name, gb)\
 415         name##_cache= AV_RL32( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) >> (name##_index&0x07);\
 416
 417 #   define SKIP_CACHE(name, gb, num)\
 418         name##_cache >>= (num);
 419 # else
 420 #   define UPDATE_CACHE(name, gb)\
 421         name##_cache= AV_RB32( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) << (name##_index&0x07);\
 422
 423 #   define SKIP_CACHE(name, gb, num)\
 424         name##_cache <<= (num);
 425 # endif
 426
 427 // FIXME name?
 428 #   define SKIP_COUNTER(name, gb, num)\
 429         name##_index += (num);\
 430
 431 #   define SKIP_BITS(name, gb, num)\
 432         {\
 433             SKIP_CACHE(name, gb, num)\
 434             SKIP_COUNTER(name, gb, num)\
 435         }\
 436
 437 #   define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
 438 #   define LAST_SKIP_CACHE(name, gb, num) ;
 439
 440 # ifdef ALT_BITSTREAM_READER_LE
 441 #   define SHOW_UBITS(name, gb, num)\
 442         ((name##_cache) & (NEG_USR32(0xffffffff,num)))
 443
 444 #   define SHOW_SBITS(name, gb, num)\
 445         NEG_SSR32((name##_cache)<<(32-(num)), num)
 446 # else
 447 #   define SHOW_UBITS(name, gb, num)\
 448         NEG_USR32(name##_cache, num)
 449
 450 #   define SHOW_SBITS(name, gb, num)\
 451         NEG_SSR32(name##_cache, num)
 452 # endif
 453
 454 #   define GET_CACHE(name, gb)\
 455         ((uint32_t)name##_cache)
 456
 457 static inline int get_bits_count(GetBitContext *s){
 458     return s->index;
 459 }
 460
 461 static inline void skip_bits_long(GetBitContext *s, int n){
 462     s->index += n;
 463 }
 464
 465 #elif defined LIBMPEG2_BITSTREAM_READER
 466 //libmpeg2 like reader
 467
 468 #   define MIN_CACHE_BITS 17
 469
 470 #   define OPEN_READER(name, gb)\
 471         int name##_bit_count=(gb)->bit_count;\
 472         int name##_cache= (gb)->cache;\
 473         uint8_t * name##_buffer_ptr=(gb)->buffer_ptr;\
 474
 475 #   define CLOSE_READER(name, gb)\
 476         (gb)->bit_count= name##_bit_count;\
 477         (gb)->cache= name##_cache;\
 478         (gb)->buffer_ptr= name##_buffer_ptr;\
 479
 480 #   define UPDATE_CACHE(name, gb)\
 481     if(name##_bit_count >= 0){\
 482         name##_cache+= AV_RB16(name##_buffer_ptr) << name##_bit_count; \
 483         name##_buffer_ptr+=2;\
 484         name##_bit_count-= 16;\
 485     }\
 486
 487 #   define SKIP_CACHE(name, gb, num)\
 488         name##_cache <<= (num);\
 489
 490 #   define SKIP_COUNTER(name, gb, num)\
 491         name##_bit_count += (num);\
 492
 493 #   define SKIP_BITS(name, gb, num)\
 494         {\
 495             SKIP_CACHE(name, gb, num)\
 496             SKIP_COUNTER(name, gb, num)\
 497         }\
 498
 499 #   define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
 500 #   define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
 501
 502 #   define SHOW_UBITS(name, gb, num)\
 503         NEG_USR32(name##_cache, num)
 504
 505 #   define SHOW_SBITS(name, gb, num)\
 506         NEG_SSR32(name##_cache, num)
 507
 508 #   define GET_CACHE(name, gb)\
 509         ((uint32_t)name##_cache)
 510
 511 static inline int get_bits_count(GetBitContext *s){
 512     return (s->buffer_ptr - s->buffer)*8 - 16 + s->bit_count;
 513 }
 514
 515 static inline void skip_bits_long(GetBitContext *s, int n){
 516     OPEN_READER(re, s)
 517     re_bit_count += n;
 518     re_buffer_ptr += 2*(re_bit_count>>4);
 519     re_bit_count &= 15;
 520     re_cache = ((re_buffer_ptr[-2]<<8) + re_buffer_ptr[-1]) << (16+re_bit_count);
 521     UPDATE_CACHE(re, s)
 522     CLOSE_READER(re, s)
 523 }
 524
 525 #elif defined A32_BITSTREAM_READER
 526
 527 #   define MIN_CACHE_BITS 32
 528
 529 #   define OPEN_READER(name, gb)\
 530         int name##_bit_count=(gb)->bit_count;\
 531         uint32_t name##_cache0= (gb)->cache0;\
 532         uint32_t name##_cache1= (gb)->cache1;\
 533         uint32_t * name##_buffer_ptr=(gb)->buffer_ptr;\
 534
 535 #   define CLOSE_READER(name, gb)\
 536         (gb)->bit_count= name##_bit_count;\
 537         (gb)->cache0= name##_cache0;\
 538         (gb)->cache1= name##_cache1;\
 539         (gb)->buffer_ptr= name##_buffer_ptr;\
 540
 541 #   define UPDATE_CACHE(name, gb)\
 542     if(name##_bit_count > 0){\
 543         const uint32_t next= be2me_32( *name##_buffer_ptr );\
 544         name##_cache0 |= NEG_USR32(next,name##_bit_count);\
 545         name##_cache1 |= next<<name##_bit_count;\
 546         name##_buffer_ptr++;\
 547         name##_bit_count-= 32;\
 548     }\
 549
 550 #if ARCH_X86
 551 #   define SKIP_CACHE(name, gb, num)\
 552         __asm__(\
 553             "shldl %2, %1, %0          \n\t"\
 554             "shll %2, %1               \n\t"\
 555             : "+r" (name##_cache0), "+r" (name##_cache1)\
 556             : "Ic" ((uint8_t)(num))\
 557            );
 558 #else
 559 #   define SKIP_CACHE(name, gb, num)\
 560         name##_cache0 <<= (num);\
 561         name##_cache0 |= NEG_USR32(name##_cache1,num);\
 562         name##_cache1 <<= (num);
 563 #endif
 564
 565 #   define SKIP_COUNTER(name, gb, num)\
 566         name##_bit_count += (num);\
 567
 568 #   define SKIP_BITS(name, gb, num)\
 569         {\
 570             SKIP_CACHE(name, gb, num)\
 571             SKIP_COUNTER(name, gb, num)\
 572         }\
 573
 574 #   define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
 575 #   define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
 576
 577 #   define SHOW_UBITS(name, gb, num)\
 578         NEG_USR32(name##_cache0, num)
 579
 580 #   define SHOW_SBITS(name, gb, num)\
 581         NEG_SSR32(name##_cache0, num)
 582
 583 #   define GET_CACHE(name, gb)\
 584         (name##_cache0)
 585
 586 static inline int get_bits_count(GetBitContext *s){
 587     return ((uint8_t*)s->buffer_ptr - s->buffer)*8 - 32 + s->bit_count;
 588 }
 589
 590 static inline void skip_bits_long(GetBitContext *s, int n){
 591     OPEN_READER(re, s)
 592     re_bit_count += n;
 593     re_buffer_ptr += re_bit_count>>5;
 594     re_bit_count &= 31;
 595     re_cache0 = be2me_32( re_buffer_ptr[-1] ) << re_bit_count;
 596     re_cache1 = 0;
 597     UPDATE_CACHE(re, s)
 598     CLOSE_READER(re, s)
 599 }
 600
 601 #endif
 602
 603 /**
 604  * read mpeg1 dc style vlc (sign bit + mantisse with no MSB).
 605  * if MSB not set it is negative
 606  * @param n length in bits
 607  * @author BERO
 608  */
 609 static inline int get_xbits(GetBitContext *s, int n){
 610     register int sign;
 611     register int32_t cache;
 612     OPEN_READER(re, s)
 613     UPDATE_CACHE(re, s)
 614     cache = GET_CACHE(re,s);
 615     sign=(~cache)>>31;
 616     LAST_SKIP_BITS(re, s, n)
 617     CLOSE_READER(re, s)
 618     return (NEG_USR32(sign ^ cache, n) ^ sign) - sign;
 619 }
 620
 621 static inline int get_sbits(GetBitContext *s, int n){
 622     register int tmp;
 623     OPEN_READER(re, s)
 624     UPDATE_CACHE(re, s)
 625     tmp= SHOW_SBITS(re, s, n);
 626     LAST_SKIP_BITS(re, s, n)
 627     CLOSE_READER(re, s)
 628     return tmp;
 629 }
 630
 631 /**
 632  * reads 1-17 bits.
 633  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
 634  */
 635 static inline unsigned int get_bits(GetBitContext *s, int n){
 636     register int tmp;
 637     OPEN_READER(re, s)
 638     UPDATE_CACHE(re, s)
 639     tmp= SHOW_UBITS(re, s, n);
 640     LAST_SKIP_BITS(re, s, n)
 641     CLOSE_READER(re, s)
 642     return tmp;
 643 }
 644
 645 /**
 646  * shows 1-17 bits.
 647  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
 648  */
 649 static inline unsigned int show_bits(GetBitContext *s, int n){
 650     register int tmp;
 651     OPEN_READER(re, s)
 652     UPDATE_CACHE(re, s)
 653     tmp= SHOW_UBITS(re, s, n);
 654 //    CLOSE_READER(re, s)
 655     return tmp;
 656 }
 657
 658 static inline void skip_bits(GetBitContext *s, int n){
 659  //Note gcc seems to optimize this to s->index+=n for the ALT_READER :))
 660     OPEN_READER(re, s)
 661     UPDATE_CACHE(re, s)
 662     LAST_SKIP_BITS(re, s, n)
 663     CLOSE_READER(re, s)
 664 }
 665
 666 static inline unsigned int get_bits1(GetBitContext *s){
 667 #ifdef ALT_BITSTREAM_READER
 668     int index= s->index;
 669     uint8_t result= s->buffer[ index>>3 ];
 670 #ifdef ALT_BITSTREAM_READER_LE
 671     result>>= (index&0x07);
 672     result&= 1;
 673 #else
 674     result<<= (index&0x07);
 675     result>>= 8 - 1;
 676 #endif
 677     index++;
 678     s->index= index;
 679
 680     return result;
 681 #else
 682     return get_bits(s, 1);
 683 #endif
 684 }
 685
 686 static inline unsigned int show_bits1(GetBitContext *s){
 687     return show_bits(s, 1);
 688 }
 689
 690 static inline void skip_bits1(GetBitContext *s){
 691     skip_bits(s, 1);
 692 }
 693
 694 /**
 695  * reads 0-32 bits.
 696  */
 697 static inline unsigned int get_bits_long(GetBitContext *s, int n){
 698     if(n<=17) return get_bits(s, n);
 699     else{
 700 #ifdef ALT_BITSTREAM_READER_LE
 701         int ret= get_bits(s, 16);
 702         return ret | (get_bits(s, n-16) << 16);
 703 #else
 704         int ret= get_bits(s, 16) << (n-16);
 705         return ret | get_bits(s, n-16);
 706 #endif
 707     }
 708 }
 709
 710 /**
 711  * reads 0-32 bits as a signed integer.
 712  */
 713 static inline int get_sbits_long(GetBitContext *s, int n) {
 714     return sign_extend(get_bits_long(s, n), n);
 715 }
 716
 717 /**
 718  * shows 0-32 bits.
 719  */
 720 static inline unsigned int show_bits_long(GetBitContext *s, int n){
 721     if(n<=17) return show_bits(s, n);
 722     else{
 723         GetBitContext gb= *s;
 724         return get_bits_long(&gb, n);
 725     }
 726 }
 727
 728 static inline int check_marker(GetBitContext *s, const char *msg)
 729 {
 730     int bit= get_bits1(s);
 731     if(!bit)
 732         av_log(NULL, AV_LOG_INFO, "Marker bit missing %s\n", msg);
 733
 734     return bit;
 735 }
 736
 737 /**
 738  * init GetBitContext.
 739  * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger then the actual read bits
 740  * because some optimized bitstream readers read 32 or 64 bit at once and could read over the end
 741  * @param bit_size the size of the buffer in bits
 742  */
 743 static inline void init_get_bits(GetBitContext *s,
 744                    const uint8_t *buffer, int bit_size)
 745 {
 746     int buffer_size= (bit_size+7)>>3;
 747     if(buffer_size < 0 || bit_size < 0) {
 748         buffer_size = bit_size = 0;
 749         buffer = NULL;
 750     }
 751
 752     s->buffer= buffer;
 753     s->size_in_bits= bit_size;
 754     s->buffer_end= buffer + buffer_size;
 755 #ifdef ALT_BITSTREAM_READER
 756     s->index=0;
 757 #elif defined LIBMPEG2_BITSTREAM_READER
 758     s->buffer_ptr = (uint8_t*)((intptr_t)buffer&(~1));
 759     s->bit_count = 16 + 8*((intptr_t)buffer&1);
 760     skip_bits_long(s, 0);
 761 #elif defined A32_BITSTREAM_READER
 762     s->buffer_ptr = (uint32_t*)((intptr_t)buffer&(~3));
 763     s->bit_count = 32 + 8*((intptr_t)buffer&3);
 764     skip_bits_long(s, 0);
 765 #endif
 766 }
 767
 768 static inline void align_get_bits(GetBitContext *s)
 769 {
 770     int n= (-get_bits_count(s)) & 7;
 771     if(n) skip_bits(s, n);
 772 }
 773
 774 #define init_vlc(vlc, nb_bits, nb_codes,\
 775                  bits, bits_wrap, bits_size,\
 776                  codes, codes_wrap, codes_size,\
 777                  flags)\
 778         init_vlc_sparse(vlc, nb_bits, nb_codes,\
 779                  bits, bits_wrap, bits_size,\
 780                  codes, codes_wrap, codes_size,\
 781                  NULL, 0, 0, flags)
 782
 783 int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,
 784              const void *bits, int bits_wrap, int bits_size,
 785              const void *codes, int codes_wrap, int codes_size,
 786              const void *symbols, int symbols_wrap, int symbols_size,
 787              int flags);
 788 #define INIT_VLC_USE_STATIC 1 ///< VERY strongly deprecated and forbidden
 789 #define INIT_VLC_LE         2
 790 #define INIT_VLC_USE_NEW_STATIC 4
 791 void free_vlc(VLC *vlc);
 792
 793 #define INIT_VLC_STATIC(vlc, bits, a,b,c,d,e,f,g, static_size)\
 794 {\
 795     static VLC_TYPE table[static_size][2];\
 796     (vlc)->table= table;\
 797     (vlc)->table_allocated= static_size;\
 798     init_vlc(vlc, bits, a,b,c,d,e,f,g, INIT_VLC_USE_NEW_STATIC);\
 799 }
 800
 801
 802 /**
 803  *
 804  * if the vlc code is invalid and max_depth=1 than no bits will be removed
 805  * if the vlc code is invalid and max_depth>1 than the number of bits removed
 806  * is undefined
 807  */
 808 #define GET_VLC(code, name, gb, table, bits, max_depth)\
 809 {\
 810     int n, index, nb_bits;\
 811 \
 812     index= SHOW_UBITS(name, gb, bits);\
 813     code = table[index][0];\
 814     n    = table[index][1];\
 815 \
 816     if(max_depth > 1 && n < 0){\
 817         LAST_SKIP_BITS(name, gb, bits)\
 818         UPDATE_CACHE(name, gb)\
 819 \
 820         nb_bits = -n;\
 821 \
 822         index= SHOW_UBITS(name, gb, nb_bits) + code;\
 823         code = table[index][0];\
 824         n    = table[index][1];\
 825         if(max_depth > 2 && n < 0){\
 826             LAST_SKIP_BITS(name, gb, nb_bits)\
 827             UPDATE_CACHE(name, gb)\
 828 \
 829             nb_bits = -n;\
 830 \
 831             index= SHOW_UBITS(name, gb, nb_bits) + code;\
 832             code = table[index][0];\
 833             n    = table[index][1];\
 834         }\
 835     }\
 836     SKIP_BITS(name, gb, n)\
 837 }
 838
 839 #define GET_RL_VLC(level, run, name, gb, table, bits, max_depth, need_update)\
 840 {\
 841     int n, index, nb_bits;\
 842 \
 843     index= SHOW_UBITS(name, gb, bits);\
 844     level = table[index].level;\
 845     n     = table[index].len;\
 846 \
 847     if(max_depth > 1 && n < 0){\
 848         SKIP_BITS(name, gb, bits)\
 849         if(need_update){\
 850             UPDATE_CACHE(name, gb)\
 851         }\
 852 \
 853         nb_bits = -n;\
 854 \
 855         index= SHOW_UBITS(name, gb, nb_bits) + level;\
 856         level = table[index].level;\
 857         n     = table[index].len;\
 858     }\
 859     run= table[index].run;\
 860     SKIP_BITS(name, gb, n)\
 861 }
 862
 863
 864 /**
 865  * parses a vlc code, faster then get_vlc()
 866  * @param bits is the number of bits which will be read at once, must be
 867  *             identical to nb_bits in init_vlc()
 868  * @param max_depth is the number of times bits bits must be read to completely
 869  *                  read the longest vlc code
 870  *                  = (max_vlc_length + bits - 1) / bits
 871  */
 872 static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2],
 873                                   int bits, int max_depth)
 874 {
 875     int code;
 876
 877     OPEN_READER(re, s)
 878     UPDATE_CACHE(re, s)
 879
 880     GET_VLC(code, re, s, table, bits, max_depth)
 881
 882     CLOSE_READER(re, s)
 883     return code;
 884 }
 885
 886 //#define TRACE
 887
 888 #ifdef TRACE
 889 static inline void print_bin(int bits, int n){
 890     int i;
 891
 892     for(i=n-1; i>=0; i--){
 893         av_log(NULL, AV_LOG_DEBUG, "%d", (bits>>i)&1);
 894     }
 895     for(i=n; i<24; i++)
 896         av_log(NULL, AV_LOG_DEBUG, " ");
 897 }
 898
 899 static inline int get_bits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
 900     int r= get_bits(s, n);
 901
 902     print_bin(r, n);
 903     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);
 904     return r;
 905 }
 906 static inline int get_vlc_trace(GetBitContext *s, VLC_TYPE (*table)[2], int bits, int max_depth, char *file, const char *func, int line){
 907     int show= show_bits(s, 24);
 908     int pos= get_bits_count(s);
 909     int r= get_vlc2(s, table, bits, max_depth);
 910     int len= get_bits_count(s) - pos;
 911     int bits2= show>>(24-len);
 912
 913     print_bin(bits2, len);
 914
 915     av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d vlc @%5d in %s %s:%d\n", bits2, len, r, pos, file, func, line);
 916     return r;
 917 }
 918 static inline int get_xbits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
 919     int show= show_bits(s, n);
 920     int r= get_xbits(s, n);
 921
 922     print_bin(show, n);
 923     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);
 924     return r;
 925 }
 926
 927 #define get_bits(s, n)  get_bits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 928 #define get_bits1(s)    get_bits_trace(s, 1, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 929 #define get_xbits(s, n) get_xbits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 930 #define get_vlc(s, vlc)            get_vlc_trace(s, (vlc)->table, (vlc)->bits, 3, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 931 #define get_vlc2(s, tab, bits, max) get_vlc_trace(s, tab, bits, max, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 932
 933 #define tprintf(p, ...) av_log(p, AV_LOG_DEBUG, __VA_ARGS__)
 934
 935 #else //TRACE
 936 #define tprintf(p, ...) {}
 937 #endif
 938
 939 static inline int decode012(GetBitContext *gb){
 940     int n;
 941     n = get_bits1(gb);
 942     if (n == 0)
 943         return 0;
 944     else
 945         return get_bits1(gb) + 1;
 946 }
 947
 948 static inline int decode210(GetBitContext *gb){
 949     if (get_bits1(gb))
 950         return 0;
 951     else
 952         return 2 - get_bits1(gb);
 953 }
 954
 955 #endif /* AVCODEC_BITSTREAM_H */