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 FFMPEG_BITSTREAM_H
  27 #define FFMPEG_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 #   ifdef ARCH_ARMV4L
  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 #define LIBMPEG2_BITSTREAM_READER_HACK //add BERO
  53
  54 extern const uint8_t ff_reverse[256];
  55
  56 #if defined(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 } 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->buf = buffer;
  99     s->buf_end = s->buf + buffer_size;
 100 #ifdef ALT_BITSTREAM_WRITER
 101     s->index=0;
 102     ((uint32_t*)(s->buf))[0]=0;
 103 //    memset(buffer, 0, buffer_size);
 104 #else
 105     s->buf_ptr = s->buf;
 106     s->bit_left=32;
 107     s->bit_buf=0;
 108 #endif
 109 }
 110
 111 /* return the number of bits output */
 112 static inline int put_bits_count(PutBitContext *s)
 113 {
 114 #ifdef ALT_BITSTREAM_WRITER
 115     return s->index;
 116 #else
 117     return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
 118 #endif
 119 }
 120
 121 /* pad the end of the output stream with zeros */
 122 static inline void flush_put_bits(PutBitContext *s)
 123 {
 124 #ifdef ALT_BITSTREAM_WRITER
 125     align_put_bits(s);
 126 #else
 127     s->bit_buf<<= s->bit_left;
 128     while (s->bit_left < 32) {
 129         /* XXX: should test end of buffer */
 130         *s->buf_ptr++=s->bit_buf >> 24;
 131         s->bit_buf<<=8;
 132         s->bit_left+=8;
 133     }
 134     s->bit_left=32;
 135     s->bit_buf=0;
 136 #endif
 137 }
 138
 139 void align_put_bits(PutBitContext *s);
 140 void ff_put_string(PutBitContext * pbc, const char *s, int put_zero);
 141 void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
 142
 143 /* bit input */
 144 /* buffer, buffer_end and size_in_bits must be present and used by every reader */
 145 typedef struct GetBitContext {
 146     const uint8_t *buffer, *buffer_end;
 147 #ifdef ALT_BITSTREAM_READER
 148     int index;
 149 #elif defined LIBMPEG2_BITSTREAM_READER
 150     uint8_t *buffer_ptr;
 151     uint32_t cache;
 152     int bit_count;
 153 #elif defined A32_BITSTREAM_READER
 154     uint32_t *buffer_ptr;
 155     uint32_t cache0;
 156     uint32_t cache1;
 157     int bit_count;
 158 #endif
 159     int size_in_bits;
 160 } GetBitContext;
 161
 162 #define VLC_TYPE int16_t
 163
 164 typedef struct VLC {
 165     int bits;
 166     VLC_TYPE (*table)[2]; ///< code, bits
 167     int table_size, table_allocated;
 168 } VLC;
 169
 170 typedef struct RL_VLC_ELEM {
 171     int16_t level;
 172     int8_t len;
 173     uint8_t run;
 174 } RL_VLC_ELEM;
 175
 176 #if defined(ARCH_SPARC) || defined(ARCH_ARMV4L) || defined(ARCH_MIPS) || defined(ARCH_BFIN)
 177 #define UNALIGNED_STORES_ARE_BAD
 178 #endif
 179
 180 /* used to avoid misaligned exceptions on some archs (alpha, ...) */
 181 #if defined(ARCH_X86)
 182 #    define unaligned16(a) (*(const uint16_t*)(a))
 183 #    define unaligned32(a) (*(const uint32_t*)(a))
 184 #    define unaligned64(a) (*(const uint64_t*)(a))
 185 #else
 186 #    ifdef __GNUC__
 187 #    define unaligned(x)                                \
 188 static inline uint##x##_t unaligned##x(const void *v) { \
 189     struct Unaligned {                                  \
 190         uint##x##_t i;                                  \
 191     } __attribute__((packed));                          \
 192                                                         \
 193     return ((const struct Unaligned *) v)->i;           \
 194 }
 195 #    elif defined(__DECC)
 196 #    define unaligned(x)                                        \
 197 static inline uint##x##_t unaligned##x(const void *v) {         \
 198     return *(const __unaligned uint##x##_t *) v;                \
 199 }
 200 #    else
 201 #    define unaligned(x)                                        \
 202 static inline uint##x##_t unaligned##x(const void *v) {         \
 203     return *(const uint##x##_t *) v;                            \
 204 }
 205 #    endif
 206 unaligned(16)
 207 unaligned(32)
 208 unaligned(64)
 209 #undef unaligned
 210 #endif /* defined(ARCH_X86) */
 211
 212 #ifndef ALT_BITSTREAM_WRITER
 213 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
 214 {
 215     unsigned int bit_buf;
 216     int bit_left;
 217
 218     //    printf("put_bits=%d %x\n", n, value);
 219     assert(n == 32 || value < (1U << n));
 220
 221     bit_buf = s->bit_buf;
 222     bit_left = s->bit_left;
 223
 224     //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
 225     /* XXX: optimize */
 226     if (n < bit_left) {
 227         bit_buf = (bit_buf<<n) | value;
 228         bit_left-=n;
 229     } else {
 230         bit_buf<<=bit_left;
 231         bit_buf |= value >> (n - bit_left);
 232 #ifdef UNALIGNED_STORES_ARE_BAD
 233         if (3 & (intptr_t) s->buf_ptr) {
 234             s->buf_ptr[0] = bit_buf >> 24;
 235             s->buf_ptr[1] = bit_buf >> 16;
 236             s->buf_ptr[2] = bit_buf >>  8;
 237             s->buf_ptr[3] = bit_buf      ;
 238         } else
 239 #endif
 240         *(uint32_t *)s->buf_ptr = be2me_32(bit_buf);
 241         //printf("bitbuf = %08x\n", bit_buf);
 242         s->buf_ptr+=4;
 243         bit_left+=32 - n;
 244         bit_buf = value;
 245     }
 246
 247     s->bit_buf = bit_buf;
 248     s->bit_left = bit_left;
 249 }
 250 #endif
 251
 252
 253 #ifdef ALT_BITSTREAM_WRITER
 254 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
 255 {
 256 #    ifdef ALIGNED_BITSTREAM_WRITER
 257 #        if defined(ARCH_X86)
 258     asm volatile(
 259         "movl %0, %%ecx                 \n\t"
 260         "xorl %%eax, %%eax              \n\t"
 261         "shrdl %%cl, %1, %%eax          \n\t"
 262         "shrl %%cl, %1                  \n\t"
 263         "movl %0, %%ecx                 \n\t"
 264         "shrl $3, %%ecx                 \n\t"
 265         "andl $0xFFFFFFFC, %%ecx        \n\t"
 266         "bswapl %1                      \n\t"
 267         "orl %1, (%2, %%ecx)            \n\t"
 268         "bswapl %%eax                   \n\t"
 269         "addl %3, %0                    \n\t"
 270         "movl %%eax, 4(%2, %%ecx)       \n\t"
 271         : "=&r" (s->index), "=&r" (value)
 272         : "r" (s->buf), "r" (n), "0" (s->index), "1" (value<<(-n))
 273         : "%eax", "%ecx"
 274     );
 275 #        else
 276     int index= s->index;
 277     uint32_t *ptr= ((uint32_t *)s->buf)+(index>>5);
 278
 279     value<<= 32-n;
 280
 281     ptr[0] |= be2me_32(value>>(index&31));
 282     ptr[1]  = be2me_32(value<<(32-(index&31)));
 283 //if(n>24) printf("%d %d\n", n, value);
 284     index+= n;
 285     s->index= index;
 286 #        endif
 287 #    else //ALIGNED_BITSTREAM_WRITER
 288 #        if defined(ARCH_X86)
 289     asm volatile(
 290         "movl $7, %%ecx                 \n\t"
 291         "andl %0, %%ecx                 \n\t"
 292         "addl %3, %%ecx                 \n\t"
 293         "negl %%ecx                     \n\t"
 294         "shll %%cl, %1                  \n\t"
 295         "bswapl %1                      \n\t"
 296         "movl %0, %%ecx                 \n\t"
 297         "shrl $3, %%ecx                 \n\t"
 298         "orl %1, (%%ecx, %2)            \n\t"
 299         "addl %3, %0                    \n\t"
 300         "movl $0, 4(%%ecx, %2)          \n\t"
 301         : "=&r" (s->index), "=&r" (value)
 302         : "r" (s->buf), "r" (n), "0" (s->index), "1" (value)
 303         : "%ecx"
 304     );
 305 #        else
 306     int index= s->index;
 307     uint32_t *ptr= (uint32_t*)(((uint8_t *)s->buf)+(index>>3));
 308
 309     ptr[0] |= be2me_32(value<<(32-n-(index&7) ));
 310     ptr[1] = 0;
 311 //if(n>24) printf("%d %d\n", n, value);
 312     index+= n;
 313     s->index= index;
 314 #        endif
 315 #    endif //!ALIGNED_BITSTREAM_WRITER
 316 }
 317 #endif
 318
 319
 320 static inline uint8_t* pbBufPtr(PutBitContext *s)
 321 {
 322 #ifdef ALT_BITSTREAM_WRITER
 323         return s->buf + (s->index>>3);
 324 #else
 325         return s->buf_ptr;
 326 #endif
 327 }
 328
 329 /**
 330  *
 331  * PutBitContext must be flushed & aligned to a byte boundary before calling this.
 332  */
 333 static inline void skip_put_bytes(PutBitContext *s, int n){
 334         assert((put_bits_count(s)&7)==0);
 335 #ifdef ALT_BITSTREAM_WRITER
 336         FIXME may need some cleaning of the buffer
 337         s->index += n<<3;
 338 #else
 339         assert(s->bit_left==32);
 340         s->buf_ptr += n;
 341 #endif
 342 }
 343
 344 /**
 345  * Skips the given number of bits.
 346  * Must only be used if the actual values in the bitstream do not matter.
 347  */
 348 static inline void skip_put_bits(PutBitContext *s, int n){
 349 #ifdef ALT_BITSTREAM_WRITER
 350     s->index += n;
 351 #else
 352     s->bit_left -= n;
 353     s->buf_ptr-= s->bit_left>>5;
 354     s->bit_left &= 31;
 355 #endif
 356 }
 357
 358 /**
 359  * Changes the end of the buffer.
 360  */
 361 static inline void set_put_bits_buffer_size(PutBitContext *s, int size){
 362     s->buf_end= s->buf + size;
 363 }
 364
 365 /* Bitstream reader API docs:
 366 name
 367     abritary name which is used as prefix for the internal variables
 368
 369 gb
 370     getbitcontext
 371
 372 OPEN_READER(name, gb)
 373     loads gb into local variables
 374
 375 CLOSE_READER(name, gb)
 376     stores local vars in gb
 377
 378 UPDATE_CACHE(name, gb)
 379     refills the internal cache from the bitstream
 380     after this call at least MIN_CACHE_BITS will be available,
 381
 382 GET_CACHE(name, gb)
 383     will output the contents of the internal cache, next bit is MSB of 32 or 64 bit (FIXME 64bit)
 384
 385 SHOW_UBITS(name, gb, num)
 386     will return the next num bits
 387
 388 SHOW_SBITS(name, gb, num)
 389     will return the next num bits and do sign extension
 390
 391 SKIP_BITS(name, gb, num)
 392     will skip over the next num bits
 393     note, this is equivalent to SKIP_CACHE; SKIP_COUNTER
 394
 395 SKIP_CACHE(name, gb, num)
 396     will remove the next num bits from the cache (note SKIP_COUNTER MUST be called before UPDATE_CACHE / CLOSE_READER)
 397
 398 SKIP_COUNTER(name, gb, num)
 399     will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS)
 400
 401 LAST_SKIP_CACHE(name, gb, num)
 402     will remove the next num bits from the cache if it is needed for UPDATE_CACHE otherwise it will do nothing
 403
 404 LAST_SKIP_BITS(name, gb, num)
 405     is equivalent to SKIP_LAST_CACHE; SKIP_COUNTER
 406
 407 for examples see get_bits, show_bits, skip_bits, get_vlc
 408 */
 409
 410 #ifdef ALT_BITSTREAM_READER
 411 #   define MIN_CACHE_BITS 25
 412
 413 #   define OPEN_READER(name, gb)\
 414         int name##_index= (gb)->index;\
 415         int name##_cache= 0;\
 416
 417 #   define CLOSE_READER(name, gb)\
 418         (gb)->index= name##_index;\
 419
 420 # ifdef ALT_BITSTREAM_READER_LE
 421 #   define UPDATE_CACHE(name, gb)\
 422         name##_cache= AV_RL32( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) >> (name##_index&0x07);\
 423
 424 #   define SKIP_CACHE(name, gb, num)\
 425         name##_cache >>= (num);
 426 # else
 427 #   define UPDATE_CACHE(name, gb)\
 428         name##_cache= AV_RB32( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) << (name##_index&0x07);\
 429
 430 #   define SKIP_CACHE(name, gb, num)\
 431         name##_cache <<= (num);
 432 # endif
 433
 434 // FIXME name?
 435 #   define SKIP_COUNTER(name, gb, num)\
 436         name##_index += (num);\
 437
 438 #   define SKIP_BITS(name, gb, num)\
 439         {\
 440             SKIP_CACHE(name, gb, num)\
 441             SKIP_COUNTER(name, gb, num)\
 442         }\
 443
 444 #   define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
 445 #   define LAST_SKIP_CACHE(name, gb, num) ;
 446
 447 # ifdef ALT_BITSTREAM_READER_LE
 448 #   define SHOW_UBITS(name, gb, num)\
 449         ((name##_cache) & (NEG_USR32(0xffffffff,num)))
 450
 451 #   define SHOW_SBITS(name, gb, num)\
 452         NEG_SSR32((name##_cache)<<(32-(num)), num)
 453 # else
 454 #   define SHOW_UBITS(name, gb, num)\
 455         NEG_USR32(name##_cache, num)
 456
 457 #   define SHOW_SBITS(name, gb, num)\
 458         NEG_SSR32(name##_cache, num)
 459 # endif
 460
 461 #   define GET_CACHE(name, gb)\
 462         ((uint32_t)name##_cache)
 463
 464 static inline int get_bits_count(GetBitContext *s){
 465     return s->index;
 466 }
 467
 468 static inline void skip_bits_long(GetBitContext *s, int n){
 469     s->index += n;
 470 }
 471
 472 #elif defined LIBMPEG2_BITSTREAM_READER
 473 //libmpeg2 like reader
 474
 475 #   define MIN_CACHE_BITS 17
 476
 477 #   define OPEN_READER(name, gb)\
 478         int name##_bit_count=(gb)->bit_count;\
 479         int name##_cache= (gb)->cache;\
 480         uint8_t * name##_buffer_ptr=(gb)->buffer_ptr;\
 481
 482 #   define CLOSE_READER(name, gb)\
 483         (gb)->bit_count= name##_bit_count;\
 484         (gb)->cache= name##_cache;\
 485         (gb)->buffer_ptr= name##_buffer_ptr;\
 486
 487 #ifdef LIBMPEG2_BITSTREAM_READER_HACK
 488
 489 #   define UPDATE_CACHE(name, gb)\
 490     if(name##_bit_count >= 0){\
 491         name##_cache+= (int)be2me_16(*(uint16_t*)name##_buffer_ptr) << name##_bit_count;\
 492         name##_buffer_ptr += 2;\
 493         name##_bit_count-= 16;\
 494     }\
 495
 496 #else
 497
 498 #   define UPDATE_CACHE(name, gb)\
 499     if(name##_bit_count >= 0){\
 500         name##_cache+= ((name##_buffer_ptr[0]<<8) + name##_buffer_ptr[1]) << name##_bit_count;\
 501         name##_buffer_ptr+=2;\
 502         name##_bit_count-= 16;\
 503     }\
 504
 505 #endif
 506
 507 #   define SKIP_CACHE(name, gb, num)\
 508         name##_cache <<= (num);\
 509
 510 #   define SKIP_COUNTER(name, gb, num)\
 511         name##_bit_count += (num);\
 512
 513 #   define SKIP_BITS(name, gb, num)\
 514         {\
 515             SKIP_CACHE(name, gb, num)\
 516             SKIP_COUNTER(name, gb, num)\
 517         }\
 518
 519 #   define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
 520 #   define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
 521
 522 #   define SHOW_UBITS(name, gb, num)\
 523         NEG_USR32(name##_cache, num)
 524
 525 #   define SHOW_SBITS(name, gb, num)\
 526         NEG_SSR32(name##_cache, num)
 527
 528 #   define GET_CACHE(name, gb)\
 529         ((uint32_t)name##_cache)
 530
 531 static inline int get_bits_count(GetBitContext *s){
 532     return (s->buffer_ptr - s->buffer)*8 - 16 + s->bit_count;
 533 }
 534
 535 static inline void skip_bits_long(GetBitContext *s, int n){
 536     OPEN_READER(re, s)
 537     re_bit_count += n;
 538     re_buffer_ptr += 2*(re_bit_count>>4);
 539     re_bit_count &= 15;
 540     re_cache = ((re_buffer_ptr[-2]<<8) + re_buffer_ptr[-1]) << (16+re_bit_count);
 541     UPDATE_CACHE(re, s)
 542     CLOSE_READER(re, s)
 543 }
 544
 545 #elif defined A32_BITSTREAM_READER
 546
 547 #   define MIN_CACHE_BITS 32
 548
 549 #   define OPEN_READER(name, gb)\
 550         int name##_bit_count=(gb)->bit_count;\
 551         uint32_t name##_cache0= (gb)->cache0;\
 552         uint32_t name##_cache1= (gb)->cache1;\
 553         uint32_t * name##_buffer_ptr=(gb)->buffer_ptr;\
 554
 555 #   define CLOSE_READER(name, gb)\
 556         (gb)->bit_count= name##_bit_count;\
 557         (gb)->cache0= name##_cache0;\
 558         (gb)->cache1= name##_cache1;\
 559         (gb)->buffer_ptr= name##_buffer_ptr;\
 560
 561 #   define UPDATE_CACHE(name, gb)\
 562     if(name##_bit_count > 0){\
 563         const uint32_t next= be2me_32( *name##_buffer_ptr );\
 564         name##_cache0 |= NEG_USR32(next,name##_bit_count);\
 565         name##_cache1 |= next<<name##_bit_count;\
 566         name##_buffer_ptr++;\
 567         name##_bit_count-= 32;\
 568     }\
 569
 570 #if defined(ARCH_X86)
 571 #   define SKIP_CACHE(name, gb, num)\
 572         asm(\
 573             "shldl %2, %1, %0          \n\t"\
 574             "shll %2, %1               \n\t"\
 575             : "+r" (name##_cache0), "+r" (name##_cache1)\
 576             : "Ic" ((uint8_t)(num))\
 577            );
 578 #else
 579 #   define SKIP_CACHE(name, gb, num)\
 580         name##_cache0 <<= (num);\
 581         name##_cache0 |= NEG_USR32(name##_cache1,num);\
 582         name##_cache1 <<= (num);
 583 #endif
 584
 585 #   define SKIP_COUNTER(name, gb, num)\
 586         name##_bit_count += (num);\
 587
 588 #   define SKIP_BITS(name, gb, num)\
 589         {\
 590             SKIP_CACHE(name, gb, num)\
 591             SKIP_COUNTER(name, gb, num)\
 592         }\
 593
 594 #   define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
 595 #   define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
 596
 597 #   define SHOW_UBITS(name, gb, num)\
 598         NEG_USR32(name##_cache0, num)
 599
 600 #   define SHOW_SBITS(name, gb, num)\
 601         NEG_SSR32(name##_cache0, num)
 602
 603 #   define GET_CACHE(name, gb)\
 604         (name##_cache0)
 605
 606 static inline int get_bits_count(GetBitContext *s){
 607     return ((uint8_t*)s->buffer_ptr - s->buffer)*8 - 32 + s->bit_count;
 608 }
 609
 610 static inline void skip_bits_long(GetBitContext *s, int n){
 611     OPEN_READER(re, s)
 612     re_bit_count += n;
 613     re_buffer_ptr += re_bit_count>>5;
 614     re_bit_count &= 31;
 615     re_cache0 = be2me_32( re_buffer_ptr[-1] ) << re_bit_count;
 616     re_cache1 = 0;
 617     UPDATE_CACHE(re, s)
 618     CLOSE_READER(re, s)
 619 }
 620
 621 #endif
 622
 623 /**
 624  * read mpeg1 dc style vlc (sign bit + mantisse with no MSB).
 625  * if MSB not set it is negative
 626  * @param n length in bits
 627  * @author BERO
 628  */
 629 static inline int get_xbits(GetBitContext *s, int n){
 630     register int sign;
 631     register int32_t cache;
 632     OPEN_READER(re, s)
 633     UPDATE_CACHE(re, s)
 634     cache = GET_CACHE(re,s);
 635     sign=(~cache)>>31;
 636     LAST_SKIP_BITS(re, s, n)
 637     CLOSE_READER(re, s)
 638     return (NEG_USR32(sign ^ cache, n) ^ sign) - sign;
 639 }
 640
 641 static inline int get_sbits(GetBitContext *s, int n){
 642     register int tmp;
 643     OPEN_READER(re, s)
 644     UPDATE_CACHE(re, s)
 645     tmp= SHOW_SBITS(re, s, n);
 646     LAST_SKIP_BITS(re, s, n)
 647     CLOSE_READER(re, s)
 648     return tmp;
 649 }
 650
 651 /**
 652  * reads 1-17 bits.
 653  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
 654  */
 655 static inline unsigned int get_bits(GetBitContext *s, int n){
 656     register int tmp;
 657     OPEN_READER(re, s)
 658     UPDATE_CACHE(re, s)
 659     tmp= SHOW_UBITS(re, s, n);
 660     LAST_SKIP_BITS(re, s, n)
 661     CLOSE_READER(re, s)
 662     return tmp;
 663 }
 664
 665 /**
 666  * shows 1-17 bits.
 667  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
 668  */
 669 static inline unsigned int show_bits(GetBitContext *s, int n){
 670     register int tmp;
 671     OPEN_READER(re, s)
 672     UPDATE_CACHE(re, s)
 673     tmp= SHOW_UBITS(re, s, n);
 674 //    CLOSE_READER(re, s)
 675     return tmp;
 676 }
 677
 678 static inline void skip_bits(GetBitContext *s, int n){
 679  //Note gcc seems to optimize this to s->index+=n for the ALT_READER :))
 680     OPEN_READER(re, s)
 681     UPDATE_CACHE(re, s)
 682     LAST_SKIP_BITS(re, s, n)
 683     CLOSE_READER(re, s)
 684 }
 685
 686 static inline unsigned int get_bits1(GetBitContext *s){
 687 #ifdef ALT_BITSTREAM_READER
 688     int index= s->index;
 689     uint8_t result= s->buffer[ index>>3 ];
 690 #ifdef ALT_BITSTREAM_READER_LE
 691     result>>= (index&0x07);
 692     result&= 1;
 693 #else
 694     result<<= (index&0x07);
 695     result>>= 8 - 1;
 696 #endif
 697     index++;
 698     s->index= index;
 699
 700     return result;
 701 #else
 702     return get_bits(s, 1);
 703 #endif
 704 }
 705
 706 static inline unsigned int show_bits1(GetBitContext *s){
 707     return show_bits(s, 1);
 708 }
 709
 710 static inline void skip_bits1(GetBitContext *s){
 711     skip_bits(s, 1);
 712 }
 713
 714 /**
 715  * reads 0-32 bits.
 716  */
 717 static inline unsigned int get_bits_long(GetBitContext *s, int n){
 718     if(n<=17) return get_bits(s, n);
 719     else{
 720 #ifdef ALT_BITSTREAM_READER_LE
 721         int ret= get_bits(s, 16);
 722         return ret | (get_bits(s, n-16) << 16);
 723 #else
 724         int ret= get_bits(s, 16) << (n-16);
 725         return ret | get_bits(s, n-16);
 726 #endif
 727     }
 728 }
 729
 730 /**
 731  * shows 0-32 bits.
 732  */
 733 static inline unsigned int show_bits_long(GetBitContext *s, int n){
 734     if(n<=17) return show_bits(s, n);
 735     else{
 736         GetBitContext gb= *s;
 737         int ret= get_bits_long(s, n);
 738         *s= gb;
 739         return ret;
 740     }
 741 }
 742
 743 static inline int check_marker(GetBitContext *s, const char *msg)
 744 {
 745     int bit= get_bits1(s);
 746     if(!bit)
 747         av_log(NULL, AV_LOG_INFO, "Marker bit missing %s\n", msg);
 748
 749     return bit;
 750 }
 751
 752 /**
 753  * init GetBitContext.
 754  * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger then the actual read bits
 755  * because some optimized bitstream readers read 32 or 64 bit at once and could read over the end
 756  * @param bit_size the size of the buffer in bits
 757  */
 758 static inline void init_get_bits(GetBitContext *s,
 759                    const uint8_t *buffer, int bit_size)
 760 {
 761     int buffer_size= (bit_size+7)>>3;
 762     if(buffer_size < 0 || bit_size < 0) {
 763         buffer_size = bit_size = 0;
 764         buffer = NULL;
 765     }
 766
 767     s->buffer= buffer;
 768     s->size_in_bits= bit_size;
 769     s->buffer_end= buffer + buffer_size;
 770 #ifdef ALT_BITSTREAM_READER
 771     s->index=0;
 772 #elif defined LIBMPEG2_BITSTREAM_READER
 773     s->buffer_ptr = (uint8_t*)((intptr_t)buffer&(~1));
 774     s->bit_count = 16 + 8*((intptr_t)buffer&1);
 775     skip_bits_long(s, 0);
 776 #elif defined A32_BITSTREAM_READER
 777     s->buffer_ptr = (uint32_t*)((intptr_t)buffer&(~3));
 778     s->bit_count = 32 + 8*((intptr_t)buffer&3);
 779     skip_bits_long(s, 0);
 780 #endif
 781 }
 782
 783 static inline void align_get_bits(GetBitContext *s)
 784 {
 785     int n= (-get_bits_count(s)) & 7;
 786     if(n) skip_bits(s, n);
 787 }
 788
 789 #define init_vlc(vlc, nb_bits, nb_codes,\
 790                  bits, bits_wrap, bits_size,\
 791                  codes, codes_wrap, codes_size,\
 792                  flags)\
 793         init_vlc_sparse(vlc, nb_bits, nb_codes,\
 794                  bits, bits_wrap, bits_size,\
 795                  codes, codes_wrap, codes_size,\
 796                  NULL, 0, 0, flags)
 797
 798 int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,
 799              const void *bits, int bits_wrap, int bits_size,
 800              const void *codes, int codes_wrap, int codes_size,
 801              const void *symbols, int symbols_wrap, int symbols_size,
 802              int flags);
 803 #define INIT_VLC_USE_STATIC 1 ///< VERY strongly deprecated and forbidden
 804 #define INIT_VLC_LE         2
 805 #define INIT_VLC_USE_NEW_STATIC 4
 806 void free_vlc(VLC *vlc);
 807
 808 #define INIT_VLC_STATIC(vlc, bits, a,b,c,d,e,f,g, static_size)\
 809 {\
 810     static VLC_TYPE table[static_size][2];\
 811     (vlc)->table= table;\
 812     (vlc)->table_allocated= static_size;\
 813     init_vlc(vlc, bits, a,b,c,d,e,f,g, INIT_VLC_USE_NEW_STATIC);\
 814 }
 815
 816
 817 /**
 818  *
 819  * if the vlc code is invalid and max_depth=1 than no bits will be removed
 820  * if the vlc code is invalid and max_depth>1 than the number of bits removed
 821  * is undefined
 822  */
 823 #define GET_VLC(code, name, gb, table, bits, max_depth)\
 824 {\
 825     int n, index, nb_bits;\
 826 \
 827     index= SHOW_UBITS(name, gb, bits);\
 828     code = table[index][0];\
 829     n    = table[index][1];\
 830 \
 831     if(max_depth > 1 && n < 0){\
 832         LAST_SKIP_BITS(name, gb, bits)\
 833         UPDATE_CACHE(name, gb)\
 834 \
 835         nb_bits = -n;\
 836 \
 837         index= SHOW_UBITS(name, gb, nb_bits) + code;\
 838         code = table[index][0];\
 839         n    = table[index][1];\
 840         if(max_depth > 2 && n < 0){\
 841             LAST_SKIP_BITS(name, gb, nb_bits)\
 842             UPDATE_CACHE(name, gb)\
 843 \
 844             nb_bits = -n;\
 845 \
 846             index= SHOW_UBITS(name, gb, nb_bits) + code;\
 847             code = table[index][0];\
 848             n    = table[index][1];\
 849         }\
 850     }\
 851     SKIP_BITS(name, gb, n)\
 852 }
 853
 854 #define GET_RL_VLC(level, run, name, gb, table, bits, max_depth, need_update)\
 855 {\
 856     int n, index, nb_bits;\
 857 \
 858     index= SHOW_UBITS(name, gb, bits);\
 859     level = table[index].level;\
 860     n     = table[index].len;\
 861 \
 862     if(max_depth > 1 && n < 0){\
 863         SKIP_BITS(name, gb, bits)\
 864         if(need_update){\
 865             UPDATE_CACHE(name, gb)\
 866         }\
 867 \
 868         nb_bits = -n;\
 869 \
 870         index= SHOW_UBITS(name, gb, nb_bits) + level;\
 871         level = table[index].level;\
 872         n     = table[index].len;\
 873     }\
 874     run= table[index].run;\
 875     SKIP_BITS(name, gb, n)\
 876 }
 877
 878
 879 /**
 880  * parses a vlc code, faster then get_vlc()
 881  * @param bits is the number of bits which will be read at once, must be
 882  *             identical to nb_bits in init_vlc()
 883  * @param max_depth is the number of times bits bits must be read to completely
 884  *                  read the longest vlc code
 885  *                  = (max_vlc_length + bits - 1) / bits
 886  */
 887 static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2],
 888                                   int bits, int max_depth)
 889 {
 890     int code;
 891
 892     OPEN_READER(re, s)
 893     UPDATE_CACHE(re, s)
 894
 895     GET_VLC(code, re, s, table, bits, max_depth)
 896
 897     CLOSE_READER(re, s)
 898     return code;
 899 }
 900
 901 //#define TRACE
 902
 903 #ifdef TRACE
 904 static inline void print_bin(int bits, int n){
 905     int i;
 906
 907     for(i=n-1; i>=0; i--){
 908         av_log(NULL, AV_LOG_DEBUG, "%d", (bits>>i)&1);
 909     }
 910     for(i=n; i<24; i++)
 911         av_log(NULL, AV_LOG_DEBUG, " ");
 912 }
 913
 914 static inline int get_bits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
 915     int r= get_bits(s, n);
 916
 917     print_bin(r, n);
 918     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);
 919     return r;
 920 }
 921 static inline int get_vlc_trace(GetBitContext *s, VLC_TYPE (*table)[2], int bits, int max_depth, char *file, const char *func, int line){
 922     int show= show_bits(s, 24);
 923     int pos= get_bits_count(s);
 924     int r= get_vlc2(s, table, bits, max_depth);
 925     int len= get_bits_count(s) - pos;
 926     int bits2= show>>(24-len);
 927
 928     print_bin(bits2, len);
 929
 930     av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d vlc @%5d in %s %s:%d\n", bits2, len, r, pos, file, func, line);
 931     return r;
 932 }
 933 static inline int get_xbits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
 934     int show= show_bits(s, n);
 935     int r= get_xbits(s, n);
 936
 937     print_bin(show, n);
 938     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);
 939     return r;
 940 }
 941
 942 #define get_bits(s, n)  get_bits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 943 #define get_bits1(s)    get_bits_trace(s, 1, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 944 #define get_xbits(s, n) get_xbits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 945 #define get_vlc(s, vlc)            get_vlc_trace(s, (vlc)->table, (vlc)->bits, 3, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 946 #define get_vlc2(s, tab, bits, max) get_vlc_trace(s, tab, bits, max, __FILE__, __PRETTY_FUNCTION__, __LINE__)
 947
 948 #define tprintf(p, ...) av_log(p, AV_LOG_DEBUG, __VA_ARGS__)
 949
 950 #else //TRACE
 951 #define tprintf(p, ...) {}
 952 #endif
 953
 954 static inline int decode012(GetBitContext *gb){
 955     int n;
 956     n = get_bits1(gb);
 957     if (n == 0)
 958         return 0;
 959     else
 960         return get_bits1(gb) + 1;
 961 }
 962
 963 static inline int decode210(GetBitContext *gb){
 964     if (get_bits1(gb))
 965         return 0;
 966     else
 967         return 2 - get_bits1(gb);
 968 }
 969
 970 #endif /* FFMPEG_BITSTREAM_H */