FFmpeg
get_bits.h
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1 /*
2  * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
3  * Copyright (c) 2016 Alexandra Hájková
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * @file
24  * bitstream reader API header.
25  */
26 
27 #ifndef AVCODEC_GET_BITS_H
28 #define AVCODEC_GET_BITS_H
29 
30 #include <stdint.h>
31 
32 #include "libavutil/common.h"
33 #include "libavutil/intreadwrite.h"
34 #include "libavutil/log.h"
35 #include "libavutil/avassert.h"
36 #include "avcodec.h"
37 #include "mathops.h"
38 #include "vlc.h"
39 
40 /*
41  * Safe bitstream reading:
42  * optionally, the get_bits API can check to ensure that we
43  * don't read past input buffer boundaries. This is protected
44  * with CONFIG_SAFE_BITSTREAM_READER at the global level, and
45  * then below that with UNCHECKED_BITSTREAM_READER at the per-
46  * decoder level. This means that decoders that check internally
47  * can "#define UNCHECKED_BITSTREAM_READER 1" to disable
48  * overread checks.
49  * Boundary checking causes a minor performance penalty so for
50  * applications that won't want/need this, it can be disabled
51  * globally using "#define CONFIG_SAFE_BITSTREAM_READER 0".
52  */
53 #ifndef UNCHECKED_BITSTREAM_READER
54 #define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER
55 #endif
56 
57 #ifndef CACHED_BITSTREAM_READER
58 #define CACHED_BITSTREAM_READER 0
59 #endif
60 
61 typedef struct GetBitContext {
63 #if CACHED_BITSTREAM_READER
64  uint64_t cache;
65  unsigned bits_left;
66 #endif
67  int index;
71 
72 static inline unsigned int get_bits(GetBitContext *s, int n);
73 static inline void skip_bits(GetBitContext *s, int n);
74 static inline unsigned int show_bits(GetBitContext *s, int n);
75 
76 /* Bitstream reader API docs:
77  * name
78  * arbitrary name which is used as prefix for the internal variables
79  *
80  * gb
81  * getbitcontext
82  *
83  * OPEN_READER(name, gb)
84  * load gb into local variables
85  *
86  * CLOSE_READER(name, gb)
87  * store local vars in gb
88  *
89  * UPDATE_CACHE(name, gb)
90  * Refill the internal cache from the bitstream.
91  * After this call at least MIN_CACHE_BITS will be available.
92  *
93  * GET_CACHE(name, gb)
94  * Will output the contents of the internal cache,
95  * next bit is MSB of 32 or 64 bits (FIXME 64 bits).
96  *
97  * SHOW_UBITS(name, gb, num)
98  * Will return the next num bits.
99  *
100  * SHOW_SBITS(name, gb, num)
101  * Will return the next num bits and do sign extension.
102  *
103  * SKIP_BITS(name, gb, num)
104  * Will skip over the next num bits.
105  * Note, this is equivalent to SKIP_CACHE; SKIP_COUNTER.
106  *
107  * SKIP_CACHE(name, gb, num)
108  * Will remove the next num bits from the cache (note SKIP_COUNTER
109  * MUST be called before UPDATE_CACHE / CLOSE_READER).
110  *
111  * SKIP_COUNTER(name, gb, num)
112  * Will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS).
113  *
114  * LAST_SKIP_BITS(name, gb, num)
115  * Like SKIP_BITS, to be used if next call is UPDATE_CACHE or CLOSE_READER.
116  *
117  * BITS_LEFT(name, gb)
118  * Return the number of bits left
119  *
120  * For examples see get_bits, show_bits, skip_bits, get_vlc.
121  */
122 
123 #if CACHED_BITSTREAM_READER
124 # define MIN_CACHE_BITS 64
125 #elif defined LONG_BITSTREAM_READER
126 # define MIN_CACHE_BITS 32
127 #else
128 # define MIN_CACHE_BITS 25
129 #endif
130 
131 #if !CACHED_BITSTREAM_READER
132 
133 #define OPEN_READER_NOSIZE(name, gb) \
134  unsigned int name ## _index = (gb)->index; \
135  unsigned int av_unused name ## _cache
136 
137 #if UNCHECKED_BITSTREAM_READER
138 #define OPEN_READER(name, gb) OPEN_READER_NOSIZE(name, gb)
139 
140 #define BITS_AVAILABLE(name, gb) 1
141 #else
142 #define OPEN_READER(name, gb) \
143  OPEN_READER_NOSIZE(name, gb); \
144  unsigned int name ## _size_plus8 = (gb)->size_in_bits_plus8
145 
146 #define BITS_AVAILABLE(name, gb) name ## _index < name ## _size_plus8
147 #endif
148 
149 #define CLOSE_READER(name, gb) (gb)->index = name ## _index
150 
151 # ifdef LONG_BITSTREAM_READER
152 
153 # define UPDATE_CACHE_LE(name, gb) name ## _cache = \
154  AV_RL64((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7)
155 
156 # define UPDATE_CACHE_BE(name, gb) name ## _cache = \
157  AV_RB64((gb)->buffer + (name ## _index >> 3)) >> (32 - (name ## _index & 7))
158 
159 #else
160 
161 # define UPDATE_CACHE_LE(name, gb) name ## _cache = \
162  AV_RL32((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7)
163 
164 # define UPDATE_CACHE_BE(name, gb) name ## _cache = \
165  AV_RB32((gb)->buffer + (name ## _index >> 3)) << (name ## _index & 7)
166 
167 #endif
168 
169 
170 #ifdef BITSTREAM_READER_LE
171 
172 # define UPDATE_CACHE(name, gb) UPDATE_CACHE_LE(name, gb)
173 
174 # define SKIP_CACHE(name, gb, num) name ## _cache >>= (num)
175 
176 #else
177 
178 # define UPDATE_CACHE(name, gb) UPDATE_CACHE_BE(name, gb)
179 
180 # define SKIP_CACHE(name, gb, num) name ## _cache <<= (num)
181 
182 #endif
183 
184 #if UNCHECKED_BITSTREAM_READER
185 # define SKIP_COUNTER(name, gb, num) name ## _index += (num)
186 #else
187 # define SKIP_COUNTER(name, gb, num) \
188  name ## _index = FFMIN(name ## _size_plus8, name ## _index + (num))
189 #endif
190 
191 #define BITS_LEFT(name, gb) ((int)((gb)->size_in_bits - name ## _index))
192 
193 #define SKIP_BITS(name, gb, num) \
194  do { \
195  SKIP_CACHE(name, gb, num); \
196  SKIP_COUNTER(name, gb, num); \
197  } while (0)
198 
199 #define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
200 
201 #define SHOW_UBITS_LE(name, gb, num) zero_extend(name ## _cache, num)
202 #define SHOW_SBITS_LE(name, gb, num) sign_extend(name ## _cache, num)
203 
204 #define SHOW_UBITS_BE(name, gb, num) NEG_USR32(name ## _cache, num)
205 #define SHOW_SBITS_BE(name, gb, num) NEG_SSR32(name ## _cache, num)
206 
207 #ifdef BITSTREAM_READER_LE
208 # define SHOW_UBITS(name, gb, num) SHOW_UBITS_LE(name, gb, num)
209 # define SHOW_SBITS(name, gb, num) SHOW_SBITS_LE(name, gb, num)
210 #else
211 # define SHOW_UBITS(name, gb, num) SHOW_UBITS_BE(name, gb, num)
212 # define SHOW_SBITS(name, gb, num) SHOW_SBITS_BE(name, gb, num)
213 #endif
214 
215 #define GET_CACHE(name, gb) ((uint32_t) name ## _cache)
216 
217 #endif
218 
219 static inline int get_bits_count(const GetBitContext *s)
220 {
221 #if CACHED_BITSTREAM_READER
222  return s->index - s->bits_left;
223 #else
224  return s->index;
225 #endif
226 }
227 
228 #if CACHED_BITSTREAM_READER
229 static inline void refill_32(GetBitContext *s)
230 {
231 #if !UNCHECKED_BITSTREAM_READER
232  if (s->index >> 3 >= s->buffer_end - s->buffer)
233  return;
234 #endif
235 
236 #ifdef BITSTREAM_READER_LE
237  s->cache = (uint64_t)AV_RL32(s->buffer + (s->index >> 3)) << s->bits_left | s->cache;
238 #else
239  s->cache = s->cache | (uint64_t)AV_RB32(s->buffer + (s->index >> 3)) << (32 - s->bits_left);
240 #endif
241  s->index += 32;
242  s->bits_left += 32;
243 }
244 
245 static inline void refill_64(GetBitContext *s)
246 {
247 #if !UNCHECKED_BITSTREAM_READER
248  if (s->index >> 3 >= s->buffer_end - s->buffer)
249  return;
250 #endif
251 
252 #ifdef BITSTREAM_READER_LE
253  s->cache = AV_RL64(s->buffer + (s->index >> 3));
254 #else
255  s->cache = AV_RB64(s->buffer + (s->index >> 3));
256 #endif
257  s->index += 64;
258  s->bits_left = 64;
259 }
260 
261 static inline uint64_t get_val(GetBitContext *s, unsigned n, int is_le)
262 {
263  uint64_t ret;
264  av_assert2(n>0 && n<=63);
265  if (is_le) {
266  ret = s->cache & ((UINT64_C(1) << n) - 1);
267  s->cache >>= n;
268  } else {
269  ret = s->cache >> (64 - n);
270  s->cache <<= n;
271  }
272  s->bits_left -= n;
273  return ret;
274 }
275 
276 static inline unsigned show_val(const GetBitContext *s, unsigned n)
277 {
278 #ifdef BITSTREAM_READER_LE
279  return s->cache & ((UINT64_C(1) << n) - 1);
280 #else
281  return s->cache >> (64 - n);
282 #endif
283 }
284 #endif
285 
286 /**
287  * Skips the specified number of bits.
288  * @param n the number of bits to skip,
289  * For the UNCHECKED_BITSTREAM_READER this must not cause the distance
290  * from the start to overflow int32_t. Staying within the bitstream + padding
291  * is sufficient, too.
292  */
293 static inline void skip_bits_long(GetBitContext *s, int n)
294 {
295 #if CACHED_BITSTREAM_READER
296  skip_bits(s, n);
297 #else
298 #if UNCHECKED_BITSTREAM_READER
299  s->index += n;
300 #else
301  s->index += av_clip(n, -s->index, s->size_in_bits_plus8 - s->index);
302 #endif
303 #endif
304 }
305 
306 #if CACHED_BITSTREAM_READER
307 static inline void skip_remaining(GetBitContext *s, unsigned n)
308 {
309 #ifdef BITSTREAM_READER_LE
310  s->cache >>= n;
311 #else
312  s->cache <<= n;
313 #endif
314  s->bits_left -= n;
315 }
316 #endif
317 
318 /**
319  * Read MPEG-1 dc-style VLC (sign bit + mantissa with no MSB).
320  * if MSB not set it is negative
321  * @param n length in bits
322  */
323 static inline int get_xbits(GetBitContext *s, int n)
324 {
325 #if CACHED_BITSTREAM_READER
326  int32_t cache = show_bits(s, 32);
327  int sign = ~cache >> 31;
328  skip_remaining(s, n);
329 
330  return ((((uint32_t)(sign ^ cache)) >> (32 - n)) ^ sign) - sign;
331 #else
332  register int sign;
333  register int32_t cache;
334  OPEN_READER(re, s);
335  av_assert2(n>0 && n<=25);
336  UPDATE_CACHE(re, s);
337  cache = GET_CACHE(re, s);
338  sign = ~cache >> 31;
339  LAST_SKIP_BITS(re, s, n);
340  CLOSE_READER(re, s);
341  return (NEG_USR32(sign ^ cache, n) ^ sign) - sign;
342 #endif
343 }
344 
345 #if !CACHED_BITSTREAM_READER
346 static inline int get_xbits_le(GetBitContext *s, int n)
347 {
348  register int sign;
349  register int32_t cache;
350  OPEN_READER(re, s);
351  av_assert2(n>0 && n<=25);
352  UPDATE_CACHE_LE(re, s);
353  cache = GET_CACHE(re, s);
354  sign = sign_extend(~cache, n) >> 31;
355  LAST_SKIP_BITS(re, s, n);
356  CLOSE_READER(re, s);
357  return (zero_extend(sign ^ cache, n) ^ sign) - sign;
358 }
359 #endif
360 
361 static inline int get_sbits(GetBitContext *s, int n)
362 {
363  register int tmp;
364 #if CACHED_BITSTREAM_READER
365  av_assert2(n>0 && n<=25);
366  tmp = sign_extend(get_bits(s, n), n);
367 #else
368  OPEN_READER(re, s);
369  av_assert2(n>0 && n<=25);
370  UPDATE_CACHE(re, s);
371  tmp = SHOW_SBITS(re, s, n);
372  LAST_SKIP_BITS(re, s, n);
373  CLOSE_READER(re, s);
374 #endif
375  return tmp;
376 }
377 
378 /**
379  * Read 1-25 bits.
380  */
381 static inline unsigned int get_bits(GetBitContext *s, int n)
382 {
383  register unsigned int tmp;
384 #if CACHED_BITSTREAM_READER
385 
386  av_assert2(n>0 && n<=32);
387  if (n > s->bits_left) {
388  refill_32(s);
389  if (s->bits_left < 32)
390  s->bits_left = n;
391  }
392 
393 #ifdef BITSTREAM_READER_LE
394  tmp = get_val(s, n, 1);
395 #else
396  tmp = get_val(s, n, 0);
397 #endif
398 #else
399  OPEN_READER(re, s);
400  av_assert2(n>0 && n<=25);
401  UPDATE_CACHE(re, s);
402  tmp = SHOW_UBITS(re, s, n);
403  LAST_SKIP_BITS(re, s, n);
404  CLOSE_READER(re, s);
405 #endif
406  av_assert2(tmp < UINT64_C(1) << n);
407  return tmp;
408 }
409 
410 /**
411  * Read 0-25 bits.
412  */
414 {
415  return n ? get_bits(s, n) : 0;
416 }
417 
418 static inline unsigned int get_bits_le(GetBitContext *s, int n)
419 {
420 #if CACHED_BITSTREAM_READER
421  av_assert2(n>0 && n<=32);
422  if (n > s->bits_left) {
423  refill_32(s);
424  if (s->bits_left < 32)
425  s->bits_left = n;
426  }
427 
428  return get_val(s, n, 1);
429 #else
430  register int tmp;
431  OPEN_READER(re, s);
432  av_assert2(n>0 && n<=25);
433  UPDATE_CACHE_LE(re, s);
434  tmp = SHOW_UBITS_LE(re, s, n);
435  LAST_SKIP_BITS(re, s, n);
436  CLOSE_READER(re, s);
437  return tmp;
438 #endif
439 }
440 
441 /**
442  * Show 1-25 bits.
443  */
444 static inline unsigned int show_bits(GetBitContext *s, int n)
445 {
446  register unsigned int tmp;
447 #if CACHED_BITSTREAM_READER
448  if (n > s->bits_left)
449  refill_32(s);
450 
451  tmp = show_val(s, n);
452 #else
454  av_assert2(n>0 && n<=25);
455  UPDATE_CACHE(re, s);
456  tmp = SHOW_UBITS(re, s, n);
457 #endif
458  return tmp;
459 }
460 
461 static inline void skip_bits(GetBitContext *s, int n)
462 {
463 #if CACHED_BITSTREAM_READER
464  if (n < s->bits_left)
465  skip_remaining(s, n);
466  else {
467  n -= s->bits_left;
468  s->cache = 0;
469  s->bits_left = 0;
470 
471  if (n >= 64) {
472  unsigned skip = (n / 8) * 8;
473 
474  n -= skip;
475  s->index += skip;
476  }
477  refill_64(s);
478  if (n)
479  skip_remaining(s, n);
480  }
481 #else
482  OPEN_READER(re, s);
483  LAST_SKIP_BITS(re, s, n);
484  CLOSE_READER(re, s);
485 #endif
486 }
487 
488 static inline unsigned int get_bits1(GetBitContext *s)
489 {
490 #if CACHED_BITSTREAM_READER
491  if (!s->bits_left)
492  refill_64(s);
493 
494 #ifdef BITSTREAM_READER_LE
495  return get_val(s, 1, 1);
496 #else
497  return get_val(s, 1, 0);
498 #endif
499 #else
500  unsigned int index = s->index;
501  uint8_t result = s->buffer[index >> 3];
502 #ifdef BITSTREAM_READER_LE
503  result >>= index & 7;
504  result &= 1;
505 #else
506  result <<= index & 7;
507  result >>= 8 - 1;
508 #endif
509 #if !UNCHECKED_BITSTREAM_READER
510  if (s->index < s->size_in_bits_plus8)
511 #endif
512  index++;
513  s->index = index;
514 
515  return result;
516 #endif
517 }
518 
519 static inline unsigned int show_bits1(GetBitContext *s)
520 {
521  return show_bits(s, 1);
522 }
523 
524 static inline void skip_bits1(GetBitContext *s)
525 {
526  skip_bits(s, 1);
527 }
528 
529 /**
530  * Read 0-32 bits.
531  */
532 static inline unsigned int get_bits_long(GetBitContext *s, int n)
533 {
534  av_assert2(n>=0 && n<=32);
535  if (!n) {
536  return 0;
537 #if CACHED_BITSTREAM_READER
538  }
539  return get_bits(s, n);
540 #else
541  } else if (n <= MIN_CACHE_BITS) {
542  return get_bits(s, n);
543  } else {
544 #ifdef BITSTREAM_READER_LE
545  unsigned ret = get_bits(s, 16);
546  return ret | (get_bits(s, n - 16) << 16);
547 #else
548  unsigned ret = get_bits(s, 16) << (n - 16);
549  return ret | get_bits(s, n - 16);
550 #endif
551  }
552 #endif
553 }
554 
555 /**
556  * Read 0-64 bits.
557  */
558 static inline uint64_t get_bits64(GetBitContext *s, int n)
559 {
560  if (n <= 32) {
561  return get_bits_long(s, n);
562  } else {
563 #ifdef BITSTREAM_READER_LE
564  uint64_t ret = get_bits_long(s, 32);
565  return ret | (uint64_t) get_bits_long(s, n - 32) << 32;
566 #else
567  uint64_t ret = (uint64_t) get_bits_long(s, n - 32) << 32;
568  return ret | get_bits_long(s, 32);
569 #endif
570  }
571 }
572 
573 /**
574  * Read 0-32 bits as a signed integer.
575  */
576 static inline int get_sbits_long(GetBitContext *s, int n)
577 {
578  // sign_extend(x, 0) is undefined
579  if (!n)
580  return 0;
581 
582  return sign_extend(get_bits_long(s, n), n);
583 }
584 
585 /**
586  * Show 0-32 bits.
587  */
588 static inline unsigned int show_bits_long(GetBitContext *s, int n)
589 {
590  if (n <= MIN_CACHE_BITS) {
591  return show_bits(s, n);
592  } else {
593  GetBitContext gb = *s;
594  return get_bits_long(&gb, n);
595  }
596 }
597 
598 static inline int check_marker(void *logctx, GetBitContext *s, const char *msg)
599 {
600  int bit = get_bits1(s);
601  if (!bit)
602  av_log(logctx, AV_LOG_INFO, "Marker bit missing at %d of %d %s\n",
603  get_bits_count(s) - 1, s->size_in_bits, msg);
604 
605  return bit;
606 }
607 
608 /**
609  * Initialize GetBitContext.
610  * @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes
611  * larger than the actual read bits because some optimized bitstream
612  * readers read 32 or 64 bit at once and could read over the end
613  * @param bit_size the size of the buffer in bits
614  * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow.
615  */
616 static inline int init_get_bits(GetBitContext *s, const uint8_t *buffer,
617  int bit_size)
618 {
619  int buffer_size;
620  int ret = 0;
621 
622  if (bit_size >= INT_MAX - FFMAX(7, AV_INPUT_BUFFER_PADDING_SIZE*8) || bit_size < 0 || !buffer) {
623  bit_size = 0;
624  buffer = NULL;
625  ret = AVERROR_INVALIDDATA;
626  }
627 
628  buffer_size = (bit_size + 7) >> 3;
629 
630  s->buffer = buffer;
631  s->size_in_bits = bit_size;
632  s->size_in_bits_plus8 = bit_size + 8;
633  s->buffer_end = buffer + buffer_size;
634  s->index = 0;
635 
636 #if CACHED_BITSTREAM_READER
637  refill_64(s);
638 #endif
639 
640  return ret;
641 }
642 
643 /**
644  * Initialize GetBitContext.
645  * @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes
646  * larger than the actual read bits because some optimized bitstream
647  * readers read 32 or 64 bit at once and could read over the end
648  * @param byte_size the size of the buffer in bytes
649  * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow.
650  */
651 static inline int init_get_bits8(GetBitContext *s, const uint8_t *buffer,
652  int byte_size)
653 {
654  if (byte_size > INT_MAX / 8 || byte_size < 0)
655  byte_size = -1;
656  return init_get_bits(s, buffer, byte_size * 8);
657 }
658 
659 static inline const uint8_t *align_get_bits(GetBitContext *s)
660 {
661  int n = -get_bits_count(s) & 7;
662  if (n)
663  skip_bits(s, n);
664  return s->buffer + (s->index >> 3);
665 }
666 
667 /**
668  * If the vlc code is invalid and max_depth=1, then no bits will be removed.
669  * If the vlc code is invalid and max_depth>1, then the number of bits removed
670  * is undefined.
671  */
672 #define GET_VLC(code, name, gb, table, bits, max_depth) \
673  do { \
674  int n, nb_bits; \
675  unsigned int index; \
676  \
677  index = SHOW_UBITS(name, gb, bits); \
678  code = table[index][0]; \
679  n = table[index][1]; \
680  \
681  if (max_depth > 1 && n < 0) { \
682  LAST_SKIP_BITS(name, gb, bits); \
683  UPDATE_CACHE(name, gb); \
684  \
685  nb_bits = -n; \
686  \
687  index = SHOW_UBITS(name, gb, nb_bits) + code; \
688  code = table[index][0]; \
689  n = table[index][1]; \
690  if (max_depth > 2 && n < 0) { \
691  LAST_SKIP_BITS(name, gb, nb_bits); \
692  UPDATE_CACHE(name, gb); \
693  \
694  nb_bits = -n; \
695  \
696  index = SHOW_UBITS(name, gb, nb_bits) + code; \
697  code = table[index][0]; \
698  n = table[index][1]; \
699  } \
700  } \
701  SKIP_BITS(name, gb, n); \
702  } while (0)
703 
704 #define GET_RL_VLC(level, run, name, gb, table, bits, \
705  max_depth, need_update) \
706  do { \
707  int n, nb_bits; \
708  unsigned int index; \
709  \
710  index = SHOW_UBITS(name, gb, bits); \
711  level = table[index].level; \
712  n = table[index].len; \
713  \
714  if (max_depth > 1 && n < 0) { \
715  SKIP_BITS(name, gb, bits); \
716  if (need_update) { \
717  UPDATE_CACHE(name, gb); \
718  } \
719  \
720  nb_bits = -n; \
721  \
722  index = SHOW_UBITS(name, gb, nb_bits) + level; \
723  level = table[index].level; \
724  n = table[index].len; \
725  if (max_depth > 2 && n < 0) { \
726  LAST_SKIP_BITS(name, gb, nb_bits); \
727  if (need_update) { \
728  UPDATE_CACHE(name, gb); \
729  } \
730  nb_bits = -n; \
731  \
732  index = SHOW_UBITS(name, gb, nb_bits) + level; \
733  level = table[index].level; \
734  n = table[index].len; \
735  } \
736  } \
737  run = table[index].run; \
738  SKIP_BITS(name, gb, n); \
739  } while (0)
740 
741 /* Return the LUT element for the given bitstream configuration. */
742 static inline int set_idx(GetBitContext *s, int code, int *n, int *nb_bits,
743  VLC_TYPE (*table)[2])
744 {
745  unsigned idx;
746 
747  *nb_bits = -*n;
748  idx = show_bits(s, *nb_bits) + code;
749  *n = table[idx][1];
750 
751  return table[idx][0];
752 }
753 
754 /**
755  * Parse a vlc code.
756  * @param bits is the number of bits which will be read at once, must be
757  * identical to nb_bits in init_vlc()
758  * @param max_depth is the number of times bits bits must be read to completely
759  * read the longest vlc code
760  * = (max_vlc_length + bits - 1) / bits
761  * @returns the code parsed or -1 if no vlc matches
762  */
764  int bits, int max_depth)
765 {
766 #if CACHED_BITSTREAM_READER
767  int nb_bits;
768  unsigned idx = show_bits(s, bits);
769  int code = table[idx][0];
770  int n = table[idx][1];
771 
772  if (max_depth > 1 && n < 0) {
773  skip_remaining(s, bits);
774  code = set_idx(s, code, &n, &nb_bits, table);
775  if (max_depth > 2 && n < 0) {
776  skip_remaining(s, nb_bits);
777  code = set_idx(s, code, &n, &nb_bits, table);
778  }
779  }
780  skip_remaining(s, n);
781 
782  return code;
783 #else
784  int code;
785 
786  OPEN_READER(re, s);
787  UPDATE_CACHE(re, s);
788 
789  GET_VLC(code, re, s, table, bits, max_depth);
790 
791  CLOSE_READER(re, s);
792 
793  return code;
794 #endif
795 }
796 
797 static inline int decode012(GetBitContext *gb)
798 {
799  int n;
800  n = get_bits1(gb);
801  if (n == 0)
802  return 0;
803  else
804  return get_bits1(gb) + 1;
805 }
806 
807 static inline int decode210(GetBitContext *gb)
808 {
809  if (get_bits1(gb))
810  return 0;
811  else
812  return 2 - get_bits1(gb);
813 }
814 
815 static inline int get_bits_left(GetBitContext *gb)
816 {
817  return gb->size_in_bits - get_bits_count(gb);
818 }
819 
820 static inline int skip_1stop_8data_bits(GetBitContext *gb)
821 {
822  if (get_bits_left(gb) <= 0)
823  return AVERROR_INVALIDDATA;
824 
825  while (get_bits1(gb)) {
826  skip_bits(gb, 8);
827  if (get_bits_left(gb) <= 0)
828  return AVERROR_INVALIDDATA;
829  }
830 
831  return 0;
832 }
833 
834 #endif /* AVCODEC_GET_BITS_H */
static int get_xbits_le(GetBitContext *s, int n)
Definition: get_bits.h:346
static unsigned int show_bits_long(GetBitContext *s, int n)
Show 0-32 bits.
Definition: get_bits.h:588
static unsigned int show_bits1(GetBitContext *s)
Definition: get_bits.h:519
#define NULL
Definition: coverity.c:32
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
float re
Definition: fft.c:82
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:381
static void skip_bits_long(GetBitContext *s, int n)
Skips the specified number of bits.
Definition: get_bits.h:293
static int set_idx(GetBitContext *s, int code, int *n, int *nb_bits, VLC_TYPE(*table)[2])
Definition: get_bits.h:742
static int check_marker(void *logctx, GetBitContext *s, const char *msg)
Definition: get_bits.h:598
const uint8_t * buffer
Definition: get_bits.h:62
uint64_t_TMPL AV_RL64
Definition: bytestream.h:87
static av_const unsigned zero_extend(unsigned val, unsigned bits)
Definition: mathops.h:139
static int get_sbits(GetBitContext *s, int n)
Definition: get_bits.h:361
static int get_sbits_long(GetBitContext *s, int n)
Read 0-32 bits as a signed integer.
Definition: get_bits.h:576
uint8_t
#define av_assert2(cond)
assert() equivalent, that does lie in speed critical code.
Definition: avassert.h:64
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_RB32
Definition: bytestream.h:87
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:219
#define SHOW_UBITS_LE(name, gb, num)
Definition: get_bits.h:201
#define av_log(a,...)
static const uint16_t table[]
Definition: prosumer.c:201
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:815
static uint64_t get_bits64(GetBitContext *s, int n)
Read 0-64 bits.
Definition: get_bits.h:558
#define UPDATE_CACHE(name, gb)
Definition: get_bits.h:178
simple assert() macros that are a bit more flexible than ISO C assert().
#define CLOSE_READER(name, gb)
Definition: get_bits.h:149
#define FFMAX(a, b)
Definition: common.h:94
#define NEG_USR32(a, s)
Definition: mathops.h:166
int size_in_bits
Definition: get_bits.h:68
int32_t
static unsigned int show_bits(GetBitContext *s, int n)
Show 1-25 bits.
Definition: get_bits.h:444
#define s(width, name)
Definition: cbs_vp9.c:257
#define LAST_SKIP_BITS(name, gb, num)
Definition: get_bits.h:199
static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE(*table)[2], int bits, int max_depth)
Parse a vlc code.
Definition: get_bits.h:763
int n
Definition: avisynth_c.h:684
#define GET_VLC(code, name, gb, table, bits, max_depth)
If the vlc code is invalid and max_depth=1, then no bits will be removed.
Definition: get_bits.h:672
#define SHOW_UBITS(name, gb, num)
Definition: get_bits.h:211
static int decode210(GetBitContext *gb)
Definition: get_bits.h:807
#define AV_LOG_INFO
Standard information.
Definition: log.h:187
Libavcodec external API header.
int size_in_bits_plus8
Definition: get_bits.h:69
static int init_get_bits8(GetBitContext *s, const uint8_t *buffer, int byte_size)
Initialize GetBitContext.
Definition: get_bits.h:651
static int get_xbits(GetBitContext *s, int n)
Read MPEG-1 dc-style VLC (sign bit + mantissa with no MSB).
Definition: get_bits.h:323
#define OPEN_READER(name, gb)
Definition: get_bits.h:138
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:488
static void skip_bits1(GetBitContext *s)
Definition: get_bits.h:524
static void skip_bits(GetBitContext *s, int n)
Definition: get_bits.h:461
#define UPDATE_CACHE_LE(name, gb)
Definition: get_bits.h:161
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:616
#define GET_CACHE(name, gb)
Definition: get_bits.h:215
static unsigned int get_bits_long(GetBitContext *s, int n)
Read 0-32 bits.
Definition: get_bits.h:532
#define MIN_CACHE_BITS
Definition: get_bits.h:128
static av_const int sign_extend(int val, unsigned bits)
Definition: mathops.h:130
and forward the test the status of outputs and forward it to the corresponding return FFERROR_NOT_READY If the filters stores internally one or a few frame for some it can consider them to be part of the FIFO and delay acknowledging a status change accordingly Example code
static unsigned int get_bits_le(GetBitContext *s, int n)
Definition: get_bits.h:418
#define SHOW_SBITS(name, gb, num)
Definition: get_bits.h:212
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_RB64
Definition: bytestream.h:87
#define OPEN_READER_NOSIZE(name, gb)
Definition: get_bits.h:133
common internal and external API header
const uint8_t * buffer_end
Definition: get_bits.h:62
#define AV_INPUT_BUFFER_PADDING_SIZE
Required number of additionally allocated bytes at the end of the input bitstream for decoding...
Definition: avcodec.h:786
static int decode012(GetBitContext *gb)
Definition: get_bits.h:797
static const uint8_t * align_get_bits(GetBitContext *s)
Definition: get_bits.h:659
and forward the result(frame or status change) to the corresponding input.If nothing is possible
static int skip_1stop_8data_bits(GetBitContext *gb)
Definition: get_bits.h:820
#define av_always_inline
Definition: attributes.h:39
#define VLC_TYPE
Definition: vlc.h:24
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_RL32
Definition: bytestream.h:87
static av_always_inline int get_bitsz(GetBitContext *s, int n)
Read 0-25 bits.
Definition: get_bits.h:413
GLuint buffer
Definition: opengl_enc.c:102
static uint8_t tmp[11]
Definition: aes_ctr.c:26