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, int is_le)
230 {
231 #if !UNCHECKED_BITSTREAM_READER
232  if (s->index >> 3 >= s->buffer_end - s->buffer)
233  return;
234 #endif
235 
236  if (is_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  s->index += 32;
241  s->bits_left += 32;
242 }
243 
244 static inline void refill_64(GetBitContext *s, int is_le)
245 {
246 #if !UNCHECKED_BITSTREAM_READER
247  if (s->index >> 3 >= s->buffer_end - s->buffer)
248  return;
249 #endif
250 
251  if (is_le)
252  s->cache = AV_RL64(s->buffer + (s->index >> 3));
253  else
254  s->cache = AV_RB64(s->buffer + (s->index >> 3));
255  s->index += 64;
256  s->bits_left = 64;
257 }
258 
259 static inline uint64_t get_val(GetBitContext *s, unsigned n, int is_le)
260 {
261  uint64_t ret;
262  av_assert2(n>0 && n<=63);
263  if (is_le) {
264  ret = s->cache & ((UINT64_C(1) << n) - 1);
265  s->cache >>= n;
266  } else {
267  ret = s->cache >> (64 - n);
268  s->cache <<= n;
269  }
270  s->bits_left -= n;
271  return ret;
272 }
273 
274 static inline unsigned show_val(const GetBitContext *s, unsigned n)
275 {
276 #ifdef BITSTREAM_READER_LE
277  return s->cache & ((UINT64_C(1) << n) - 1);
278 #else
279  return s->cache >> (64 - n);
280 #endif
281 }
282 #endif
283 
284 /**
285  * Skips the specified number of bits.
286  * @param n the number of bits to skip,
287  * For the UNCHECKED_BITSTREAM_READER this must not cause the distance
288  * from the start to overflow int32_t. Staying within the bitstream + padding
289  * is sufficient, too.
290  */
291 static inline void skip_bits_long(GetBitContext *s, int n)
292 {
293 #if CACHED_BITSTREAM_READER
294  skip_bits(s, n);
295 #else
296 #if UNCHECKED_BITSTREAM_READER
297  s->index += n;
298 #else
299  s->index += av_clip(n, -s->index, s->size_in_bits_plus8 - s->index);
300 #endif
301 #endif
302 }
303 
304 #if CACHED_BITSTREAM_READER
305 static inline void skip_remaining(GetBitContext *s, unsigned n)
306 {
307 #ifdef BITSTREAM_READER_LE
308  s->cache >>= n;
309 #else
310  s->cache <<= n;
311 #endif
312  s->bits_left -= n;
313 }
314 #endif
315 
316 /**
317  * Read MPEG-1 dc-style VLC (sign bit + mantissa with no MSB).
318  * if MSB not set it is negative
319  * @param n length in bits
320  */
321 static inline int get_xbits(GetBitContext *s, int n)
322 {
323 #if CACHED_BITSTREAM_READER
324  int32_t cache = show_bits(s, 32);
325  int sign = ~cache >> 31;
326  skip_remaining(s, n);
327 
328  return ((((uint32_t)(sign ^ cache)) >> (32 - n)) ^ sign) - sign;
329 #else
330  register int sign;
331  register int32_t cache;
332  OPEN_READER(re, s);
333  av_assert2(n>0 && n<=25);
334  UPDATE_CACHE(re, s);
335  cache = GET_CACHE(re, s);
336  sign = ~cache >> 31;
337  LAST_SKIP_BITS(re, s, n);
338  CLOSE_READER(re, s);
339  return (NEG_USR32(sign ^ cache, n) ^ sign) - sign;
340 #endif
341 }
342 
343 #if !CACHED_BITSTREAM_READER
344 static inline int get_xbits_le(GetBitContext *s, int n)
345 {
346  register int sign;
347  register int32_t cache;
348  OPEN_READER(re, s);
349  av_assert2(n>0 && n<=25);
350  UPDATE_CACHE_LE(re, s);
351  cache = GET_CACHE(re, s);
352  sign = sign_extend(~cache, n) >> 31;
353  LAST_SKIP_BITS(re, s, n);
354  CLOSE_READER(re, s);
355  return (zero_extend(sign ^ cache, n) ^ sign) - sign;
356 }
357 #endif
358 
359 static inline int get_sbits(GetBitContext *s, int n)
360 {
361  register int tmp;
362 #if CACHED_BITSTREAM_READER
363  av_assert2(n>0 && n<=25);
364  tmp = sign_extend(get_bits(s, n), n);
365 #else
366  OPEN_READER(re, s);
367  av_assert2(n>0 && n<=25);
368  UPDATE_CACHE(re, s);
369  tmp = SHOW_SBITS(re, s, n);
370  LAST_SKIP_BITS(re, s, n);
371  CLOSE_READER(re, s);
372 #endif
373  return tmp;
374 }
375 
376 /**
377  * Read 1-25 bits.
378  */
379 static inline unsigned int get_bits(GetBitContext *s, int n)
380 {
381  register unsigned int tmp;
382 #if CACHED_BITSTREAM_READER
383 
384  av_assert2(n>0 && n<=32);
385  if (n > s->bits_left) {
386 #ifdef BITSTREAM_READER_LE
387  refill_32(s, 1);
388 #else
389  refill_32(s, 0);
390 #endif
391  if (s->bits_left < 32)
392  s->bits_left = n;
393  }
394 
395 #ifdef BITSTREAM_READER_LE
396  tmp = get_val(s, n, 1);
397 #else
398  tmp = get_val(s, n, 0);
399 #endif
400 #else
401  OPEN_READER(re, s);
402  av_assert2(n>0 && n<=25);
403  UPDATE_CACHE(re, s);
404  tmp = SHOW_UBITS(re, s, n);
405  LAST_SKIP_BITS(re, s, n);
406  CLOSE_READER(re, s);
407 #endif
408  av_assert2(tmp < UINT64_C(1) << n);
409  return tmp;
410 }
411 
412 /**
413  * Read 0-25 bits.
414  */
416 {
417  return n ? get_bits(s, n) : 0;
418 }
419 
420 static inline unsigned int get_bits_le(GetBitContext *s, int n)
421 {
422 #if CACHED_BITSTREAM_READER
423  av_assert2(n>0 && n<=32);
424  if (n > s->bits_left) {
425  refill_32(s, 1);
426  if (s->bits_left < 32)
427  s->bits_left = n;
428  }
429 
430  return get_val(s, n, 1);
431 #else
432  register int tmp;
433  OPEN_READER(re, s);
434  av_assert2(n>0 && n<=25);
435  UPDATE_CACHE_LE(re, s);
436  tmp = SHOW_UBITS_LE(re, s, n);
437  LAST_SKIP_BITS(re, s, n);
438  CLOSE_READER(re, s);
439  return tmp;
440 #endif
441 }
442 
443 /**
444  * Show 1-25 bits.
445  */
446 static inline unsigned int show_bits(GetBitContext *s, int n)
447 {
448  register unsigned int tmp;
449 #if CACHED_BITSTREAM_READER
450  if (n > s->bits_left)
451 #ifdef BITSTREAM_READER_LE
452  refill_32(s, 1);
453 #else
454  refill_32(s, 0);
455 #endif
456 
457  tmp = show_val(s, n);
458 #else
460  av_assert2(n>0 && n<=25);
461  UPDATE_CACHE(re, s);
462  tmp = SHOW_UBITS(re, s, n);
463 #endif
464  return tmp;
465 }
466 
467 static inline void skip_bits(GetBitContext *s, int n)
468 {
469 #if CACHED_BITSTREAM_READER
470  if (n < s->bits_left)
471  skip_remaining(s, n);
472  else {
473  n -= s->bits_left;
474  s->cache = 0;
475  s->bits_left = 0;
476 
477  if (n >= 64) {
478  unsigned skip = (n / 8) * 8;
479 
480  n -= skip;
481  s->index += skip;
482  }
483 #ifdef BITSTREAM_READER_LE
484  refill_64(s, 1);
485 #else
486  refill_64(s, 0);
487 #endif
488  if (n)
489  skip_remaining(s, n);
490  }
491 #else
492  OPEN_READER(re, s);
493  LAST_SKIP_BITS(re, s, n);
494  CLOSE_READER(re, s);
495 #endif
496 }
497 
498 static inline unsigned int get_bits1(GetBitContext *s)
499 {
500 #if CACHED_BITSTREAM_READER
501  if (!s->bits_left)
502 #ifdef BITSTREAM_READER_LE
503  refill_64(s, 1);
504 #else
505  refill_64(s, 0);
506 #endif
507 
508 #ifdef BITSTREAM_READER_LE
509  return get_val(s, 1, 1);
510 #else
511  return get_val(s, 1, 0);
512 #endif
513 #else
514  unsigned int index = s->index;
515  uint8_t result = s->buffer[index >> 3];
516 #ifdef BITSTREAM_READER_LE
517  result >>= index & 7;
518  result &= 1;
519 #else
520  result <<= index & 7;
521  result >>= 8 - 1;
522 #endif
523 #if !UNCHECKED_BITSTREAM_READER
524  if (s->index < s->size_in_bits_plus8)
525 #endif
526  index++;
527  s->index = index;
528 
529  return result;
530 #endif
531 }
532 
533 static inline unsigned int show_bits1(GetBitContext *s)
534 {
535  return show_bits(s, 1);
536 }
537 
538 static inline void skip_bits1(GetBitContext *s)
539 {
540  skip_bits(s, 1);
541 }
542 
543 /**
544  * Read 0-32 bits.
545  */
546 static inline unsigned int get_bits_long(GetBitContext *s, int n)
547 {
548  av_assert2(n>=0 && n<=32);
549  if (!n) {
550  return 0;
551 #if CACHED_BITSTREAM_READER
552  }
553  return get_bits(s, n);
554 #else
555  } else if (n <= MIN_CACHE_BITS) {
556  return get_bits(s, n);
557  } else {
558 #ifdef BITSTREAM_READER_LE
559  unsigned ret = get_bits(s, 16);
560  return ret | (get_bits(s, n - 16) << 16);
561 #else
562  unsigned ret = get_bits(s, 16) << (n - 16);
563  return ret | get_bits(s, n - 16);
564 #endif
565  }
566 #endif
567 }
568 
569 /**
570  * Read 0-64 bits.
571  */
572 static inline uint64_t get_bits64(GetBitContext *s, int n)
573 {
574  if (n <= 32) {
575  return get_bits_long(s, n);
576  } else {
577 #ifdef BITSTREAM_READER_LE
578  uint64_t ret = get_bits_long(s, 32);
579  return ret | (uint64_t) get_bits_long(s, n - 32) << 32;
580 #else
581  uint64_t ret = (uint64_t) get_bits_long(s, n - 32) << 32;
582  return ret | get_bits_long(s, 32);
583 #endif
584  }
585 }
586 
587 /**
588  * Read 0-32 bits as a signed integer.
589  */
590 static inline int get_sbits_long(GetBitContext *s, int n)
591 {
592  // sign_extend(x, 0) is undefined
593  if (!n)
594  return 0;
595 
596  return sign_extend(get_bits_long(s, n), n);
597 }
598 
599 /**
600  * Show 0-32 bits.
601  */
602 static inline unsigned int show_bits_long(GetBitContext *s, int n)
603 {
604  if (n <= MIN_CACHE_BITS) {
605  return show_bits(s, n);
606  } else {
607  GetBitContext gb = *s;
608  return get_bits_long(&gb, n);
609  }
610 }
611 
612 static inline int check_marker(void *logctx, GetBitContext *s, const char *msg)
613 {
614  int bit = get_bits1(s);
615  if (!bit)
616  av_log(logctx, AV_LOG_INFO, "Marker bit missing at %d of %d %s\n",
617  get_bits_count(s) - 1, s->size_in_bits, msg);
618 
619  return bit;
620 }
621 
622 static inline int init_get_bits_xe(GetBitContext *s, const uint8_t *buffer,
623  int bit_size, int is_le)
624 {
625  int buffer_size;
626  int ret = 0;
627 
628  if (bit_size >= INT_MAX - FFMAX(7, AV_INPUT_BUFFER_PADDING_SIZE*8) || bit_size < 0 || !buffer) {
629  bit_size = 0;
630  buffer = NULL;
631  ret = AVERROR_INVALIDDATA;
632  }
633 
634  buffer_size = (bit_size + 7) >> 3;
635 
636  s->buffer = buffer;
637  s->size_in_bits = bit_size;
638  s->size_in_bits_plus8 = bit_size + 8;
639  s->buffer_end = buffer + buffer_size;
640  s->index = 0;
641 
642 #if CACHED_BITSTREAM_READER
643  s->cache = 0;
644  s->bits_left = 0;
645  refill_64(s, is_le);
646 #endif
647 
648  return ret;
649 }
650 
651 /**
652  * Initialize GetBitContext.
653  * @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes
654  * larger than the actual read bits because some optimized bitstream
655  * readers read 32 or 64 bit at once and could read over the end
656  * @param bit_size the size of the buffer in bits
657  * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow.
658  */
659 static inline int init_get_bits(GetBitContext *s, const uint8_t *buffer,
660  int bit_size)
661 {
662 #ifdef BITSTREAM_READER_LE
663  return init_get_bits_xe(s, buffer, bit_size, 1);
664 #else
665  return init_get_bits_xe(s, buffer, bit_size, 0);
666 #endif
667 }
668 
669 /**
670  * Initialize GetBitContext.
671  * @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes
672  * larger than the actual read bits because some optimized bitstream
673  * readers read 32 or 64 bit at once and could read over the end
674  * @param byte_size the size of the buffer in bytes
675  * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow.
676  */
677 static inline int init_get_bits8(GetBitContext *s, const uint8_t *buffer,
678  int byte_size)
679 {
680  if (byte_size > INT_MAX / 8 || byte_size < 0)
681  byte_size = -1;
682  return init_get_bits(s, buffer, byte_size * 8);
683 }
684 
685 static inline int init_get_bits8_le(GetBitContext *s, const uint8_t *buffer,
686  int byte_size)
687 {
688  if (byte_size > INT_MAX / 8 || byte_size < 0)
689  byte_size = -1;
690  return init_get_bits_xe(s, buffer, byte_size * 8, 1);
691 }
692 
693 static inline const uint8_t *align_get_bits(GetBitContext *s)
694 {
695  int n = -get_bits_count(s) & 7;
696  if (n)
697  skip_bits(s, n);
698  return s->buffer + (s->index >> 3);
699 }
700 
701 /**
702  * If the vlc code is invalid and max_depth=1, then no bits will be removed.
703  * If the vlc code is invalid and max_depth>1, then the number of bits removed
704  * is undefined.
705  */
706 #define GET_VLC(code, name, gb, table, bits, max_depth) \
707  do { \
708  int n, nb_bits; \
709  unsigned int index; \
710  \
711  index = SHOW_UBITS(name, gb, bits); \
712  code = table[index][0]; \
713  n = table[index][1]; \
714  \
715  if (max_depth > 1 && n < 0) { \
716  LAST_SKIP_BITS(name, gb, bits); \
717  UPDATE_CACHE(name, gb); \
718  \
719  nb_bits = -n; \
720  \
721  index = SHOW_UBITS(name, gb, nb_bits) + code; \
722  code = table[index][0]; \
723  n = table[index][1]; \
724  if (max_depth > 2 && n < 0) { \
725  LAST_SKIP_BITS(name, gb, nb_bits); \
726  UPDATE_CACHE(name, gb); \
727  \
728  nb_bits = -n; \
729  \
730  index = SHOW_UBITS(name, gb, nb_bits) + code; \
731  code = table[index][0]; \
732  n = table[index][1]; \
733  } \
734  } \
735  SKIP_BITS(name, gb, n); \
736  } while (0)
737 
738 #define GET_RL_VLC(level, run, name, gb, table, bits, \
739  max_depth, need_update) \
740  do { \
741  int n, nb_bits; \
742  unsigned int index; \
743  \
744  index = SHOW_UBITS(name, gb, bits); \
745  level = table[index].level; \
746  n = table[index].len; \
747  \
748  if (max_depth > 1 && n < 0) { \
749  SKIP_BITS(name, gb, bits); \
750  if (need_update) { \
751  UPDATE_CACHE(name, gb); \
752  } \
753  \
754  nb_bits = -n; \
755  \
756  index = SHOW_UBITS(name, gb, nb_bits) + level; \
757  level = table[index].level; \
758  n = table[index].len; \
759  if (max_depth > 2 && n < 0) { \
760  LAST_SKIP_BITS(name, gb, nb_bits); \
761  if (need_update) { \
762  UPDATE_CACHE(name, gb); \
763  } \
764  nb_bits = -n; \
765  \
766  index = SHOW_UBITS(name, gb, nb_bits) + level; \
767  level = table[index].level; \
768  n = table[index].len; \
769  } \
770  } \
771  run = table[index].run; \
772  SKIP_BITS(name, gb, n); \
773  } while (0)
774 
775 /* Return the LUT element for the given bitstream configuration. */
776 static inline int set_idx(GetBitContext *s, int code, int *n, int *nb_bits,
777  VLC_TYPE (*table)[2])
778 {
779  unsigned idx;
780 
781  *nb_bits = -*n;
782  idx = show_bits(s, *nb_bits) + code;
783  *n = table[idx][1];
784 
785  return table[idx][0];
786 }
787 
788 /**
789  * Parse a vlc code.
790  * @param bits is the number of bits which will be read at once, must be
791  * identical to nb_bits in init_vlc()
792  * @param max_depth is the number of times bits bits must be read to completely
793  * read the longest vlc code
794  * = (max_vlc_length + bits - 1) / bits
795  * @returns the code parsed or -1 if no vlc matches
796  */
798  int bits, int max_depth)
799 {
800 #if CACHED_BITSTREAM_READER
801  int nb_bits;
802  unsigned idx = show_bits(s, bits);
803  int code = table[idx][0];
804  int n = table[idx][1];
805 
806  if (max_depth > 1 && n < 0) {
807  skip_remaining(s, bits);
808  code = set_idx(s, code, &n, &nb_bits, table);
809  if (max_depth > 2 && n < 0) {
810  skip_remaining(s, nb_bits);
811  code = set_idx(s, code, &n, &nb_bits, table);
812  }
813  }
814  skip_remaining(s, n);
815 
816  return code;
817 #else
818  int code;
819 
820  OPEN_READER(re, s);
821  UPDATE_CACHE(re, s);
822 
823  GET_VLC(code, re, s, table, bits, max_depth);
824 
825  CLOSE_READER(re, s);
826 
827  return code;
828 #endif
829 }
830 
831 static inline int decode012(GetBitContext *gb)
832 {
833  int n;
834  n = get_bits1(gb);
835  if (n == 0)
836  return 0;
837  else
838  return get_bits1(gb) + 1;
839 }
840 
841 static inline int decode210(GetBitContext *gb)
842 {
843  if (get_bits1(gb))
844  return 0;
845  else
846  return 2 - get_bits1(gb);
847 }
848 
849 static inline int get_bits_left(GetBitContext *gb)
850 {
851  return gb->size_in_bits - get_bits_count(gb);
852 }
853 
854 static inline int skip_1stop_8data_bits(GetBitContext *gb)
855 {
856  if (get_bits_left(gb) <= 0)
857  return AVERROR_INVALIDDATA;
858 
859  while (get_bits1(gb)) {
860  skip_bits(gb, 8);
861  if (get_bits_left(gb) <= 0)
862  return AVERROR_INVALIDDATA;
863  }
864 
865  return 0;
866 }
867 
868 #endif /* AVCODEC_GET_BITS_H */
static int get_xbits_le(GetBitContext *s, int n)
Definition: get_bits.h:344
static unsigned int show_bits_long(GetBitContext *s, int n)
Show 0-32 bits.
Definition: get_bits.h:602
static unsigned int show_bits1(GetBitContext *s)
Definition: get_bits.h:533
#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:379
static void skip_bits_long(GetBitContext *s, int n)
Skips the specified number of bits.
Definition: get_bits.h:291
static int set_idx(GetBitContext *s, int code, int *n, int *nb_bits, VLC_TYPE(*table)[2])
Definition: get_bits.h:776
static int check_marker(void *logctx, GetBitContext *s, const char *msg)
Definition: get_bits.h:612
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:359
static int get_sbits_long(GetBitContext *s, int n)
Read 0-32 bits as a signed integer.
Definition: get_bits.h:590
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 int init_get_bits_xe(GetBitContext *s, const uint8_t *buffer, int bit_size, int is_le)
Definition: get_bits.h:622
static const uint16_t table[]
Definition: prosumer.c:206
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:849
static uint64_t get_bits64(GetBitContext *s, int n)
Read 0-64 bits.
Definition: get_bits.h:572
#define UPDATE_CACHE(name, gb)
Definition: get_bits.h:178
simple assert() macros that are a bit more flexible than ISO C assert().
uint8_t bits
Definition: vp3data.h:202
#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:446
#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:797
int n
Definition: avisynth_c.h:760
#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:706
#define SHOW_UBITS(name, gb, num)
Definition: get_bits.h:211
static int decode210(GetBitContext *gb)
Definition: get_bits.h:841
#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:677
static int get_xbits(GetBitContext *s, int n)
Read MPEG-1 dc-style VLC (sign bit + mantissa with no MSB).
Definition: get_bits.h:321
#define OPEN_READER(name, gb)
Definition: get_bits.h:138
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:498
static void skip_bits1(GetBitContext *s)
Definition: get_bits.h:538
static void skip_bits(GetBitContext *s, int n)
Definition: get_bits.h:467
#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:659
#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:546
#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:420
#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
#define bit(string, value)
Definition: cbs_mpeg2.c:58
const uint8_t * buffer_end
Definition: get_bits.h:62
static int init_get_bits8_le(GetBitContext *s, const uint8_t *buffer, int byte_size)
Definition: get_bits.h:685
#define AV_INPUT_BUFFER_PADDING_SIZE
Required number of additionally allocated bytes at the end of the input bitstream for decoding...
Definition: avcodec.h:791
static int decode012(GetBitContext *gb)
Definition: get_bits.h:831
static const uint8_t * align_get_bits(GetBitContext *s)
Definition: get_bits.h:693
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:854
#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:415
GLuint buffer
Definition: opengl_enc.c:101
static uint8_t tmp[11]
Definition: aes_ctr.c:26