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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 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  return tmp;
407 }
408 
409 /**
410  * Read 0-25 bits.
411  */
413 {
414  return n ? get_bits(s, n) : 0;
415 }
416 
417 static inline unsigned int get_bits_le(GetBitContext *s, int n)
418 {
419 #if CACHED_BITSTREAM_READER
420  av_assert2(n>0 && n<=32);
421  if (n > s->bits_left) {
422  refill_32(s);
423  if (s->bits_left < 32)
424  s->bits_left = n;
425  }
426 
427  return get_val(s, n, 1);
428 #else
429  register int tmp;
430  OPEN_READER(re, s);
431  av_assert2(n>0 && n<=25);
432  UPDATE_CACHE_LE(re, s);
433  tmp = SHOW_UBITS_LE(re, s, n);
434  LAST_SKIP_BITS(re, s, n);
435  CLOSE_READER(re, s);
436  return tmp;
437 #endif
438 }
439 
440 /**
441  * Show 1-25 bits.
442  */
443 static inline unsigned int show_bits(GetBitContext *s, int n)
444 {
445  register int tmp;
446 #if CACHED_BITSTREAM_READER
447  if (n > s->bits_left)
448  refill_32(s);
449 
450  tmp = show_val(s, n);
451 #else
453  av_assert2(n>0 && n<=25);
454  UPDATE_CACHE(re, s);
455  tmp = SHOW_UBITS(re, s, n);
456 #endif
457  return tmp;
458 }
459 
460 static inline void skip_bits(GetBitContext *s, int n)
461 {
462 #if CACHED_BITSTREAM_READER
463  if (n < s->bits_left)
464  skip_remaining(s, n);
465  else {
466  n -= s->bits_left;
467  s->cache = 0;
468  s->bits_left = 0;
469 
470  if (n >= 64) {
471  unsigned skip = (n / 8) * 8;
472 
473  n -= skip;
474  s->index += skip;
475  }
476  refill_64(s);
477  if (n)
478  skip_remaining(s, n);
479  }
480 #else
481  OPEN_READER(re, s);
482  LAST_SKIP_BITS(re, s, n);
483  CLOSE_READER(re, s);
484 #endif
485 }
486 
487 static inline unsigned int get_bits1(GetBitContext *s)
488 {
489 #if CACHED_BITSTREAM_READER
490  if (!s->bits_left)
491  refill_64(s);
492 
493 #ifdef BITSTREAM_READER_LE
494  return get_val(s, 1, 1);
495 #else
496  return get_val(s, 1, 0);
497 #endif
498 #else
499  unsigned int index = s->index;
500  uint8_t result = s->buffer[index >> 3];
501 #ifdef BITSTREAM_READER_LE
502  result >>= index & 7;
503  result &= 1;
504 #else
505  result <<= index & 7;
506  result >>= 8 - 1;
507 #endif
508 #if !UNCHECKED_BITSTREAM_READER
509  if (s->index < s->size_in_bits_plus8)
510 #endif
511  index++;
512  s->index = index;
513 
514  return result;
515 #endif
516 }
517 
518 static inline unsigned int show_bits1(GetBitContext *s)
519 {
520  return show_bits(s, 1);
521 }
522 
523 static inline void skip_bits1(GetBitContext *s)
524 {
525  skip_bits(s, 1);
526 }
527 
528 /**
529  * Read 0-32 bits.
530  */
531 static inline unsigned int get_bits_long(GetBitContext *s, int n)
532 {
533  av_assert2(n>=0 && n<=32);
534  if (!n) {
535  return 0;
536 #if CACHED_BITSTREAM_READER
537  }
538  return get_bits(s, n);
539 #else
540  } else if (n <= MIN_CACHE_BITS) {
541  return get_bits(s, n);
542  } else {
543 #ifdef BITSTREAM_READER_LE
544  unsigned ret = get_bits(s, 16);
545  return ret | (get_bits(s, n - 16) << 16);
546 #else
547  unsigned ret = get_bits(s, 16) << (n - 16);
548  return ret | get_bits(s, n - 16);
549 #endif
550  }
551 #endif
552 }
553 
554 /**
555  * Read 0-64 bits.
556  */
557 static inline uint64_t get_bits64(GetBitContext *s, int n)
558 {
559  if (n <= 32) {
560  return get_bits_long(s, n);
561  } else {
562 #ifdef BITSTREAM_READER_LE
563  uint64_t ret = get_bits_long(s, 32);
564  return ret | (uint64_t) get_bits_long(s, n - 32) << 32;
565 #else
566  uint64_t ret = (uint64_t) get_bits_long(s, n - 32) << 32;
567  return ret | get_bits_long(s, 32);
568 #endif
569  }
570 }
571 
572 /**
573  * Read 0-32 bits as a signed integer.
574  */
575 static inline int get_sbits_long(GetBitContext *s, int n)
576 {
577  // sign_extend(x, 0) is undefined
578  if (!n)
579  return 0;
580 
581  return sign_extend(get_bits_long(s, n), n);
582 }
583 
584 /**
585  * Show 0-32 bits.
586  */
587 static inline unsigned int show_bits_long(GetBitContext *s, int n)
588 {
589  if (n <= MIN_CACHE_BITS) {
590  return show_bits(s, n);
591  } else {
592  GetBitContext gb = *s;
593  return get_bits_long(&gb, n);
594  }
595 }
596 
597 static inline int check_marker(void *logctx, GetBitContext *s, const char *msg)
598 {
599  int bit = get_bits1(s);
600  if (!bit)
601  av_log(logctx, AV_LOG_INFO, "Marker bit missing at %d of %d %s\n",
602  get_bits_count(s) - 1, s->size_in_bits, msg);
603 
604  return bit;
605 }
606 
607 /**
608  * Initialize GetBitContext.
609  * @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes
610  * larger than the actual read bits because some optimized bitstream
611  * readers read 32 or 64 bit at once and could read over the end
612  * @param bit_size the size of the buffer in bits
613  * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow.
614  */
615 static inline int init_get_bits(GetBitContext *s, const uint8_t *buffer,
616  int bit_size)
617 {
618  int buffer_size;
619  int ret = 0;
620 
621  if (bit_size >= INT_MAX - FFMAX(7, AV_INPUT_BUFFER_PADDING_SIZE*8) || bit_size < 0 || !buffer) {
622  bit_size = 0;
623  buffer = NULL;
624  ret = AVERROR_INVALIDDATA;
625  }
626 
627  buffer_size = (bit_size + 7) >> 3;
628 
629  s->buffer = buffer;
630  s->size_in_bits = bit_size;
631  s->size_in_bits_plus8 = bit_size + 8;
632  s->buffer_end = buffer + buffer_size;
633  s->index = 0;
634 
635 #if CACHED_BITSTREAM_READER
636  refill_64(s);
637 #endif
638 
639  return ret;
640 }
641 
642 /**
643  * Initialize GetBitContext.
644  * @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes
645  * larger than the actual read bits because some optimized bitstream
646  * readers read 32 or 64 bit at once and could read over the end
647  * @param byte_size the size of the buffer in bytes
648  * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow.
649  */
650 static inline int init_get_bits8(GetBitContext *s, const uint8_t *buffer,
651  int byte_size)
652 {
653  if (byte_size > INT_MAX / 8 || byte_size < 0)
654  byte_size = -1;
655  return init_get_bits(s, buffer, byte_size * 8);
656 }
657 
658 static inline const uint8_t *align_get_bits(GetBitContext *s)
659 {
660  int n = -get_bits_count(s) & 7;
661  if (n)
662  skip_bits(s, n);
663  return s->buffer + (s->index >> 3);
664 }
665 
666 /**
667  * If the vlc code is invalid and max_depth=1, then no bits will be removed.
668  * If the vlc code is invalid and max_depth>1, then the number of bits removed
669  * is undefined.
670  */
671 #define GET_VLC(code, name, gb, table, bits, max_depth) \
672  do { \
673  int n, nb_bits; \
674  unsigned int index; \
675  \
676  index = SHOW_UBITS(name, gb, bits); \
677  code = table[index][0]; \
678  n = table[index][1]; \
679  \
680  if (max_depth > 1 && n < 0) { \
681  LAST_SKIP_BITS(name, gb, bits); \
682  UPDATE_CACHE(name, gb); \
683  \
684  nb_bits = -n; \
685  \
686  index = SHOW_UBITS(name, gb, nb_bits) + code; \
687  code = table[index][0]; \
688  n = table[index][1]; \
689  if (max_depth > 2 && n < 0) { \
690  LAST_SKIP_BITS(name, gb, nb_bits); \
691  UPDATE_CACHE(name, gb); \
692  \
693  nb_bits = -n; \
694  \
695  index = SHOW_UBITS(name, gb, nb_bits) + code; \
696  code = table[index][0]; \
697  n = table[index][1]; \
698  } \
699  } \
700  SKIP_BITS(name, gb, n); \
701  } while (0)
702 
703 #define GET_RL_VLC(level, run, name, gb, table, bits, \
704  max_depth, need_update) \
705  do { \
706  int n, nb_bits; \
707  unsigned int index; \
708  \
709  index = SHOW_UBITS(name, gb, bits); \
710  level = table[index].level; \
711  n = table[index].len; \
712  \
713  if (max_depth > 1 && n < 0) { \
714  SKIP_BITS(name, gb, bits); \
715  if (need_update) { \
716  UPDATE_CACHE(name, gb); \
717  } \
718  \
719  nb_bits = -n; \
720  \
721  index = SHOW_UBITS(name, gb, nb_bits) + level; \
722  level = table[index].level; \
723  n = table[index].len; \
724  if (max_depth > 2 && n < 0) { \
725  LAST_SKIP_BITS(name, gb, nb_bits); \
726  if (need_update) { \
727  UPDATE_CACHE(name, gb); \
728  } \
729  nb_bits = -n; \
730  \
731  index = SHOW_UBITS(name, gb, nb_bits) + level; \
732  level = table[index].level; \
733  n = table[index].len; \
734  } \
735  } \
736  run = table[index].run; \
737  SKIP_BITS(name, gb, n); \
738  } while (0)
739 
740 /* Return the LUT element for the given bitstream configuration. */
741 static inline int set_idx(GetBitContext *s, int code, int *n, int *nb_bits,
742  VLC_TYPE (*table)[2])
743 {
744  unsigned idx;
745 
746  *nb_bits = -*n;
747  idx = show_bits(s, *nb_bits) + code;
748  *n = table[idx][1];
749 
750  return table[idx][0];
751 }
752 
753 /**
754  * Parse a vlc code.
755  * @param bits is the number of bits which will be read at once, must be
756  * identical to nb_bits in init_vlc()
757  * @param max_depth is the number of times bits bits must be read to completely
758  * read the longest vlc code
759  * = (max_vlc_length + bits - 1) / bits
760  * @returns the code parsed or -1 if no vlc matches
761  */
763  int bits, int max_depth)
764 {
765 #if CACHED_BITSTREAM_READER
766  int nb_bits;
767  unsigned idx = show_bits(s, bits);
768  int code = table[idx][0];
769  int n = table[idx][1];
770 
771  if (max_depth > 1 && n < 0) {
772  skip_remaining(s, bits);
773  code = set_idx(s, code, &n, &nb_bits, table);
774  if (max_depth > 2 && n < 0) {
775  skip_remaining(s, nb_bits);
776  code = set_idx(s, code, &n, &nb_bits, table);
777  }
778  }
779  skip_remaining(s, n);
780 
781  return code;
782 #else
783  int code;
784 
785  OPEN_READER(re, s);
786  UPDATE_CACHE(re, s);
787 
788  GET_VLC(code, re, s, table, bits, max_depth);
789 
790  CLOSE_READER(re, s);
791 
792  return code;
793 #endif
794 }
795 
796 static inline int decode012(GetBitContext *gb)
797 {
798  int n;
799  n = get_bits1(gb);
800  if (n == 0)
801  return 0;
802  else
803  return get_bits1(gb) + 1;
804 }
805 
806 static inline int decode210(GetBitContext *gb)
807 {
808  if (get_bits1(gb))
809  return 0;
810  else
811  return 2 - get_bits1(gb);
812 }
813 
814 static inline int get_bits_left(GetBitContext *gb)
815 {
816  return gb->size_in_bits - get_bits_count(gb);
817 }
818 
819 static inline int skip_1stop_8data_bits(GetBitContext *gb)
820 {
821  if (get_bits_left(gb) <= 0)
822  return AVERROR_INVALIDDATA;
823 
824  while (get_bits1(gb)) {
825  skip_bits(gb, 8);
826  if (get_bits_left(gb) <= 0)
827  return AVERROR_INVALIDDATA;
828  }
829 
830  return 0;
831 }
832 
833 #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:587
static unsigned int show_bits1(GetBitContext *s)
Definition: get_bits.h:518
#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:741
static int check_marker(void *logctx, GetBitContext *s, const char *msg)
Definition: get_bits.h:597
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:575
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 get_bits_left(GetBitContext *gb)
Definition: get_bits.h:814
static uint64_t get_bits64(GetBitContext *s, int n)
Read 0-64 bits.
Definition: get_bits.h:557
#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:443
#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:762
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:671
#define SHOW_UBITS(name, gb, num)
Definition: get_bits.h:211
static int decode210(GetBitContext *gb)
Definition: get_bits.h:806
#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:650
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:487
static void skip_bits1(GetBitContext *s)
Definition: get_bits.h:523
static const uint32_t table[]
Definition: prosumer.c:204
static void skip_bits(GetBitContext *s, int n)
Definition: get_bits.h:460
int index
Definition: gxfenc.c:89
#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:615
#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:531
#define MIN_CACHE_BITS
Definition: get_bits.h:128
static av_const int sign_extend(int val, unsigned bits)
Definition: mathops.h:130
static unsigned int get_bits_le(GetBitContext *s, int n)
Definition: get_bits.h:417
#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:781
static int decode012(GetBitContext *gb)
Definition: get_bits.h:796
static const uint8_t * align_get_bits(GetBitContext *s)
Definition: get_bits.h:658
static int skip_1stop_8data_bits(GetBitContext *gb)
Definition: get_bits.h:819
#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:412
GLuint buffer
Definition: opengl_enc.c:102
static uint8_t tmp[11]
Definition: aes_ctr.c:26