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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 | ||
23 | * bitstream reader API header. | ||
24 | */ | ||
25 | |||
26 | #ifndef AVCODEC_GET_BITS_H | ||
27 | #define AVCODEC_GET_BITS_H | ||
28 | |||
29 | #include <stdint.h> | ||
30 | |||
31 | #include "libavutil/common.h" | ||
32 | #include "libavutil/intreadwrite.h" | ||
33 | #include "libavutil/avassert.h" | ||
34 | |||
35 | #include "defs.h" | ||
36 | #include "mathops.h" | ||
37 | #include "vlc.h" | ||
38 | |||
39 | /* | ||
40 | * Safe bitstream reading: | ||
41 | * optionally, the get_bits API can check to ensure that we | ||
42 | * don't read past input buffer boundaries. This is protected | ||
43 | * with CONFIG_SAFE_BITSTREAM_READER at the global level, and | ||
44 | * then below that with UNCHECKED_BITSTREAM_READER at the per- | ||
45 | * decoder level. This means that decoders that check internally | ||
46 | * can "#define UNCHECKED_BITSTREAM_READER 1" to disable | ||
47 | * overread checks. | ||
48 | * Boundary checking causes a minor performance penalty so for | ||
49 | * applications that won't want/need this, it can be disabled | ||
50 | * globally using "#define CONFIG_SAFE_BITSTREAM_READER 0". | ||
51 | */ | ||
52 | #ifndef UNCHECKED_BITSTREAM_READER | ||
53 | #define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER | ||
54 | #endif | ||
55 | |||
56 | #ifndef CACHED_BITSTREAM_READER | ||
57 | #define CACHED_BITSTREAM_READER 0 | ||
58 | #endif | ||
59 | |||
60 | #if CACHED_BITSTREAM_READER | ||
61 | |||
62 | // we always want the LE implementation, to provide get_bits_le() | ||
63 | #define BITSTREAM_LE | ||
64 | |||
65 | #ifndef BITSTREAM_READER_LE | ||
66 | # define BITSTREAM_BE | ||
67 | # define BITSTREAM_DEFAULT_BE | ||
68 | #endif | ||
69 | |||
70 | #include "bitstream.h" | ||
71 | |||
72 | #undef BITSTREAM_LE | ||
73 | #undef BITSTREAM_BE | ||
74 | #undef BITSTREAM_DEFAULT_BE | ||
75 | |||
76 | typedef BitstreamContext GetBitContext; | ||
77 | |||
78 | #define get_bits_count bits_tell | ||
79 | #define get_bits_left bits_left | ||
80 | #define skip_bits_long bits_skip | ||
81 | #define skip_bits bits_skip | ||
82 | #define get_bits bits_read_nz | ||
83 | #define get_bitsz bits_read | ||
84 | #define get_bits_long bits_read | ||
85 | #define get_bits1 bits_read_bit | ||
86 | #define get_bits64 bits_read_64 | ||
87 | #define get_xbits bits_read_xbits | ||
88 | #define get_sbits bits_read_signed_nz | ||
89 | #define get_sbits_long bits_read_signed | ||
90 | #define show_bits bits_peek | ||
91 | #define show_bits_long bits_peek | ||
92 | #define init_get_bits bits_init | ||
93 | #define init_get_bits8 bits_init8 | ||
94 | #define align_get_bits bits_align | ||
95 | #define get_vlc2 bits_read_vlc | ||
96 | #define get_vlc_multi bits_read_vlc_multi | ||
97 | |||
98 | #define init_get_bits8_le(s, buffer, byte_size) bits_init8_le((BitstreamContextLE*)s, buffer, byte_size) | ||
99 | #define get_bits_le(s, n) bits_read_le((BitstreamContextLE*)s, n) | ||
100 | |||
101 | #define show_bits1(s) bits_peek(s, 1) | ||
102 | #define skip_bits1(s) bits_skip(s, 1) | ||
103 | |||
104 | #define skip_1stop_8data_bits bits_skip_1stop_8data | ||
105 | |||
106 | #else // CACHED_BITSTREAM_READER | ||
107 | |||
108 | typedef struct GetBitContext { | ||
109 | const uint8_t *buffer, *buffer_end; | ||
110 | int index; | ||
111 | int size_in_bits; | ||
112 | int size_in_bits_plus8; | ||
113 | } GetBitContext; | ||
114 | |||
115 | static inline unsigned int get_bits(GetBitContext *s, int n); | ||
116 | static inline void skip_bits(GetBitContext *s, int n); | ||
117 | static inline unsigned int show_bits(GetBitContext *s, int n); | ||
118 | |||
119 | /* Bitstream reader API docs: | ||
120 | * name | ||
121 | * arbitrary name which is used as prefix for the internal variables | ||
122 | * | ||
123 | * gb | ||
124 | * getbitcontext | ||
125 | * | ||
126 | * OPEN_READER(name, gb) | ||
127 | * load gb into local variables | ||
128 | * | ||
129 | * CLOSE_READER(name, gb) | ||
130 | * store local vars in gb | ||
131 | * | ||
132 | * UPDATE_CACHE(name, gb) | ||
133 | * Refill the internal cache from the bitstream. | ||
134 | * After this call at least MIN_CACHE_BITS will be available. | ||
135 | * | ||
136 | * GET_CACHE(name, gb) | ||
137 | * Will output the contents of the internal cache, | ||
138 | * next bit is MSB of 32 or 64 bits (FIXME 64 bits). | ||
139 | * | ||
140 | * SHOW_UBITS(name, gb, num) | ||
141 | * Will return the next num bits. | ||
142 | * | ||
143 | * SHOW_SBITS(name, gb, num) | ||
144 | * Will return the next num bits and do sign extension. | ||
145 | * | ||
146 | * SKIP_BITS(name, gb, num) | ||
147 | * Will skip over the next num bits. | ||
148 | * Note, this is equivalent to SKIP_CACHE; SKIP_COUNTER. | ||
149 | * | ||
150 | * SKIP_CACHE(name, gb, num) | ||
151 | * Will remove the next num bits from the cache (note SKIP_COUNTER | ||
152 | * MUST be called before UPDATE_CACHE / CLOSE_READER). | ||
153 | * | ||
154 | * SKIP_COUNTER(name, gb, num) | ||
155 | * Will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS). | ||
156 | * | ||
157 | * LAST_SKIP_BITS(name, gb, num) | ||
158 | * Like SKIP_BITS, to be used if next call is UPDATE_CACHE or CLOSE_READER. | ||
159 | * | ||
160 | * BITS_LEFT(name, gb) | ||
161 | * Return the number of bits left | ||
162 | * | ||
163 | * For examples see get_bits, show_bits, skip_bits, get_vlc. | ||
164 | */ | ||
165 | |||
166 | #if defined LONG_BITSTREAM_READER | ||
167 | # define MIN_CACHE_BITS 32 | ||
168 | #else | ||
169 | # define MIN_CACHE_BITS 25 | ||
170 | #endif | ||
171 | |||
172 | #define OPEN_READER_NOSIZE(name, gb) \ | ||
173 | unsigned int name ## _index = (gb)->index; \ | ||
174 | unsigned int av_unused name ## _cache | ||
175 | |||
176 | #if UNCHECKED_BITSTREAM_READER | ||
177 | #define OPEN_READER(name, gb) OPEN_READER_NOSIZE(name, gb) | ||
178 | |||
179 | #define BITS_AVAILABLE(name, gb) 1 | ||
180 | #else | ||
181 | #define OPEN_READER(name, gb) \ | ||
182 | OPEN_READER_NOSIZE(name, gb); \ | ||
183 | unsigned int name ## _size_plus8 = (gb)->size_in_bits_plus8 | ||
184 | |||
185 | #define BITS_AVAILABLE(name, gb) name ## _index < name ## _size_plus8 | ||
186 | #endif | ||
187 | |||
188 | #define CLOSE_READER(name, gb) (gb)->index = name ## _index | ||
189 | |||
190 | #define UPDATE_CACHE_BE_EXT(name, gb, bits, dst_bits) name ## _cache = \ | ||
191 | AV_RB ## bits((gb)->buffer + (name ## _index >> 3)) << (name ## _index & 7) >> (bits - dst_bits) | ||
192 | |||
193 | #define UPDATE_CACHE_LE_EXT(name, gb, bits, dst_bits) name ## _cache = \ | ||
194 | (uint ## dst_bits ## _t)(AV_RL ## bits((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7)) | ||
195 | |||
196 | /* Using these two macros ensures that 32 bits are available. */ | ||
197 | # define UPDATE_CACHE_LE_32(name, gb) UPDATE_CACHE_LE_EXT(name, (gb), 64, 32) | ||
198 | |||
199 | # define UPDATE_CACHE_BE_32(name, gb) UPDATE_CACHE_BE_EXT(name, (gb), 64, 32) | ||
200 | |||
201 | # ifdef LONG_BITSTREAM_READER | ||
202 | |||
203 | # define UPDATE_CACHE_LE(name, gb) UPDATE_CACHE_LE_32(name, (gb)) | ||
204 | |||
205 | # define UPDATE_CACHE_BE(name, gb) UPDATE_CACHE_BE_32(name, (gb)) | ||
206 | |||
207 | #else | ||
208 | |||
209 | # define UPDATE_CACHE_LE(name, gb) UPDATE_CACHE_LE_EXT(name, (gb), 32, 32) | ||
210 | |||
211 | # define UPDATE_CACHE_BE(name, gb) UPDATE_CACHE_BE_EXT(name, (gb), 32, 32) | ||
212 | |||
213 | #endif | ||
214 | |||
215 | |||
216 | #ifdef BITSTREAM_READER_LE | ||
217 | |||
218 | # define UPDATE_CACHE(name, gb) UPDATE_CACHE_LE(name, gb) | ||
219 | # define UPDATE_CACHE_32(name, gb) UPDATE_CACHE_LE_32(name, (gb)) | ||
220 | |||
221 | # define SKIP_CACHE(name, gb, num) name ## _cache >>= (num) | ||
222 | |||
223 | #else | ||
224 | |||
225 | # define UPDATE_CACHE(name, gb) UPDATE_CACHE_BE(name, gb) | ||
226 | # define UPDATE_CACHE_32(name, gb) UPDATE_CACHE_BE_32(name, (gb)) | ||
227 | |||
228 | # define SKIP_CACHE(name, gb, num) name ## _cache <<= (num) | ||
229 | |||
230 | #endif | ||
231 | |||
232 | #if UNCHECKED_BITSTREAM_READER | ||
233 | # define SKIP_COUNTER(name, gb, num) name ## _index += (num) | ||
234 | #else | ||
235 | # define SKIP_COUNTER(name, gb, num) \ | ||
236 | name ## _index = FFMIN(name ## _size_plus8, name ## _index + (num)) | ||
237 | #endif | ||
238 | |||
239 | #define BITS_LEFT(name, gb) ((int)((gb)->size_in_bits - name ## _index)) | ||
240 | |||
241 | #define SKIP_BITS(name, gb, num) \ | ||
242 | do { \ | ||
243 | SKIP_CACHE(name, gb, num); \ | ||
244 | SKIP_COUNTER(name, gb, num); \ | ||
245 | } while (0) | ||
246 | |||
247 | #define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num) | ||
248 | |||
249 | #define SHOW_UBITS_LE(name, gb, num) zero_extend(name ## _cache, num) | ||
250 | #define SHOW_SBITS_LE(name, gb, num) sign_extend(name ## _cache, num) | ||
251 | |||
252 | #define SHOW_UBITS_BE(name, gb, num) NEG_USR32(name ## _cache, num) | ||
253 | #define SHOW_SBITS_BE(name, gb, num) NEG_SSR32(name ## _cache, num) | ||
254 | |||
255 | #ifdef BITSTREAM_READER_LE | ||
256 | # define SHOW_UBITS(name, gb, num) SHOW_UBITS_LE(name, gb, num) | ||
257 | # define SHOW_SBITS(name, gb, num) SHOW_SBITS_LE(name, gb, num) | ||
258 | #else | ||
259 | # define SHOW_UBITS(name, gb, num) SHOW_UBITS_BE(name, gb, num) | ||
260 | # define SHOW_SBITS(name, gb, num) SHOW_SBITS_BE(name, gb, num) | ||
261 | #endif | ||
262 | |||
263 | #define GET_CACHE(name, gb) ((uint32_t) name ## _cache) | ||
264 | |||
265 | |||
266 | 306785119 | static inline int get_bits_count(const GetBitContext *s) | |
267 | { | ||
268 | 306785119 | return s->index; | |
269 | } | ||
270 | |||
271 | /** | ||
272 | * Skips the specified number of bits. | ||
273 | * @param n the number of bits to skip, | ||
274 | * For the UNCHECKED_BITSTREAM_READER this must not cause the distance | ||
275 | * from the start to overflow int32_t. Staying within the bitstream + padding | ||
276 | * is sufficient, too. | ||
277 | */ | ||
278 | 4607349 | static inline void skip_bits_long(GetBitContext *s, int n) | |
279 | { | ||
280 | #if UNCHECKED_BITSTREAM_READER | ||
281 | 2783472 | s->index += n; | |
282 | #else | ||
283 | 1823877 | s->index += av_clip(n, -s->index, s->size_in_bits_plus8 - s->index); | |
284 | #endif | ||
285 | 4607349 | } | |
286 | |||
287 | /** | ||
288 | * Read MPEG-1 dc-style VLC (sign bit + mantissa with no MSB). | ||
289 | * if MSB not set it is negative | ||
290 | * @param n length in bits | ||
291 | */ | ||
292 | 26894473 | static inline int get_xbits(GetBitContext *s, int n) | |
293 | { | ||
294 | register int sign; | ||
295 | register int32_t cache; | ||
296 | 26894473 | OPEN_READER(re, s); | |
297 | av_assert2(n>0 && n<=25); | ||
298 | 26894473 | UPDATE_CACHE(re, s); | |
299 | 26894473 | cache = GET_CACHE(re, s); | |
300 | 26894473 | sign = ~cache >> 31; | |
301 | 26894473 | LAST_SKIP_BITS(re, s, n); | |
302 | 26894473 | CLOSE_READER(re, s); | |
303 | 26894473 | return (NEG_USR32(sign ^ cache, n) ^ sign) - sign; | |
304 | } | ||
305 | |||
306 | 1534760 | static inline int get_xbits_le(GetBitContext *s, int n) | |
307 | { | ||
308 | register int sign; | ||
309 | register int32_t cache; | ||
310 | 1534760 | OPEN_READER(re, s); | |
311 | av_assert2(n>0 && n<=25); | ||
312 | 1534760 | UPDATE_CACHE_LE(re, s); | |
313 | 1534760 | cache = GET_CACHE(re, s); | |
314 | 1534760 | sign = sign_extend(~cache, n) >> 31; | |
315 | 1534760 | LAST_SKIP_BITS(re, s, n); | |
316 | 1534760 | CLOSE_READER(re, s); | |
317 | 1534760 | return (zero_extend(sign ^ cache, n) ^ sign) - sign; | |
318 | } | ||
319 | |||
320 | 33303191 | static inline int get_sbits(GetBitContext *s, int n) | |
321 | { | ||
322 | register int tmp; | ||
323 | 33303191 | OPEN_READER(re, s); | |
324 | av_assert2(n>0 && n<=25); | ||
325 | 33303191 | UPDATE_CACHE(re, s); | |
326 | 33303191 | tmp = SHOW_SBITS(re, s, n); | |
327 | 33303191 | LAST_SKIP_BITS(re, s, n); | |
328 | 33303191 | CLOSE_READER(re, s); | |
329 | 33303191 | return tmp; | |
330 | } | ||
331 | |||
332 | /** | ||
333 | * Read 1-25 bits. | ||
334 | */ | ||
335 | 269915185 | static inline unsigned int get_bits(GetBitContext *s, int n) | |
336 | { | ||
337 | register unsigned int tmp; | ||
338 | 269915185 | OPEN_READER(re, s); | |
339 | av_assert2(n>0 && n<=25); | ||
340 | 269915185 | UPDATE_CACHE(re, s); | |
341 | 269915185 | tmp = SHOW_UBITS(re, s, n); | |
342 | 269915185 | LAST_SKIP_BITS(re, s, n); | |
343 | 269915185 | CLOSE_READER(re, s); | |
344 | av_assert2(tmp < UINT64_C(1) << n); | ||
345 | 269915185 | return tmp; | |
346 | } | ||
347 | |||
348 | /** | ||
349 | * Read 0-25 bits. | ||
350 | */ | ||
351 | 746532 | static av_always_inline int get_bitsz(GetBitContext *s, int n) | |
352 | { | ||
353 |
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746532 | return n ? get_bits(s, n) : 0; |
354 | } | ||
355 | |||
356 | 718813 | static inline unsigned int get_bits_le(GetBitContext *s, int n) | |
357 | { | ||
358 | register int tmp; | ||
359 | 718813 | OPEN_READER(re, s); | |
360 | av_assert2(n>0 && n<=25); | ||
361 | 718813 | UPDATE_CACHE_LE(re, s); | |
362 | 718813 | tmp = SHOW_UBITS_LE(re, s, n); | |
363 | 718813 | LAST_SKIP_BITS(re, s, n); | |
364 | 718813 | CLOSE_READER(re, s); | |
365 | 718813 | return tmp; | |
366 | } | ||
367 | |||
368 | /** | ||
369 | * Show 1-25 bits. | ||
370 | */ | ||
371 | 113616678 | static inline unsigned int show_bits(GetBitContext *s, int n) | |
372 | { | ||
373 | register unsigned int tmp; | ||
374 | 113616678 | OPEN_READER_NOSIZE(re, s); | |
375 | av_assert2(n>0 && n<=25); | ||
376 | 113616678 | UPDATE_CACHE(re, s); | |
377 | 113616678 | tmp = SHOW_UBITS(re, s, n); | |
378 | 113616678 | return tmp; | |
379 | } | ||
380 | |||
381 | 110732197 | static inline void skip_bits(GetBitContext *s, int n) | |
382 | { | ||
383 | 110732197 | OPEN_READER(re, s); | |
384 | 110732197 | LAST_SKIP_BITS(re, s, n); | |
385 | 110732197 | CLOSE_READER(re, s); | |
386 | 110732197 | } | |
387 | |||
388 | 459151984 | static inline unsigned int get_bits1(GetBitContext *s) | |
389 | { | ||
390 | 459151984 | unsigned int index = s->index; | |
391 | 459151984 | uint8_t result = s->buffer[index >> 3]; | |
392 | #ifdef BITSTREAM_READER_LE | ||
393 | 265288507 | result >>= index & 7; | |
394 | 265288507 | result &= 1; | |
395 | #else | ||
396 | 193863477 | result <<= index & 7; | |
397 | 193863477 | result >>= 8 - 1; | |
398 | #endif | ||
399 | #if !UNCHECKED_BITSTREAM_READER | ||
400 |
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415893980 | if (s->index < s->size_in_bits_plus8) |
401 | #endif | ||
402 | 459136753 | index++; | |
403 | 459151984 | s->index = index; | |
404 | |||
405 | 459151984 | return result; | |
406 | } | ||
407 | |||
408 | 43281 | static inline unsigned int show_bits1(GetBitContext *s) | |
409 | { | ||
410 | 43281 | return show_bits(s, 1); | |
411 | } | ||
412 | |||
413 | 303833 | static inline void skip_bits1(GetBitContext *s) | |
414 | { | ||
415 | 303833 | skip_bits(s, 1); | |
416 | 303833 | } | |
417 | |||
418 | /** | ||
419 | * Read 0-32 bits. | ||
420 | */ | ||
421 | 57013767 | static inline unsigned int get_bits_long(GetBitContext *s, int n) | |
422 | { | ||
423 | av_assert2(n>=0 && n<=32); | ||
424 |
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57013767 | if (!n) { |
425 | 3404960 | return 0; | |
426 | } else if ((!HAVE_FAST_64BIT || av_builtin_constant_p(n <= MIN_CACHE_BITS)) | ||
427 | && n <= MIN_CACHE_BITS) { | ||
428 | return get_bits(s, n); | ||
429 | } else { | ||
430 | #if HAVE_FAST_64BIT | ||
431 | unsigned tmp; | ||
432 | 53608807 | OPEN_READER(re, s); | |
433 | 53608807 | UPDATE_CACHE_32(re, s); | |
434 | 53608807 | tmp = SHOW_UBITS(re, s, n); | |
435 | 53608807 | LAST_SKIP_BITS(re, s, n); | |
436 | 53608807 | CLOSE_READER(re, s); | |
437 | 53608807 | return tmp; | |
438 | #else | ||
439 | #ifdef BITSTREAM_READER_LE | ||
440 | unsigned ret = get_bits(s, 16); | ||
441 | return ret | (get_bits(s, n - 16) << 16); | ||
442 | #else | ||
443 | unsigned ret = get_bits(s, 16) << (n - 16); | ||
444 | return ret | get_bits(s, n - 16); | ||
445 | #endif | ||
446 | #endif | ||
447 | } | ||
448 | } | ||
449 | |||
450 | /** | ||
451 | * Read 0-64 bits. | ||
452 | */ | ||
453 | 11370 | static inline uint64_t get_bits64(GetBitContext *s, int n) | |
454 | { | ||
455 |
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11370 | if (n <= 32) { |
456 | 6375 | return get_bits_long(s, n); | |
457 | } else { | ||
458 | #ifdef BITSTREAM_READER_LE | ||
459 | 1 | uint64_t ret = get_bits_long(s, 32); | |
460 | 1 | return ret | (uint64_t) get_bits_long(s, n - 32) << 32; | |
461 | #else | ||
462 | 4994 | uint64_t ret = (uint64_t) get_bits_long(s, n - 32) << 32; | |
463 | 4994 | return ret | get_bits_long(s, 32); | |
464 | #endif | ||
465 | } | ||
466 | } | ||
467 | |||
468 | /** | ||
469 | * Read 0-32 bits as a signed integer. | ||
470 | */ | ||
471 | 4766752 | static inline int get_sbits_long(GetBitContext *s, int n) | |
472 | { | ||
473 | // sign_extend(x, 0) is undefined | ||
474 |
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4766752 | if (!n) |
475 | ✗ | return 0; | |
476 | |||
477 | 4766752 | return sign_extend(get_bits_long(s, n), n); | |
478 | } | ||
479 | |||
480 | /** | ||
481 | * Read 0-64 bits as a signed integer. | ||
482 | */ | ||
483 | 4624 | static inline int64_t get_sbits64(GetBitContext *s, int n) | |
484 | { | ||
485 | // sign_extend(x, 0) is undefined | ||
486 |
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4624 | if (!n) |
487 | ✗ | return 0; | |
488 | |||
489 | 4624 | return sign_extend64(get_bits64(s, n), n); | |
490 | } | ||
491 | |||
492 | /** | ||
493 | * Show 0-32 bits. | ||
494 | */ | ||
495 | 3412737 | static inline unsigned int show_bits_long(GetBitContext *s, int n) | |
496 | { | ||
497 |
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3412737 | if (n <= MIN_CACHE_BITS) { |
498 | 17732 | return show_bits(s, n); | |
499 | } else { | ||
500 | 3395005 | GetBitContext gb = *s; | |
501 | 3395005 | return get_bits_long(&gb, n); | |
502 | } | ||
503 | } | ||
504 | |||
505 | |||
506 | /** | ||
507 | * Initialize GetBitContext. | ||
508 | * @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes | ||
509 | * larger than the actual read bits because some optimized bitstream | ||
510 | * readers read 32 or 64 bit at once and could read over the end | ||
511 | * @param bit_size the size of the buffer in bits | ||
512 | * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow. | ||
513 | */ | ||
514 | 29829872 | static inline int init_get_bits(GetBitContext *s, const uint8_t *buffer, | |
515 | int bit_size) | ||
516 | { | ||
517 | int buffer_size; | ||
518 | 29829872 | int ret = 0; | |
519 | |||
520 |
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29829872 | if (bit_size >= INT_MAX - FFMAX(7, AV_INPUT_BUFFER_PADDING_SIZE*8) || bit_size < 0 || !buffer) { |
521 | 4 | bit_size = 0; | |
522 | 4 | buffer = NULL; | |
523 | 4 | ret = AVERROR_INVALIDDATA; | |
524 | } | ||
525 | |||
526 | 29829872 | buffer_size = (bit_size + 7) >> 3; | |
527 | |||
528 | 29829872 | s->buffer = buffer; | |
529 | 29829872 | s->size_in_bits = bit_size; | |
530 | 29829872 | s->size_in_bits_plus8 = bit_size + 8; | |
531 | 29829872 | s->buffer_end = buffer + buffer_size; | |
532 | 29829872 | s->index = 0; | |
533 | |||
534 | 29829872 | return ret; | |
535 | } | ||
536 | |||
537 | /** | ||
538 | * Initialize GetBitContext. | ||
539 | * @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes | ||
540 | * larger than the actual read bits because some optimized bitstream | ||
541 | * readers read 32 or 64 bit at once and could read over the end | ||
542 | * @param byte_size the size of the buffer in bytes | ||
543 | * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow. | ||
544 | */ | ||
545 | 685341 | static inline int init_get_bits8(GetBitContext *s, const uint8_t *buffer, | |
546 | int byte_size) | ||
547 | { | ||
548 |
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685341 | if (byte_size > INT_MAX / 8 || byte_size < 0) |
549 | ✗ | byte_size = -1; | |
550 | 685341 | return init_get_bits(s, buffer, byte_size * 8); | |
551 | } | ||
552 | |||
553 | 200 | static inline int init_get_bits8_le(GetBitContext *s, const uint8_t *buffer, | |
554 | int byte_size) | ||
555 | { | ||
556 |
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200 | if (byte_size > INT_MAX / 8 || byte_size < 0) |
557 | ✗ | byte_size = -1; | |
558 | 200 | return init_get_bits(s, buffer, byte_size * 8); | |
559 | } | ||
560 | |||
561 | 253822 | static inline const uint8_t *align_get_bits(GetBitContext *s) | |
562 | { | ||
563 | 253822 | int n = -get_bits_count(s) & 7; | |
564 |
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253822 | if (n) |
565 | 69975 | skip_bits(s, n); | |
566 | 253822 | return s->buffer + (s->index >> 3); | |
567 | } | ||
568 | |||
569 | /** | ||
570 | * If the vlc code is invalid and max_depth=1, then no bits will be removed. | ||
571 | * If the vlc code is invalid and max_depth>1, then the number of bits removed | ||
572 | * is undefined. | ||
573 | */ | ||
574 | #define GET_VLC(code, name, gb, table, bits, max_depth) \ | ||
575 | do { \ | ||
576 | int n, nb_bits; \ | ||
577 | unsigned int index; \ | ||
578 | \ | ||
579 | index = SHOW_UBITS(name, gb, bits); \ | ||
580 | code = table[index].sym; \ | ||
581 | n = table[index].len; \ | ||
582 | \ | ||
583 | if (max_depth > 1 && n < 0) { \ | ||
584 | LAST_SKIP_BITS(name, gb, bits); \ | ||
585 | UPDATE_CACHE(name, gb); \ | ||
586 | \ | ||
587 | nb_bits = -n; \ | ||
588 | \ | ||
589 | index = SHOW_UBITS(name, gb, nb_bits) + code; \ | ||
590 | code = table[index].sym; \ | ||
591 | n = table[index].len; \ | ||
592 | if (max_depth > 2 && n < 0) { \ | ||
593 | LAST_SKIP_BITS(name, gb, nb_bits); \ | ||
594 | UPDATE_CACHE(name, gb); \ | ||
595 | \ | ||
596 | nb_bits = -n; \ | ||
597 | \ | ||
598 | index = SHOW_UBITS(name, gb, nb_bits) + code; \ | ||
599 | code = table[index].sym; \ | ||
600 | n = table[index].len; \ | ||
601 | } \ | ||
602 | } \ | ||
603 | SKIP_BITS(name, gb, n); \ | ||
604 | } while (0) | ||
605 | |||
606 | #define GET_RL_VLC(level, run, name, gb, table, bits, \ | ||
607 | max_depth, need_update) \ | ||
608 | do { \ | ||
609 | int n, nb_bits; \ | ||
610 | unsigned int index; \ | ||
611 | \ | ||
612 | index = SHOW_UBITS(name, gb, bits); \ | ||
613 | level = table[index].level; \ | ||
614 | n = table[index].len; \ | ||
615 | \ | ||
616 | if (max_depth > 1 && n < 0) { \ | ||
617 | SKIP_BITS(name, gb, bits); \ | ||
618 | if (need_update) { \ | ||
619 | UPDATE_CACHE(name, gb); \ | ||
620 | } \ | ||
621 | \ | ||
622 | nb_bits = -n; \ | ||
623 | \ | ||
624 | index = SHOW_UBITS(name, gb, nb_bits) + level; \ | ||
625 | level = table[index].level; \ | ||
626 | n = table[index].len; \ | ||
627 | if (max_depth > 2 && n < 0) { \ | ||
628 | LAST_SKIP_BITS(name, gb, nb_bits); \ | ||
629 | if (need_update) { \ | ||
630 | UPDATE_CACHE(name, gb); \ | ||
631 | } \ | ||
632 | nb_bits = -n; \ | ||
633 | \ | ||
634 | index = SHOW_UBITS(name, gb, nb_bits) + level; \ | ||
635 | level = table[index].level; \ | ||
636 | n = table[index].len; \ | ||
637 | } \ | ||
638 | } \ | ||
639 | run = table[index].run; \ | ||
640 | SKIP_BITS(name, gb, n); \ | ||
641 | } while (0) | ||
642 | |||
643 | /** | ||
644 | * Parse a vlc code. | ||
645 | * @param bits is the number of bits which will be read at once, must be | ||
646 | * identical to nb_bits in vlc_init() | ||
647 | * @param max_depth is the number of times bits bits must be read to completely | ||
648 | * read the longest vlc code | ||
649 | * = (max_vlc_length + bits - 1) / bits | ||
650 | * @returns the code parsed or -1 if no vlc matches | ||
651 | */ | ||
652 | 291797191 | static av_always_inline int get_vlc2(GetBitContext *s, const VLCElem *table, | |
653 | int bits, int max_depth) | ||
654 | { | ||
655 | int code; | ||
656 | |||
657 | 291797191 | OPEN_READER(re, s); | |
658 | 291797191 | UPDATE_CACHE(re, s); | |
659 | |||
660 |
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291797191 | GET_VLC(code, re, s, table, bits, max_depth); |
661 | |||
662 | 291797191 | CLOSE_READER(re, s); | |
663 | |||
664 | 291797191 | return code; | |
665 | } | ||
666 | |||
667 | static inline int get_vlc_multi(GetBitContext *s, uint8_t *dst, | ||
668 | const VLC_MULTI_ELEM *const Jtable, | ||
669 | const VLCElem *const table, | ||
670 | const int bits, const int max_depth, | ||
671 | const int symbols_size) | ||
672 | { | ||
673 | dst[0] = get_vlc2(s, table, bits, max_depth); | ||
674 | return 1; | ||
675 | } | ||
676 | |||
677 | 378878 | static inline int decode012(GetBitContext *gb) | |
678 | { | ||
679 | int n; | ||
680 | 378878 | n = get_bits1(gb); | |
681 |
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378878 | if (n == 0) |
682 | 263931 | return 0; | |
683 | else | ||
684 | 114947 | return get_bits1(gb) + 1; | |
685 | } | ||
686 | |||
687 | 191971 | static inline int decode210(GetBitContext *gb) | |
688 | { | ||
689 |
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191971 | if (get_bits1(gb)) |
690 | 135836 | return 0; | |
691 | else | ||
692 | 56135 | return 2 - get_bits1(gb); | |
693 | } | ||
694 | |||
695 | 271081208 | static inline int get_bits_left(GetBitContext *gb) | |
696 | { | ||
697 | 271081208 | return gb->size_in_bits - get_bits_count(gb); | |
698 | } | ||
699 | |||
700 | 134686 | static inline int skip_1stop_8data_bits(GetBitContext *gb) | |
701 | { | ||
702 |
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134686 | if (get_bits_left(gb) <= 0) |
703 | ✗ | return AVERROR_INVALIDDATA; | |
704 | |||
705 |
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137800 | while (get_bits1(gb)) { |
706 | 3114 | skip_bits(gb, 8); | |
707 |
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3114 | if (get_bits_left(gb) <= 0) |
708 | ✗ | return AVERROR_INVALIDDATA; | |
709 | } | ||
710 | |||
711 | 134686 | return 0; | |
712 | } | ||
713 | |||
714 | #endif // CACHED_BITSTREAM_READER | ||
715 | |||
716 | #endif /* AVCODEC_GET_BITS_H */ | ||
717 |