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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_bytesize bits_bytesize | ||
80 | #define get_bits_left bits_left | ||
81 | #define skip_bits_long bits_skip | ||
82 | #define skip_bits bits_skip | ||
83 | #define get_bits bits_read_nz | ||
84 | #define get_bitsz bits_read | ||
85 | #define get_bits_long bits_read | ||
86 | #define get_bits1 bits_read_bit | ||
87 | #define get_bits64 bits_read_64 | ||
88 | #define get_xbits bits_read_xbits | ||
89 | #define get_sbits bits_read_signed_nz | ||
90 | #define get_sbits_long bits_read_signed | ||
91 | #define show_bits bits_peek | ||
92 | #define show_bits_long bits_peek | ||
93 | #define init_get_bits bits_init | ||
94 | #define init_get_bits8 bits_init8 | ||
95 | #define align_get_bits bits_align | ||
96 | #define get_vlc2 bits_read_vlc | ||
97 | #define get_vlc_multi bits_read_vlc_multi | ||
98 | |||
99 | #define init_get_bits8_le(s, buffer, byte_size) bits_init8_le((BitstreamContextLE*)s, buffer, byte_size) | ||
100 | #define get_bits_le(s, n) bits_read_le((BitstreamContextLE*)s, n) | ||
101 | |||
102 | #define show_bits1(s) bits_peek(s, 1) | ||
103 | #define skip_bits1(s) bits_skip(s, 1) | ||
104 | |||
105 | #define skip_1stop_8data_bits bits_skip_1stop_8data | ||
106 | |||
107 | #else // CACHED_BITSTREAM_READER | ||
108 | |||
109 | typedef struct GetBitContext { | ||
110 | const uint8_t *buffer; | ||
111 | int index; | ||
112 | int size_in_bits; | ||
113 | int size_in_bits_plus8; | ||
114 | } GetBitContext; | ||
115 | |||
116 | static inline unsigned int get_bits(GetBitContext *s, int n); | ||
117 | static inline void skip_bits(GetBitContext *s, int n); | ||
118 | static inline unsigned int show_bits(GetBitContext *s, int n); | ||
119 | |||
120 | /* Bitstream reader API docs: | ||
121 | * name | ||
122 | * arbitrary name which is used as prefix for the internal variables | ||
123 | * | ||
124 | * gb | ||
125 | * getbitcontext | ||
126 | * | ||
127 | * OPEN_READER(name, gb) | ||
128 | * load gb into local variables | ||
129 | * | ||
130 | * CLOSE_READER(name, gb) | ||
131 | * store local vars in gb | ||
132 | * | ||
133 | * UPDATE_CACHE(name, gb) | ||
134 | * Refill the internal cache from the bitstream. | ||
135 | * After this call at least MIN_CACHE_BITS will be available. | ||
136 | * | ||
137 | * GET_CACHE(name, gb) | ||
138 | * Will output the contents of the internal cache, | ||
139 | * next bit is MSB of 32 or 64 bits (FIXME 64 bits). | ||
140 | * | ||
141 | * SHOW_UBITS(name, gb, num) | ||
142 | * Will return the next num bits. | ||
143 | * | ||
144 | * SHOW_SBITS(name, gb, num) | ||
145 | * Will return the next num bits and do sign extension. | ||
146 | * | ||
147 | * SKIP_BITS(name, gb, num) | ||
148 | * Will skip over the next num bits. | ||
149 | * Note, this is equivalent to SKIP_CACHE; SKIP_COUNTER. | ||
150 | * | ||
151 | * SKIP_CACHE(name, gb, num) | ||
152 | * Will remove the next num bits from the cache (note SKIP_COUNTER | ||
153 | * MUST be called before UPDATE_CACHE / CLOSE_READER). | ||
154 | * | ||
155 | * SKIP_COUNTER(name, gb, num) | ||
156 | * Will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS). | ||
157 | * | ||
158 | * LAST_SKIP_BITS(name, gb, num) | ||
159 | * Like SKIP_BITS, to be used if next call is UPDATE_CACHE or CLOSE_READER. | ||
160 | * | ||
161 | * BITS_LEFT(name, gb) | ||
162 | * Return the number of bits left | ||
163 | * | ||
164 | * For examples see get_bits, show_bits, skip_bits, get_vlc. | ||
165 | */ | ||
166 | |||
167 | #define MIN_CACHE_BITS 25 | ||
168 | |||
169 | #define OPEN_READER_NOSIZE(name, gb) \ | ||
170 | unsigned int name ## _index = (gb)->index; \ | ||
171 | unsigned int av_unused name ## _cache | ||
172 | |||
173 | #if UNCHECKED_BITSTREAM_READER | ||
174 | #define OPEN_READER(name, gb) OPEN_READER_NOSIZE(name, gb) | ||
175 | |||
176 | #define BITS_AVAILABLE(name, gb) 1 | ||
177 | #else | ||
178 | #define OPEN_READER(name, gb) \ | ||
179 | OPEN_READER_NOSIZE(name, gb); \ | ||
180 | unsigned int name ## _size_plus8 = (gb)->size_in_bits_plus8 | ||
181 | |||
182 | #define BITS_AVAILABLE(name, gb) name ## _index < name ## _size_plus8 | ||
183 | #endif | ||
184 | |||
185 | #define CLOSE_READER(name, gb) (gb)->index = name ## _index | ||
186 | |||
187 | #define UPDATE_CACHE_BE_EXT(name, gb, bits, dst_bits) name ## _cache = \ | ||
188 | AV_RB ## bits((gb)->buffer + (name ## _index >> 3)) << (name ## _index & 7) >> (bits - dst_bits) | ||
189 | |||
190 | #define UPDATE_CACHE_LE_EXT(name, gb, bits, dst_bits) name ## _cache = \ | ||
191 | (uint ## dst_bits ## _t)(AV_RL ## bits((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7)) | ||
192 | |||
193 | /* Using these two macros ensures that 32 bits are available. */ | ||
194 | # define UPDATE_CACHE_LE_32(name, gb) UPDATE_CACHE_LE_EXT(name, (gb), 64, 32) | ||
195 | # define UPDATE_CACHE_BE_32(name, gb) UPDATE_CACHE_BE_EXT(name, (gb), 64, 32) | ||
196 | |||
197 | # define UPDATE_CACHE_LE(name, gb) UPDATE_CACHE_LE_EXT(name, (gb), 32, 32) | ||
198 | # define UPDATE_CACHE_BE(name, gb) UPDATE_CACHE_BE_EXT(name, (gb), 32, 32) | ||
199 | |||
200 | #ifdef BITSTREAM_READER_LE | ||
201 | |||
202 | # define UPDATE_CACHE(name, gb) UPDATE_CACHE_LE(name, gb) | ||
203 | # define UPDATE_CACHE_32(name, gb) UPDATE_CACHE_LE_32(name, (gb)) | ||
204 | |||
205 | # define SKIP_CACHE(name, gb, num) name ## _cache >>= (num) | ||
206 | |||
207 | #else | ||
208 | |||
209 | # define UPDATE_CACHE(name, gb) UPDATE_CACHE_BE(name, gb) | ||
210 | # define UPDATE_CACHE_32(name, gb) UPDATE_CACHE_BE_32(name, (gb)) | ||
211 | |||
212 | # define SKIP_CACHE(name, gb, num) name ## _cache <<= (num) | ||
213 | |||
214 | #endif | ||
215 | |||
216 | #if UNCHECKED_BITSTREAM_READER | ||
217 | # define SKIP_COUNTER(name, gb, num) name ## _index += (num) | ||
218 | #else | ||
219 | # define SKIP_COUNTER(name, gb, num) \ | ||
220 | name ## _index = FFMIN(name ## _size_plus8, name ## _index + (num)) | ||
221 | #endif | ||
222 | |||
223 | #define BITS_LEFT(name, gb) ((int)((gb)->size_in_bits - name ## _index)) | ||
224 | |||
225 | #define SKIP_BITS(name, gb, num) \ | ||
226 | do { \ | ||
227 | SKIP_CACHE(name, gb, num); \ | ||
228 | SKIP_COUNTER(name, gb, num); \ | ||
229 | } while (0) | ||
230 | |||
231 | #define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num) | ||
232 | |||
233 | #define SHOW_UBITS_LE(name, gb, num) zero_extend(name ## _cache, num) | ||
234 | #define SHOW_SBITS_LE(name, gb, num) sign_extend(name ## _cache, num) | ||
235 | |||
236 | #define SHOW_UBITS_BE(name, gb, num) NEG_USR32(name ## _cache, num) | ||
237 | #define SHOW_SBITS_BE(name, gb, num) NEG_SSR32(name ## _cache, num) | ||
238 | |||
239 | #ifdef BITSTREAM_READER_LE | ||
240 | # define SHOW_UBITS(name, gb, num) SHOW_UBITS_LE(name, gb, num) | ||
241 | # define SHOW_SBITS(name, gb, num) SHOW_SBITS_LE(name, gb, num) | ||
242 | #else | ||
243 | # define SHOW_UBITS(name, gb, num) SHOW_UBITS_BE(name, gb, num) | ||
244 | # define SHOW_SBITS(name, gb, num) SHOW_SBITS_BE(name, gb, num) | ||
245 | #endif | ||
246 | |||
247 | #define GET_CACHE(name, gb) ((uint32_t) name ## _cache) | ||
248 | |||
249 | |||
250 | 320532409 | static inline int get_bits_count(const GetBitContext *s) | |
251 | { | ||
252 | 320532409 | return s->index; | |
253 | } | ||
254 | |||
255 | /** | ||
256 | * Get the size of the GetBitContext's buffer in bytes. | ||
257 | * | ||
258 | * @param s the GetBitContext | ||
259 | * @param round_up If set, the number of bits will be rounded up to full bytes; | ||
260 | * this does not matter if the number of bits is known to be | ||
261 | * a multiple of eight, e.g. if the GetBitContext has been | ||
262 | * initialized with init_get_bits8. | ||
263 | */ | ||
264 | 24432 | static inline int get_bits_bytesize(const GetBitContext *s, int round_up) | |
265 | { | ||
266 |
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24432 | return (s->size_in_bits + (round_up ? 7 : 0)) >> 3; |
267 | } | ||
268 | |||
269 | /** | ||
270 | * Skips the specified number of bits. | ||
271 | * @param n the number of bits to skip, | ||
272 | * For the UNCHECKED_BITSTREAM_READER this must not cause the distance | ||
273 | * from the start to overflow int32_t. Staying within the bitstream + padding | ||
274 | * is sufficient, too. | ||
275 | */ | ||
276 | 4664827 | static inline void skip_bits_long(GetBitContext *s, int n) | |
277 | { | ||
278 | #if UNCHECKED_BITSTREAM_READER | ||
279 | 2784663 | s->index += n; | |
280 | #else | ||
281 | 1880164 | s->index += av_clip(n, -s->index, s->size_in_bits_plus8 - s->index); | |
282 | #endif | ||
283 | 4664827 | } | |
284 | |||
285 | /** | ||
286 | * Read MPEG-1 dc-style VLC (sign bit + mantissa with no MSB). | ||
287 | * if MSB not set it is negative | ||
288 | * @param n length in bits | ||
289 | */ | ||
290 | 26952221 | static inline int get_xbits(GetBitContext *s, int n) | |
291 | { | ||
292 | register int sign; | ||
293 | register int32_t cache; | ||
294 | 26952221 | OPEN_READER(re, s); | |
295 | av_assert2(n>0 && n<=25); | ||
296 | 26952221 | UPDATE_CACHE(re, s); | |
297 | 26952221 | cache = GET_CACHE(re, s); | |
298 | 26952221 | sign = ~cache >> 31; | |
299 | 26952221 | LAST_SKIP_BITS(re, s, n); | |
300 | 26952221 | CLOSE_READER(re, s); | |
301 | 26952221 | return (NEG_USR32(sign ^ cache, n) ^ sign) - sign; | |
302 | } | ||
303 | |||
304 | 1534760 | static inline int get_xbits_le(GetBitContext *s, int n) | |
305 | { | ||
306 | register int sign; | ||
307 | register int32_t cache; | ||
308 | 1534760 | OPEN_READER(re, s); | |
309 | av_assert2(n>0 && n<=25); | ||
310 | 1534760 | UPDATE_CACHE_LE(re, s); | |
311 | 1534760 | cache = GET_CACHE(re, s); | |
312 | 1534760 | sign = sign_extend(~cache, n) >> 31; | |
313 | 1534760 | LAST_SKIP_BITS(re, s, n); | |
314 | 1534760 | CLOSE_READER(re, s); | |
315 | 1534760 | return (zero_extend(sign ^ cache, n) ^ sign) - sign; | |
316 | } | ||
317 | |||
318 | 33305050 | static inline int get_sbits(GetBitContext *s, int n) | |
319 | { | ||
320 | register int tmp; | ||
321 | 33305050 | OPEN_READER(re, s); | |
322 | av_assert2(n>0 && n<=25); | ||
323 | 33305050 | UPDATE_CACHE(re, s); | |
324 | 33305050 | tmp = SHOW_SBITS(re, s, n); | |
325 | 33305050 | LAST_SKIP_BITS(re, s, n); | |
326 | 33305050 | CLOSE_READER(re, s); | |
327 | 33305050 | return tmp; | |
328 | } | ||
329 | |||
330 | /** | ||
331 | * Read 1-25 bits. | ||
332 | */ | ||
333 | 276589654 | static inline unsigned int get_bits(GetBitContext *s, int n) | |
334 | { | ||
335 | register unsigned int tmp; | ||
336 | 276589654 | OPEN_READER(re, s); | |
337 | av_assert2(n>0 && n<=25); | ||
338 | 276589654 | UPDATE_CACHE(re, s); | |
339 | 276589654 | tmp = SHOW_UBITS(re, s, n); | |
340 | 276589654 | LAST_SKIP_BITS(re, s, n); | |
341 | 276589654 | CLOSE_READER(re, s); | |
342 | av_assert2(tmp < UINT64_C(1) << n); | ||
343 | 276589654 | return tmp; | |
344 | } | ||
345 | |||
346 | /** | ||
347 | * Read 0-25 bits. | ||
348 | */ | ||
349 | 746532 | static av_always_inline int get_bitsz(GetBitContext *s, int n) | |
350 | { | ||
351 |
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746532 | return n ? get_bits(s, n) : 0; |
352 | } | ||
353 | |||
354 | 718813 | static inline unsigned int get_bits_le(GetBitContext *s, int n) | |
355 | { | ||
356 | register int tmp; | ||
357 | 718813 | OPEN_READER(re, s); | |
358 | av_assert2(n>0 && n<=25); | ||
359 | 718813 | UPDATE_CACHE_LE(re, s); | |
360 | 718813 | tmp = SHOW_UBITS_LE(re, s, n); | |
361 | 718813 | LAST_SKIP_BITS(re, s, n); | |
362 | 718813 | CLOSE_READER(re, s); | |
363 | 718813 | return tmp; | |
364 | } | ||
365 | |||
366 | /** | ||
367 | * Show 1-25 bits. | ||
368 | */ | ||
369 | 118265395 | static inline unsigned int show_bits(GetBitContext *s, int n) | |
370 | { | ||
371 | register unsigned int tmp; | ||
372 | 118265395 | OPEN_READER_NOSIZE(re, s); | |
373 | av_assert2(n>0 && n<=25); | ||
374 | 118265395 | UPDATE_CACHE(re, s); | |
375 | 118265395 | tmp = SHOW_UBITS(re, s, n); | |
376 | 118265395 | return tmp; | |
377 | } | ||
378 | |||
379 | 115800244 | static inline void skip_bits(GetBitContext *s, int n) | |
380 | { | ||
381 | 115800244 | OPEN_READER(re, s); | |
382 | 115800244 | LAST_SKIP_BITS(re, s, n); | |
383 | 115800244 | CLOSE_READER(re, s); | |
384 | 115800244 | } | |
385 | |||
386 | 473759956 | static inline unsigned int get_bits1(GetBitContext *s) | |
387 | { | ||
388 | 473759956 | unsigned int index = s->index; | |
389 | 473759956 | uint8_t result = s->buffer[index >> 3]; | |
390 | #ifdef BITSTREAM_READER_LE | ||
391 | 265293723 | result >>= index & 7; | |
392 | 265293723 | result &= 1; | |
393 | #else | ||
394 | 208466233 | result <<= index & 7; | |
395 | 208466233 | result >>= 8 - 1; | |
396 | #endif | ||
397 | #if !UNCHECKED_BITSTREAM_READER | ||
398 |
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430036965 | if (s->index < s->size_in_bits_plus8) |
399 | #endif | ||
400 | 473727887 | index++; | |
401 | 473759956 | s->index = index; | |
402 | |||
403 | 473759956 | return result; | |
404 | } | ||
405 | |||
406 | 43299 | static inline unsigned int show_bits1(GetBitContext *s) | |
407 | { | ||
408 | 43299 | return show_bits(s, 1); | |
409 | } | ||
410 | |||
411 | 391516 | static inline void skip_bits1(GetBitContext *s) | |
412 | { | ||
413 | 391516 | skip_bits(s, 1); | |
414 | 391516 | } | |
415 | |||
416 | /** | ||
417 | * Read 0-32 bits. | ||
418 | */ | ||
419 | 57213187 | static inline unsigned int get_bits_long(GetBitContext *s, int n) | |
420 | { | ||
421 | av_assert2(n>=0 && n<=32); | ||
422 |
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57213187 | if (!n) { |
423 | 3404960 | return 0; | |
424 | } else if ((!HAVE_FAST_64BIT || av_builtin_constant_p(n <= MIN_CACHE_BITS)) | ||
425 | && n <= MIN_CACHE_BITS) { | ||
426 | return get_bits(s, n); | ||
427 | } else { | ||
428 | #if HAVE_FAST_64BIT | ||
429 | unsigned tmp; | ||
430 | 53808227 | OPEN_READER(re, s); | |
431 | 53808227 | UPDATE_CACHE_32(re, s); | |
432 | 53808227 | tmp = SHOW_UBITS(re, s, n); | |
433 | 53808227 | LAST_SKIP_BITS(re, s, n); | |
434 | 53808227 | CLOSE_READER(re, s); | |
435 | 53808227 | return tmp; | |
436 | #else | ||
437 | #ifdef BITSTREAM_READER_LE | ||
438 | unsigned ret = get_bits(s, 16); | ||
439 | return ret | (get_bits(s, n - 16) << 16); | ||
440 | #else | ||
441 | unsigned ret = get_bits(s, 16) << (n - 16); | ||
442 | return ret | get_bits(s, n - 16); | ||
443 | #endif | ||
444 | #endif | ||
445 | } | ||
446 | } | ||
447 | |||
448 | /** | ||
449 | * Read 0-64 bits. | ||
450 | */ | ||
451 | 11443 | static inline uint64_t get_bits64(GetBitContext *s, int n) | |
452 | { | ||
453 |
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11443 | if (n <= 32) { |
454 | 6375 | return get_bits_long(s, n); | |
455 | } else { | ||
456 | #ifdef BITSTREAM_READER_LE | ||
457 | 1 | uint64_t ret = get_bits_long(s, 32); | |
458 | 1 | return ret | (uint64_t) get_bits_long(s, n - 32) << 32; | |
459 | #else | ||
460 | 5067 | uint64_t ret = (uint64_t) get_bits_long(s, n - 32) << 32; | |
461 | 5067 | return ret | get_bits_long(s, 32); | |
462 | #endif | ||
463 | } | ||
464 | } | ||
465 | |||
466 | /** | ||
467 | * Read 0-32 bits as a signed integer. | ||
468 | */ | ||
469 | 4766805 | static inline int get_sbits_long(GetBitContext *s, int n) | |
470 | { | ||
471 | // sign_extend(x, 0) is undefined | ||
472 |
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4766805 | if (!n) |
473 | ✗ | return 0; | |
474 | |||
475 | 4766805 | return sign_extend(get_bits_long(s, n), n); | |
476 | } | ||
477 | |||
478 | /** | ||
479 | * Read 0-64 bits as a signed integer. | ||
480 | */ | ||
481 | 4624 | static inline int64_t get_sbits64(GetBitContext *s, int n) | |
482 | { | ||
483 | // sign_extend(x, 0) is undefined | ||
484 |
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4624 | if (!n) |
485 | ✗ | return 0; | |
486 | |||
487 | 4624 | return sign_extend64(get_bits64(s, n), n); | |
488 | } | ||
489 | |||
490 | /** | ||
491 | * Show 0-32 bits. | ||
492 | */ | ||
493 | 3465890 | static inline unsigned int show_bits_long(GetBitContext *s, int n) | |
494 | { | ||
495 |
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3465890 | if (n <= MIN_CACHE_BITS) { |
496 | 18557 | return show_bits(s, n); | |
497 | } else { | ||
498 | 3447333 | GetBitContext gb = *s; | |
499 | 3447333 | return get_bits_long(&gb, n); | |
500 | } | ||
501 | } | ||
502 | |||
503 | |||
504 | /** | ||
505 | * Initialize GetBitContext. | ||
506 | * @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes | ||
507 | * larger than the actual read bits because some optimized bitstream | ||
508 | * readers read 32 or 64 bit at once and could read over the end | ||
509 | * @param bit_size the size of the buffer in bits | ||
510 | * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow. | ||
511 | */ | ||
512 | 42528150 | static inline int init_get_bits(GetBitContext *s, const uint8_t *buffer, | |
513 | int bit_size) | ||
514 | { | ||
515 | 42528150 | int ret = 0; | |
516 | |||
517 |
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42528150 | if (bit_size >= INT_MAX - FFMAX(7, AV_INPUT_BUFFER_PADDING_SIZE*8) || bit_size < 0 || !buffer) { |
518 | 8 | bit_size = 0; | |
519 | 8 | buffer = NULL; | |
520 | 8 | ret = AVERROR_INVALIDDATA; | |
521 | } | ||
522 | |||
523 | 42528150 | s->buffer = buffer; | |
524 | 42528150 | s->size_in_bits = bit_size; | |
525 | 42528150 | s->size_in_bits_plus8 = bit_size + 8; | |
526 | 42528150 | s->index = 0; | |
527 | |||
528 | 42528150 | return ret; | |
529 | } | ||
530 | |||
531 | /** | ||
532 | * Initialize GetBitContext. | ||
533 | * @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes | ||
534 | * larger than the actual read bits because some optimized bitstream | ||
535 | * readers read 32 or 64 bit at once and could read over the end | ||
536 | * @param byte_size the size of the buffer in bytes | ||
537 | * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow. | ||
538 | */ | ||
539 | 13374986 | static inline int init_get_bits8(GetBitContext *s, const uint8_t *buffer, | |
540 | int byte_size) | ||
541 | { | ||
542 |
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13374986 | if (byte_size > INT_MAX / 8 || byte_size < 0) |
543 | ✗ | byte_size = -1; | |
544 | 13374986 | return init_get_bits(s, buffer, byte_size * 8); | |
545 | } | ||
546 | |||
547 | 200 | static inline int init_get_bits8_le(GetBitContext *s, const uint8_t *buffer, | |
548 | int byte_size) | ||
549 | { | ||
550 |
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200 | if (byte_size > INT_MAX / 8 || byte_size < 0) |
551 | ✗ | byte_size = -1; | |
552 | 200 | return init_get_bits(s, buffer, byte_size * 8); | |
553 | } | ||
554 | |||
555 | 257032 | static inline const uint8_t *align_get_bits(GetBitContext *s) | |
556 | { | ||
557 | 257032 | int n = -get_bits_count(s) & 7; | |
558 |
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257032 | if (n) |
559 | 72693 | skip_bits(s, n); | |
560 | 257032 | return s->buffer + (s->index >> 3); | |
561 | } | ||
562 | |||
563 | /** | ||
564 | * If the vlc code is invalid and max_depth=1, then no bits will be removed. | ||
565 | * If the vlc code is invalid and max_depth>1, then the number of bits removed | ||
566 | * is undefined. | ||
567 | */ | ||
568 | #define GET_VLC(code, name, gb, table, bits, max_depth) \ | ||
569 | do { \ | ||
570 | int n, nb_bits; \ | ||
571 | unsigned int index; \ | ||
572 | \ | ||
573 | index = SHOW_UBITS(name, gb, bits); \ | ||
574 | code = table[index].sym; \ | ||
575 | n = table[index].len; \ | ||
576 | \ | ||
577 | if (max_depth > 1 && n < 0) { \ | ||
578 | LAST_SKIP_BITS(name, gb, bits); \ | ||
579 | UPDATE_CACHE(name, gb); \ | ||
580 | \ | ||
581 | nb_bits = -n; \ | ||
582 | \ | ||
583 | index = SHOW_UBITS(name, gb, nb_bits) + code; \ | ||
584 | code = table[index].sym; \ | ||
585 | n = table[index].len; \ | ||
586 | if (max_depth > 2 && n < 0) { \ | ||
587 | LAST_SKIP_BITS(name, gb, nb_bits); \ | ||
588 | UPDATE_CACHE(name, gb); \ | ||
589 | \ | ||
590 | nb_bits = -n; \ | ||
591 | \ | ||
592 | index = SHOW_UBITS(name, gb, nb_bits) + code; \ | ||
593 | code = table[index].sym; \ | ||
594 | n = table[index].len; \ | ||
595 | } \ | ||
596 | } \ | ||
597 | SKIP_BITS(name, gb, n); \ | ||
598 | } while (0) | ||
599 | |||
600 | #define GET_RL_VLC(level, run, name, gb, table, bits, \ | ||
601 | max_depth, need_update) \ | ||
602 | do { \ | ||
603 | int n, nb_bits; \ | ||
604 | unsigned int index; \ | ||
605 | \ | ||
606 | index = SHOW_UBITS(name, gb, bits); \ | ||
607 | level = table[index].level; \ | ||
608 | n = table[index].len8; \ | ||
609 | \ | ||
610 | if (max_depth > 1 && n < 0) { \ | ||
611 | SKIP_BITS(name, gb, bits); \ | ||
612 | if (need_update) { \ | ||
613 | UPDATE_CACHE(name, gb); \ | ||
614 | } \ | ||
615 | \ | ||
616 | nb_bits = -n; \ | ||
617 | \ | ||
618 | index = SHOW_UBITS(name, gb, nb_bits) + level; \ | ||
619 | level = table[index].level; \ | ||
620 | n = table[index].len8; \ | ||
621 | if (max_depth > 2 && n < 0) { \ | ||
622 | LAST_SKIP_BITS(name, gb, nb_bits); \ | ||
623 | if (need_update) { \ | ||
624 | UPDATE_CACHE(name, gb); \ | ||
625 | } \ | ||
626 | nb_bits = -n; \ | ||
627 | \ | ||
628 | index = SHOW_UBITS(name, gb, nb_bits) + level; \ | ||
629 | level = table[index].level; \ | ||
630 | n = table[index].len8; \ | ||
631 | } \ | ||
632 | } \ | ||
633 | run = table[index].run; \ | ||
634 | SKIP_BITS(name, gb, n); \ | ||
635 | } while (0) | ||
636 | |||
637 | /** | ||
638 | * Parse a vlc code. | ||
639 | * @param bits is the number of bits which will be read at once, must be | ||
640 | * identical to nb_bits in vlc_init() | ||
641 | * @param max_depth is the number of times bits bits must be read to completely | ||
642 | * read the longest vlc code | ||
643 | * = (max_vlc_length + bits - 1) / bits | ||
644 | * @returns the code parsed or -1 if no vlc matches | ||
645 | */ | ||
646 | 286128042 | static av_always_inline int get_vlc2(GetBitContext *s, const VLCElem *table, | |
647 | int bits, int max_depth) | ||
648 | { | ||
649 | int code; | ||
650 | |||
651 | 286128042 | OPEN_READER(re, s); | |
652 | 286128042 | UPDATE_CACHE(re, s); | |
653 | |||
654 |
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286128042 | GET_VLC(code, re, s, table, bits, max_depth); |
655 | |||
656 | 286128042 | CLOSE_READER(re, s); | |
657 | |||
658 | 286128042 | return code; | |
659 | } | ||
660 | |||
661 | static inline int get_vlc_multi(GetBitContext *s, uint8_t *dst, | ||
662 | const VLC_MULTI_ELEM *const Jtable, | ||
663 | const VLCElem *const table, | ||
664 | const int bits, const int max_depth, | ||
665 | const int symbols_size) | ||
666 | { | ||
667 | dst[0] = get_vlc2(s, table, bits, max_depth); | ||
668 | return 1; | ||
669 | } | ||
670 | |||
671 | 378883 | static inline int decode012(GetBitContext *gb) | |
672 | { | ||
673 | int n; | ||
674 | 378883 | n = get_bits1(gb); | |
675 |
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378883 | if (n == 0) |
676 | 263935 | return 0; | |
677 | else | ||
678 | 114948 | return get_bits1(gb) + 1; | |
679 | } | ||
680 | |||
681 | 191971 | static inline int decode210(GetBitContext *gb) | |
682 | { | ||
683 |
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191971 | if (get_bits1(gb)) |
684 | 135836 | return 0; | |
685 | else | ||
686 | 56135 | return 2 - get_bits1(gb); | |
687 | } | ||
688 | |||
689 | 271854480 | static inline int get_bits_left(GetBitContext *gb) | |
690 | { | ||
691 | 271854480 | return gb->size_in_bits - get_bits_count(gb); | |
692 | } | ||
693 | |||
694 | 135234 | static inline int skip_1stop_8data_bits(GetBitContext *gb) | |
695 | { | ||
696 |
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135234 | if (get_bits_left(gb) <= 0) |
697 | ✗ | return AVERROR_INVALIDDATA; | |
698 | |||
699 |
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138348 | while (get_bits1(gb)) { |
700 | 3114 | skip_bits(gb, 8); | |
701 |
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3114 | if (get_bits_left(gb) <= 0) |
702 | ✗ | return AVERROR_INVALIDDATA; | |
703 | } | ||
704 | |||
705 | 135234 | return 0; | |
706 | } | ||
707 | |||
708 | #endif // CACHED_BITSTREAM_READER | ||
709 | |||
710 | #endif /* AVCODEC_GET_BITS_H */ | ||
711 |