2 * copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
4 * This file is part of FFmpeg.
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.
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.
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
23 * bitstream reader API header.
26 #ifndef AVCODEC_GET_BITS_H
27 #define AVCODEC_GET_BITS_H
32 #include "libavutil/bswap.h"
33 #include "libavutil/common.h"
34 #include "libavutil/intreadwrite.h"
35 #include "libavutil/log.h"
38 #if defined(ALT_BITSTREAM_READER_LE) && !defined(ALT_BITSTREAM_READER)
39 # define ALT_BITSTREAM_READER
42 #if !defined(LIBMPEG2_BITSTREAM_READER) && !defined(A32_BITSTREAM_READER) && !defined(ALT_BITSTREAM_READER)
43 # if ARCH_ARM && !HAVE_FAST_UNALIGNED
44 # define A32_BITSTREAM_READER
46 # define ALT_BITSTREAM_READER
47 //#define LIBMPEG2_BITSTREAM_READER
48 //#define A32_BITSTREAM_READER
53 /* buffer, buffer_end and size_in_bits must be present and used by every reader */
54 typedef struct GetBitContext {
55 const uint8_t *buffer, *buffer_end;
56 #ifdef ALT_BITSTREAM_READER
58 #elif defined LIBMPEG2_BITSTREAM_READER
62 #elif defined A32_BITSTREAM_READER
71 #define VLC_TYPE int16_t
75 VLC_TYPE (*table)[2]; ///< code, bits
76 int table_size, table_allocated;
79 typedef struct RL_VLC_ELEM {
85 /* Bitstream reader API docs:
87 arbitrary name which is used as prefix for the internal variables
93 loads gb into local variables
95 CLOSE_READER(name, gb)
96 stores local vars in gb
98 UPDATE_CACHE(name, gb)
99 refills the internal cache from the bitstream
100 after this call at least MIN_CACHE_BITS will be available,
103 will output the contents of the internal cache, next bit is MSB of 32 or 64 bit (FIXME 64bit)
105 SHOW_UBITS(name, gb, num)
106 will return the next num bits
108 SHOW_SBITS(name, gb, num)
109 will return the next num bits and do sign extension
111 SKIP_BITS(name, gb, num)
112 will skip over the next num bits
113 note, this is equivalent to SKIP_CACHE; SKIP_COUNTER
115 SKIP_CACHE(name, gb, num)
116 will remove the next num bits from the cache (note SKIP_COUNTER MUST be called before UPDATE_CACHE / CLOSE_READER)
118 SKIP_COUNTER(name, gb, num)
119 will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS)
121 LAST_SKIP_CACHE(name, gb, num)
122 will remove the next num bits from the cache if it is needed for UPDATE_CACHE otherwise it will do nothing
124 LAST_SKIP_BITS(name, gb, num)
125 is equivalent to LAST_SKIP_CACHE; SKIP_COUNTER
127 for examples see get_bits, show_bits, skip_bits, get_vlc
130 #ifdef ALT_BITSTREAM_READER
131 # define MIN_CACHE_BITS 25
133 # define OPEN_READER(name, gb)\
134 unsigned int name##_index= (gb)->index;\
135 int name##_cache= 0;\
137 # define CLOSE_READER(name, gb)\
138 (gb)->index= name##_index;\
140 # ifdef ALT_BITSTREAM_READER_LE
141 # define UPDATE_CACHE(name, gb)\
142 name##_cache= AV_RL32( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) >> (name##_index&0x07);\
144 # define SKIP_CACHE(name, gb, num)\
145 name##_cache >>= (num);
147 # define UPDATE_CACHE(name, gb)\
148 name##_cache= AV_RB32( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) << (name##_index&0x07);\
150 # define SKIP_CACHE(name, gb, num)\
151 name##_cache <<= (num);
155 # define SKIP_COUNTER(name, gb, num)\
156 name##_index += (num);\
158 # define SKIP_BITS(name, gb, num)\
160 SKIP_CACHE(name, gb, num)\
161 SKIP_COUNTER(name, gb, num)\
164 # define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
165 # define LAST_SKIP_CACHE(name, gb, num) ;
167 # ifdef ALT_BITSTREAM_READER_LE
168 # define SHOW_UBITS(name, gb, num)\
169 zero_extend(name##_cache, num)
171 # define SHOW_SBITS(name, gb, num)\
172 sign_extend(name##_cache, num)
174 # define SHOW_UBITS(name, gb, num)\
175 NEG_USR32(name##_cache, num)
177 # define SHOW_SBITS(name, gb, num)\
178 NEG_SSR32(name##_cache, num)
181 # define GET_CACHE(name, gb)\
182 ((uint32_t)name##_cache)
184 static inline int get_bits_count(const GetBitContext *s){
188 static inline void skip_bits_long(GetBitContext *s, int n){
192 #elif defined LIBMPEG2_BITSTREAM_READER
193 //libmpeg2 like reader
195 # define MIN_CACHE_BITS 17
197 # define OPEN_READER(name, gb)\
198 int name##_bit_count=(gb)->bit_count;\
199 int name##_cache= (gb)->cache;\
200 uint8_t * name##_buffer_ptr=(gb)->buffer_ptr;\
202 # define CLOSE_READER(name, gb)\
203 (gb)->bit_count= name##_bit_count;\
204 (gb)->cache= name##_cache;\
205 (gb)->buffer_ptr= name##_buffer_ptr;\
207 # define UPDATE_CACHE(name, gb)\
208 if(name##_bit_count >= 0){\
209 name##_cache+= AV_RB16(name##_buffer_ptr) << name##_bit_count; \
210 name##_buffer_ptr+=2;\
211 name##_bit_count-= 16;\
214 # define SKIP_CACHE(name, gb, num)\
215 name##_cache <<= (num);\
217 # define SKIP_COUNTER(name, gb, num)\
218 name##_bit_count += (num);\
220 # define SKIP_BITS(name, gb, num)\
222 SKIP_CACHE(name, gb, num)\
223 SKIP_COUNTER(name, gb, num)\
226 # define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
227 # define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
229 # define SHOW_UBITS(name, gb, num)\
230 NEG_USR32(name##_cache, num)
232 # define SHOW_SBITS(name, gb, num)\
233 NEG_SSR32(name##_cache, num)
235 # define GET_CACHE(name, gb)\
236 ((uint32_t)name##_cache)
238 static inline int get_bits_count(const GetBitContext *s){
239 return (s->buffer_ptr - s->buffer)*8 - 16 + s->bit_count;
242 static inline void skip_bits_long(GetBitContext *s, int n){
245 re_buffer_ptr += 2*(re_bit_count>>4);
247 re_cache = ((re_buffer_ptr[-2]<<8) + re_buffer_ptr[-1]) << (16+re_bit_count);
252 #elif defined A32_BITSTREAM_READER
254 # define MIN_CACHE_BITS 32
256 # define OPEN_READER(name, gb)\
257 int name##_bit_count=(gb)->bit_count;\
258 uint32_t name##_cache0= (gb)->cache0;\
259 uint32_t name##_cache1= (gb)->cache1;\
260 uint32_t * name##_buffer_ptr=(gb)->buffer_ptr;\
262 # define CLOSE_READER(name, gb)\
263 (gb)->bit_count= name##_bit_count;\
264 (gb)->cache0= name##_cache0;\
265 (gb)->cache1= name##_cache1;\
266 (gb)->buffer_ptr= name##_buffer_ptr;\
268 # define UPDATE_CACHE(name, gb)\
269 if(name##_bit_count > 0){\
270 const uint32_t next= av_be2ne32( *name##_buffer_ptr );\
271 name##_cache0 |= NEG_USR32(next,name##_bit_count);\
272 name##_cache1 |= next<<name##_bit_count;\
273 name##_buffer_ptr++;\
274 name##_bit_count-= 32;\
278 # define SKIP_CACHE(name, gb, num)\
280 "shldl %2, %1, %0 \n\t"\
282 : "+r" (name##_cache0), "+r" (name##_cache1)\
283 : "Ic" ((uint8_t)(num))\
286 # define SKIP_CACHE(name, gb, num)\
287 name##_cache0 <<= (num);\
288 name##_cache0 |= NEG_USR32(name##_cache1,num);\
289 name##_cache1 <<= (num);
292 # define SKIP_COUNTER(name, gb, num)\
293 name##_bit_count += (num);\
295 # define SKIP_BITS(name, gb, num)\
297 SKIP_CACHE(name, gb, num)\
298 SKIP_COUNTER(name, gb, num)\
301 # define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
302 # define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
304 # define SHOW_UBITS(name, gb, num)\
305 NEG_USR32(name##_cache0, num)
307 # define SHOW_SBITS(name, gb, num)\
308 NEG_SSR32(name##_cache0, num)
310 # define GET_CACHE(name, gb)\
313 static inline int get_bits_count(const GetBitContext *s){
314 return ((uint8_t*)s->buffer_ptr - s->buffer)*8 - 32 + s->bit_count;
317 static inline void skip_bits_long(GetBitContext *s, int n){
320 re_buffer_ptr += re_bit_count>>5;
322 re_cache0 = av_be2ne32( re_buffer_ptr[-1] ) << re_bit_count;
331 * read mpeg1 dc style vlc (sign bit + mantisse with no MSB).
332 * if MSB not set it is negative
333 * @param n length in bits
336 static inline int get_xbits(GetBitContext *s, int n){
338 register int32_t cache;
341 cache = GET_CACHE(re,s);
343 LAST_SKIP_BITS(re, s, n)
345 return (NEG_USR32(sign ^ cache, n) ^ sign) - sign;
348 static inline int get_sbits(GetBitContext *s, int n){
352 tmp= SHOW_SBITS(re, s, n);
353 LAST_SKIP_BITS(re, s, n)
360 * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
362 static inline unsigned int get_bits(GetBitContext *s, int n){
366 tmp= SHOW_UBITS(re, s, n);
367 LAST_SKIP_BITS(re, s, n)
374 * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
376 static inline unsigned int show_bits(GetBitContext *s, int n){
380 tmp= SHOW_UBITS(re, s, n);
381 // CLOSE_READER(re, s)
385 static inline void skip_bits(GetBitContext *s, int n){
386 //Note gcc seems to optimize this to s->index+=n for the ALT_READER :))
389 LAST_SKIP_BITS(re, s, n)
393 static inline unsigned int get_bits1(GetBitContext *s){
394 #ifdef ALT_BITSTREAM_READER
395 unsigned int index= s->index;
396 uint8_t result= s->buffer[ index>>3 ];
397 #ifdef ALT_BITSTREAM_READER_LE
398 result>>= (index&0x07);
401 result<<= (index&0x07);
409 return get_bits(s, 1);
413 static inline unsigned int show_bits1(GetBitContext *s){
414 return show_bits(s, 1);
417 static inline void skip_bits1(GetBitContext *s){
424 static inline unsigned int get_bits_long(GetBitContext *s, int n){
425 if(n<=MIN_CACHE_BITS) return get_bits(s, n);
427 #ifdef ALT_BITSTREAM_READER_LE
428 int ret= get_bits(s, 16);
429 return ret | (get_bits(s, n-16) << 16);
431 int ret= get_bits(s, 16) << (n-16);
432 return ret | get_bits(s, n-16);
438 * reads 0-32 bits as a signed integer.
440 static inline int get_sbits_long(GetBitContext *s, int n) {
441 return sign_extend(get_bits_long(s, n), n);
447 static inline unsigned int show_bits_long(GetBitContext *s, int n){
448 if(n<=MIN_CACHE_BITS) return show_bits(s, n);
450 GetBitContext gb= *s;
451 return get_bits_long(&gb, n);
455 static inline int check_marker(GetBitContext *s, const char *msg)
457 int bit= get_bits1(s);
459 av_log(NULL, AV_LOG_INFO, "Marker bit missing %s\n", msg);
465 * init GetBitContext.
466 * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger then the actual read bits
467 * because some optimized bitstream readers read 32 or 64 bit at once and could read over the end
468 * @param bit_size the size of the buffer in bits
470 * While GetBitContext stores the buffer size, for performance reasons you are
471 * responsible for checking for the buffer end yourself (take advantage of the padding)!
473 static inline void init_get_bits(GetBitContext *s,
474 const uint8_t *buffer, int bit_size)
476 int buffer_size= (bit_size+7)>>3;
477 if(buffer_size < 0 || bit_size < 0) {
478 buffer_size = bit_size = 0;
483 s->size_in_bits= bit_size;
484 s->buffer_end= buffer + buffer_size;
485 #ifdef ALT_BITSTREAM_READER
487 #elif defined LIBMPEG2_BITSTREAM_READER
488 s->buffer_ptr = (uint8_t*)((intptr_t)buffer&(~1));
489 s->bit_count = 16 + 8*((intptr_t)buffer&1);
490 skip_bits_long(s, 0);
491 #elif defined A32_BITSTREAM_READER
492 s->buffer_ptr = (uint32_t*)((intptr_t)buffer&(~3));
493 s->bit_count = 32 + 8*((intptr_t)buffer&3);
494 skip_bits_long(s, 0);
498 static inline void align_get_bits(GetBitContext *s)
500 int n= (-get_bits_count(s)) & 7;
501 if(n) skip_bits(s, n);
504 #define init_vlc(vlc, nb_bits, nb_codes,\
505 bits, bits_wrap, bits_size,\
506 codes, codes_wrap, codes_size,\
508 init_vlc_sparse(vlc, nb_bits, nb_codes,\
509 bits, bits_wrap, bits_size,\
510 codes, codes_wrap, codes_size,\
513 int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,
514 const void *bits, int bits_wrap, int bits_size,
515 const void *codes, int codes_wrap, int codes_size,
516 const void *symbols, int symbols_wrap, int symbols_size,
518 #define INIT_VLC_LE 2
519 #define INIT_VLC_USE_NEW_STATIC 4
520 void free_vlc(VLC *vlc);
522 #define INIT_VLC_STATIC(vlc, bits, a,b,c,d,e,f,g, static_size)\
524 static VLC_TYPE table[static_size][2];\
525 (vlc)->table= table;\
526 (vlc)->table_allocated= static_size;\
527 init_vlc(vlc, bits, a,b,c,d,e,f,g, INIT_VLC_USE_NEW_STATIC);\
533 * If the vlc code is invalid and max_depth=1, then no bits will be removed.
534 * If the vlc code is invalid and max_depth>1, then the number of bits removed
537 #define GET_VLC(code, name, gb, table, bits, max_depth)\
542 index= SHOW_UBITS(name, gb, bits);\
543 code = table[index][0];\
544 n = table[index][1];\
546 if(max_depth > 1 && n < 0){\
547 LAST_SKIP_BITS(name, gb, bits)\
548 UPDATE_CACHE(name, gb)\
552 index= SHOW_UBITS(name, gb, nb_bits) + code;\
553 code = table[index][0];\
554 n = table[index][1];\
555 if(max_depth > 2 && n < 0){\
556 LAST_SKIP_BITS(name, gb, nb_bits)\
557 UPDATE_CACHE(name, gb)\
561 index= SHOW_UBITS(name, gb, nb_bits) + code;\
562 code = table[index][0];\
563 n = table[index][1];\
566 SKIP_BITS(name, gb, n)\
569 #define GET_RL_VLC(level, run, name, gb, table, bits, max_depth, need_update)\
574 index= SHOW_UBITS(name, gb, bits);\
575 level = table[index].level;\
576 n = table[index].len;\
578 if(max_depth > 1 && n < 0){\
579 SKIP_BITS(name, gb, bits)\
581 UPDATE_CACHE(name, gb)\
586 index= SHOW_UBITS(name, gb, nb_bits) + level;\
587 level = table[index].level;\
588 n = table[index].len;\
590 run= table[index].run;\
591 SKIP_BITS(name, gb, n)\
596 * parses a vlc code, faster then get_vlc()
597 * @param bits is the number of bits which will be read at once, must be
598 * identical to nb_bits in init_vlc()
599 * @param max_depth is the number of times bits bits must be read to completely
600 * read the longest vlc code
601 * = (max_vlc_length + bits - 1) / bits
603 static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2],
604 int bits, int max_depth)
611 GET_VLC(code, re, s, table, bits, max_depth)
620 static inline void print_bin(int bits, int n){
623 for(i=n-1; i>=0; i--){
624 av_log(NULL, AV_LOG_DEBUG, "%d", (bits>>i)&1);
627 av_log(NULL, AV_LOG_DEBUG, " ");
630 static inline int get_bits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
631 int r= get_bits(s, n);
634 av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d bit @%5d in %s %s:%d\n", r, n, r, get_bits_count(s)-n, file, func, line);
637 static inline int get_vlc_trace(GetBitContext *s, VLC_TYPE (*table)[2], int bits, int max_depth, char *file, const char *func, int line){
638 int show= show_bits(s, 24);
639 int pos= get_bits_count(s);
640 int r= get_vlc2(s, table, bits, max_depth);
641 int len= get_bits_count(s) - pos;
642 int bits2= show>>(24-len);
644 print_bin(bits2, len);
646 av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d vlc @%5d in %s %s:%d\n", bits2, len, r, pos, file, func, line);
649 static inline int get_xbits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
650 int show= show_bits(s, n);
651 int r= get_xbits(s, n);
654 av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d xbt @%5d in %s %s:%d\n", show, n, r, get_bits_count(s)-n, file, func, line);
658 #define get_bits(s, n) get_bits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
659 #define get_bits1(s) get_bits_trace(s, 1, __FILE__, __PRETTY_FUNCTION__, __LINE__)
660 #define get_xbits(s, n) get_xbits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
661 #define get_vlc(s, vlc) get_vlc_trace(s, (vlc)->table, (vlc)->bits, 3, __FILE__, __PRETTY_FUNCTION__, __LINE__)
662 #define get_vlc2(s, tab, bits, max) get_vlc_trace(s, tab, bits, max, __FILE__, __PRETTY_FUNCTION__, __LINE__)
664 #define tprintf(p, ...) av_log(p, AV_LOG_DEBUG, __VA_ARGS__)
667 #define tprintf(p, ...) {}
670 static inline int decode012(GetBitContext *gb){
676 return get_bits1(gb) + 1;
679 static inline int decode210(GetBitContext *gb){
683 return 2 - get_bits1(gb);
686 static inline int get_bits_left(GetBitContext *gb)
688 return gb->size_in_bits - get_bits_count(gb);
691 #endif /* AVCODEC_GET_BITS_H */