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
22 * @file libavcodec/put_bits.h
23 * bitstream writer API
26 #ifndef AVCODEC_PUT_BITS_H
27 #define AVCODEC_PUT_BITS_H
32 #include "libavutil/bswap.h"
33 #include "libavutil/common.h"
34 #include "libavutil/intreadwrite.h"
35 #include "libavutil/log.h"
38 //#define ALT_BITSTREAM_WRITER
39 //#define ALIGNED_BITSTREAM_WRITER
41 /* buf and buf_end must be present and used by every alternative writer. */
42 typedef struct PutBitContext
{
43 #ifdef ALT_BITSTREAM_WRITER
44 uint8_t *buf
, *buf_end
;
49 uint8_t *buf
, *buf_ptr
, *buf_end
;
55 * Initializes the PutBitContext s.
57 * @param buffer the buffer where to put bits
58 * @param buffer_size the size in bytes of buffer
60 static inline void init_put_bits(PutBitContext
*s
, uint8_t *buffer
, int buffer_size
)
67 s
->size_in_bits
= 8*buffer_size
;
69 s
->buf_end
= s
->buf
+ buffer_size
;
70 #ifdef ALT_BITSTREAM_WRITER
72 ((uint32_t*)(s
->buf
))[0]=0;
73 // memset(buffer, 0, buffer_size);
82 * Returns the total number of bits written to the bitstream.
84 static inline int put_bits_count(PutBitContext
*s
)
86 #ifdef ALT_BITSTREAM_WRITER
89 return (s
->buf_ptr
- s
->buf
) * 8 + 32 - s
->bit_left
;
94 * Pads the end of the output stream with zeros.
96 static inline void flush_put_bits(PutBitContext
*s
)
98 #ifdef ALT_BITSTREAM_WRITER
101 #ifndef BITSTREAM_WRITER_LE
102 s
->bit_buf
<<= s
->bit_left
;
104 while (s
->bit_left
< 32) {
105 /* XXX: should test end of buffer */
106 #ifdef BITSTREAM_WRITER_LE
107 *s
->buf_ptr
++=s
->bit_buf
;
110 *s
->buf_ptr
++=s
->bit_buf
>> 24;
121 * Pads the bitstream with zeros up to the next byte boundary.
123 void align_put_bits(PutBitContext
*s
);
126 * Puts the string s in the bitstream.
128 * @param terminate_string 0-terminates the written string if value is 1
130 void ff_put_string(PutBitContext
* pbc
, const char *s
, int terminate_string
);
133 * Copies the content of src to the bitstream.
135 * @param length the number of bits of src to copy
137 void ff_copy_bits(PutBitContext
*pb
, const uint8_t *src
, int length
);
140 * Write up to 31 bits into a bitstream.
141 * Use put_bits32 to write 32 bits.
143 static inline void put_bits(PutBitContext
*s
, int n
, unsigned int value
)
144 #ifndef ALT_BITSTREAM_WRITER
146 unsigned int bit_buf
;
149 // printf("put_bits=%d %x\n", n, value);
150 assert(n
<= 31 && value
< (1U << n
));
152 bit_buf
= s
->bit_buf
;
153 bit_left
= s
->bit_left
;
155 // printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
157 #ifdef BITSTREAM_WRITER_LE
158 bit_buf
|= value
<< (32 - bit_left
);
160 #if !HAVE_FAST_UNALIGNED
161 if (3 & (intptr_t) s
->buf_ptr
) {
162 AV_WL32(s
->buf_ptr
, bit_buf
);
165 *(uint32_t *)s
->buf_ptr
= le2me_32(bit_buf
);
167 bit_buf
= (bit_left
==32)?0:value
>> bit_left
;
173 bit_buf
= (bit_buf
<<n
) | value
;
177 bit_buf
|= value
>> (n
- bit_left
);
178 #if !HAVE_FAST_UNALIGNED
179 if (3 & (intptr_t) s
->buf_ptr
) {
180 AV_WB32(s
->buf_ptr
, bit_buf
);
183 *(uint32_t *)s
->buf_ptr
= be2me_32(bit_buf
);
184 //printf("bitbuf = %08x\n", bit_buf);
191 s
->bit_buf
= bit_buf
;
192 s
->bit_left
= bit_left
;
194 #else /* ALT_BITSTREAM_WRITER defined */
196 # ifdef ALIGNED_BITSTREAM_WRITER
199 "movl %0, %%ecx \n\t"
200 "xorl %%eax, %%eax \n\t"
201 "shrdl %%cl, %1, %%eax \n\t"
203 "movl %0, %%ecx \n\t"
204 "shrl $3, %%ecx \n\t"
205 "andl $0xFFFFFFFC, %%ecx \n\t"
207 "orl %1, (%2, %%ecx) \n\t"
210 "movl %%eax, 4(%2, %%ecx) \n\t"
211 : "=&r" (s
->index
), "=&r" (value
)
212 : "r" (s
->buf
), "r" (n
), "0" (s
->index
), "1" (value
<<(-n
))
217 uint32_t *ptr
= ((uint32_t *)s
->buf
)+(index
>>5);
221 ptr
[0] |= be2me_32(value
>>(index
&31));
222 ptr
[1] = be2me_32(value
<<(32-(index
&31)));
223 //if(n>24) printf("%d %d\n", n, value);
227 # else //ALIGNED_BITSTREAM_WRITER
230 "movl $7, %%ecx \n\t"
231 "andl %0, %%ecx \n\t"
232 "addl %3, %%ecx \n\t"
236 "movl %0, %%ecx \n\t"
237 "shrl $3, %%ecx \n\t"
238 "orl %1, (%%ecx, %2) \n\t"
240 "movl $0, 4(%%ecx, %2) \n\t"
241 : "=&r" (s
->index
), "=&r" (value
)
242 : "r" (s
->buf
), "r" (n
), "0" (s
->index
), "1" (value
)
247 uint32_t *ptr
= (uint32_t*)(((uint8_t *)s
->buf
)+(index
>>3));
249 ptr
[0] |= be2me_32(value
<<(32-n
-(index
&7) ));
251 //if(n>24) printf("%d %d\n", n, value);
255 # endif //!ALIGNED_BITSTREAM_WRITER
259 static inline void put_sbits(PutBitContext
*pb
, int bits
, int32_t val
)
261 assert(bits
>= 0 && bits
<= 31);
263 put_bits(pb
, bits
, val
& ((1<<bits
)-1));
267 * Write exactly 32 bits into a bitstream
269 static void av_unused
put_bits32(PutBitContext
*s
, uint32_t value
)
271 int lo
= value
& 0xffff;
272 int hi
= value
>> 16;
273 #ifdef ALT_BITSTREAM_WRITER_LE
283 * Returns the pointer to the byte where the bitstream writer will put
286 static inline uint8_t* put_bits_ptr(PutBitContext
*s
)
288 #ifdef ALT_BITSTREAM_WRITER
289 return s
->buf
+ (s
->index
>>3);
296 * Skips the given number of bytes.
297 * PutBitContext must be flushed & aligned to a byte boundary before calling this.
299 static inline void skip_put_bytes(PutBitContext
*s
, int n
){
300 assert((put_bits_count(s
)&7)==0);
301 #ifdef ALT_BITSTREAM_WRITER
302 FIXME may need some cleaning of the buffer
305 assert(s
->bit_left
==32);
311 * Skips the given number of bits.
312 * Must only be used if the actual values in the bitstream do not matter.
313 * If n is 0 the behavior is undefined.
315 static inline void skip_put_bits(PutBitContext
*s
, int n
){
316 #ifdef ALT_BITSTREAM_WRITER
320 s
->buf_ptr
-= 4*(s
->bit_left
>>5);
326 * Changes the end of the buffer.
328 * @param size the new size in bytes of the buffer where to put bits
330 static inline void set_put_bits_buffer_size(PutBitContext
*s
, int size
){
331 s
->buf_end
= s
->buf
+ size
;
334 #endif /* AVCODEC_PUT_BITS_H */