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 string in the bitstream.
128 * @param terminate_string 0-terminates the written string if value is 1
130 void ff_put_string(PutBitContext *pb, const char *string, 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 * Writes 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 n, int32_t value)
261 assert(n >= 0 && n <= 31);
263 put_bits(pb, n, value & ((1<<n)-1));
267 * Writes 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)
301 assert((put_bits_count(s)&7)==0);
302 #ifdef ALT_BITSTREAM_WRITER
303 FIXME may need some cleaning of the buffer
306 assert(s->bit_left==32);
312 * Skips the given number of bits.
313 * Must only be used if the actual values in the bitstream do not matter.
314 * If n is 0 the behavior is undefined.
316 static inline void skip_put_bits(PutBitContext *s, int n)
318 #ifdef ALT_BITSTREAM_WRITER
322 s->buf_ptr-= 4*(s->bit_left>>5);
328 * Changes the end of the buffer.
330 * @param size the new size in bytes of the buffer where to put bits
332 static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
334 s->buf_end= s->buf + size;
337 #endif /* AVCODEC_PUT_BITS_H */