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);
139 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
140 #ifndef ALT_BITSTREAM_WRITER
142 unsigned int bit_buf;
145 // printf("put_bits=%d %x\n", n, value);
146 assert(n == 32 || value < (1U << n));
148 bit_buf = s->bit_buf;
149 bit_left = s->bit_left;
151 // printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
153 #ifdef BITSTREAM_WRITER_LE
154 bit_buf |= value << (32 - bit_left);
156 #if !HAVE_FAST_UNALIGNED
157 if (3 & (intptr_t) s->buf_ptr) {
158 AV_WL32(s->buf_ptr, bit_buf);
161 *(uint32_t *)s->buf_ptr = le2me_32(bit_buf);
163 bit_buf = (bit_left==32)?0:value >> bit_left;
169 bit_buf = (bit_buf<<n) | value;
173 bit_buf |= value >> (n - bit_left);
174 #if !HAVE_FAST_UNALIGNED
175 if (3 & (intptr_t) s->buf_ptr) {
176 AV_WB32(s->buf_ptr, bit_buf);
179 *(uint32_t *)s->buf_ptr = be2me_32(bit_buf);
180 //printf("bitbuf = %08x\n", bit_buf);
187 s->bit_buf = bit_buf;
188 s->bit_left = bit_left;
190 #else /* ALT_BITSTREAM_WRITER defined */
192 # ifdef ALIGNED_BITSTREAM_WRITER
195 "movl %0, %%ecx \n\t"
196 "xorl %%eax, %%eax \n\t"
197 "shrdl %%cl, %1, %%eax \n\t"
199 "movl %0, %%ecx \n\t"
200 "shrl $3, %%ecx \n\t"
201 "andl $0xFFFFFFFC, %%ecx \n\t"
203 "orl %1, (%2, %%ecx) \n\t"
206 "movl %%eax, 4(%2, %%ecx) \n\t"
207 : "=&r" (s->index), "=&r" (value)
208 : "r" (s->buf), "r" (n), "0" (s->index), "1" (value<<(-n))
213 uint32_t *ptr= ((uint32_t *)s->buf)+(index>>5);
217 ptr[0] |= be2me_32(value>>(index&31));
218 ptr[1] = be2me_32(value<<(32-(index&31)));
219 //if(n>24) printf("%d %d\n", n, value);
223 # else //ALIGNED_BITSTREAM_WRITER
226 "movl $7, %%ecx \n\t"
227 "andl %0, %%ecx \n\t"
228 "addl %3, %%ecx \n\t"
232 "movl %0, %%ecx \n\t"
233 "shrl $3, %%ecx \n\t"
234 "orl %1, (%%ecx, %2) \n\t"
236 "movl $0, 4(%%ecx, %2) \n\t"
237 : "=&r" (s->index), "=&r" (value)
238 : "r" (s->buf), "r" (n), "0" (s->index), "1" (value)
243 uint32_t *ptr= (uint32_t*)(((uint8_t *)s->buf)+(index>>3));
245 ptr[0] |= be2me_32(value<<(32-n-(index&7) ));
247 //if(n>24) printf("%d %d\n", n, value);
251 # endif //!ALIGNED_BITSTREAM_WRITER
255 static inline void put_sbits(PutBitContext *pb, int bits, int32_t val)
257 assert(bits >= 0 && bits <= 31);
259 put_bits(pb, bits, val & ((1<<bits)-1));
263 * Returns the pointer to the byte where the bitstream writer will put
266 static inline uint8_t* put_bits_ptr(PutBitContext *s)
268 #ifdef ALT_BITSTREAM_WRITER
269 return s->buf + (s->index>>3);
276 * Skips the given number of bytes.
277 * PutBitContext must be flushed & aligned to a byte boundary before calling this.
279 static inline void skip_put_bytes(PutBitContext *s, int n){
280 assert((put_bits_count(s)&7)==0);
281 #ifdef ALT_BITSTREAM_WRITER
282 FIXME may need some cleaning of the buffer
285 assert(s->bit_left==32);
291 * Skips the given number of bits.
292 * Must only be used if the actual values in the bitstream do not matter.
293 * If n is 0 the behavior is undefined.
295 static inline void skip_put_bits(PutBitContext *s, int n){
296 #ifdef ALT_BITSTREAM_WRITER
300 s->buf_ptr-= 4*(s->bit_left>>5);
306 * Changes the end of the buffer.
308 * @param size the new size in bytes of the buffer where to put bits
310 static inline void set_put_bits_buffer_size(PutBitContext *s, int size){
311 s->buf_end= s->buf + size;
314 #endif /* AVCODEC_PUT_BITS_H */