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 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"
39 //#define ALT_BITSTREAM_WRITER
40 //#define ALIGNED_BITSTREAM_WRITER
42 /* buf and buf_end must be present and used by every alternative writer. */
43 typedef struct PutBitContext {
44 #ifdef ALT_BITSTREAM_WRITER
45 uint8_t *buf, *buf_end;
50 uint8_t *buf, *buf_ptr, *buf_end;
56 * Initialize the PutBitContext s.
58 * @param buffer the buffer where to put bits
59 * @param buffer_size the size in bytes of buffer
61 static inline void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
68 s->size_in_bits= 8*buffer_size;
70 s->buf_end = s->buf + buffer_size;
71 #ifdef ALT_BITSTREAM_WRITER
73 ((uint32_t*)(s->buf))[0]=0;
74 // memset(buffer, 0, buffer_size);
83 * @return the total number of bits written to the bitstream.
85 static inline int put_bits_count(PutBitContext *s)
87 #ifdef ALT_BITSTREAM_WRITER
90 return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
95 * Pad the end of the output stream with zeros.
97 static inline void flush_put_bits(PutBitContext *s)
99 #ifdef ALT_BITSTREAM_WRITER
102 #ifndef BITSTREAM_WRITER_LE
103 s->bit_buf<<= s->bit_left;
105 while (s->bit_left < 32) {
106 /* XXX: should test end of buffer */
107 #ifdef BITSTREAM_WRITER_LE
108 *s->buf_ptr++=s->bit_buf;
111 *s->buf_ptr++=s->bit_buf >> 24;
121 #if defined(ALT_BITSTREAM_WRITER) || defined(BITSTREAM_WRITER_LE)
122 #define align_put_bits align_put_bits_unsupported_here
123 #define ff_put_string ff_put_string_unsupported_here
124 #define ff_copy_bits ff_copy_bits_unsupported_here
127 * Pad the bitstream with zeros up to the next byte boundary.
129 void align_put_bits(PutBitContext *s);
132 * Put the string string in the bitstream.
134 * @param terminate_string 0-terminates the written string if value is 1
136 void ff_put_string(PutBitContext *pb, const char *string, int terminate_string);
139 * Copy the content of src to the bitstream.
141 * @param length the number of bits of src to copy
143 void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
147 * Write up to 31 bits into a bitstream.
148 * Use put_bits32 to write 32 bits.
150 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
151 #ifndef ALT_BITSTREAM_WRITER
153 unsigned int bit_buf;
156 // printf("put_bits=%d %x\n", n, value);
157 assert(n <= 31 && value < (1U << n));
159 bit_buf = s->bit_buf;
160 bit_left = s->bit_left;
162 // printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
164 #ifdef BITSTREAM_WRITER_LE
165 bit_buf |= value << (32 - bit_left);
167 #if !HAVE_FAST_UNALIGNED
168 if (3 & (intptr_t) s->buf_ptr) {
169 AV_WL32(s->buf_ptr, bit_buf);
172 *(uint32_t *)s->buf_ptr = av_le2ne32(bit_buf);
174 bit_buf = (bit_left==32)?0:value >> bit_left;
180 bit_buf = (bit_buf<<n) | value;
184 bit_buf |= value >> (n - bit_left);
185 #if !HAVE_FAST_UNALIGNED
186 if (3 & (intptr_t) s->buf_ptr) {
187 AV_WB32(s->buf_ptr, bit_buf);
190 *(uint32_t *)s->buf_ptr = av_be2ne32(bit_buf);
191 //printf("bitbuf = %08x\n", bit_buf);
198 s->bit_buf = bit_buf;
199 s->bit_left = bit_left;
201 #else /* ALT_BITSTREAM_WRITER defined */
203 # ifdef ALIGNED_BITSTREAM_WRITER
206 "movl %0, %%ecx \n\t"
207 "xorl %%eax, %%eax \n\t"
208 "shrdl %%cl, %1, %%eax \n\t"
210 "movl %0, %%ecx \n\t"
211 "shrl $3, %%ecx \n\t"
212 "andl $0xFFFFFFFC, %%ecx \n\t"
214 "orl %1, (%2, %%ecx) \n\t"
217 "movl %%eax, 4(%2, %%ecx) \n\t"
218 : "=&r" (s->index), "=&r" (value)
219 : "r" (s->buf), "r" (n), "0" (s->index), "1" (value<<(-n))
224 uint32_t *ptr= ((uint32_t *)s->buf)+(index>>5);
228 ptr[0] |= av_be2ne32(value>>(index&31));
229 ptr[1] = av_be2ne32(value<<(32-(index&31)));
230 //if(n>24) printf("%d %d\n", n, value);
234 # else //ALIGNED_BITSTREAM_WRITER
237 "movl $7, %%ecx \n\t"
238 "andl %0, %%ecx \n\t"
239 "addl %3, %%ecx \n\t"
243 "movl %0, %%ecx \n\t"
244 "shrl $3, %%ecx \n\t"
245 "orl %1, (%%ecx, %2) \n\t"
247 "movl $0, 4(%%ecx, %2) \n\t"
248 : "=&r" (s->index), "=&r" (value)
249 : "r" (s->buf), "r" (n), "0" (s->index), "1" (value)
254 uint32_t *ptr= (uint32_t*)(((uint8_t *)s->buf)+(index>>3));
256 ptr[0] |= av_be2ne32(value<<(32-n-(index&7) ));
258 //if(n>24) printf("%d %d\n", n, value);
262 # endif //!ALIGNED_BITSTREAM_WRITER
266 static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
268 assert(n >= 0 && n <= 31);
270 put_bits(pb, n, value & ((1<<n)-1));
274 * Write exactly 32 bits into a bitstream.
276 static void av_unused put_bits32(PutBitContext *s, uint32_t value)
278 int lo = value & 0xffff;
279 int hi = value >> 16;
280 #ifdef BITSTREAM_WRITER_LE
290 * Return the pointer to the byte where the bitstream writer will put
293 static inline uint8_t* put_bits_ptr(PutBitContext *s)
295 #ifdef ALT_BITSTREAM_WRITER
296 return s->buf + (s->index>>3);
303 * Skip the given number of bytes.
304 * PutBitContext must be flushed & aligned to a byte boundary before calling this.
306 static inline void skip_put_bytes(PutBitContext *s, int n)
308 assert((put_bits_count(s)&7)==0);
309 #ifdef ALT_BITSTREAM_WRITER
310 FIXME may need some cleaning of the buffer
313 assert(s->bit_left==32);
319 * Skip the given number of bits.
320 * Must only be used if the actual values in the bitstream do not matter.
321 * If n is 0 the behavior is undefined.
323 static inline void skip_put_bits(PutBitContext *s, int n)
325 #ifdef ALT_BITSTREAM_WRITER
329 s->buf_ptr-= 4*(s->bit_left>>5);
335 * Change the end of the buffer.
337 * @param size the new size in bytes of the buffer where to put bits
339 static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
341 s->buf_end= s->buf + size;
344 #endif /* AVCODEC_PUT_BITS_H */