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"
36 #include "libavutil/avassert.h"
40 typedef struct PutBitContext {
43 uint8_t *buf, *buf_ptr, *buf_end;
48 * Initialize the PutBitContext s.
50 * @param buffer the buffer where to put bits
51 * @param buffer_size the size in bytes of buffer
53 static inline void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
60 s->size_in_bits= 8*buffer_size;
62 s->buf_end = s->buf + buffer_size;
69 * @return the total number of bits written to the bitstream.
71 static inline int put_bits_count(PutBitContext *s)
73 return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
77 * Pad the end of the output stream with zeros.
79 static inline void flush_put_bits(PutBitContext *s)
81 #ifndef BITSTREAM_WRITER_LE
83 s->bit_buf<<= s->bit_left;
85 while (s->bit_left < 32) {
86 /* XXX: should test end of buffer */
87 #ifdef BITSTREAM_WRITER_LE
88 *s->buf_ptr++=s->bit_buf;
91 *s->buf_ptr++=s->bit_buf >> 24;
100 #ifdef BITSTREAM_WRITER_LE
101 #define avpriv_align_put_bits align_put_bits_unsupported_here
102 #define avpriv_put_string ff_put_string_unsupported_here
103 #define avpriv_copy_bits avpriv_copy_bits_unsupported_here
106 * Pad the bitstream with zeros up to the next byte boundary.
108 void avpriv_align_put_bits(PutBitContext *s);
111 * Put the string string in the bitstream.
113 * @param terminate_string 0-terminates the written string if value is 1
115 void avpriv_put_string(PutBitContext *pb, const char *string, int terminate_string);
118 * Copy the content of src to the bitstream.
120 * @param length the number of bits of src to copy
122 void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
126 * Write up to 31 bits into a bitstream.
127 * Use put_bits32 to write 32 bits.
129 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
131 unsigned int bit_buf;
134 av_assert2(n <= 31 && value < (1U << n));
136 bit_buf = s->bit_buf;
137 bit_left = s->bit_left;
140 #ifdef BITSTREAM_WRITER_LE
141 bit_buf |= value << (32 - bit_left);
143 av_assert2(s->buf_ptr+3<s->buf_end);
144 AV_WL32(s->buf_ptr, bit_buf);
146 bit_buf = (bit_left==32)?0:value >> bit_left;
152 bit_buf = (bit_buf<<n) | value;
156 bit_buf |= value >> (n - bit_left);
157 av_assert2(s->buf_ptr+3<s->buf_end);
158 AV_WB32(s->buf_ptr, bit_buf);
165 s->bit_buf = bit_buf;
166 s->bit_left = bit_left;
169 static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
171 av_assert2(n >= 0 && n <= 31);
173 put_bits(pb, n, value & ((1<<n)-1));
177 * Write exactly 32 bits into a bitstream.
179 static void av_unused put_bits32(PutBitContext *s, uint32_t value)
181 int lo = value & 0xffff;
182 int hi = value >> 16;
183 #ifdef BITSTREAM_WRITER_LE
193 * Return the pointer to the byte where the bitstream writer will put
196 static inline uint8_t* put_bits_ptr(PutBitContext *s)
202 * Skip the given number of bytes.
203 * PutBitContext must be flushed & aligned to a byte boundary before calling this.
205 static inline void skip_put_bytes(PutBitContext *s, int n)
207 av_assert2((put_bits_count(s)&7)==0);
208 av_assert2(s->bit_left==32);
213 * Skip the given number of bits.
214 * Must only be used if the actual values in the bitstream do not matter.
215 * If n is 0 the behavior is undefined.
217 static inline void skip_put_bits(PutBitContext *s, int n)
220 s->buf_ptr-= 4*(s->bit_left>>5);
225 * Change the end of the buffer.
227 * @param size the new size in bytes of the buffer where to put bits
229 static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
231 s->buf_end= s->buf + size;
234 #endif /* AVCODEC_PUT_BITS_H */