2 * copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
4 * This file is part of Libav.
6 * Libav 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 * Libav 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 Libav; 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 typedef struct PutBitContext {
42 uint8_t *buf, *buf_ptr, *buf_end;
47 * Initialize the PutBitContext s.
49 * @param buffer the buffer where to put bits
50 * @param buffer_size the size in bytes of buffer
52 static inline void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
59 s->size_in_bits= 8*buffer_size;
61 s->buf_end = s->buf + buffer_size;
68 * @return the total number of bits written to the bitstream.
70 static inline int put_bits_count(PutBitContext *s)
72 return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
76 * Pad the end of the output stream with zeros.
78 static inline void flush_put_bits(PutBitContext *s)
80 #ifndef BITSTREAM_WRITER_LE
82 s->bit_buf<<= s->bit_left;
84 while (s->bit_left < 32) {
85 /* XXX: should test end of buffer */
86 #ifdef BITSTREAM_WRITER_LE
87 *s->buf_ptr++=s->bit_buf;
90 *s->buf_ptr++=s->bit_buf >> 24;
99 #ifdef BITSTREAM_WRITER_LE
100 #define avpriv_align_put_bits align_put_bits_unsupported_here
101 #define avpriv_put_string ff_put_string_unsupported_here
102 #define avpriv_copy_bits avpriv_copy_bits_unsupported_here
105 * Pad the bitstream with zeros up to the next byte boundary.
107 void avpriv_align_put_bits(PutBitContext *s);
110 * Put the string string in the bitstream.
112 * @param terminate_string 0-terminates the written string if value is 1
114 void avpriv_put_string(PutBitContext *pb, const char *string, int terminate_string);
117 * Copy the content of src to the bitstream.
119 * @param length the number of bits of src to copy
121 void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
125 * Write up to 31 bits into a bitstream.
126 * Use put_bits32 to write 32 bits.
128 static inline void put_bits(PutBitContext *s, int n, unsigned int value)
130 unsigned int bit_buf;
133 assert(n <= 31 && value < (1U << n));
135 bit_buf = s->bit_buf;
136 bit_left = s->bit_left;
139 #ifdef BITSTREAM_WRITER_LE
140 bit_buf |= value << (32 - bit_left);
142 AV_WL32(s->buf_ptr, bit_buf);
144 bit_buf = (bit_left==32)?0:value >> bit_left;
150 bit_buf = (bit_buf<<n) | value;
154 bit_buf |= value >> (n - bit_left);
155 AV_WB32(s->buf_ptr, bit_buf);
162 s->bit_buf = bit_buf;
163 s->bit_left = bit_left;
166 static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
168 assert(n >= 0 && n <= 31);
170 put_bits(pb, n, value & ((1<<n)-1));
174 * Write exactly 32 bits into a bitstream.
176 static void av_unused put_bits32(PutBitContext *s, uint32_t value)
178 int lo = value & 0xffff;
179 int hi = value >> 16;
180 #ifdef BITSTREAM_WRITER_LE
190 * Return the pointer to the byte where the bitstream writer will put
193 static inline uint8_t* put_bits_ptr(PutBitContext *s)
199 * Skip the given number of bytes.
200 * PutBitContext must be flushed & aligned to a byte boundary before calling this.
202 static inline void skip_put_bytes(PutBitContext *s, int n)
204 assert((put_bits_count(s)&7)==0);
205 assert(s->bit_left==32);
210 * Skip the given number of bits.
211 * Must only be used if the actual values in the bitstream do not matter.
212 * If n is 0 the behavior is undefined.
214 static inline void skip_put_bits(PutBitContext *s, int n)
217 s->buf_ptr-= 4*(s->bit_left>>5);
222 * Change the end of the buffer.
224 * @param size the new size in bytes of the buffer where to put bits
226 static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
228 s->buf_end= s->buf + size;
231 #endif /* AVCODEC_PUT_BITS_H */