1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
|
/*
* copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* bitstream writer API
*/
#ifndef AVCODEC_PUT_BITS_H
#define AVCODEC_PUT_BITS_H
#include <stdint.h>
#include <stdlib.h>
#include <assert.h>
#include "libavutil/bswap.h"
#include "libavutil/common.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/log.h"
#include "mathops.h"
#include "config.h"
typedef struct PutBitContext {
uint32_t bit_buf;
int bit_left;
uint8_t *buf, *buf_ptr, *buf_end;
int size_in_bits;
} PutBitContext;
/**
* Initialize the PutBitContext s.
*
* @param buffer the buffer where to put bits
* @param buffer_size the size in bytes of buffer
*/
static inline void init_put_bits(PutBitContext *s, uint8_t *buffer,
int buffer_size)
{
if (buffer_size < 0) {
buffer_size = 0;
buffer = NULL;
}
s->size_in_bits = 8 * buffer_size;
s->buf = buffer;
s->buf_end = s->buf + buffer_size;
s->buf_ptr = s->buf;
s->bit_left = 32;
s->bit_buf = 0;
}
/**
* @return the total number of bits written to the bitstream.
*/
static inline int put_bits_count(PutBitContext *s)
{
return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
}
/**
* Pad the end of the output stream with zeros.
*/
static inline void flush_put_bits(PutBitContext *s)
{
#ifndef BITSTREAM_WRITER_LE
if (s->bit_left < 32)
s->bit_buf <<= s->bit_left;
#endif
while (s->bit_left < 32) {
/* XXX: should test end of buffer */
#ifdef BITSTREAM_WRITER_LE
*s->buf_ptr++ = s->bit_buf;
s->bit_buf >>= 8;
#else
*s->buf_ptr++ = s->bit_buf >> 24;
s->bit_buf <<= 8;
#endif
s->bit_left += 8;
}
s->bit_left = 32;
s->bit_buf = 0;
}
#ifdef BITSTREAM_WRITER_LE
#define avpriv_align_put_bits align_put_bits_unsupported_here
#define avpriv_put_string ff_put_string_unsupported_here
#define avpriv_copy_bits avpriv_copy_bits_unsupported_here
#else
/**
* Pad the bitstream with zeros up to the next byte boundary.
*/
void avpriv_align_put_bits(PutBitContext *s);
/**
* Put the string string in the bitstream.
*
* @param terminate_string 0-terminates the written string if value is 1
*/
void avpriv_put_string(PutBitContext *pb, const char *string,
int terminate_string);
/**
* Copy the content of src to the bitstream.
*
* @param length the number of bits of src to copy
*/
void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
#endif
/**
* Write up to 31 bits into a bitstream.
* Use put_bits32 to write 32 bits.
*/
static inline void put_bits(PutBitContext *s, int n, unsigned int value)
{
unsigned int bit_buf;
int bit_left;
assert(n <= 31 && value < (1U << n));
bit_buf = s->bit_buf;
bit_left = s->bit_left;
/* XXX: optimize */
#ifdef BITSTREAM_WRITER_LE
bit_buf |= value << (32 - bit_left);
if (n >= bit_left) {
AV_WL32(s->buf_ptr, bit_buf);
s->buf_ptr += 4;
bit_buf = (bit_left == 32) ? 0 : value >> bit_left;
bit_left += 32;
}
bit_left -= n;
#else
if (n < bit_left) {
bit_buf = (bit_buf << n) | value;
bit_left -= n;
} else {
bit_buf <<= bit_left;
bit_buf |= value >> (n - bit_left);
AV_WB32(s->buf_ptr, bit_buf);
s->buf_ptr += 4;
bit_left += 32 - n;
bit_buf = value;
}
#endif
s->bit_buf = bit_buf;
s->bit_left = bit_left;
}
static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
{
assert(n >= 0 && n <= 31);
put_bits(pb, n, value & ((1 << n) - 1));
}
/**
* Write exactly 32 bits into a bitstream.
*/
static void av_unused put_bits32(PutBitContext *s, uint32_t value)
{
int lo = value & 0xffff;
int hi = value >> 16;
#ifdef BITSTREAM_WRITER_LE
put_bits(s, 16, lo);
put_bits(s, 16, hi);
#else
put_bits(s, 16, hi);
put_bits(s, 16, lo);
#endif
}
/**
* Return the pointer to the byte where the bitstream writer will put
* the next bit.
*/
static inline uint8_t *put_bits_ptr(PutBitContext *s)
{
return s->buf_ptr;
}
/**
* Skip the given number of bytes.
* PutBitContext must be flushed & aligned to a byte boundary before calling this.
*/
static inline void skip_put_bytes(PutBitContext *s, int n)
{
assert((put_bits_count(s) & 7) == 0);
assert(s->bit_left == 32);
s->buf_ptr += n;
}
/**
* Skip the given number of bits.
* Must only be used if the actual values in the bitstream do not matter.
* If n is 0 the behavior is undefined.
*/
static inline void skip_put_bits(PutBitContext *s, int n)
{
s->bit_left -= n;
s->buf_ptr -= 4 * (s->bit_left >> 5);
s->bit_left &= 31;
}
/**
* Change the end of the buffer.
*
* @param size the new size in bytes of the buffer where to put bits
*/
static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
{
s->buf_end = s->buf + size;
}
#endif /* AVCODEC_PUT_BITS_H */
|
