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
|
/*
* Copyright (c) 2016 Alexandra Hájková
*
* This file is part of FFmpeg.
*
* FFmpeg 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.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* bitstream reader API header.
*/
/*
* Bit order (endianness) is controlled by #defining BITSTREAM_BE and/or
* BITSTREAM_LE before #including this header. The corresponding bitreading
* functions are provided as bits_*_be()/bits_*_le() respectively.
*
* If neither or only BITSTREAM_BE is defined, then the default (unsuffixed)
* bits_*() will resolve to the big-endian implementation. If only BITSTREAM_LE
* is defined, little-endian will be the default.
*
* If both are defined, then the default can be controlled by defining at most
* one of BITSTREAM_DEFAULT_LE/BE. When BITSTREAM_DEFAULT_* is not defined, no
* default is provided and you must always explicitly use the _be() or _le()
* variants.
*/
#ifndef AVCODEC_BITSTREAM_H
#define AVCODEC_BITSTREAM_H
#include <stdint.h>
#include "config.h"
#include "libavutil/avassert.h"
#include "libavutil/common.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/log.h"
#include "mathops.h"
#include "vlc.h"
#ifndef UNCHECKED_BITSTREAM_READER
#define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER
#endif
// select the default endianness, if any
#if defined(BITSTREAM_LE) && defined(BITSTREAM_BE)
# if defined(BITSTREAM_DEFAULT_BE) && defined(BITSTREAM_DEFAULT_LE)
# error "At most one of BITSTREAM_DEFAULT_BE/LE must be defined"
# elif defined(BITSTREAM_DEFAULT_BE)
# define BITS_DEFAULT_BE
# elif defined(BITSTREAM_DEFAULT_LE)
# define BITS_DEFAULT_LE
# endif
#elif defined(BITSTREAM_LE)
# define BITS_DEFAULT_LE
#else // select BE if nothing is requested explicitly
# define BITS_DEFAULT_BE
# define BITSTREAM_WANT_BE
#endif
#if defined(BITS_DEFAULT_LE)
# define BitstreamContext BitstreamContextLE
# define bits_init bits_init_le
# define bits_init8 bits_init8_le
# define bits_tell bits_tell_le
# define bits_size bits_size_le
# define bits_left bits_left_le
# define bits_read_bit bits_read_bit_le
# define bits_read_nz bits_read_nz_le
# define bits_read bits_read_le
# define bits_read_63 bits_read_63_le
# define bits_read_64 bits_read_64_le
# define bits_read_signed bits_read_signed_le
# define bits_read_signed_nz bits_read_signed_nz_le
# define bits_peek_nz bits_peek_nz_le
# define bits_peek bits_peek_le
# define bits_peek_signed bits_peek_signed_le
# define bits_peek_signed_nz bits_peek_signed_nz_le
# define bits_skip bits_skip_le
# define bits_seek bits_seek_le
# define bits_align bits_align_le
# define bits_read_xbits bits_read_xbits_le
# define bits_decode012 bits_decode012_le
# define bits_decode210 bits_decode210_le
# define bits_apply_sign bits_apply_sign_le
# define bits_read_vlc bits_read_vlc_le
# define bits_read_vlc_multi bits_read_vlc_multi_le
# define bits_read_leb bits_read_leb_le
#elif defined(BITS_DEFAULT_BE)
# define BitstreamContext BitstreamContextBE
# define bits_init bits_init_be
# define bits_init8 bits_init8_be
# define bits_tell bits_tell_be
# define bits_size bits_size_be
# define bits_left bits_left_be
# define bits_read_bit bits_read_bit_be
# define bits_read_nz bits_read_nz_be
# define bits_read bits_read_be
# define bits_read_63 bits_read_63_be
# define bits_read_64 bits_read_64_be
# define bits_read_signed bits_read_signed_be
# define bits_read_signed_nz bits_read_signed_nz_be
# define bits_peek_nz bits_peek_nz_be
# define bits_peek bits_peek_be
# define bits_peek_signed bits_peek_signed_be
# define bits_peek_signed_nz bits_peek_signed_nz_be
# define bits_skip bits_skip_be
# define bits_seek bits_seek_be
# define bits_align bits_align_be
# define bits_read_xbits bits_read_xbits_be
# define bits_decode012 bits_decode012_be
# define bits_decode210 bits_decode210_be
# define bits_apply_sign bits_apply_sign_be
# define bits_read_vlc bits_read_vlc_be
# define bits_read_vlc_multi bits_read_vlc_multi_be
# define bits_read_leb bits_read_leb_be
#endif
#undef BITS_DEFAULT_LE
#undef BITS_DEFAULT_BE
#define BITS_RL_VLC(level, run, bc, table, bits, max_depth) \
do { \
int n, nb_bits; \
unsigned int index = bits_peek(bc, bits); \
level = table[index].level; \
n = table[index].len; \
\
if (max_depth > 1 && n < 0) { \
bits_skip(bc, bits); \
\
nb_bits = -n; \
\
index = bits_peek(bc, nb_bits) + level; \
level = table[index].level; \
n = table[index].len; \
if (max_depth > 2 && n < 0) { \
bits_skip(bc, nb_bits); \
nb_bits = -n; \
\
index = bits_peek(bc, nb_bits) + level; \
level = table[index].level; \
n = table[index].len; \
} \
} \
run = table[index].run; \
bits_skip(bc, n); \
} while (0)
#endif /* AVCODEC_BITSTREAM_H */
// the following is deliberately outside of the standard #include guards
#if defined(BITSTREAM_LE) && !defined(BITSTREAM_WANT_LE)
# define BITSTREAM_WANT_LE
#endif
#if defined(BITSTREAM_BE) && !defined(BITSTREAM_WANT_BE)
# define BITSTREAM_WANT_BE
#endif
#if defined(BITSTREAM_WANT_LE) && !defined(AVCODEC_BITSTREAM_LE)
#define AVCODEC_BITSTREAM_LE
#define BITSTREAM_TEMPLATE_LE
#include "bitstream_template.h"
#undef BITSTREAM_TEMPLATE_LE
#endif
#if defined(BITSTREAM_WANT_BE) && !defined(AVCODEC_BITSTREAM_BE)
#define AVCODEC_BITSTREAM_BE
#include "bitstream_template.h"
#endif
#undef BITSTREAM_WANT_LE
#undef BITSTREAM_WANT_BE
|
