avformat/asfdec_o: Check size vs. offset in detect_unknown_subobject()
[ffmpeg.git] / libavcodec / vlc.h
1 /*
2  * This file is part of FFmpeg.
3  *
4  * FFmpeg is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * FFmpeg is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12  * Lesser General Public License for more details.
13  *
14  * You should have received a copy of the GNU Lesser General Public
15  * License along with FFmpeg; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17  */
18
19 #ifndef AVCODEC_VLC_H
20 #define AVCODEC_VLC_H
21
22 #include <stdint.h>
23
24 #define VLC_TYPE int16_t
25
26 typedef struct VLC {
27     int bits;
28     VLC_TYPE (*table)[2]; ///< code, bits
29     int table_size, table_allocated;
30 } VLC;
31
32 typedef struct RL_VLC_ELEM {
33     int16_t level;
34     int8_t len;
35     uint8_t run;
36 } RL_VLC_ELEM;
37
38 #define init_vlc(vlc, nb_bits, nb_codes,                \
39                  bits, bits_wrap, bits_size,            \
40                  codes, codes_wrap, codes_size,         \
41                  flags)                                 \
42     ff_init_vlc_sparse(vlc, nb_bits, nb_codes,          \
43                        bits, bits_wrap, bits_size,      \
44                        codes, codes_wrap, codes_size,   \
45                        NULL, 0, 0, flags)
46
47 int ff_init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,
48                        const void *bits, int bits_wrap, int bits_size,
49                        const void *codes, int codes_wrap, int codes_size,
50                        const void *symbols, int symbols_wrap, int symbols_size,
51                        int flags);
52
53 /**
54  * Build VLC decoding tables suitable for use with get_vlc2()
55  *
56  * This function takes lengths and symbols and calculates the codes from them.
57  * For this the input lengths and symbols have to be sorted according to "left
58  * nodes in the corresponding tree first".
59  *
60  * @param[in,out] vlc      The VLC to be initialized; table and table_allocated
61  *                         must have been set when initializing a static VLC,
62  *                         otherwise this will be treated as uninitialized.
63  * @param[in] nb_bits      The number of bits to use for the VLC table;
64  *                         higher values take up more memory and cache, but
65  *                         allow to read codes with fewer reads.
66  * @param[in] nb_codes     The number of provided length and (if supplied) symbol
67  *                         entries.
68  * @param[in] lens         The lengths of the codes. Entries > 0 correspond to
69  *                         valid codes; entries == 0 will be skipped and entries
70  *                         with len < 0 indicate that the tree is incomplete and
71  *                         has an open end of length -len at this position.
72  * @param[in] lens_wrap    Stride (in bytes) of the lengths.
73  * @param[in] symbols      The symbols, i.e. what is returned from get_vlc2()
74  *                         when the corresponding code is encountered.
75  *                         May be NULL, then 0, 1, 2, 3, 4,... will be used.
76  * @param[in] symbols_wrap Stride (in bytes) of the symbols.
77  * @param[in] symbols_size Size of the symbols. 1 and 2 are supported.
78  * @param[in] offset       An offset to apply to all the valid symbols.
79  * @param[in] flags        A combination of the INIT_VLC_* flags; notice that
80  *                         INIT_VLC_INPUT_LE is pointless and ignored.
81  */
82 int ff_init_vlc_from_lengths(VLC *vlc, int nb_bits, int nb_codes,
83                              const int8_t *lens, int lens_wrap,
84                              const void *symbols, int symbols_wrap, int symbols_size,
85                              int offset, int flags, void *logctx);
86
87 void ff_free_vlc(VLC *vlc);
88
89 /* If INIT_VLC_INPUT_LE is set, the LSB bit of the codes used to
90  * initialize the VLC table is the first bit to be read. */
91 #define INIT_VLC_INPUT_LE       2
92 /* If set the VLC is intended for a little endian bitstream reader. */
93 #define INIT_VLC_OUTPUT_LE      8
94 #define INIT_VLC_LE             (INIT_VLC_INPUT_LE | INIT_VLC_OUTPUT_LE)
95 #define INIT_VLC_USE_NEW_STATIC 4
96 #define INIT_VLC_STATIC_OVERLONG (1 | INIT_VLC_USE_NEW_STATIC)
97
98 #define INIT_CUSTOM_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g,      \
99                                       h, i, j, flags, static_size)         \
100     do {                                                                   \
101         static VLC_TYPE table[static_size][2];                             \
102         (vlc)->table           = table;                                    \
103         (vlc)->table_allocated = static_size;                              \
104         ff_init_vlc_sparse(vlc, bits, a, b, c, d, e, f, g, h, i, j,        \
105                            flags | INIT_VLC_USE_NEW_STATIC);               \
106     } while (0)
107
108 #define INIT_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, h, i, j, static_size) \
109     INIT_CUSTOM_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g,          \
110                                   h, i, j, 0, static_size)
111
112 #define INIT_LE_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, h, i, j, static_size) \
113     INIT_CUSTOM_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g,          \
114                                   h, i, j, INIT_VLC_LE, static_size)
115
116 #define INIT_CUSTOM_VLC_STATIC(vlc, bits, a, b, c, d, e, f, g, flags, static_size) \
117     INIT_CUSTOM_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g,          \
118                                   NULL, 0, 0, flags, static_size)
119
120 #define INIT_VLC_STATIC(vlc, bits, a, b, c, d, e, f, g, static_size)       \
121     INIT_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, NULL, 0, 0, static_size)
122
123 #define INIT_LE_VLC_STATIC(vlc, bits, a, b, c, d, e, f, g, static_size) \
124     INIT_LE_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, NULL, 0, 0, static_size)
125
126 #define INIT_VLC_STATIC_FROM_LENGTHS(vlc, bits, nb_codes, lens, len_wrap,  \
127                                      symbols, symbols_wrap, symbols_size,  \
128                                      offset, flags, static_size)           \
129     do {                                                                   \
130         static VLC_TYPE table[static_size][2];                             \
131         (vlc)->table           = table;                                    \
132         (vlc)->table_allocated = static_size;                              \
133         ff_init_vlc_from_lengths(vlc, bits, nb_codes, lens, len_wrap,      \
134                                  symbols, symbols_wrap, symbols_size,      \
135                                  offset, flags | INIT_VLC_USE_NEW_STATIC,  \
136                                  NULL);                                    \
137     } while (0)
138
139 #endif /* AVCODEC_VLC_H */