FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/vlc.h
Date: 2024-04-12 08:31:17
Exec Total Coverage
Lines: 2 2 100.0%
Functions: 1 1 100.0%
Branches: 0 0 -%

Line Branch Exec Source
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 <stddef.h>
23 #include <stdint.h>
24
25 #include "libavutil/macros.h"
26
27 #define VLC_MULTI_MAX_SYMBOLS 6
28
29 // When changing this, be sure to also update tableprint_vlc.h accordingly.
30 typedef int16_t VLCBaseType;
31
32 typedef struct VLCElem {
33 VLCBaseType sym, len;
34 } VLCElem;
35
36 typedef struct VLC {
37 int bits;
38 VLCElem *table;
39 int table_size, table_allocated;
40 } VLC;
41
42 typedef struct VLC_MULTI_ELEM {
43 union {
44 uint8_t val8[VLC_MULTI_MAX_SYMBOLS];
45 uint16_t val16[VLC_MULTI_MAX_SYMBOLS / 2];
46 };
47 int8_t len; // -31,32
48 uint8_t num;
49 } VLC_MULTI_ELEM;
50
51 typedef struct VLC_MULTI {
52 VLC_MULTI_ELEM *table;
53 int table_size, table_allocated;
54 } VLC_MULTI;
55
56 typedef struct RL_VLC_ELEM {
57 int16_t level;
58 int8_t len;
59 uint8_t run;
60 } RL_VLC_ELEM;
61
62 #define vlc_init(vlc, nb_bits, nb_codes, \
63 bits, bits_wrap, bits_size, \
64 codes, codes_wrap, codes_size, \
65 flags) \
66 ff_vlc_init_sparse(vlc, nb_bits, nb_codes, \
67 bits, bits_wrap, bits_size, \
68 codes, codes_wrap, codes_size, \
69 NULL, 0, 0, flags)
70
71 /**
72 * Build VLC decoding tables suitable for use with get_vlc2().
73 *
74 * @param[in,out] vlc The VLC to be initialized; table and table_allocated
75 * must have been set when initializing a static VLC,
76 * otherwise this will be treated as uninitialized.
77 * @param[in] nb_bits The number of bits to use for the VLC table;
78 * higher values take up more memory and cache, but
79 * allow to read codes with fewer reads.
80 * Corresponds to the `bits` parameter of get_vlc2().
81 * @param[in] nb_codes The number of provided bits, codes and (if supplied)
82 * symbol entries.
83 * @param[in] bits The lengths (in bits) of the codes. Entries > 0
84 * correspond to valid codes; entries == 0 will be skipped.
85 * @param[in] bits_wrap Stride (in bytes) of the bits table.
86 * @param[in] codes_size Size of the bits. 1, 2 and 4 are supported.
87 * @param[in] codes Table which gives the bit pattern of of each vlc code.
88 * @param[in] codes_wrap Stride (in bytes) of the codes table.
89 * @param[in] codes_size Size of the codes. 1, 2 and 4 are supported.
90 * @param[in] symbols The symbols, i.e. what is returned from get_vlc2()
91 * when the corresponding code is encountered.
92 * May be NULL, then 0, 1, 2, 3, 4,... will be used.
93 * @param[in] symbols_wrap Stride (in bytes) of the symbols table.
94 * @param[in] symbols_size Size of the symbols. 1 and 2 are supported.
95 * @param[in] flags A combination of the VLC_INIT_* flags.
96 *
97 * 'wrap' and 'size' make it possible to use any memory configuration and types
98 * (byte/word/int) to store the 'bits', 'codes', and 'symbols' tables.
99 */
100 int ff_vlc_init_sparse(VLC *vlc, int nb_bits, int nb_codes,
101 const void *bits, int bits_wrap, int bits_size,
102 const void *codes, int codes_wrap, int codes_size,
103 const void *symbols, int symbols_wrap, int symbols_size,
104 int flags);
105
106 /**
107 * Build VLC decoding tables suitable for use with get_vlc2()
108 *
109 * This function takes lengths and symbols and calculates the codes from them.
110 * For this the input lengths and symbols have to be sorted according to "left
111 * nodes in the corresponding tree first".
112 *
113 * @param[in,out] vlc The VLC to be initialized; table and table_allocated
114 * must have been set when initializing a static VLC,
115 * otherwise this will be treated as uninitialized.
116 * @param[in] nb_bits The number of bits to use for the VLC table;
117 * higher values take up more memory and cache, but
118 * allow to read codes with fewer reads.
119 * @param[in] nb_codes The number of provided length and (if supplied) symbol
120 * entries.
121 * @param[in] lens The lengths of the codes. Entries > 0 correspond to
122 * valid codes; entries == 0 will be skipped and entries
123 * with len < 0 indicate that the tree is incomplete and
124 * has an open end of length -len at this position.
125 * @param[in] lens_wrap Stride (in bytes) of the lengths.
126 * @param[in] symbols The symbols, i.e. what is returned from get_vlc2()
127 * when the corresponding code is encountered.
128 * May be NULL, then 0, 1, 2, 3, 4,... will be used.
129 * @param[in] symbols_wrap Stride (in bytes) of the symbols.
130 * @param[in] symbols_size Size of the symbols. 1 and 2 are supported.
131 * @param[in] offset An offset to apply to all the valid symbols.
132 * @param[in] flags A combination of the VLC_INIT_* flags; notice that
133 * VLC_INIT_INPUT_LE is pointless and ignored.
134 */
135 int ff_vlc_init_from_lengths(VLC *vlc, int nb_bits, int nb_codes,
136 const int8_t *lens, int lens_wrap,
137 const void *symbols, int symbols_wrap, int symbols_size,
138 int offset, int flags, void *logctx);
139
140 /**
141 * Build VLC decoding tables suitable for use with get_vlc_multi()
142 *
143 * This function takes lengths and symbols and calculates the codes from them.
144 * For this the input lengths and symbols have to be sorted according to "left
145 * nodes in the corresponding tree first".
146 *
147 * @param[in,out] vlc The VLC to be initialized; table and table_allocated
148 * must have been set when initializing a static VLC,
149 * otherwise this will be treated as uninitialized.
150 * @param[in,out] multi The VLC_MULTI to be initialized; table and table_allocated
151 * must have been set when initializing a static VLC,
152 * otherwise this will be treated as uninitialized.
153 * @param[in] nb_bits The number of bits to use for the VLC table;
154 * higher values take up more memory and cache, but
155 * allow to read codes with fewer reads.
156 * @param[in] nb_elems The max possible number of elements.
157 * @param[in] nb_codes The number of provided length and (if supplied) symbol
158 * entries.
159 * @param[in] lens The lengths of the codes. Entries > 0 correspond to
160 * valid codes; entries == 0 will be skipped and entries
161 * with len < 0 indicate that the tree is incomplete and
162 * has an open end of length -len at this position.
163 * @param[in] lens_wrap Stride (in bytes) of the lengths.
164 * @param[in] symbols The symbols, i.e. what is returned from get_vlc2()
165 * when the corresponding code is encountered.
166 * May be NULL, then 0, 1, 2, 3, 4,... will be used.
167 * @param[in] symbols_wrap Stride (in bytes) of the symbols.
168 * @param[in] symbols_size Size of the symbols. 1 and 2 are supported.
169 * @param[in] offset An offset to apply to all the valid symbols.
170 * @param[in] flags A combination of the VLC_INIT_* flags; notice that
171 * VLC_INIT_INPUT_LE is pointless and ignored.
172 */
173 int ff_vlc_init_multi_from_lengths(VLC *vlc, VLC_MULTI *multi, int nb_bits, int nb_elems,
174 int nb_codes, const int8_t *lens, int lens_wrap,
175 const void *symbols, int symbols_wrap, int symbols_size,
176 int offset, int flags, void *logctx);
177
178
179 void ff_vlc_free_multi(VLC_MULTI *vlc);
180 void ff_vlc_free(VLC *vlc);
181
182 #define VLC_INIT_USE_STATIC 1
183 #define VLC_INIT_STATIC_OVERLONG (2 | VLC_INIT_USE_STATIC)
184 /* If VLC_INIT_INPUT_LE is set, the LSB bit of the codes used to
185 * initialize the VLC table is the first bit to be read. */
186 #define VLC_INIT_INPUT_LE 4
187 /* If set the VLC is intended for a little endian bitstream reader. */
188 #define VLC_INIT_OUTPUT_LE 8
189 #define VLC_INIT_LE (VLC_INIT_INPUT_LE | VLC_INIT_OUTPUT_LE)
190
191 /**
192 * For static VLCs, the number of bits can often be hardcoded
193 * at each get_vlc2() callsite. Then using a full VLC would be uneconomical,
194 * because only VLC.table would ever be accessed after initialization.
195 * The following functions provide wrappers around the relevant ff_vlc_init_*
196 * functions suitable for said task.
197 *
198 * The ff_vlc_init_tables_* functions are intended to be used for initializing
199 * a series of VLCs. The user initializes a VLCInitState with the details
200 * about the underlying array of VLCElem; it is automatically updated by
201 * the ff_vlc_init_tables_* functions (i.e. table is incremented and size
202 * decremented by the number of elements of the current table).
203 * The VLC_INIT_STATIC_OVERLONG flag is also automatically added.
204 * These functions return a pointer to the table just initialized,
205 * potentially to be used in arrays of pointer to VLC tables.
206 *
207 * The ff_vlc_init_table_* functions are intended to be used for initializing
208 * a single VLC table, given by table and table_size. The VLC_INIT_USE_STATIC
209 * flag is automatically added.
210 */
211
212 typedef struct VLCInitState {
213 VLCElem *table; ///< points to where the next VLC table will be placed
214 unsigned size; ///< remaining number of elements in table
215 } VLCInitState;
216
217 #define VLC_INIT_STATE(_table) { .table = (_table), .size = FF_ARRAY_ELEMS(_table) }
218
219 void ff_vlc_init_table_from_lengths(VLCElem table[], int table_size,
220 int nb_bits, int nb_codes,
221 const int8_t *lens, int lens_wrap,
222 const void *symbols, int symbols_wrap, int symbols_size,
223 int offset, int flags);
224
225 const VLCElem *ff_vlc_init_tables_from_lengths(VLCInitState *state,
226 int nb_bits, int nb_codes,
227 const int8_t *lens, int lens_wrap,
228 const void *symbols, int symbols_wrap, int symbols_size,
229 int offset, int flags);
230
231 void ff_vlc_init_table_sparse(VLCElem table[], int table_size,
232 int nb_bits, int nb_codes,
233 const void *bits, int bits_wrap, int bits_size,
234 const void *codes, int codes_wrap, int codes_size,
235 const void *symbols, int symbols_wrap, int symbols_size,
236 int flags);
237
238 const VLCElem *ff_vlc_init_tables_sparse(VLCInitState *state,
239 int nb_bits, int nb_codes,
240 const void *bits, int bits_wrap, int bits_size,
241 const void *codes, int codes_wrap, int codes_size,
242 const void *symbols, int symbols_wrap, int symbols_size,
243 int flags);
244
245 static inline
246 13329 const VLCElem *ff_vlc_init_tables(VLCInitState *state,
247 int nb_bits, int nb_codes,
248 const void *bits, int bits_wrap, int bits_size,
249 const void *codes, int codes_wrap, int codes_size,
250 int flags)
251 {
252 13329 return ff_vlc_init_tables_sparse(state, nb_bits, nb_codes,
253 bits, bits_wrap, bits_size,
254 codes, codes_wrap, codes_size,
255 NULL, 0, 0, flags);
256 }
257
258 #define VLC_INIT_STATIC_SPARSE_TABLE(vlc_table, nb_bits, nb_codes, \
259 bits, bits_wrap, bits_size, \
260 codes, codes_wrap, codes_size, \
261 symbols, symbols_wrap, symbols_size, \
262 flags) \
263 ff_vlc_init_table_sparse(vlc_table, FF_ARRAY_ELEMS(vlc_table), \
264 (nb_bits), (nb_codes), \
265 (bits), (bits_wrap), (bits_size), \
266 (codes), (codes_wrap), (codes_size), \
267 (symbols), (symbols_wrap), (symbols_size), \
268 (flags))
269
270 #define VLC_INIT_STATIC_TABLE(vlc_table, nb_bits, nb_codes, \
271 bits, bits_wrap, bits_size, \
272 codes, codes_wrap, codes_size, \
273 flags) \
274 ff_vlc_init_table_sparse(vlc_table, FF_ARRAY_ELEMS(vlc_table), \
275 (nb_bits), (nb_codes), \
276 (bits), (bits_wrap), (bits_size), \
277 (codes), (codes_wrap), (codes_size), \
278 NULL, 0, 0, (flags))
279
280 #define VLC_INIT_STATIC_TABLE_FROM_LENGTHS(vlc_table, nb_bits, nb_codes, \
281 lens, lens_wrap, \
282 syms, syms_wrap, syms_size, \
283 offset, flags) \
284 ff_vlc_init_table_from_lengths(vlc_table, FF_ARRAY_ELEMS(vlc_table), \
285 (nb_bits), (nb_codes), \
286 (lens), (lens_wrap), \
287 (syms), (syms_wrap), (syms_size), \
288 (offset), (flags))
289
290 #endif /* AVCODEC_VLC_H */
291