GCC Code Coverage Report
Directory: ../../../ffmpeg/ Exec Total Coverage
File: src/libavcodec/bitstream.c Lines: 120 139 86.3 %
Date: 2020-11-28 20:53:16 Branches: 146 186 78.5 %

Line Branch Exec Source
1
/*
2
 * Common bit i/o utils
3
 * Copyright (c) 2000, 2001 Fabrice Bellard
4
 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
5
 * Copyright (c) 2010 Loren Merritt
6
 *
7
 * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
8
 *
9
 * This file is part of FFmpeg.
10
 *
11
 * FFmpeg is free software; you can redistribute it and/or
12
 * modify it under the terms of the GNU Lesser General Public
13
 * License as published by the Free Software Foundation; either
14
 * version 2.1 of the License, or (at your option) any later version.
15
 *
16
 * FFmpeg is distributed in the hope that it will be useful,
17
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
19
 * Lesser General Public License for more details.
20
 *
21
 * You should have received a copy of the GNU Lesser General Public
22
 * License along with FFmpeg; if not, write to the Free Software
23
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24
 */
25
26
/**
27
 * @file
28
 * bitstream api.
29
 */
30
31
#include "libavutil/avassert.h"
32
#include "libavutil/qsort.h"
33
#include "avcodec.h"
34
#include "internal.h"
35
#include "mathops.h"
36
#include "put_bits.h"
37
#include "vlc.h"
38
39
const uint8_t ff_log2_run[41]={
40
 0, 0, 0, 0, 1, 1, 1, 1,
41
 2, 2, 2, 2, 3, 3, 3, 3,
42
 4, 4, 5, 5, 6, 6, 7, 7,
43
 8, 9,10,11,12,13,14,15,
44
16,17,18,19,20,21,22,23,
45
24,
46
};
47
48
#if FF_API_AVPRIV_PUT_BITS
49
void avpriv_align_put_bits(PutBitContext *s)
50
{
51
    align_put_bits(s);
52
}
53
void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length)
54
{
55
    ff_copy_bits(pb, src, length);
56
}
57
#endif
58
59
1025
void ff_put_string(PutBitContext *pb, const char *string, int terminate_string)
60
{
61
6125
    while (*string) {
62
5100
        put_bits(pb, 8, *string);
63
5100
        string++;
64
    }
65
1025
    if (terminate_string)
66
365
        put_bits(pb, 8, 0);
67
1025
}
68
69
1232206
void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length)
70
{
71
1232206
    int words = length >> 4;
72
1232206
    int bits  = length & 15;
73
    int i;
74
75
1232206
    if (length == 0)
76
114010
        return;
77
78
1118196
    av_assert0(length <= put_bits_left(pb));
79
80

1118196
    if (CONFIG_SMALL || words < 16 || put_bits_count(pb) & 7) {
81
7767502
        for (i = 0; i < words; i++)
82
6664080
            put_bits(pb, 16, AV_RB16(src + 2 * i));
83
    } else {
84
35902
        for (i = 0; put_bits_count(pb) & 31; i++)
85
21128
            put_bits(pb, 8, src[i]);
86
14774
        flush_put_bits(pb);
87
14774
        memcpy(put_bits_ptr(pb), src + i, 2 * words - i);
88
14774
        skip_put_bytes(pb, 2 * words - i);
89
    }
90
91
1118196
    put_bits(pb, bits, AV_RB16(src + 2 * words) >> (16 - bits));
92
}
93
94
/* VLC decoding */
95
96
#define GET_DATA(v, table, i, wrap, size)                   \
97
{                                                           \
98
    const uint8_t *ptr = (const uint8_t *)table + i * wrap; \
99
    switch(size) {                                          \
100
    case 1:                                                 \
101
        v = *(const uint8_t *)ptr;                          \
102
        break;                                              \
103
    case 2:                                                 \
104
        v = *(const uint16_t *)ptr;                         \
105
        break;                                              \
106
    case 4:                                                 \
107
        v = *(const uint32_t *)ptr;                         \
108
        break;                                              \
109
    default:                                                \
110
        av_assert1(0);                                      \
111
    }                                                       \
112
}
113
114
115
436621
static int alloc_table(VLC *vlc, int size, int use_static)
116
{
117
436621
    int index = vlc->table_size;
118
119
436621
    vlc->table_size += size;
120
436621
    if (vlc->table_size > vlc->table_allocated) {
121
53853
        if (use_static)
122
            abort(); // cannot do anything, init_vlc() is used with too little memory
123
53853
        vlc->table_allocated += (1 << vlc->bits);
124
53853
        vlc->table = av_realloc_f(vlc->table, vlc->table_allocated, sizeof(VLC_TYPE) * 2);
125
53853
        if (!vlc->table) {
126
            vlc->table_allocated = 0;
127
            vlc->table_size = 0;
128
            return AVERROR(ENOMEM);
129
        }
130
53853
        memset(vlc->table + vlc->table_allocated - (1 << vlc->bits), 0, sizeof(VLC_TYPE) * 2 << vlc->bits);
131
    }
132
436621
    return index;
133
}
134
135
typedef struct VLCcode {
136
    uint8_t bits;
137
    VLC_TYPE symbol;
138
    /** codeword, with the first bit-to-be-read in the msb
139
     * (even if intended for a little-endian bitstream reader) */
140
    uint32_t code;
141
} VLCcode;
142
143
23204405
static int compare_vlcspec(const void *a, const void *b)
144
{
145
23204405
    const VLCcode *sa = a, *sb = b;
146
23204405
    return (sa->code >> 1) - (sb->code >> 1);
147
}
148
/**
149
 * Build VLC decoding tables suitable for use with get_vlc().
150
 *
151
 * @param vlc            the context to be initialized
152
 *
153
 * @param table_nb_bits  max length of vlc codes to store directly in this table
154
 *                       (Longer codes are delegated to subtables.)
155
 *
156
 * @param nb_codes       number of elements in codes[]
157
 *
158
 * @param codes          descriptions of the vlc codes
159
 *                       These must be ordered such that codes going into the same subtable are contiguous.
160
 *                       Sorting by VLCcode.code is sufficient, though not necessary.
161
 */
162
436621
static int build_table(VLC *vlc, int table_nb_bits, int nb_codes,
163
                       VLCcode *codes, int flags)
164
{
165
    int table_size, table_index, index, code_prefix, symbol, subtable_bits;
166
    int i, j, k, n, nb, inc;
167
    uint32_t code;
168
    volatile VLC_TYPE (* volatile table)[2]; // the double volatile is needed to prevent an internal compiler error in gcc 4.2
169
170
436621
    if (table_nb_bits > 30)
171
       return AVERROR(EINVAL);
172
436621
    table_size = 1 << table_nb_bits;
173
436621
    table_index = alloc_table(vlc, table_size, flags & INIT_VLC_USE_NEW_STATIC);
174
    ff_dlog(NULL, "new table index=%d size=%d\n", table_index, table_size);
175
436621
    if (table_index < 0)
176
        return table_index;
177
436621
    table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];
178
179
    /* first pass: map codes and compute auxiliary table sizes */
180
5392930
    for (i = 0; i < nb_codes; i++) {
181
4956309
        n      = codes[i].bits;
182
4956309
        code   = codes[i].code;
183
4956309
        symbol = codes[i].symbol;
184
        ff_dlog(NULL, "i=%d n=%d code=0x%"PRIx32"\n", i, n, code);
185
4956309
        if (n <= table_nb_bits) {
186
            /* no need to add another table */
187
4579123
            j = code >> (32 - table_nb_bits);
188
4579123
            nb = 1 << (table_nb_bits - n);
189
4579123
            inc = 1;
190
4579123
            if (flags & INIT_VLC_OUTPUT_LE) {
191
459703
                j = bitswap_32(code);
192
459703
                inc = 1 << n;
193
            }
194
45935589
            for (k = 0; k < nb; k++) {
195
41356466
                int bits = table[j][1];
196
41356466
                int oldsym  = table[j][0];
197
                ff_dlog(NULL, "%4x: code=%d n=%d\n", j, i, n);
198


41356466
                if ((bits || oldsym) && (bits != n || oldsym != symbol)) {
199
                    av_log(NULL, AV_LOG_ERROR, "incorrect codes\n");
200
                    return AVERROR_INVALIDDATA;
201
                }
202
41356466
                table[j][1] = n; //bits
203
41356466
                table[j][0] = symbol;
204
41356466
                j += inc;
205
            }
206
        } else {
207
            /* fill auxiliary table recursively */
208
377186
            n -= table_nb_bits;
209
377186
            code_prefix = code >> (32 - table_nb_bits);
210
377186
            subtable_bits = n;
211
377186
            codes[i].bits = n;
212
377186
            codes[i].code = code << table_nb_bits;
213
3436753
            for (k = i+1; k < nb_codes; k++) {
214
3435352
                n = codes[k].bits - table_nb_bits;
215
3435352
                if (n <= 0)
216
43457
                    break;
217
3391895
                code = codes[k].code;
218
3391895
                if (code >> (32 - table_nb_bits) != code_prefix)
219
332328
                    break;
220
3059567
                codes[k].bits = n;
221
3059567
                codes[k].code = code << table_nb_bits;
222
3059567
                subtable_bits = FFMAX(subtable_bits, n);
223
            }
224
377186
            subtable_bits = FFMIN(subtable_bits, table_nb_bits);
225
377186
            j = (flags & INIT_VLC_OUTPUT_LE) ? bitswap_32(code_prefix) >> (32 - table_nb_bits) : code_prefix;
226
377186
            table[j][1] = -subtable_bits;
227
            ff_dlog(NULL, "%4x: n=%d (subtable)\n",
228
                    j, codes[i].bits + table_nb_bits);
229
377186
            index = build_table(vlc, subtable_bits, k-i, codes+i, flags);
230
377186
            if (index < 0)
231
                return index;
232
            /* note: realloc has been done, so reload tables */
233
377186
            table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];
234
377186
            table[j][0] = index; //code
235
377186
            if (table[j][0] != index) {
236
                avpriv_request_sample(NULL, "strange codes");
237
                return AVERROR_PATCHWELCOME;
238
            }
239
377186
            i = k-1;
240
        }
241
    }
242
243
42690251
    for (i = 0; i < table_size; i++) {
244
42253630
        if (table[i][1] == 0) //bits
245
519978
            table[i][0] = -1; //codes
246
    }
247
248
436621
    return table_index;
249
}
250
251
252
/* Build VLC decoding tables suitable for use with get_vlc().
253
254
   'nb_bits' sets the decoding table size (2^nb_bits) entries. The
255
   bigger it is, the faster is the decoding. But it should not be too
256
   big to save memory and L1 cache. '9' is a good compromise.
257
258
   'nb_codes' : number of vlcs codes
259
260
   'bits' : table which gives the size (in bits) of each vlc code.
261
262
   'codes' : table which gives the bit pattern of of each vlc code.
263
264
   'symbols' : table which gives the values to be returned from get_vlc().
265
266
   'xxx_wrap' : give the number of bytes between each entry of the
267
   'bits' or 'codes' tables.
268
269
   'xxx_size' : gives the number of bytes of each entry of the 'bits'
270
   or 'codes' tables. Currently 1,2 and 4 are supported.
271
272
   'wrap' and 'size' make it possible to use any memory configuration and types
273
   (byte/word/long) to store the 'bits', 'codes', and 'symbols' tables.
274
*/
275
59435
int ff_init_vlc_sparse(VLC *vlc_arg, int nb_bits, int nb_codes,
276
                       const void *bits, int bits_wrap, int bits_size,
277
                       const void *codes, int codes_wrap, int codes_size,
278
                       const void *symbols, int symbols_wrap, int symbols_size,
279
                       int flags)
280
{
281
    VLCcode *buf;
282
    int i, j, ret;
283
    VLCcode localbuf[1500]; // the maximum currently needed is 1296 by rv34
284
    VLC localvlc, *vlc;
285
286
59435
    vlc = vlc_arg;
287
59435
    vlc->bits = nb_bits;
288
59435
    if (flags & INIT_VLC_USE_NEW_STATIC) {
289
30467
        av_assert0(nb_codes <= FF_ARRAY_ELEMS(localbuf));
290
30467
        localvlc = *vlc_arg;
291
30467
        vlc = &localvlc;
292
30467
        vlc->table_size = 0;
293
    } else {
294
28968
        vlc->table           = NULL;
295
28968
        vlc->table_allocated = 0;
296
28968
        vlc->table_size      = 0;
297
    }
298
59435
    if (nb_codes > FF_ARRAY_ELEMS(localbuf)) {
299
120
        buf = av_malloc_array(nb_codes, sizeof(VLCcode));
300
120
        if (!buf)
301
            return AVERROR(ENOMEM);
302
    } else
303
59315
        buf = localbuf;
304
305
306

59435
    av_assert0(symbols_size <= 2 || !symbols);
307
59435
    j = 0;
308
#define COPY(condition)\
309
    for (i = 0; i < nb_codes; i++) {                                        \
310
        unsigned len;                                                       \
311
        GET_DATA(len, bits, i, bits_wrap, bits_size);                       \
312
        if (!(condition))                                                   \
313
            continue;                                                       \
314
        if (len > 3*nb_bits || len > 32) {                                  \
315
            av_log(NULL, AV_LOG_ERROR, "Too long VLC (%u) in init_vlc\n", len);\
316
            if (buf != localbuf)                                            \
317
                av_free(buf);                                               \
318
            return AVERROR(EINVAL);                                         \
319
        }                                                                   \
320
        buf[j].bits = len;                                                  \
321
        GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size);            \
322
        if (buf[j].code >= (1LL<<buf[j].bits)) {                            \
323
            av_log(NULL, AV_LOG_ERROR, "Invalid code %"PRIx32" for %d in "  \
324
                   "init_vlc\n", buf[j].code, i);                           \
325
            if (buf != localbuf)                                            \
326
                av_free(buf);                                               \
327
            return AVERROR(EINVAL);                                         \
328
        }                                                                   \
329
        if (flags & INIT_VLC_INPUT_LE)                                      \
330
            buf[j].code = bitswap_32(buf[j].code);                          \
331
        else                                                                \
332
            buf[j].code <<= 32 - buf[j].bits;                               \
333
        if (symbols)                                                        \
334
            GET_DATA(buf[j].symbol, symbols, i, symbols_wrap, symbols_size) \
335
        else                                                                \
336
            buf[j].symbol = i;                                              \
337
        j++;                                                                \
338
    }
339







5308144
    COPY(len > nb_bits);
340
    // qsort is the slowest part of init_vlc, and could probably be improved or avoided
341











19658878
    AV_QSORT(buf, j, struct VLCcode, compare_vlcspec);
342








5308144
    COPY(len && len <= nb_bits);
343
59435
    nb_codes = j;
344
345
59435
    ret = build_table(vlc, nb_bits, nb_codes, buf, flags);
346
347
59435
    if (flags & INIT_VLC_USE_NEW_STATIC) {
348
30467
        if(vlc->table_size != vlc->table_allocated)
349
            av_log(NULL, AV_LOG_ERROR, "needed %d had %d\n", vlc->table_size, vlc->table_allocated);
350
351
30467
        av_assert0(ret >= 0);
352
30467
        *vlc_arg = *vlc;
353
    } else {
354
28968
        if (buf != localbuf)
355
120
            av_free(buf);
356
28968
        if (ret < 0) {
357
            av_freep(&vlc->table);
358
            return ret;
359
        }
360
    }
361
59435
    return 0;
362
}
363
364
365
32046
void ff_free_vlc(VLC *vlc)
366
{
367
32046
    av_freep(&vlc->table);
368
32046
}