Statistics
| Branch: | Revision:

ffmpeg / libavcodec / common.c @ 18f77016

History | View | Annotate | Download (9.12 KB)

1
/*
2
 * Common bit i/o utils
3
 * Copyright (c) 2000, 2001 Fabrice Bellard.
4
 *
5
 * This library is free software; you can redistribute it and/or
6
 * modify it under the terms of the GNU Lesser General Public
7
 * License as published by the Free Software Foundation; either
8
 * version 2 of the License, or (at your option) any later version.
9
 *
10
 * This library is distributed in the hope that it will be useful,
11
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13
 * Lesser General Public License for more details.
14
 *
15
 * You should have received a copy of the GNU Lesser General Public
16
 * License along with this library; if not, write to the Free Software
17
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18
 *
19
 * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
20
 */
21
#include "avcodec.h"
22

    
23
const UINT8 ff_sqrt_tab[128]={
24
        0, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5,
25
        5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
26
        8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
27
        9, 9, 9, 9,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,11,11,11,11,11,11,11
28
};
29

    
30
void init_put_bits(PutBitContext *s, 
31
                   UINT8 *buffer, int buffer_size,
32
                   void *opaque,
33
                   void (*write_data)(void *, UINT8 *, int))
34
{
35
    s->buf = buffer;
36
    s->buf_end = s->buf + buffer_size;
37
    s->data_out_size = 0;
38
    if(write_data!=NULL) 
39
    {
40
            fprintf(stderr, "write Data callback is not supported\n");
41
    }
42
#ifdef ALT_BITSTREAM_WRITER
43
    s->index=0;
44
    ((uint32_t*)(s->buf))[0]=0;
45
//    memset(buffer, 0, buffer_size);
46
#else
47
    s->buf_ptr = s->buf;
48
    s->bit_left=32;
49
    s->bit_buf=0;
50
#endif
51
}
52

    
53
/* return the number of bits output */
54
INT64 get_bit_count(PutBitContext *s)
55
{
56
#ifdef ALT_BITSTREAM_WRITER
57
    return s->data_out_size * 8 + s->index;
58
#else
59
    return (s->buf_ptr - s->buf + s->data_out_size) * 8 + 32 - (INT64)s->bit_left;
60
#endif
61
}
62

    
63
void align_put_bits(PutBitContext *s)
64
{
65
#ifdef ALT_BITSTREAM_WRITER
66
    put_bits(s,(  - s->index) & 7,0);
67
#else
68
    put_bits(s,s->bit_left & 7,0);
69
#endif
70
}
71

    
72
/* pad the end of the output stream with zeros */
73
void flush_put_bits(PutBitContext *s)
74
{
75
#ifdef ALT_BITSTREAM_WRITER
76
    align_put_bits(s);
77
#else
78
    s->bit_buf<<= s->bit_left;
79
    while (s->bit_left < 32) {
80
        /* XXX: should test end of buffer */
81
        *s->buf_ptr++=s->bit_buf >> 24;
82
        s->bit_buf<<=8;
83
        s->bit_left+=8;
84
    }
85
    s->bit_left=32;
86
    s->bit_buf=0;
87
#endif
88
}
89

    
90
void put_string(PutBitContext * pbc, char *s)
91
{
92
    while(*s){
93
        put_bits(pbc, 8, *s);
94
        s++;
95
    }
96
    put_bits(pbc, 8, 0);
97
}
98

    
99
/* bit input functions */
100

    
101
void init_get_bits(GetBitContext *s,
102
                   UINT8 *buffer, int buffer_size)
103
{
104
    s->buffer= buffer;
105
    s->size= buffer_size;
106
    s->buffer_end= buffer + buffer_size;
107
#ifdef ALT_BITSTREAM_READER
108
    s->index=0;
109
#elif defined LIBMPEG2_BITSTREAM_READER
110
    s->buffer_ptr = buffer;
111
    s->bit_count = 16;
112
    s->cache = 0;
113
#elif defined A32_BITSTREAM_READER
114
    s->buffer_ptr = (uint32_t*)buffer;
115
    s->bit_count = 32;
116
    s->cache0 = 0;
117
    s->cache1 = 0;
118
#endif
119
    {
120
        OPEN_READER(re, s)
121
        UPDATE_CACHE(re, s)
122
//        UPDATE_CACHE(re, s)
123
        CLOSE_READER(re, s)
124
    }
125
#ifdef A32_BITSTREAM_READER
126
    s->cache1 = 0;
127
#endif
128
}
129

    
130
void align_get_bits(GetBitContext *s)
131
{
132
    int n= (-get_bits_count(s)) & 7;
133
    if(n) skip_bits(s, n);
134
}
135

    
136
int check_marker(GetBitContext *s, const char *msg)
137
{
138
    int bit= get_bits1(s);
139
    if(!bit) printf("Marker bit missing %s\n", msg);
140

    
141
    return bit;
142
}
143

    
144
/* VLC decoding */
145

    
146
//#define DEBUG_VLC
147

    
148
#define GET_DATA(v, table, i, wrap, size) \
149
{\
150
    const UINT8 *ptr = (UINT8 *)table + i * wrap;\
151
    switch(size) {\
152
    case 1:\
153
        v = *(UINT8 *)ptr;\
154
        break;\
155
    case 2:\
156
        v = *(UINT16 *)ptr;\
157
        break;\
158
    default:\
159
        v = *(UINT32 *)ptr;\
160
        break;\
161
    }\
162
}
163

    
164

    
165
static int alloc_table(VLC *vlc, int size)
166
{
167
    int index;
168
    index = vlc->table_size;
169
    vlc->table_size += size;
170
    if (vlc->table_size > vlc->table_allocated) {
171
        vlc->table_allocated += (1 << vlc->bits);
172
        vlc->table = realloc(vlc->table,
173
                             sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
174
        if (!vlc->table)
175
            return -1;
176
    }
177
    return index;
178
}
179

    
180
static int build_table(VLC *vlc, int table_nb_bits,
181
                       int nb_codes,
182
                       const void *bits, int bits_wrap, int bits_size,
183
                       const void *codes, int codes_wrap, int codes_size,
184
                       UINT32 code_prefix, int n_prefix)
185
{
186
    int i, j, k, n, table_size, table_index, nb, n1, index;
187
    UINT32 code;
188
    VLC_TYPE (*table)[2];
189

    
190
    table_size = 1 << table_nb_bits;
191
    table_index = alloc_table(vlc, table_size);
192
#ifdef DEBUG_VLC
193
    printf("new table index=%d size=%d code_prefix=%x n=%d\n",
194
           table_index, table_size, code_prefix, n_prefix);
195
#endif
196
    if (table_index < 0)
197
        return -1;
198
    table = &vlc->table[table_index];
199

    
200
    for(i=0;i<table_size;i++) {
201
        table[i][1] = 0; //bits
202
        table[i][0] = -1; //codes
203
    }
204

    
205
    /* first pass: map codes and compute auxillary table sizes */
206
    for(i=0;i<nb_codes;i++) {
207
        GET_DATA(n, bits, i, bits_wrap, bits_size);
208
        GET_DATA(code, codes, i, codes_wrap, codes_size);
209
        /* we accept tables with holes */
210
        if (n <= 0)
211
            continue;
212
#if defined(DEBUG_VLC) && 0
213
        printf("i=%d n=%d code=0x%x\n", i, n, code);
214
#endif
215
        /* if code matches the prefix, it is in the table */
216
        n -= n_prefix;
217
        if (n > 0 && (code >> n) == code_prefix) {
218
            if (n <= table_nb_bits) {
219
                /* no need to add another table */
220
                j = (code << (table_nb_bits - n)) & (table_size - 1);
221
                nb = 1 << (table_nb_bits - n);
222
                for(k=0;k<nb;k++) {
223
#ifdef DEBUG_VLC
224
                    printf("%4x: code=%d n=%d\n",
225
                           j, i, n);
226
#endif
227
                    if (table[j][1] /*bits*/ != 0) {
228
                        fprintf(stderr, "incorrect codes\n");
229
                        exit(1);
230
                    }
231
                    table[j][1] = n; //bits
232
                    table[j][0] = i; //code
233
                    j++;
234
                }
235
            } else {
236
                n -= table_nb_bits;
237
                j = (code >> n) & ((1 << table_nb_bits) - 1);
238
#ifdef DEBUG_VLC
239
                printf("%4x: n=%d (subtable)\n",
240
                       j, n);
241
#endif
242
                /* compute table size */
243
                n1 = -table[j][1]; //bits
244
                if (n > n1)
245
                    n1 = n;
246
                table[j][1] = -n1; //bits
247
            }
248
        }
249
    }
250

    
251
    /* second pass : fill auxillary tables recursively */
252
    for(i=0;i<table_size;i++) {
253
        n = table[i][1]; //bits
254
        if (n < 0) {
255
            n = -n;
256
            if (n > table_nb_bits) {
257
                n = table_nb_bits;
258
                table[i][1] = -n; //bits
259
            }
260
            index = build_table(vlc, n, nb_codes,
261
                                bits, bits_wrap, bits_size,
262
                                codes, codes_wrap, codes_size,
263
                                (code_prefix << table_nb_bits) | i,
264
                                n_prefix + table_nb_bits);
265
            if (index < 0)
266
                return -1;
267
            /* note: realloc has been done, so reload tables */
268
            table = &vlc->table[table_index];
269
            table[i][0] = index; //code
270
        }
271
    }
272
    return table_index;
273
}
274

    
275

    
276
/* Build VLC decoding tables suitable for use with get_vlc().
277

278
   'nb_bits' set thee decoding table size (2^nb_bits) entries. The
279
   bigger it is, the faster is the decoding. But it should not be too
280
   big to save memory and L1 cache. '9' is a good compromise.
281
   
282
   'nb_codes' : number of vlcs codes
283

284
   'bits' : table which gives the size (in bits) of each vlc code.
285

286
   'codes' : table which gives the bit pattern of of each vlc code.
287

288
   'xxx_wrap' : give the number of bytes between each entry of the
289
   'bits' or 'codes' tables.
290

291
   'xxx_size' : gives the number of bytes of each entry of the 'bits'
292
   or 'codes' tables.
293

294
   'wrap' and 'size' allows to use any memory configuration and types
295
   (byte/word/long) to store the 'bits' and 'codes' tables.  
296
*/
297
int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
298
             const void *bits, int bits_wrap, int bits_size,
299
             const void *codes, int codes_wrap, int codes_size)
300
{
301
    vlc->bits = nb_bits;
302
    vlc->table = NULL;
303
    vlc->table_allocated = 0;
304
    vlc->table_size = 0;
305
#ifdef DEBUG_VLC
306
    printf("build table nb_codes=%d\n", nb_codes);
307
#endif
308

    
309
    if (build_table(vlc, nb_bits, nb_codes,
310
                    bits, bits_wrap, bits_size,
311
                    codes, codes_wrap, codes_size,
312
                    0, 0) < 0) {
313
        av_free(vlc->table);
314
        return -1;
315
    }
316
    return 0;
317
}
318

    
319

    
320
void free_vlc(VLC *vlc)
321
{
322
    av_free(vlc->table);
323
}
324

    
325
int ff_gcd(int a, int b){
326
    if(b) return ff_gcd(b, a%b);
327
    else  return a;
328
}