-fPIC compileable
[libav.git] / libavcodec / common.c
CommitLineData
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1/*
2 * Common bit i/o utils
ff4ec49e 3 * Copyright (c) 2000, 2001 Fabrice Bellard.
de6d9b64 4 *
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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.
de6d9b64 9 *
ff4ec49e 10 * This library is distributed in the hope that it will be useful,
de6d9b64 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
de6d9b64 14 *
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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
27a3e2c5 18 *
17592475 19 * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
de6d9b64 20 */
df595131 21#include "avcodec.h"
a9b3f630 22
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23const 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
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30const uint8_t ff_log2_tab[256]={
31 0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
32 5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
33 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
34 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
35 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
36 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
37 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
38 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
39};
40
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41void init_put_bits(PutBitContext *s,
42 UINT8 *buffer, int buffer_size,
43 void *opaque,
44 void (*write_data)(void *, UINT8 *, int))
45{
46 s->buf = buffer;
de6d9b64 47 s->buf_end = s->buf + buffer_size;
de6d9b64 48 s->data_out_size = 0;
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49 if(write_data!=NULL)
50 {
51 fprintf(stderr, "write Data callback is not supported\n");
52 }
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53#ifdef ALT_BITSTREAM_WRITER
54 s->index=0;
55 ((uint32_t*)(s->buf))[0]=0;
56// memset(buffer, 0, buffer_size);
17592475 57#else
17592475 58 s->buf_ptr = s->buf;
d8cf5aea 59 s->bit_left=32;
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60 s->bit_buf=0;
61#endif
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62}
63
de6d9b64 64/* return the number of bits output */
1a565432 65INT64 get_bit_count(PutBitContext *s)
de6d9b64 66{
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67#ifdef ALT_BITSTREAM_WRITER
68 return s->data_out_size * 8 + s->index;
69#else
d8cf5aea 70 return (s->buf_ptr - s->buf + s->data_out_size) * 8 + 32 - (INT64)s->bit_left;
17592475 71#endif
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72}
73
74void align_put_bits(PutBitContext *s)
75{
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76#ifdef ALT_BITSTREAM_WRITER
77 put_bits(s,( - s->index) & 7,0);
78#else
d8cf5aea 79 put_bits(s,s->bit_left & 7,0);
17592475 80#endif
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81}
82
83/* pad the end of the output stream with zeros */
84void flush_put_bits(PutBitContext *s)
85{
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86#ifdef ALT_BITSTREAM_WRITER
87 align_put_bits(s);
88#else
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89 s->bit_buf<<= s->bit_left;
90 while (s->bit_left < 32) {
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91 /* XXX: should test end of buffer */
92 *s->buf_ptr++=s->bit_buf >> 24;
93 s->bit_buf<<=8;
d8cf5aea 94 s->bit_left+=8;
de6d9b64 95 }
d8cf5aea 96 s->bit_left=32;
de6d9b64 97 s->bit_buf=0;
17592475 98#endif
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99}
100
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101void put_string(PutBitContext * pbc, char *s)
102{
103 while(*s){
104 put_bits(pbc, 8, *s);
105 s++;
106 }
107 put_bits(pbc, 8, 0);
108}
109
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110/* bit input functions */
111
8db1a1dd 112void init_get_bits(GetBitContext *s,
68f593b4 113 UINT8 *buffer, int bit_size)
de6d9b64 114{
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115 const int buffer_size= (bit_size+7)>>3;
116
27a3e2c5 117 s->buffer= buffer;
68f593b4 118 s->size_in_bits= bit_size;
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119 s->buffer_end= buffer + buffer_size;
120#ifdef ALT_BITSTREAM_READER
121 s->index=0;
122#elif defined LIBMPEG2_BITSTREAM_READER
123 s->buffer_ptr = buffer;
124 s->bit_count = 16;
125 s->cache = 0;
126#elif defined A32_BITSTREAM_READER
127 s->buffer_ptr = (uint32_t*)buffer;
128 s->bit_count = 32;
129 s->cache0 = 0;
130 s->cache1 = 0;
de6d9b64 131#endif
2931ecb9 132 {
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133 OPEN_READER(re, s)
134 UPDATE_CACHE(re, s)
135// UPDATE_CACHE(re, s)
136 CLOSE_READER(re, s)
de6d9b64 137 }
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138#ifdef A32_BITSTREAM_READER
139 s->cache1 = 0;
27a3e2c5 140#endif
8db1a1dd 141}
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142
143void align_get_bits(GetBitContext *s)
144{
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145 int n= (-get_bits_count(s)) & 7;
146 if(n) skip_bits(s, n);
de6d9b64 147}
27a3e2c5 148
18f77016 149int check_marker(GetBitContext *s, const char *msg)
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150{
151 int bit= get_bits1(s);
152 if(!bit) printf("Marker bit missing %s\n", msg);
153
154 return bit;
155}
156
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157/* VLC decoding */
158
159//#define DEBUG_VLC
160
161#define GET_DATA(v, table, i, wrap, size) \
162{\
5c91a675 163 const UINT8 *ptr = (const UINT8 *)table + i * wrap;\
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164 switch(size) {\
165 case 1:\
5c91a675 166 v = *(const UINT8 *)ptr;\
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167 break;\
168 case 2:\
5c91a675 169 v = *(const UINT16 *)ptr;\
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170 break;\
171 default:\
5c91a675 172 v = *(const UINT32 *)ptr;\
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173 break;\
174 }\
175}
176
177
178static int alloc_table(VLC *vlc, int size)
179{
180 int index;
181 index = vlc->table_size;
182 vlc->table_size += size;
183 if (vlc->table_size > vlc->table_allocated) {
184 vlc->table_allocated += (1 << vlc->bits);
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185 vlc->table = av_realloc(vlc->table,
186 sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
8db1a1dd 187 if (!vlc->table)
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188 return -1;
189 }
190 return index;
191}
192
8db1a1dd 193static int build_table(VLC *vlc, int table_nb_bits,
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194 int nb_codes,
195 const void *bits, int bits_wrap, int bits_size,
196 const void *codes, int codes_wrap, int codes_size,
197 UINT32 code_prefix, int n_prefix)
198{
199 int i, j, k, n, table_size, table_index, nb, n1, index;
200 UINT32 code;
8db1a1dd 201 VLC_TYPE (*table)[2];
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202
203 table_size = 1 << table_nb_bits;
204 table_index = alloc_table(vlc, table_size);
205#ifdef DEBUG_VLC
8db1a1dd 206 printf("new table index=%d size=%d code_prefix=%x n=%d\n",
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207 table_index, table_size, code_prefix, n_prefix);
208#endif
209 if (table_index < 0)
210 return -1;
8db1a1dd 211 table = &vlc->table[table_index];
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212
213 for(i=0;i<table_size;i++) {
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214 table[i][1] = 0; //bits
215 table[i][0] = -1; //codes
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216 }
217
218 /* first pass: map codes and compute auxillary table sizes */
219 for(i=0;i<nb_codes;i++) {
220 GET_DATA(n, bits, i, bits_wrap, bits_size);
221 GET_DATA(code, codes, i, codes_wrap, codes_size);
222 /* we accept tables with holes */
223 if (n <= 0)
224 continue;
225#if defined(DEBUG_VLC) && 0
226 printf("i=%d n=%d code=0x%x\n", i, n, code);
227#endif
228 /* if code matches the prefix, it is in the table */
229 n -= n_prefix;
230 if (n > 0 && (code >> n) == code_prefix) {
231 if (n <= table_nb_bits) {
232 /* no need to add another table */
233 j = (code << (table_nb_bits - n)) & (table_size - 1);
234 nb = 1 << (table_nb_bits - n);
235 for(k=0;k<nb;k++) {
236#ifdef DEBUG_VLC
237 printf("%4x: code=%d n=%d\n",
238 j, i, n);
239#endif
8db1a1dd 240 if (table[j][1] /*bits*/ != 0) {
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241 fprintf(stderr, "incorrect codes\n");
242 exit(1);
243 }
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244 table[j][1] = n; //bits
245 table[j][0] = i; //code
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246 j++;
247 }
248 } else {
249 n -= table_nb_bits;
250 j = (code >> n) & ((1 << table_nb_bits) - 1);
251#ifdef DEBUG_VLC
252 printf("%4x: n=%d (subtable)\n",
253 j, n);
254#endif
255 /* compute table size */
8db1a1dd 256 n1 = -table[j][1]; //bits
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257 if (n > n1)
258 n1 = n;
8db1a1dd 259 table[j][1] = -n1; //bits
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260 }
261 }
262 }
263
264 /* second pass : fill auxillary tables recursively */
265 for(i=0;i<table_size;i++) {
8db1a1dd 266 n = table[i][1]; //bits
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267 if (n < 0) {
268 n = -n;
269 if (n > table_nb_bits) {
270 n = table_nb_bits;
8db1a1dd 271 table[i][1] = -n; //bits
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272 }
273 index = build_table(vlc, n, nb_codes,
274 bits, bits_wrap, bits_size,
275 codes, codes_wrap, codes_size,
276 (code_prefix << table_nb_bits) | i,
277 n_prefix + table_nb_bits);
278 if (index < 0)
279 return -1;
280 /* note: realloc has been done, so reload tables */
8db1a1dd 281 table = &vlc->table[table_index];
6300c80a 282 table[i][0] = index; //code
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283 }
284 }
285 return table_index;
286}
287
288
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289/* Build VLC decoding tables suitable for use with get_vlc().
290
291 'nb_bits' set thee decoding table size (2^nb_bits) entries. The
292 bigger it is, the faster is the decoding. But it should not be too
293 big to save memory and L1 cache. '9' is a good compromise.
294
295 'nb_codes' : number of vlcs codes
296
297 'bits' : table which gives the size (in bits) of each vlc code.
298
299 'codes' : table which gives the bit pattern of of each vlc code.
300
301 'xxx_wrap' : give the number of bytes between each entry of the
302 'bits' or 'codes' tables.
303
304 'xxx_size' : gives the number of bytes of each entry of the 'bits'
305 or 'codes' tables.
306
307 'wrap' and 'size' allows to use any memory configuration and types
308 (byte/word/long) to store the 'bits' and 'codes' tables.
309*/
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310int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
311 const void *bits, int bits_wrap, int bits_size,
312 const void *codes, int codes_wrap, int codes_size)
313{
314 vlc->bits = nb_bits;
8db1a1dd 315 vlc->table = NULL;
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316 vlc->table_allocated = 0;
317 vlc->table_size = 0;
318#ifdef DEBUG_VLC
319 printf("build table nb_codes=%d\n", nb_codes);
320#endif
321
322 if (build_table(vlc, nb_bits, nb_codes,
323 bits, bits_wrap, bits_size,
324 codes, codes_wrap, codes_size,
325 0, 0) < 0) {
8db1a1dd 326 av_free(vlc->table);
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327 return -1;
328 }
329 return 0;
330}
331
332
333void free_vlc(VLC *vlc)
334{
8db1a1dd 335 av_free(vlc->table);
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336}
337
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338int ff_gcd(int a, int b){
339 if(b) return ff_gcd(b, a%b);
340 else return a;
341}
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342
343void ff_float2fraction(int *nom_arg, int *denom_arg, double f, int max){
344 double best_diff=1E10, diff;
345 int best_denom=1, best_nom=1;
346 int nom, denom, gcd;
347
348 //brute force here, perhaps we should try continued fractions if we need large max ...
349 for(denom=1; denom<=max; denom++){
350 nom= (int)(f*denom + 0.5);
351 if(nom<=0 || nom>max) continue;
352
353 diff= ABS( f - (double)nom / (double)denom );
354 if(diff < best_diff){
355 best_diff= diff;
356 best_nom= nom;
357 best_denom= denom;
358 }
359 }
360
361 gcd= ff_gcd(best_nom, best_denom);
362 best_nom /= gcd;
363 best_denom /= gcd;
364
365 *nom_arg= best_nom;
366 *denom_arg= best_denom;
367}