AVRational
[libav.git] / libavcodec / common.c
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
22 /**
23 * @file common.c
24 * common internal api.
25 */
26
27 #include "avcodec.h"
28
29 const uint8_t ff_sqrt_tab[128]={
30 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,
31 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,
32 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,
33 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
34 };
35
36 const uint8_t ff_log2_tab[256]={
37 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,
38 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,
39 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,
40 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,
41 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,
42 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,
43 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,
44 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
45 };
46
47 void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
48 {
49 s->buf = buffer;
50 s->buf_end = s->buf + buffer_size;
51 s->data_out_size = 0;
52 #ifdef ALT_BITSTREAM_WRITER
53 s->index=0;
54 ((uint32_t*)(s->buf))[0]=0;
55 // memset(buffer, 0, buffer_size);
56 #else
57 s->buf_ptr = s->buf;
58 s->bit_left=32;
59 s->bit_buf=0;
60 #endif
61 }
62
63 #ifdef CONFIG_ENCODERS
64
65 /* return the number of bits output */
66 int64_t get_bit_count(PutBitContext *s)
67 {
68 #ifdef ALT_BITSTREAM_WRITER
69 return s->data_out_size * 8 + s->index;
70 #else
71 return (s->buf_ptr - s->buf + s->data_out_size) * 8 + 32 - (int64_t)s->bit_left;
72 #endif
73 }
74
75 void align_put_bits(PutBitContext *s)
76 {
77 #ifdef ALT_BITSTREAM_WRITER
78 put_bits(s,( - s->index) & 7,0);
79 #else
80 put_bits(s,s->bit_left & 7,0);
81 #endif
82 }
83
84 #endif //CONFIG_ENCODERS
85
86 /* pad the end of the output stream with zeros */
87 void flush_put_bits(PutBitContext *s)
88 {
89 #ifdef ALT_BITSTREAM_WRITER
90 align_put_bits(s);
91 #else
92 s->bit_buf<<= s->bit_left;
93 while (s->bit_left < 32) {
94 /* XXX: should test end of buffer */
95 *s->buf_ptr++=s->bit_buf >> 24;
96 s->bit_buf<<=8;
97 s->bit_left+=8;
98 }
99 s->bit_left=32;
100 s->bit_buf=0;
101 #endif
102 }
103
104 #ifdef CONFIG_ENCODERS
105
106 void put_string(PutBitContext * pbc, char *s)
107 {
108 while(*s){
109 put_bits(pbc, 8, *s);
110 s++;
111 }
112 put_bits(pbc, 8, 0);
113 }
114
115 /* bit input functions */
116
117 #endif //CONFIG_ENCODERS
118
119 /**
120 * init GetBitContext.
121 * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger then the actual read bits
122 * because some optimized bitstream readers read 32 or 64 bit at once and could read over the end
123 * @param bit_size the size of the buffer in bits
124 */
125 void init_get_bits(GetBitContext *s,
126 const uint8_t *buffer, int bit_size)
127 {
128 const int buffer_size= (bit_size+7)>>3;
129
130 s->buffer= buffer;
131 s->size_in_bits= bit_size;
132 s->buffer_end= buffer + buffer_size;
133 #ifdef ALT_BITSTREAM_READER
134 s->index=0;
135 #elif defined LIBMPEG2_BITSTREAM_READER
136 #ifdef LIBMPEG2_BITSTREAM_READER_HACK
137 if ((int)buffer&1) {
138 /* word alignment */
139 s->cache = (*buffer++)<<24;
140 s->buffer_ptr = buffer;
141 s->bit_count = 16-8;
142 } else
143 #endif
144 {
145 s->buffer_ptr = buffer;
146 s->bit_count = 16;
147 s->cache = 0;
148 }
149 #elif defined A32_BITSTREAM_READER
150 s->buffer_ptr = (uint32_t*)buffer;
151 s->bit_count = 32;
152 s->cache0 = 0;
153 s->cache1 = 0;
154 #endif
155 {
156 OPEN_READER(re, s)
157 UPDATE_CACHE(re, s)
158 UPDATE_CACHE(re, s)
159 CLOSE_READER(re, s)
160 }
161 #ifdef A32_BITSTREAM_READER
162 s->cache1 = 0;
163 #endif
164 }
165
166 /**
167 * reads 0-32 bits.
168 */
169 unsigned int get_bits_long(GetBitContext *s, int n){
170 if(n<=17) return get_bits(s, n);
171 else{
172 int ret= get_bits(s, 16) << (n-16);
173 return ret | get_bits(s, n-16);
174 }
175 }
176
177 /**
178 * shows 0-32 bits.
179 */
180 unsigned int show_bits_long(GetBitContext *s, int n){
181 if(n<=17) return show_bits(s, n);
182 else{
183 GetBitContext gb= *s;
184 int ret= get_bits_long(s, n);
185 *s= gb;
186 return ret;
187 }
188 }
189
190 void align_get_bits(GetBitContext *s)
191 {
192 int n= (-get_bits_count(s)) & 7;
193 if(n) skip_bits(s, n);
194 }
195
196 int check_marker(GetBitContext *s, const char *msg)
197 {
198 int bit= get_bits1(s);
199 if(!bit) printf("Marker bit missing %s\n", msg);
200
201 return bit;
202 }
203
204 /* VLC decoding */
205
206 //#define DEBUG_VLC
207
208 #define GET_DATA(v, table, i, wrap, size) \
209 {\
210 const uint8_t *ptr = (const uint8_t *)table + i * wrap;\
211 switch(size) {\
212 case 1:\
213 v = *(const uint8_t *)ptr;\
214 break;\
215 case 2:\
216 v = *(const uint16_t *)ptr;\
217 break;\
218 default:\
219 v = *(const uint32_t *)ptr;\
220 break;\
221 }\
222 }
223
224
225 static int alloc_table(VLC *vlc, int size)
226 {
227 int index;
228 index = vlc->table_size;
229 vlc->table_size += size;
230 if (vlc->table_size > vlc->table_allocated) {
231 vlc->table_allocated += (1 << vlc->bits);
232 vlc->table = av_realloc(vlc->table,
233 sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
234 if (!vlc->table)
235 return -1;
236 }
237 return index;
238 }
239
240 static int build_table(VLC *vlc, int table_nb_bits,
241 int nb_codes,
242 const void *bits, int bits_wrap, int bits_size,
243 const void *codes, int codes_wrap, int codes_size,
244 uint32_t code_prefix, int n_prefix)
245 {
246 int i, j, k, n, table_size, table_index, nb, n1, index;
247 uint32_t code;
248 VLC_TYPE (*table)[2];
249
250 table_size = 1 << table_nb_bits;
251 table_index = alloc_table(vlc, table_size);
252 #ifdef DEBUG_VLC
253 printf("new table index=%d size=%d code_prefix=%x n=%d\n",
254 table_index, table_size, code_prefix, n_prefix);
255 #endif
256 if (table_index < 0)
257 return -1;
258 table = &vlc->table[table_index];
259
260 for(i=0;i<table_size;i++) {
261 table[i][1] = 0; //bits
262 table[i][0] = -1; //codes
263 }
264
265 /* first pass: map codes and compute auxillary table sizes */
266 for(i=0;i<nb_codes;i++) {
267 GET_DATA(n, bits, i, bits_wrap, bits_size);
268 GET_DATA(code, codes, i, codes_wrap, codes_size);
269 /* we accept tables with holes */
270 if (n <= 0)
271 continue;
272 #if defined(DEBUG_VLC) && 0
273 printf("i=%d n=%d code=0x%x\n", i, n, code);
274 #endif
275 /* if code matches the prefix, it is in the table */
276 n -= n_prefix;
277 if (n > 0 && (code >> n) == code_prefix) {
278 if (n <= table_nb_bits) {
279 /* no need to add another table */
280 j = (code << (table_nb_bits - n)) & (table_size - 1);
281 nb = 1 << (table_nb_bits - n);
282 for(k=0;k<nb;k++) {
283 #ifdef DEBUG_VLC
284 printf("%4x: code=%d n=%d\n",
285 j, i, n);
286 #endif
287 if (table[j][1] /*bits*/ != 0) {
288 fprintf(stderr, "incorrect codes\n");
289 av_abort();
290 }
291 table[j][1] = n; //bits
292 table[j][0] = i; //code
293 j++;
294 }
295 } else {
296 n -= table_nb_bits;
297 j = (code >> n) & ((1 << table_nb_bits) - 1);
298 #ifdef DEBUG_VLC
299 printf("%4x: n=%d (subtable)\n",
300 j, n);
301 #endif
302 /* compute table size */
303 n1 = -table[j][1]; //bits
304 if (n > n1)
305 n1 = n;
306 table[j][1] = -n1; //bits
307 }
308 }
309 }
310
311 /* second pass : fill auxillary tables recursively */
312 for(i=0;i<table_size;i++) {
313 n = table[i][1]; //bits
314 if (n < 0) {
315 n = -n;
316 if (n > table_nb_bits) {
317 n = table_nb_bits;
318 table[i][1] = -n; //bits
319 }
320 index = build_table(vlc, n, nb_codes,
321 bits, bits_wrap, bits_size,
322 codes, codes_wrap, codes_size,
323 (code_prefix << table_nb_bits) | i,
324 n_prefix + table_nb_bits);
325 if (index < 0)
326 return -1;
327 /* note: realloc has been done, so reload tables */
328 table = &vlc->table[table_index];
329 table[i][0] = index; //code
330 }
331 }
332 return table_index;
333 }
334
335
336 /* Build VLC decoding tables suitable for use with get_vlc().
337
338 'nb_bits' set thee decoding table size (2^nb_bits) entries. The
339 bigger it is, the faster is the decoding. But it should not be too
340 big to save memory and L1 cache. '9' is a good compromise.
341
342 'nb_codes' : number of vlcs codes
343
344 'bits' : table which gives the size (in bits) of each vlc code.
345
346 'codes' : table which gives the bit pattern of of each vlc code.
347
348 'xxx_wrap' : give the number of bytes between each entry of the
349 'bits' or 'codes' tables.
350
351 'xxx_size' : gives the number of bytes of each entry of the 'bits'
352 or 'codes' tables.
353
354 'wrap' and 'size' allows to use any memory configuration and types
355 (byte/word/long) to store the 'bits' and 'codes' tables.
356 */
357 int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
358 const void *bits, int bits_wrap, int bits_size,
359 const void *codes, int codes_wrap, int codes_size)
360 {
361 vlc->bits = nb_bits;
362 vlc->table = NULL;
363 vlc->table_allocated = 0;
364 vlc->table_size = 0;
365 #ifdef DEBUG_VLC
366 printf("build table nb_codes=%d\n", nb_codes);
367 #endif
368
369 if (build_table(vlc, nb_bits, nb_codes,
370 bits, bits_wrap, bits_size,
371 codes, codes_wrap, codes_size,
372 0, 0) < 0) {
373 av_free(vlc->table);
374 return -1;
375 }
376 return 0;
377 }
378
379
380 void free_vlc(VLC *vlc)
381 {
382 av_free(vlc->table);
383 }
384
385 int64_t ff_gcd(int64_t a, int64_t b){
386 if(b) return ff_gcd(b, a%b);
387 else return a;
388 }