97788ec9dc2596f33d784ec6a0bf61d3dda8656a
[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 #include "common.h"
22
23 void init_put_bits(PutBitContext *s,
24 UINT8 *buffer, int buffer_size,
25 void *opaque,
26 void (*write_data)(void *, UINT8 *, int))
27 {
28 s->buf = buffer;
29 s->buf_end = s->buf + buffer_size;
30 s->data_out_size = 0;
31 if(write_data!=NULL)
32 {
33 fprintf(stderr, "write Data callback is not supported\n");
34 }
35 #ifdef ALT_BITSTREAM_WRITER
36 s->index=0;
37 ((uint32_t*)(s->buf))[0]=0;
38 // memset(buffer, 0, buffer_size);
39 #else
40 s->buf_ptr = s->buf;
41 s->bit_left=32;
42 s->bit_buf=0;
43 #endif
44 }
45
46 /* return the number of bits output */
47 INT64 get_bit_count(PutBitContext *s)
48 {
49 #ifdef ALT_BITSTREAM_WRITER
50 return s->data_out_size * 8 + s->index;
51 #else
52 return (s->buf_ptr - s->buf + s->data_out_size) * 8 + 32 - (INT64)s->bit_left;
53 #endif
54 }
55
56 void align_put_bits(PutBitContext *s)
57 {
58 #ifdef ALT_BITSTREAM_WRITER
59 put_bits(s,( - s->index) & 7,0);
60 #else
61 put_bits(s,s->bit_left & 7,0);
62 #endif
63 }
64
65 /* pad the end of the output stream with zeros */
66 void flush_put_bits(PutBitContext *s)
67 {
68 #ifdef ALT_BITSTREAM_WRITER
69 align_put_bits(s);
70 #else
71 s->bit_buf<<= s->bit_left;
72 while (s->bit_left < 32) {
73 /* XXX: should test end of buffer */
74 *s->buf_ptr++=s->bit_buf >> 24;
75 s->bit_buf<<=8;
76 s->bit_left+=8;
77 }
78 s->bit_left=32;
79 s->bit_buf=0;
80 #endif
81 }
82
83 /* pad the end of the output stream with zeros */
84 #ifndef ALT_BITSTREAM_WRITER
85 void jflush_put_bits(PutBitContext *s)
86 {
87 unsigned int b;
88 s->bit_buf<<= s->bit_left;
89 s->bit_buf |= ~1U >> (32 - s->bit_left); /* set all the unused bits to one */
90
91 while (s->bit_left < 32) {
92 b = s->bit_buf >> 24;
93 *s->buf_ptr++ = b;
94 if (b == 0xff)
95 *s->buf_ptr++ = 0;
96 s->bit_buf<<=8;
97 s->bit_left+=8;
98 }
99 s->bit_left=32;
100 s->bit_buf=0;
101 }
102 #else
103 void jflush_put_bits(PutBitContext *s)
104 {
105 int num= ( - s->index) & 7;
106 jput_bits(s, num,0xFF>>(8-num));
107 }
108 #endif
109
110 void put_string(PutBitContext * pbc, char *s)
111 {
112 while(*s){
113 put_bits(pbc, 8, *s);
114 s++;
115 }
116 put_bits(pbc, 8, 0);
117 }
118
119 /* bit input functions */
120
121 void init_get_bits(GetBitContext *s,
122 UINT8 *buffer, int buffer_size)
123 {
124 #ifdef ALT_BITSTREAM_READER
125 s->index=0;
126 s->buffer= buffer;
127 #else
128 s->buf = buffer;
129 s->buf_ptr = buffer;
130 s->buf_end = buffer + buffer_size;
131 s->bit_cnt = 0;
132 s->bit_buf = 0;
133 while (s->buf_ptr < s->buf_end &&
134 s->bit_cnt < 32) {
135 s->bit_buf |= (*s->buf_ptr++ << (24 - s->bit_cnt));
136 s->bit_cnt += 8;
137 }
138 #endif
139 s->size= buffer_size;
140 }
141
142 #ifndef ALT_BITSTREAM_READER
143 /* n must be >= 1 and <= 32 */
144 /* also true: n > s->bit_cnt */
145 unsigned int get_bits_long(GetBitContext *s, int n)
146 {
147 unsigned int val;
148 int bit_cnt;
149 unsigned int bit_buf;
150
151 #ifdef STATS
152 st_bit_counts[st_current_index] += n;
153 #endif
154
155 bit_buf = s->bit_buf;
156 bit_cnt = s->bit_cnt - n;
157
158 // if (bit_cnt >= 0) {
159 // val = bit_buf >> (32 - n);
160 // bit_buf <<= n;
161 // } else
162 {
163 UINT8 *buf_ptr;
164 val = bit_buf >> (32 - n);
165 buf_ptr = s->buf_ptr;
166 buf_ptr += 4;
167 /* handle common case: we can read everything */
168 if (buf_ptr <= s->buf_end) {
169 #if ARCH_X86
170 bit_buf = bswap_32(*((unsigned long*)(&buf_ptr[-4])));
171 #else
172 bit_buf = (buf_ptr[-4] << 24) |
173 (buf_ptr[-3] << 16) |
174 (buf_ptr[-2] << 8) |
175 (buf_ptr[-1]);
176 #endif
177 val |= bit_buf >> (32 + bit_cnt);
178 bit_buf <<= - bit_cnt;
179 bit_cnt += 32;
180 } else {
181 buf_ptr -= 4;
182 bit_buf = 0;
183 if (buf_ptr < s->buf_end)
184 bit_buf |= *buf_ptr++ << 24;
185 if (buf_ptr < s->buf_end)
186 bit_buf |= *buf_ptr++ << 16;
187 if (buf_ptr < s->buf_end)
188 bit_buf |= *buf_ptr++ << 8;
189 if (buf_ptr < s->buf_end)
190 bit_buf |= *buf_ptr++;
191
192 val |= bit_buf >> (32 + bit_cnt);
193 bit_buf <<= - bit_cnt;
194 bit_cnt += 8*(buf_ptr - s->buf_ptr);
195 if(bit_cnt<0) bit_cnt=0;
196 }
197 s->buf_ptr = buf_ptr;
198 }
199 s->bit_buf = bit_buf;
200 s->bit_cnt = bit_cnt;
201 return val;
202 }
203 #endif
204
205 void align_get_bits(GetBitContext *s)
206 {
207 #ifdef ALT_BITSTREAM_READER
208 s->index= (s->index + 7) & (~7);
209 #else
210 int n;
211 n = s->bit_cnt & 7;
212 if (n > 0) {
213 get_bits(s, n);
214 }
215 #endif
216 }
217
218 int check_marker(GetBitContext *s, char *msg)
219 {
220 int bit= get_bits1(s);
221 if(!bit) printf("Marker bit missing %s\n", msg);
222
223 return bit;
224 }
225
226 #ifndef ALT_BITSTREAM_READER
227 /* This function is identical to get_bits_long(), the */
228 /* only diference is that it doesn't touch the buffer */
229 /* it is usefull to see the buffer. */
230
231 unsigned int show_bits_long(GetBitContext *s, int n)
232 {
233 unsigned int val;
234 int bit_cnt;
235 unsigned int bit_buf;
236 UINT8 *buf_ptr;
237
238 bit_buf = s->bit_buf;
239 bit_cnt = s->bit_cnt - n;
240
241 val = bit_buf >> (32 - n);
242 buf_ptr = s->buf_ptr;
243 buf_ptr += 4;
244
245 /* handle common case: we can read everything */
246 if (buf_ptr <= s->buf_end) {
247 #ifdef ARCH_X86
248 bit_buf = bswap_32(*((unsigned long*)(&buf_ptr[-4])));
249 #else
250 bit_buf = (buf_ptr[-4] << 24) |
251 (buf_ptr[-3] << 16) |
252 (buf_ptr[-2] << 8) |
253 (buf_ptr[-1]);
254 #endif
255 } else {
256 buf_ptr -= 4;
257 bit_buf = 0;
258 if (buf_ptr < s->buf_end)
259 bit_buf |= *buf_ptr++ << 24;
260 if (buf_ptr < s->buf_end)
261 bit_buf |= *buf_ptr++ << 16;
262 if (buf_ptr < s->buf_end)
263 bit_buf |= *buf_ptr++ << 8;
264 if (buf_ptr < s->buf_end)
265 bit_buf |= *buf_ptr++;
266 }
267 val |= bit_buf >> (32 + bit_cnt);
268 bit_buf <<= - bit_cnt;
269 bit_cnt += 32;
270
271 return val;
272 }
273 #endif
274
275 /* VLC decoding */
276
277 //#define DEBUG_VLC
278
279 #define GET_DATA(v, table, i, wrap, size) \
280 {\
281 UINT8 *ptr = (UINT8 *)table + i * wrap;\
282 switch(size) {\
283 case 1:\
284 v = *(UINT8 *)ptr;\
285 break;\
286 case 2:\
287 v = *(UINT16 *)ptr;\
288 break;\
289 default:\
290 v = *(UINT32 *)ptr;\
291 break;\
292 }\
293 }
294
295
296 static int alloc_table(VLC *vlc, int size)
297 {
298 int index;
299 index = vlc->table_size;
300 vlc->table_size += size;
301 if (vlc->table_size > vlc->table_allocated) {
302 vlc->table_allocated += (1 << vlc->bits);
303 vlc->table_bits = realloc(vlc->table_bits,
304 sizeof(INT8) * vlc->table_allocated);
305 vlc->table_codes = realloc(vlc->table_codes,
306 sizeof(INT16) * vlc->table_allocated);
307 if (!vlc->table_bits ||
308 !vlc->table_codes)
309 return -1;
310 }
311 return index;
312 }
313
314 static int build_table(VLC *vlc, int table_nb_bits,
315 int nb_codes,
316 const void *bits, int bits_wrap, int bits_size,
317 const void *codes, int codes_wrap, int codes_size,
318 UINT32 code_prefix, int n_prefix)
319 {
320 int i, j, k, n, table_size, table_index, nb, n1, index;
321 UINT32 code;
322 INT8 *table_bits;
323 INT16 *table_codes;
324
325 table_size = 1 << table_nb_bits;
326 table_index = alloc_table(vlc, table_size);
327 #ifdef DEBUG_VLC
328 printf("new table index=%d size=%d code_prefix=%x n=%d\n",
329 table_index, table_size, code_prefix, n_prefix);
330 #endif
331 if (table_index < 0)
332 return -1;
333 table_bits = &vlc->table_bits[table_index];
334 table_codes = &vlc->table_codes[table_index];
335
336 for(i=0;i<table_size;i++) {
337 table_bits[i] = 0;
338 table_codes[i] = -1;
339 }
340
341 /* first pass: map codes and compute auxillary table sizes */
342 for(i=0;i<nb_codes;i++) {
343 GET_DATA(n, bits, i, bits_wrap, bits_size);
344 GET_DATA(code, codes, i, codes_wrap, codes_size);
345 /* we accept tables with holes */
346 if (n <= 0)
347 continue;
348 #if defined(DEBUG_VLC) && 0
349 printf("i=%d n=%d code=0x%x\n", i, n, code);
350 #endif
351 /* if code matches the prefix, it is in the table */
352 n -= n_prefix;
353 if (n > 0 && (code >> n) == code_prefix) {
354 if (n <= table_nb_bits) {
355 /* no need to add another table */
356 j = (code << (table_nb_bits - n)) & (table_size - 1);
357 nb = 1 << (table_nb_bits - n);
358 for(k=0;k<nb;k++) {
359 #ifdef DEBUG_VLC
360 printf("%4x: code=%d n=%d\n",
361 j, i, n);
362 #endif
363 if (table_bits[j] != 0) {
364 fprintf(stderr, "incorrect codes\n");
365 exit(1);
366 }
367 table_bits[j] = n;
368 table_codes[j] = i;
369 j++;
370 }
371 } else {
372 n -= table_nb_bits;
373 j = (code >> n) & ((1 << table_nb_bits) - 1);
374 #ifdef DEBUG_VLC
375 printf("%4x: n=%d (subtable)\n",
376 j, n);
377 #endif
378 /* compute table size */
379 n1 = -table_bits[j];
380 if (n > n1)
381 n1 = n;
382 table_bits[j] = -n1;
383 }
384 }
385 }
386
387 /* second pass : fill auxillary tables recursively */
388 for(i=0;i<table_size;i++) {
389 n = table_bits[i];
390 if (n < 0) {
391 n = -n;
392 if (n > table_nb_bits) {
393 n = table_nb_bits;
394 table_bits[i] = -n;
395 }
396 index = build_table(vlc, n, nb_codes,
397 bits, bits_wrap, bits_size,
398 codes, codes_wrap, codes_size,
399 (code_prefix << table_nb_bits) | i,
400 n_prefix + table_nb_bits);
401 if (index < 0)
402 return -1;
403 /* note: realloc has been done, so reload tables */
404 table_bits = &vlc->table_bits[table_index];
405 table_codes = &vlc->table_codes[table_index];
406 table_codes[i] = index;
407 }
408 }
409 return table_index;
410 }
411
412
413 /* Build VLC decoding tables suitable for use with get_vlc().
414
415 'nb_bits' set thee decoding table size (2^nb_bits) entries. The
416 bigger it is, the faster is the decoding. But it should not be too
417 big to save memory and L1 cache. '9' is a good compromise.
418
419 'nb_codes' : number of vlcs codes
420
421 'bits' : table which gives the size (in bits) of each vlc code.
422
423 'codes' : table which gives the bit pattern of of each vlc code.
424
425 'xxx_wrap' : give the number of bytes between each entry of the
426 'bits' or 'codes' tables.
427
428 'xxx_size' : gives the number of bytes of each entry of the 'bits'
429 or 'codes' tables.
430
431 'wrap' and 'size' allows to use any memory configuration and types
432 (byte/word/long) to store the 'bits' and 'codes' tables.
433 */
434 int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
435 const void *bits, int bits_wrap, int bits_size,
436 const void *codes, int codes_wrap, int codes_size)
437 {
438 vlc->bits = nb_bits;
439 vlc->table_bits = NULL;
440 vlc->table_codes = NULL;
441 vlc->table_allocated = 0;
442 vlc->table_size = 0;
443 #ifdef DEBUG_VLC
444 printf("build table nb_codes=%d\n", nb_codes);
445 #endif
446
447 if (build_table(vlc, nb_bits, nb_codes,
448 bits, bits_wrap, bits_size,
449 codes, codes_wrap, codes_size,
450 0, 0) < 0) {
451 av_free(vlc->table_bits);
452 av_free(vlc->table_codes);
453 return -1;
454 }
455 return 0;
456 }
457
458
459 void free_vlc(VLC *vlc)
460 {
461 av_free(vlc->table_bits);
462 av_free(vlc->table_codes);
463 }
464
465 int ff_gcd(int a, int b){
466 if(b) return ff_gcd(b, a%b);
467 else return a;
468 }