these functions (get_bit_count and align_put_bits) are referenced even
[libav.git] / libavcodec / common.c
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 *
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
10 *
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 *
20 * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
21 */
22
23 /**
24 * @file common.c
25 * common internal api.
26 */
27
28 #include "avcodec.h"
29
30 const uint8_t ff_sqrt_tab[128]={
31 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,
32 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,
33 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,
34 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
35 };
36
37 const uint8_t ff_log2_tab[256]={
38 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,
39 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,
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 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,
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 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
46 };
47
48 void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
49 {
50 s->buf = buffer;
51 s->buf_end = s->buf + buffer_size;
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 #if 1
65
66 /* return the number of bits output */
67 int get_bit_count(PutBitContext *s)
68 {
69 #ifdef ALT_BITSTREAM_WRITER
70 return s->index;
71 #else
72 return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
73 #endif
74 }
75
76 void align_put_bits(PutBitContext *s)
77 {
78 #ifdef ALT_BITSTREAM_WRITER
79 put_bits(s,( - s->index) & 7,0);
80 #else
81 put_bits(s,s->bit_left & 7,0);
82 #endif
83 }
84
85 #endif //CONFIG_ENCODERS
86
87 /* pad the end of the output stream with zeros */
88 void flush_put_bits(PutBitContext *s)
89 {
90 #ifdef ALT_BITSTREAM_WRITER
91 align_put_bits(s);
92 #else
93 s->bit_buf<<= s->bit_left;
94 while (s->bit_left < 32) {
95 /* XXX: should test end of buffer */
96 *s->buf_ptr++=s->bit_buf >> 24;
97 s->bit_buf<<=8;
98 s->bit_left+=8;
99 }
100 s->bit_left=32;
101 s->bit_buf=0;
102 #endif
103 }
104
105 #ifdef CONFIG_ENCODERS
106
107 void put_string(PutBitContext * pbc, char *s)
108 {
109 while(*s){
110 put_bits(pbc, 8, *s);
111 s++;
112 }
113 put_bits(pbc, 8, 0);
114 }
115
116 /* bit input functions */
117
118 #endif //CONFIG_ENCODERS
119
120 /**
121 * init GetBitContext.
122 * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger then the actual read bits
123 * because some optimized bitstream readers read 32 or 64 bit at once and could read over the end
124 * @param bit_size the size of the buffer in bits
125 */
126 void init_get_bits(GetBitContext *s,
127 const uint8_t *buffer, int bit_size)
128 {
129 const int buffer_size= (bit_size+7)>>3;
130
131 s->buffer= buffer;
132 s->size_in_bits= bit_size;
133 s->buffer_end= buffer + buffer_size;
134 #ifdef ALT_BITSTREAM_READER
135 s->index=0;
136 #elif defined LIBMPEG2_BITSTREAM_READER
137 #ifdef LIBMPEG2_BITSTREAM_READER_HACK
138 if ((int)buffer&1) {
139 /* word alignment */
140 s->cache = (*buffer++)<<24;
141 s->buffer_ptr = buffer;
142 s->bit_count = 16-8;
143 } else
144 #endif
145 {
146 s->buffer_ptr = buffer;
147 s->bit_count = 16;
148 s->cache = 0;
149 }
150 #elif defined A32_BITSTREAM_READER
151 s->buffer_ptr = (uint32_t*)buffer;
152 s->bit_count = 32;
153 s->cache0 = 0;
154 s->cache1 = 0;
155 #endif
156 {
157 OPEN_READER(re, s)
158 UPDATE_CACHE(re, s)
159 UPDATE_CACHE(re, s)
160 CLOSE_READER(re, s)
161 }
162 #ifdef A32_BITSTREAM_READER
163 s->cache1 = 0;
164 #endif
165 }
166
167 /**
168 * reads 0-32 bits.
169 */
170 unsigned int get_bits_long(GetBitContext *s, int n){
171 if(n<=17) return get_bits(s, n);
172 else{
173 int ret= get_bits(s, 16) << (n-16);
174 return ret | get_bits(s, n-16);
175 }
176 }
177
178 /**
179 * shows 0-32 bits.
180 */
181 unsigned int show_bits_long(GetBitContext *s, int n){
182 if(n<=17) return show_bits(s, n);
183 else{
184 GetBitContext gb= *s;
185 int ret= get_bits_long(s, n);
186 *s= gb;
187 return ret;
188 }
189 }
190
191 void align_get_bits(GetBitContext *s)
192 {
193 int n= (-get_bits_count(s)) & 7;
194 if(n) skip_bits(s, n);
195 }
196
197 int check_marker(GetBitContext *s, const char *msg)
198 {
199 int bit= get_bits1(s);
200 if(!bit)
201 av_log(NULL, AV_LOG_INFO, "Marker bit missing %s\n", msg);
202
203 return bit;
204 }
205
206 /* VLC decoding */
207
208 //#define DEBUG_VLC
209
210 #define GET_DATA(v, table, i, wrap, size) \
211 {\
212 const uint8_t *ptr = (const uint8_t *)table + i * wrap;\
213 switch(size) {\
214 case 1:\
215 v = *(const uint8_t *)ptr;\
216 break;\
217 case 2:\
218 v = *(const uint16_t *)ptr;\
219 break;\
220 default:\
221 v = *(const uint32_t *)ptr;\
222 break;\
223 }\
224 }
225
226
227 static int alloc_table(VLC *vlc, int size)
228 {
229 int index;
230 index = vlc->table_size;
231 vlc->table_size += size;
232 if (vlc->table_size > vlc->table_allocated) {
233 vlc->table_allocated += (1 << vlc->bits);
234 vlc->table = av_realloc(vlc->table,
235 sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
236 if (!vlc->table)
237 return -1;
238 }
239 return index;
240 }
241
242 static int build_table(VLC *vlc, int table_nb_bits,
243 int nb_codes,
244 const void *bits, int bits_wrap, int bits_size,
245 const void *codes, int codes_wrap, int codes_size,
246 uint32_t code_prefix, int n_prefix)
247 {
248 int i, j, k, n, table_size, table_index, nb, n1, index;
249 uint32_t code;
250 VLC_TYPE (*table)[2];
251
252 table_size = 1 << table_nb_bits;
253 table_index = alloc_table(vlc, table_size);
254 #ifdef DEBUG_VLC
255 printf("new table index=%d size=%d code_prefix=%x n=%d\n",
256 table_index, table_size, code_prefix, n_prefix);
257 #endif
258 if (table_index < 0)
259 return -1;
260 table = &vlc->table[table_index];
261
262 for(i=0;i<table_size;i++) {
263 table[i][1] = 0; //bits
264 table[i][0] = -1; //codes
265 }
266
267 /* first pass: map codes and compute auxillary table sizes */
268 for(i=0;i<nb_codes;i++) {
269 GET_DATA(n, bits, i, bits_wrap, bits_size);
270 GET_DATA(code, codes, i, codes_wrap, codes_size);
271 /* we accept tables with holes */
272 if (n <= 0)
273 continue;
274 #if defined(DEBUG_VLC) && 0
275 printf("i=%d n=%d code=0x%x\n", i, n, code);
276 #endif
277 /* if code matches the prefix, it is in the table */
278 n -= n_prefix;
279 if (n > 0 && (code >> n) == code_prefix) {
280 if (n <= table_nb_bits) {
281 /* no need to add another table */
282 j = (code << (table_nb_bits - n)) & (table_size - 1);
283 nb = 1 << (table_nb_bits - n);
284 for(k=0;k<nb;k++) {
285 #ifdef DEBUG_VLC
286 av_log(NULL, AV_LOG_DEBUG, "%4x: code=%d n=%d\n",
287 j, i, n);
288 #endif
289 if (table[j][1] /*bits*/ != 0) {
290 av_log(NULL, AV_LOG_ERROR, "incorrect codes\n");
291 av_abort();
292 }
293 table[j][1] = n; //bits
294 table[j][0] = i; //code
295 j++;
296 }
297 } else {
298 n -= table_nb_bits;
299 j = (code >> n) & ((1 << table_nb_bits) - 1);
300 #ifdef DEBUG_VLC
301 printf("%4x: n=%d (subtable)\n",
302 j, n);
303 #endif
304 /* compute table size */
305 n1 = -table[j][1]; //bits
306 if (n > n1)
307 n1 = n;
308 table[j][1] = -n1; //bits
309 }
310 }
311 }
312
313 /* second pass : fill auxillary tables recursively */
314 for(i=0;i<table_size;i++) {
315 n = table[i][1]; //bits
316 if (n < 0) {
317 n = -n;
318 if (n > table_nb_bits) {
319 n = table_nb_bits;
320 table[i][1] = -n; //bits
321 }
322 index = build_table(vlc, n, nb_codes,
323 bits, bits_wrap, bits_size,
324 codes, codes_wrap, codes_size,
325 (code_prefix << table_nb_bits) | i,
326 n_prefix + table_nb_bits);
327 if (index < 0)
328 return -1;
329 /* note: realloc has been done, so reload tables */
330 table = &vlc->table[table_index];
331 table[i][0] = index; //code
332 }
333 }
334 return table_index;
335 }
336
337
338 /* Build VLC decoding tables suitable for use with get_vlc().
339
340 'nb_bits' set thee decoding table size (2^nb_bits) entries. The
341 bigger it is, the faster is the decoding. But it should not be too
342 big to save memory and L1 cache. '9' is a good compromise.
343
344 'nb_codes' : number of vlcs codes
345
346 'bits' : table which gives the size (in bits) of each vlc code.
347
348 'codes' : table which gives the bit pattern of of each vlc code.
349
350 'xxx_wrap' : give the number of bytes between each entry of the
351 'bits' or 'codes' tables.
352
353 'xxx_size' : gives the number of bytes of each entry of the 'bits'
354 or 'codes' tables.
355
356 'wrap' and 'size' allows to use any memory configuration and types
357 (byte/word/long) to store the 'bits' and 'codes' tables.
358 */
359 int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
360 const void *bits, int bits_wrap, int bits_size,
361 const void *codes, int codes_wrap, int codes_size)
362 {
363 vlc->bits = nb_bits;
364 vlc->table = NULL;
365 vlc->table_allocated = 0;
366 vlc->table_size = 0;
367 #ifdef DEBUG_VLC
368 printf("build table nb_codes=%d\n", nb_codes);
369 #endif
370
371 if (build_table(vlc, nb_bits, nb_codes,
372 bits, bits_wrap, bits_size,
373 codes, codes_wrap, codes_size,
374 0, 0) < 0) {
375 av_free(vlc->table);
376 return -1;
377 }
378 return 0;
379 }
380
381
382 void free_vlc(VLC *vlc)
383 {
384 av_free(vlc->table);
385 }
386
387 int64_t ff_gcd(int64_t a, int64_t b){
388 if(b) return ff_gcd(b, a%b);
389 else return a;
390 }