3 * Copyright (c) 2000, 2001 Fabrice Bellard.
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.
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.
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
19 * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
24 * common internal api.
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
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
47 void init_put_bits(PutBitContext *s,
48 uint8_t *buffer, int buffer_size,
50 void (*write_data)(void *, uint8_t *, int))
53 s->buf_end = s->buf + buffer_size;
57 fprintf(stderr, "write Data callback is not supported\n");
59 #ifdef ALT_BITSTREAM_WRITER
61 ((uint32_t*)(s->buf))[0]=0;
62 // memset(buffer, 0, buffer_size);
70 #ifdef CONFIG_ENCODERS
72 /* return the number of bits output */
73 int64_t get_bit_count(PutBitContext *s)
75 #ifdef ALT_BITSTREAM_WRITER
76 return s->data_out_size * 8 + s->index;
78 return (s->buf_ptr - s->buf + s->data_out_size) * 8 + 32 - (int64_t)s->bit_left;
82 void align_put_bits(PutBitContext *s)
84 #ifdef ALT_BITSTREAM_WRITER
85 put_bits(s,( - s->index) & 7,0);
87 put_bits(s,s->bit_left & 7,0);
91 #endif //CONFIG_ENCODERS
93 /* pad the end of the output stream with zeros */
94 void flush_put_bits(PutBitContext *s)
96 #ifdef ALT_BITSTREAM_WRITER
99 s->bit_buf<<= s->bit_left;
100 while (s->bit_left < 32) {
101 /* XXX: should test end of buffer */
102 *s->buf_ptr++=s->bit_buf >> 24;
111 #ifdef CONFIG_ENCODERS
113 void put_string(PutBitContext * pbc, char *s)
116 put_bits(pbc, 8, *s);
122 /* bit input functions */
124 #endif //CONFIG_ENCODERS
127 * init GetBitContext.
128 * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger then the actual read bits
129 * because some optimized bitstream readers read 32 or 64 bit at once and could read over the end
130 * @param bit_size the size of the buffer in bits
132 void init_get_bits(GetBitContext *s,
133 const uint8_t *buffer, int bit_size)
135 const int buffer_size= (bit_size+7)>>3;
138 s->size_in_bits= bit_size;
139 s->buffer_end= buffer + buffer_size;
140 #ifdef ALT_BITSTREAM_READER
142 #elif defined LIBMPEG2_BITSTREAM_READER
143 #ifdef LIBMPEG2_BITSTREAM_READER_HACK
146 s->cache = (*buffer++)<<24;
147 s->buffer_ptr = buffer;
152 s->buffer_ptr = buffer;
156 #elif defined A32_BITSTREAM_READER
157 s->buffer_ptr = (uint32_t*)buffer;
168 #ifdef A32_BITSTREAM_READER
176 unsigned int get_bits_long(GetBitContext *s, int n){
177 if(n<=17) return get_bits(s, n);
179 int ret= get_bits(s, 16) << (n-16);
180 return ret | get_bits(s, n-16);
187 unsigned int show_bits_long(GetBitContext *s, int n){
188 if(n<=17) return show_bits(s, n);
190 GetBitContext gb= *s;
191 int ret= get_bits_long(s, n);
197 void align_get_bits(GetBitContext *s)
199 int n= (-get_bits_count(s)) & 7;
200 if(n) skip_bits(s, n);
203 int check_marker(GetBitContext *s, const char *msg)
205 int bit= get_bits1(s);
206 if(!bit) printf("Marker bit missing %s\n", msg);
215 #define GET_DATA(v, table, i, wrap, size) \
217 const uint8_t *ptr = (const uint8_t *)table + i * wrap;\
220 v = *(const uint8_t *)ptr;\
223 v = *(const uint16_t *)ptr;\
226 v = *(const uint32_t *)ptr;\
232 static int alloc_table(VLC *vlc, int size)
235 index = vlc->table_size;
236 vlc->table_size += size;
237 if (vlc->table_size > vlc->table_allocated) {
238 vlc->table_allocated += (1 << vlc->bits);
239 vlc->table = av_realloc(vlc->table,
240 sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
247 static int build_table(VLC *vlc, int table_nb_bits,
249 const void *bits, int bits_wrap, int bits_size,
250 const void *codes, int codes_wrap, int codes_size,
251 uint32_t code_prefix, int n_prefix)
253 int i, j, k, n, table_size, table_index, nb, n1, index;
255 VLC_TYPE (*table)[2];
257 table_size = 1 << table_nb_bits;
258 table_index = alloc_table(vlc, table_size);
260 printf("new table index=%d size=%d code_prefix=%x n=%d\n",
261 table_index, table_size, code_prefix, n_prefix);
265 table = &vlc->table[table_index];
267 for(i=0;i<table_size;i++) {
268 table[i][1] = 0; //bits
269 table[i][0] = -1; //codes
272 /* first pass: map codes and compute auxillary table sizes */
273 for(i=0;i<nb_codes;i++) {
274 GET_DATA(n, bits, i, bits_wrap, bits_size);
275 GET_DATA(code, codes, i, codes_wrap, codes_size);
276 /* we accept tables with holes */
279 #if defined(DEBUG_VLC) && 0
280 printf("i=%d n=%d code=0x%x\n", i, n, code);
282 /* if code matches the prefix, it is in the table */
284 if (n > 0 && (code >> n) == code_prefix) {
285 if (n <= table_nb_bits) {
286 /* no need to add another table */
287 j = (code << (table_nb_bits - n)) & (table_size - 1);
288 nb = 1 << (table_nb_bits - n);
291 printf("%4x: code=%d n=%d\n",
294 if (table[j][1] /*bits*/ != 0) {
295 fprintf(stderr, "incorrect codes\n");
298 table[j][1] = n; //bits
299 table[j][0] = i; //code
304 j = (code >> n) & ((1 << table_nb_bits) - 1);
306 printf("%4x: n=%d (subtable)\n",
309 /* compute table size */
310 n1 = -table[j][1]; //bits
313 table[j][1] = -n1; //bits
318 /* second pass : fill auxillary tables recursively */
319 for(i=0;i<table_size;i++) {
320 n = table[i][1]; //bits
323 if (n > table_nb_bits) {
325 table[i][1] = -n; //bits
327 index = build_table(vlc, n, nb_codes,
328 bits, bits_wrap, bits_size,
329 codes, codes_wrap, codes_size,
330 (code_prefix << table_nb_bits) | i,
331 n_prefix + table_nb_bits);
334 /* note: realloc has been done, so reload tables */
335 table = &vlc->table[table_index];
336 table[i][0] = index; //code
343 /* Build VLC decoding tables suitable for use with get_vlc().
345 'nb_bits' set thee decoding table size (2^nb_bits) entries. The
346 bigger it is, the faster is the decoding. But it should not be too
347 big to save memory and L1 cache. '9' is a good compromise.
349 'nb_codes' : number of vlcs codes
351 'bits' : table which gives the size (in bits) of each vlc code.
353 'codes' : table which gives the bit pattern of of each vlc code.
355 'xxx_wrap' : give the number of bytes between each entry of the
356 'bits' or 'codes' tables.
358 'xxx_size' : gives the number of bytes of each entry of the 'bits'
361 'wrap' and 'size' allows to use any memory configuration and types
362 (byte/word/long) to store the 'bits' and 'codes' tables.
364 int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
365 const void *bits, int bits_wrap, int bits_size,
366 const void *codes, int codes_wrap, int codes_size)
370 vlc->table_allocated = 0;
373 printf("build table nb_codes=%d\n", nb_codes);
376 if (build_table(vlc, nb_bits, nb_codes,
377 bits, bits_wrap, bits_size,
378 codes, codes_wrap, codes_size,
387 void free_vlc(VLC *vlc)
392 int64_t ff_gcd(int64_t a, int64_t b){
393 if(b) return ff_gcd(b, a%b);
397 void ff_float2fraction(int *nom_arg, int *denom_arg, double f, int max){
398 double best_diff=1E10, diff;
399 int best_denom=1, best_nom=1;
402 //brute force here, perhaps we should try continued fractions if we need large max ...
403 for(denom=1; denom<=max; denom++){
404 nom= (int)(f*denom + 0.5);
405 if(nom<=0 || nom>max) continue;
407 diff= ABS( f - (double)nom / (double)denom );
408 if(diff < best_diff){
415 gcd= ff_gcd(best_nom, best_denom);
420 *denom_arg= best_denom;