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>
23 const uint8_t 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
30 const 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
41 void init_put_bits(PutBitContext *s,
42 uint8_t *buffer, int buffer_size,
44 void (*write_data)(void *, uint8_t *, int))
47 s->buf_end = s->buf + buffer_size;
51 fprintf(stderr, "write Data callback is not supported\n");
53 #ifdef ALT_BITSTREAM_WRITER
55 ((uint32_t*)(s->buf))[0]=0;
56 // memset(buffer, 0, buffer_size);
64 /* return the number of bits output */
65 int64_t get_bit_count(PutBitContext *s)
67 #ifdef ALT_BITSTREAM_WRITER
68 return s->data_out_size * 8 + s->index;
70 return (s->buf_ptr - s->buf + s->data_out_size) * 8 + 32 - (int64_t)s->bit_left;
74 void align_put_bits(PutBitContext *s)
76 #ifdef ALT_BITSTREAM_WRITER
77 put_bits(s,( - s->index) & 7,0);
79 put_bits(s,s->bit_left & 7,0);
83 /* pad the end of the output stream with zeros */
84 void flush_put_bits(PutBitContext *s)
86 #ifdef ALT_BITSTREAM_WRITER
89 s->bit_buf<<= s->bit_left;
90 while (s->bit_left < 32) {
91 /* XXX: should test end of buffer */
92 *s->buf_ptr++=s->bit_buf >> 24;
101 void put_string(PutBitContext * pbc, char *s)
104 put_bits(pbc, 8, *s);
110 /* bit input functions */
112 void init_get_bits(GetBitContext *s,
113 uint8_t *buffer, int bit_size)
115 const int buffer_size= (bit_size+7)>>3;
118 s->size_in_bits= bit_size;
119 s->buffer_end= buffer + buffer_size;
120 #ifdef ALT_BITSTREAM_READER
122 #elif defined LIBMPEG2_BITSTREAM_READER
123 s->buffer_ptr = buffer;
126 #elif defined A32_BITSTREAM_READER
127 s->buffer_ptr = (uint32_t*)buffer;
135 // UPDATE_CACHE(re, s)
138 #ifdef A32_BITSTREAM_READER
143 void align_get_bits(GetBitContext *s)
145 int n= (-get_bits_count(s)) & 7;
146 if(n) skip_bits(s, n);
149 int check_marker(GetBitContext *s, const char *msg)
151 int bit= get_bits1(s);
152 if(!bit) printf("Marker bit missing %s\n", msg);
161 #define GET_DATA(v, table, i, wrap, size) \
163 const uint8_t *ptr = (const uint8_t *)table + i * wrap;\
166 v = *(const uint8_t *)ptr;\
169 v = *(const uint16_t *)ptr;\
172 v = *(const uint32_t *)ptr;\
178 static int alloc_table(VLC *vlc, int size)
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);
185 vlc->table = av_realloc(vlc->table,
186 sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
193 static int build_table(VLC *vlc, int table_nb_bits,
195 const void *bits, int bits_wrap, int bits_size,
196 const void *codes, int codes_wrap, int codes_size,
197 uint32_t code_prefix, int n_prefix)
199 int i, j, k, n, table_size, table_index, nb, n1, index;
201 VLC_TYPE (*table)[2];
203 table_size = 1 << table_nb_bits;
204 table_index = alloc_table(vlc, table_size);
206 printf("new table index=%d size=%d code_prefix=%x n=%d\n",
207 table_index, table_size, code_prefix, n_prefix);
211 table = &vlc->table[table_index];
213 for(i=0;i<table_size;i++) {
214 table[i][1] = 0; //bits
215 table[i][0] = -1; //codes
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 */
225 #if defined(DEBUG_VLC) && 0
226 printf("i=%d n=%d code=0x%x\n", i, n, code);
228 /* if code matches the prefix, it is in the table */
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);
237 printf("%4x: code=%d n=%d\n",
240 if (table[j][1] /*bits*/ != 0) {
241 fprintf(stderr, "incorrect codes\n");
244 table[j][1] = n; //bits
245 table[j][0] = i; //code
250 j = (code >> n) & ((1 << table_nb_bits) - 1);
252 printf("%4x: n=%d (subtable)\n",
255 /* compute table size */
256 n1 = -table[j][1]; //bits
259 table[j][1] = -n1; //bits
264 /* second pass : fill auxillary tables recursively */
265 for(i=0;i<table_size;i++) {
266 n = table[i][1]; //bits
269 if (n > table_nb_bits) {
271 table[i][1] = -n; //bits
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);
280 /* note: realloc has been done, so reload tables */
281 table = &vlc->table[table_index];
282 table[i][0] = index; //code
289 /* Build VLC decoding tables suitable for use with get_vlc().
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.
295 'nb_codes' : number of vlcs codes
297 'bits' : table which gives the size (in bits) of each vlc code.
299 'codes' : table which gives the bit pattern of of each vlc code.
301 'xxx_wrap' : give the number of bytes between each entry of the
302 'bits' or 'codes' tables.
304 'xxx_size' : gives the number of bytes of each entry of the 'bits'
307 'wrap' and 'size' allows to use any memory configuration and types
308 (byte/word/long) to store the 'bits' and 'codes' tables.
310 int 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)
316 vlc->table_allocated = 0;
319 printf("build table nb_codes=%d\n", nb_codes);
322 if (build_table(vlc, nb_bits, nb_codes,
323 bits, bits_wrap, bits_size,
324 codes, codes_wrap, codes_size,
333 void free_vlc(VLC *vlc)
338 int ff_gcd(int a, int b){
339 if(b) return ff_gcd(b, a%b);
343 void 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;
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;
353 diff= ABS( f - (double)nom / (double)denom );
354 if(diff < best_diff){
361 gcd= ff_gcd(best_nom, best_denom);
366 *denom_arg= best_denom;