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 void init_put_bits(PutBitContext *s,
24 UINT8 *buffer, int buffer_size,
26 void (*write_data)(void *, UINT8 *, int))
29 s->buf_end = s->buf + buffer_size;
33 fprintf(stderr, "write Data callback is not supported\n");
35 #ifdef ALT_BITSTREAM_WRITER
37 ((uint32_t*)(s->buf))[0]=0;
38 // memset(buffer, 0, buffer_size);
46 /* return the number of bits output */
47 INT64 get_bit_count(PutBitContext *s)
49 #ifdef ALT_BITSTREAM_WRITER
50 return s->data_out_size * 8 + s->index;
52 return (s->buf_ptr - s->buf + s->data_out_size) * 8 + 32 - (INT64)s->bit_left;
56 void align_put_bits(PutBitContext *s)
58 #ifdef ALT_BITSTREAM_WRITER
59 put_bits(s,( - s->index) & 7,0);
61 put_bits(s,s->bit_left & 7,0);
65 /* pad the end of the output stream with zeros */
66 void flush_put_bits(PutBitContext *s)
68 #ifdef ALT_BITSTREAM_WRITER
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;
83 /* pad the end of the output stream with zeros */
84 #ifndef ALT_BITSTREAM_WRITER
85 void jflush_put_bits(PutBitContext *s)
88 s->bit_buf<<= s->bit_left;
89 s->bit_buf |= ~1U >> (32 - s->bit_left); /* set all the unused bits to one */
91 while (s->bit_left < 32) {
103 void jflush_put_bits(PutBitContext *s)
105 int num= ( - s->index) & 7;
106 jput_bits(s, num,0xFF>>(8-num));
110 void put_string(PutBitContext * pbc, char *s)
113 put_bits(pbc, 8, *s);
119 /* bit input functions */
121 void init_get_bits(GetBitContext *s,
122 UINT8 *buffer, int buffer_size)
125 s->size= buffer_size;
126 s->buffer_end= buffer + buffer_size;
127 #ifdef ALT_BITSTREAM_READER
129 #elif defined LIBMPEG2_BITSTREAM_READER
130 s->buffer_ptr = buffer;
133 #elif defined A32_BITSTREAM_READER
134 s->buffer_ptr = (uint32_t*)buffer;
142 // UPDATE_CACHE(re, s)
145 #ifdef A32_BITSTREAM_READER
150 void align_get_bits(GetBitContext *s)
152 int n= (-get_bits_count(s)) & 7;
153 if(n) skip_bits(s, n);
156 int check_marker(GetBitContext *s, char *msg)
158 int bit= get_bits1(s);
159 if(!bit) printf("Marker bit missing %s\n", msg);
168 #define GET_DATA(v, table, i, wrap, size) \
170 UINT8 *ptr = (UINT8 *)table + i * wrap;\
185 static int alloc_table(VLC *vlc, int size)
188 index = vlc->table_size;
189 vlc->table_size += size;
190 if (vlc->table_size > vlc->table_allocated) {
191 vlc->table_allocated += (1 << vlc->bits);
192 vlc->table = realloc(vlc->table,
193 sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
200 static int build_table(VLC *vlc, int table_nb_bits,
202 const void *bits, int bits_wrap, int bits_size,
203 const void *codes, int codes_wrap, int codes_size,
204 UINT32 code_prefix, int n_prefix)
206 int i, j, k, n, table_size, table_index, nb, n1, index;
208 VLC_TYPE (*table)[2];
210 table_size = 1 << table_nb_bits;
211 table_index = alloc_table(vlc, table_size);
213 printf("new table index=%d size=%d code_prefix=%x n=%d\n",
214 table_index, table_size, code_prefix, n_prefix);
218 table = &vlc->table[table_index];
220 for(i=0;i<table_size;i++) {
221 table[i][1] = 0; //bits
222 table[i][0] = -1; //codes
225 /* first pass: map codes and compute auxillary table sizes */
226 for(i=0;i<nb_codes;i++) {
227 GET_DATA(n, bits, i, bits_wrap, bits_size);
228 GET_DATA(code, codes, i, codes_wrap, codes_size);
229 /* we accept tables with holes */
232 #if defined(DEBUG_VLC) && 0
233 printf("i=%d n=%d code=0x%x\n", i, n, code);
235 /* if code matches the prefix, it is in the table */
237 if (n > 0 && (code >> n) == code_prefix) {
238 if (n <= table_nb_bits) {
239 /* no need to add another table */
240 j = (code << (table_nb_bits - n)) & (table_size - 1);
241 nb = 1 << (table_nb_bits - n);
244 printf("%4x: code=%d n=%d\n",
247 if (table[j][1] /*bits*/ != 0) {
248 fprintf(stderr, "incorrect codes\n");
251 table[j][1] = n; //bits
252 table[j][0] = i; //code
257 j = (code >> n) & ((1 << table_nb_bits) - 1);
259 printf("%4x: n=%d (subtable)\n",
262 /* compute table size */
263 n1 = -table[j][1]; //bits
266 table[j][1] = -n1; //bits
271 /* second pass : fill auxillary tables recursively */
272 for(i=0;i<table_size;i++) {
273 n = table[i][1]; //bits
276 if (n > table_nb_bits) {
278 table[i][1] = -n; //bits
280 index = build_table(vlc, n, nb_codes,
281 bits, bits_wrap, bits_size,
282 codes, codes_wrap, codes_size,
283 (code_prefix << table_nb_bits) | i,
284 n_prefix + table_nb_bits);
287 /* note: realloc has been done, so reload tables */
288 table = &vlc->table[table_index];
289 table[i][0] = index; //code
296 /* Build VLC decoding tables suitable for use with get_vlc().
298 'nb_bits' set thee decoding table size (2^nb_bits) entries. The
299 bigger it is, the faster is the decoding. But it should not be too
300 big to save memory and L1 cache. '9' is a good compromise.
302 'nb_codes' : number of vlcs codes
304 'bits' : table which gives the size (in bits) of each vlc code.
306 'codes' : table which gives the bit pattern of of each vlc code.
308 'xxx_wrap' : give the number of bytes between each entry of the
309 'bits' or 'codes' tables.
311 'xxx_size' : gives the number of bytes of each entry of the 'bits'
314 'wrap' and 'size' allows to use any memory configuration and types
315 (byte/word/long) to store the 'bits' and 'codes' tables.
317 int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
318 const void *bits, int bits_wrap, int bits_size,
319 const void *codes, int codes_wrap, int codes_size)
323 vlc->table_allocated = 0;
326 printf("build table nb_codes=%d\n", nb_codes);
329 if (build_table(vlc, nb_bits, nb_codes,
330 bits, bits_wrap, bits_size,
331 codes, codes_wrap, codes_size,
340 void free_vlc(VLC *vlc)
345 int ff_gcd(int a, int b){
346 if(b) return ff_gcd(b, a%b);