823bf97f4f13cfaf8d6d05ef58674110fefee566
[libav.git] / libavcodec / bitstream.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 * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
7 *
8 * This file is part of FFmpeg.
9 *
10 * FFmpeg is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU Lesser General Public
12 * License as published by the Free Software Foundation; either
13 * version 2.1 of the License, or (at your option) any later version.
14 *
15 * FFmpeg is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * Lesser General Public License for more details.
19 *
20 * You should have received a copy of the GNU Lesser General Public
21 * License along with FFmpeg; if not, write to the Free Software
22 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 */
24
25 /**
26 * @file bitstream.c
27 * bitstream api.
28 */
29
30 #include "avcodec.h"
31 #include "bitstream.h"
32
33 /**
34 * Same as av_mallocz_static(), but does a realloc.
35 *
36 * @param[in] ptr The block of memory to reallocate.
37 * @param[in] size The requested size.
38 * @return Block of memory of requested size.
39 * @deprecated. Code which uses ff_realloc_static is broken/misdesigned
40 * and should correctly use static arrays
41 */
42 attribute_deprecated av_alloc_size(2)
43 void *ff_realloc_static(void *ptr, unsigned int size);
44
45 void align_put_bits(PutBitContext *s)
46 {
47 #ifdef ALT_BITSTREAM_WRITER
48 put_bits(s,( - s->index) & 7,0);
49 #else
50 put_bits(s,s->bit_left & 7,0);
51 #endif
52 }
53
54 void ff_put_string(PutBitContext * pbc, const char *s, int put_zero)
55 {
56 while(*s){
57 put_bits(pbc, 8, *s);
58 s++;
59 }
60 if(put_zero)
61 put_bits(pbc, 8, 0);
62 }
63
64 void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length)
65 {
66 const uint16_t *srcw= (const uint16_t*)src;
67 int words= length>>4;
68 int bits= length&15;
69 int i;
70
71 if(length==0) return;
72
73 if(ENABLE_SMALL || words < 16 || put_bits_count(pb)&7){
74 for(i=0; i<words; i++) put_bits(pb, 16, be2me_16(srcw[i]));
75 }else{
76 for(i=0; put_bits_count(pb)&31; i++)
77 put_bits(pb, 8, src[i]);
78 flush_put_bits(pb);
79 memcpy(pbBufPtr(pb), src+i, 2*words-i);
80 skip_put_bytes(pb, 2*words-i);
81 }
82
83 put_bits(pb, bits, be2me_16(srcw[words])>>(16-bits));
84 }
85
86 /* VLC decoding */
87
88 //#define DEBUG_VLC
89
90 #define GET_DATA(v, table, i, wrap, size) \
91 {\
92 const uint8_t *ptr = (const uint8_t *)table + i * wrap;\
93 switch(size) {\
94 case 1:\
95 v = *(const uint8_t *)ptr;\
96 break;\
97 case 2:\
98 v = *(const uint16_t *)ptr;\
99 break;\
100 default:\
101 v = *(const uint32_t *)ptr;\
102 break;\
103 }\
104 }
105
106
107 static int alloc_table(VLC *vlc, int size, int use_static)
108 {
109 int index;
110 index = vlc->table_size;
111 vlc->table_size += size;
112 if (vlc->table_size > vlc->table_allocated) {
113 if(use_static>1)
114 abort(); //cant do anything, init_vlc() is used with too little memory
115 vlc->table_allocated += (1 << vlc->bits);
116 if(use_static)
117 vlc->table = ff_realloc_static(vlc->table,
118 sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
119 else
120 vlc->table = av_realloc(vlc->table,
121 sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
122 if (!vlc->table)
123 return -1;
124 }
125 return index;
126 }
127
128 static int build_table(VLC *vlc, int table_nb_bits,
129 int nb_codes,
130 const void *bits, int bits_wrap, int bits_size,
131 const void *codes, int codes_wrap, int codes_size,
132 const void *symbols, int symbols_wrap, int symbols_size,
133 uint32_t code_prefix, int n_prefix, int flags)
134 {
135 int i, j, k, n, table_size, table_index, nb, n1, index, code_prefix2, symbol;
136 uint32_t code;
137 VLC_TYPE (*table)[2];
138
139 table_size = 1 << table_nb_bits;
140 table_index = alloc_table(vlc, table_size, flags & (INIT_VLC_USE_STATIC|INIT_VLC_USE_NEW_STATIC));
141 #ifdef DEBUG_VLC
142 av_log(NULL,AV_LOG_DEBUG,"new table index=%d size=%d code_prefix=%x n=%d\n",
143 table_index, table_size, code_prefix, n_prefix);
144 #endif
145 if (table_index < 0)
146 return -1;
147 table = &vlc->table[table_index];
148
149 for(i=0;i<table_size;i++) {
150 table[i][1] = 0; //bits
151 table[i][0] = -1; //codes
152 }
153
154 /* first pass: map codes and compute auxillary table sizes */
155 for(i=0;i<nb_codes;i++) {
156 GET_DATA(n, bits, i, bits_wrap, bits_size);
157 GET_DATA(code, codes, i, codes_wrap, codes_size);
158 /* we accept tables with holes */
159 if (n <= 0)
160 continue;
161 if (!symbols)
162 symbol = i;
163 else
164 GET_DATA(symbol, symbols, i, symbols_wrap, symbols_size);
165 #if defined(DEBUG_VLC) && 0
166 av_log(NULL,AV_LOG_DEBUG,"i=%d n=%d code=0x%x\n", i, n, code);
167 #endif
168 /* if code matches the prefix, it is in the table */
169 n -= n_prefix;
170 if(flags & INIT_VLC_LE)
171 code_prefix2= code & (n_prefix>=32 ? 0xffffffff : (1 << n_prefix)-1);
172 else
173 code_prefix2= code >> n;
174 if (n > 0 && code_prefix2 == code_prefix) {
175 if (n <= table_nb_bits) {
176 /* no need to add another table */
177 j = (code << (table_nb_bits - n)) & (table_size - 1);
178 nb = 1 << (table_nb_bits - n);
179 for(k=0;k<nb;k++) {
180 if(flags & INIT_VLC_LE)
181 j = (code >> n_prefix) + (k<<n);
182 #ifdef DEBUG_VLC
183 av_log(NULL, AV_LOG_DEBUG, "%4x: code=%d n=%d\n",
184 j, i, n);
185 #endif
186 if (table[j][1] /*bits*/ != 0) {
187 av_log(NULL, AV_LOG_ERROR, "incorrect codes\n");
188 return -1;
189 }
190 table[j][1] = n; //bits
191 table[j][0] = symbol;
192 j++;
193 }
194 } else {
195 n -= table_nb_bits;
196 j = (code >> ((flags & INIT_VLC_LE) ? n_prefix : n)) & ((1 << table_nb_bits) - 1);
197 #ifdef DEBUG_VLC
198 av_log(NULL,AV_LOG_DEBUG,"%4x: n=%d (subtable)\n",
199 j, n);
200 #endif
201 /* compute table size */
202 n1 = -table[j][1]; //bits
203 if (n > n1)
204 n1 = n;
205 table[j][1] = -n1; //bits
206 }
207 }
208 }
209
210 /* second pass : fill auxillary tables recursively */
211 for(i=0;i<table_size;i++) {
212 n = table[i][1]; //bits
213 if (n < 0) {
214 n = -n;
215 if (n > table_nb_bits) {
216 n = table_nb_bits;
217 table[i][1] = -n; //bits
218 }
219 index = build_table(vlc, n, nb_codes,
220 bits, bits_wrap, bits_size,
221 codes, codes_wrap, codes_size,
222 symbols, symbols_wrap, symbols_size,
223 (flags & INIT_VLC_LE) ? (code_prefix | (i << n_prefix)) : ((code_prefix << table_nb_bits) | i),
224 n_prefix + table_nb_bits, flags);
225 if (index < 0)
226 return -1;
227 /* note: realloc has been done, so reload tables */
228 table = &vlc->table[table_index];
229 table[i][0] = index; //code
230 }
231 }
232 return table_index;
233 }
234
235
236 /* Build VLC decoding tables suitable for use with get_vlc().
237
238 'nb_bits' set thee decoding table size (2^nb_bits) entries. The
239 bigger it is, the faster is the decoding. But it should not be too
240 big to save memory and L1 cache. '9' is a good compromise.
241
242 'nb_codes' : number of vlcs codes
243
244 'bits' : table which gives the size (in bits) of each vlc code.
245
246 'codes' : table which gives the bit pattern of of each vlc code.
247
248 'symbols' : table which gives the values to be returned from get_vlc().
249
250 'xxx_wrap' : give the number of bytes between each entry of the
251 'bits' or 'codes' tables.
252
253 'xxx_size' : gives the number of bytes of each entry of the 'bits'
254 or 'codes' tables.
255
256 'wrap' and 'size' allows to use any memory configuration and types
257 (byte/word/long) to store the 'bits', 'codes', and 'symbols' tables.
258
259 'use_static' should be set to 1 for tables, which should be freed
260 with av_free_static(), 0 if free_vlc() will be used.
261 */
262 int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,
263 const void *bits, int bits_wrap, int bits_size,
264 const void *codes, int codes_wrap, int codes_size,
265 const void *symbols, int symbols_wrap, int symbols_size,
266 int flags)
267 {
268 vlc->bits = nb_bits;
269 if(flags & INIT_VLC_USE_NEW_STATIC){
270 if(vlc->table_size && vlc->table_size == vlc->table_allocated){
271 return 0;
272 }else if(vlc->table_size){
273 abort(); // fatal error, we are called on a partially initialized table
274 }
275 }else if(!(flags & INIT_VLC_USE_STATIC)) {
276 vlc->table = NULL;
277 vlc->table_allocated = 0;
278 vlc->table_size = 0;
279 } else {
280 /* Static tables are initially always NULL, return
281 if vlc->table != NULL to avoid double allocation */
282 if(vlc->table)
283 return 0;
284 }
285
286 #ifdef DEBUG_VLC
287 av_log(NULL,AV_LOG_DEBUG,"build table nb_codes=%d\n", nb_codes);
288 #endif
289
290 if (build_table(vlc, nb_bits, nb_codes,
291 bits, bits_wrap, bits_size,
292 codes, codes_wrap, codes_size,
293 symbols, symbols_wrap, symbols_size,
294 0, 0, flags) < 0) {
295 av_freep(&vlc->table);
296 return -1;
297 }
298 if((flags & INIT_VLC_USE_NEW_STATIC) && vlc->table_size != vlc->table_allocated)
299 av_log(NULL, AV_LOG_ERROR, "needed %d had %d\n", vlc->table_size, vlc->table_allocated);
300 return 0;
301 }
302
303
304 void free_vlc(VLC *vlc)
305 {
306 av_freep(&vlc->table);
307 }
308