Imported Debian version 2.5.3~trusty1
[deb_ffmpeg.git] / ffmpeg / 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 * Copyright (c) 2010 Loren Merritt
6 *
7 * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
8 *
9 * This file is part of FFmpeg.
10 *
11 * FFmpeg is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU Lesser General Public
13 * License as published by the Free Software Foundation; either
14 * version 2.1 of the License, or (at your option) any later version.
15 *
16 * FFmpeg is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * Lesser General Public License for more details.
20 *
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with FFmpeg; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 */
25
26 /**
27 * @file
28 * bitstream api.
29 */
30
31 #include "libavutil/atomic.h"
32 #include "libavutil/avassert.h"
33 #include "avcodec.h"
34 #include "mathops.h"
35 #include "get_bits.h"
36 #include "put_bits.h"
37
38 const uint8_t ff_log2_run[41]={
39 0, 0, 0, 0, 1, 1, 1, 1,
40 2, 2, 2, 2, 3, 3, 3, 3,
41 4, 4, 5, 5, 6, 6, 7, 7,
42 8, 9,10,11,12,13,14,15,
43 16,17,18,19,20,21,22,23,
44 24,
45 };
46
47 void avpriv_align_put_bits(PutBitContext *s)
48 {
49 put_bits(s, s->bit_left & 7, 0);
50 }
51
52 void avpriv_put_string(PutBitContext *pb, const char *string,
53 int terminate_string)
54 {
55 while (*string) {
56 put_bits(pb, 8, *string);
57 string++;
58 }
59 if (terminate_string)
60 put_bits(pb, 8, 0);
61 }
62
63 void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length)
64 {
65 int words = length >> 4;
66 int bits = length & 15;
67 int i;
68
69 if (length == 0)
70 return;
71
72 if (CONFIG_SMALL || words < 16 || put_bits_count(pb) & 7) {
73 for (i = 0; i < words; i++)
74 put_bits(pb, 16, AV_RB16(src + 2 * 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(put_bits_ptr(pb), src + i, 2 * words - i);
80 skip_put_bytes(pb, 2 * words - i);
81 }
82
83 put_bits(pb, bits, AV_RB16(src + 2 * words) >> (16 - bits));
84 }
85
86 /* VLC decoding */
87
88 #define GET_DATA(v, table, i, wrap, size) \
89 { \
90 const uint8_t *ptr = (const uint8_t *)table + i * wrap; \
91 switch(size) { \
92 case 1: \
93 v = *(const uint8_t *)ptr; \
94 break; \
95 case 2: \
96 v = *(const uint16_t *)ptr; \
97 break; \
98 default: \
99 v = *(const uint32_t *)ptr; \
100 break; \
101 } \
102 }
103
104
105 static int alloc_table(VLC *vlc, int size, int use_static)
106 {
107 int index = vlc->table_size;
108
109 vlc->table_size += size;
110 if (vlc->table_size > vlc->table_allocated) {
111 if (use_static)
112 abort(); // cannot do anything, init_vlc() is used with too little memory
113 vlc->table_allocated += (1 << vlc->bits);
114 vlc->table = av_realloc_f(vlc->table, vlc->table_allocated, sizeof(VLC_TYPE) * 2);
115 if (!vlc->table) {
116 vlc->table_allocated = 0;
117 vlc->table_size = 0;
118 return AVERROR(ENOMEM);
119 }
120 memset(vlc->table + vlc->table_allocated - (1 << vlc->bits), 0, sizeof(VLC_TYPE) * 2 << vlc->bits);
121 }
122 return index;
123 }
124
125 static av_always_inline uint32_t bitswap_32(uint32_t x)
126 {
127 return (uint32_t)ff_reverse[ x & 0xFF] << 24 |
128 (uint32_t)ff_reverse[(x >> 8) & 0xFF] << 16 |
129 (uint32_t)ff_reverse[(x >> 16) & 0xFF] << 8 |
130 (uint32_t)ff_reverse[ x >> 24];
131 }
132
133 typedef struct {
134 uint8_t bits;
135 uint16_t symbol;
136 /** codeword, with the first bit-to-be-read in the msb
137 * (even if intended for a little-endian bitstream reader) */
138 uint32_t code;
139 } VLCcode;
140
141 static int compare_vlcspec(const void *a, const void *b)
142 {
143 const VLCcode *sa = a, *sb = b;
144 return (sa->code >> 1) - (sb->code >> 1);
145 }
146 /**
147 * Build VLC decoding tables suitable for use with get_vlc().
148 *
149 * @param vlc the context to be initted
150 *
151 * @param table_nb_bits max length of vlc codes to store directly in this table
152 * (Longer codes are delegated to subtables.)
153 *
154 * @param nb_codes number of elements in codes[]
155 *
156 * @param codes descriptions of the vlc codes
157 * These must be ordered such that codes going into the same subtable are contiguous.
158 * Sorting by VLCcode.code is sufficient, though not necessary.
159 */
160 static int build_table(VLC *vlc, int table_nb_bits, int nb_codes,
161 VLCcode *codes, int flags)
162 {
163 int table_size, table_index, index, code_prefix, symbol, subtable_bits;
164 int i, j, k, n, nb, inc;
165 uint32_t code;
166 volatile VLC_TYPE (* volatile table)[2]; // the double volatile is needed to prevent a internal compiler error in gcc 4.2
167
168 table_size = 1 << table_nb_bits;
169 if (table_nb_bits > 30)
170 return -1;
171 table_index = alloc_table(vlc, table_size, flags & INIT_VLC_USE_NEW_STATIC);
172 av_dlog(NULL, "new table index=%d size=%d\n", table_index, table_size);
173 if (table_index < 0)
174 return table_index;
175 table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];
176
177 /* first pass: map codes and compute auxiliary table sizes */
178 for (i = 0; i < nb_codes; i++) {
179 n = codes[i].bits;
180 code = codes[i].code;
181 symbol = codes[i].symbol;
182 av_dlog(NULL, "i=%d n=%d code=0x%x\n", i, n, code);
183 if (n <= table_nb_bits) {
184 /* no need to add another table */
185 j = code >> (32 - table_nb_bits);
186 nb = 1 << (table_nb_bits - n);
187 inc = 1;
188 if (flags & INIT_VLC_LE) {
189 j = bitswap_32(code);
190 inc = 1 << n;
191 }
192 for (k = 0; k < nb; k++) {
193 int bits = table[j][1];
194 av_dlog(NULL, "%4x: code=%d n=%d\n", j, i, n);
195 if (bits != 0 && bits != n) {
196 av_log(NULL, AV_LOG_ERROR, "incorrect codes\n");
197 return AVERROR_INVALIDDATA;
198 }
199 table[j][1] = n; //bits
200 table[j][0] = symbol;
201 j += inc;
202 }
203 } else {
204 /* fill auxiliary table recursively */
205 n -= table_nb_bits;
206 code_prefix = code >> (32 - table_nb_bits);
207 subtable_bits = n;
208 codes[i].bits = n;
209 codes[i].code = code << table_nb_bits;
210 for (k = i+1; k < nb_codes; k++) {
211 n = codes[k].bits - table_nb_bits;
212 if (n <= 0)
213 break;
214 code = codes[k].code;
215 if (code >> (32 - table_nb_bits) != code_prefix)
216 break;
217 codes[k].bits = n;
218 codes[k].code = code << table_nb_bits;
219 subtable_bits = FFMAX(subtable_bits, n);
220 }
221 subtable_bits = FFMIN(subtable_bits, table_nb_bits);
222 j = (flags & INIT_VLC_LE) ? bitswap_32(code_prefix) >> (32 - table_nb_bits) : code_prefix;
223 table[j][1] = -subtable_bits;
224 av_dlog(NULL, "%4x: n=%d (subtable)\n",
225 j, codes[i].bits + table_nb_bits);
226 index = build_table(vlc, subtable_bits, k-i, codes+i, flags);
227 if (index < 0)
228 return index;
229 /* note: realloc has been done, so reload tables */
230 table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];
231 table[j][0] = index; //code
232 i = k-1;
233 }
234 }
235
236 for (i = 0; i < table_size; i++) {
237 if (table[i][1] == 0) //bits
238 table[i][0] = -1; //codes
239 }
240
241 return table_index;
242 }
243
244
245 /* Build VLC decoding tables suitable for use with get_vlc().
246
247 'nb_bits' set thee decoding table size (2^nb_bits) entries. The
248 bigger it is, the faster is the decoding. But it should not be too
249 big to save memory and L1 cache. '9' is a good compromise.
250
251 'nb_codes' : number of vlcs codes
252
253 'bits' : table which gives the size (in bits) of each vlc code.
254
255 'codes' : table which gives the bit pattern of of each vlc code.
256
257 'symbols' : table which gives the values to be returned from get_vlc().
258
259 'xxx_wrap' : give the number of bytes between each entry of the
260 'bits' or 'codes' tables.
261
262 'xxx_size' : gives the number of bytes of each entry of the 'bits'
263 or 'codes' tables.
264
265 'wrap' and 'size' allows to use any memory configuration and types
266 (byte/word/long) to store the 'bits', 'codes', and 'symbols' tables.
267
268 'use_static' should be set to 1 for tables, which should be freed
269 with av_free_static(), 0 if ff_free_vlc() will be used.
270 */
271 int ff_init_vlc_sparse(VLC *vlc_arg, int nb_bits, int nb_codes,
272 const void *bits, int bits_wrap, int bits_size,
273 const void *codes, int codes_wrap, int codes_size,
274 const void *symbols, int symbols_wrap, int symbols_size,
275 int flags)
276 {
277 VLCcode *buf;
278 int i, j, ret;
279 VLCcode localbuf[1500]; // the maximum currently needed is 1296 by rv34
280 VLC localvlc, *vlc;
281
282 vlc = vlc_arg;
283 vlc->bits = nb_bits;
284 if (flags & INIT_VLC_USE_NEW_STATIC) {
285 av_assert0(nb_codes + 1 <= FF_ARRAY_ELEMS(localbuf));
286 buf = localbuf;
287 localvlc = *vlc_arg;
288 vlc = &localvlc;
289 vlc->table_size = 0;
290 } else {
291 vlc->table = NULL;
292 vlc->table_allocated = 0;
293 vlc->table_size = 0;
294
295 buf = av_malloc_array((nb_codes + 1), sizeof(VLCcode));
296 if (!buf)
297 return AVERROR(ENOMEM);
298 }
299
300
301 av_assert0(symbols_size <= 2 || !symbols);
302 j = 0;
303 #define COPY(condition)\
304 for (i = 0; i < nb_codes; i++) { \
305 GET_DATA(buf[j].bits, bits, i, bits_wrap, bits_size); \
306 if (!(condition)) \
307 continue; \
308 if (buf[j].bits > 3*nb_bits || buf[j].bits>32) { \
309 av_log(NULL, AV_LOG_ERROR, "Too long VLC (%d) in init_vlc\n", buf[j].bits);\
310 if (!(flags & INIT_VLC_USE_NEW_STATIC)) \
311 av_free(buf); \
312 return -1; \
313 } \
314 GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size); \
315 if (buf[j].code >= (1LL<<buf[j].bits)) { \
316 av_log(NULL, AV_LOG_ERROR, "Invalid code in init_vlc\n"); \
317 if (!(flags & INIT_VLC_USE_NEW_STATIC)) \
318 av_free(buf); \
319 return -1; \
320 } \
321 if (flags & INIT_VLC_LE) \
322 buf[j].code = bitswap_32(buf[j].code); \
323 else \
324 buf[j].code <<= 32 - buf[j].bits; \
325 if (symbols) \
326 GET_DATA(buf[j].symbol, symbols, i, symbols_wrap, symbols_size) \
327 else \
328 buf[j].symbol = i; \
329 j++; \
330 }
331 COPY(buf[j].bits > nb_bits);
332 // qsort is the slowest part of init_vlc, and could probably be improved or avoided
333 qsort(buf, j, sizeof(VLCcode), compare_vlcspec);
334 COPY(buf[j].bits && buf[j].bits <= nb_bits);
335 nb_codes = j;
336
337 ret = build_table(vlc, nb_bits, nb_codes, buf, flags);
338
339 if (flags & INIT_VLC_USE_NEW_STATIC) {
340 if(vlc->table_size != vlc->table_allocated)
341 av_log(NULL, AV_LOG_ERROR, "needed %d had %d\n", vlc->table_size, vlc->table_allocated);
342
343 av_assert0(ret >= 0);
344 *vlc_arg = *vlc;
345 } else {
346 av_free(buf);
347 if (ret < 0) {
348 av_freep(&vlc->table);
349 return ret;
350 }
351 }
352 return 0;
353 }
354
355
356 void ff_free_vlc(VLC *vlc)
357 {
358 av_freep(&vlc->table);
359 }