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 "avcodec.h"
32 #include "ffmpeg_get_bits.h"
33 #include "ffmpeg_intreadwrite.h"
34
35 #define av_log(...)
36
37 #ifdef ROCKBOX
38 #undef DEBUGF
39 #define DEBUGF(...)
40 #endif
41 #define trace(...) { fprintf (stderr, __VA_ARGS__); }
42 //#define trace(fmt,...)
43 #define DEBUGF trace
44
45 const uint8_t ff_log2_run[32]={
46 0, 0, 0, 0, 1, 1, 1, 1,
47 2, 2, 2, 2, 3, 3, 3, 3,
48 4, 4, 5, 5, 6, 6, 7, 7,
49 8, 9,10,11,12,13,14,15
50 };
51
52 #if 0 // unused in rockbox
53 void align_put_bits(PutBitContext *s)
54 {
55 #ifdef ALT_BITSTREAM_WRITER
56 put_bits(s,( - s->index) & 7,0);
57 #else
58 put_bits(s,s->bit_left & 7,0);
59 #endif
60 }
61
62 void ff_put_string(PutBitContext *pb, const char *string, int terminate_string)
63 {
64 while(*string){
65 put_bits(pb, 8, *string);
66 string++;
67 }
68 if(terminate_string)
69 put_bits(pb, 8, 0);
70 }
71 #endif
72
73
74 /* VLC decoding */
75
76 //#define DEBUG_VLC
77
78 #define GET_DATA(v, table, i, wrap, size) \
79 {\
80 const uint8_t *ptr = (const uint8_t *)table + i * wrap;\
81 switch(size) {\
82 case 1:\
83 v = *(const uint8_t *)ptr;\
84 break;\
85 case 2:\
86 v = *(const uint16_t *)ptr;\
87 break;\
88 default:\
89 v = *(const uint32_t *)ptr;\
90 break;\
91 }\
92 }
93
94
alloc_table(VLC * vlc,int size,int use_static)95 static int alloc_table(VLC *vlc, int size, int use_static)
96 {
97 int index;
98 index = vlc->table_size;
99 vlc->table_size += size;
100 if (vlc->table_size > vlc->table_allocated) {
101 if(use_static)
102 {
103 DEBUGF("init_vlc() used with too little memory : table_size > allocated_memory\n");
104 return -1;
105 }
106 // abort(); //cant do anything, init_vlc() is used with too little memory
107 // vlc->table_allocated += (1 << vlc->bits);
108 // vlc->table = av_realloc(vlc->table,
109 // sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
110 if (!vlc->table)
111 return -1;
112 }
113 return index;
114 }
115
116 /*
117 static av_always_inline uint32_t bitswap_32(uint32_t x) {
118 return av_reverse[x&0xFF]<<24
119 | av_reverse[(x>>8)&0xFF]<<16
120 | av_reverse[(x>>16)&0xFF]<<8
121 | av_reverse[x>>24];
122 }
123 */
124
125 typedef struct {
126 uint8_t bits;
127 uint16_t symbol;
128 /** codeword, with the first bit-to-be-read in the msb
129 * (even if intended for a little-endian bitstream reader) */
130 uint32_t code;
131 } __attribute__((__packed__)) VLCcode; /* packed to save space */
132
compare_vlcspec(const void * a,const void * b)133 static int compare_vlcspec(const void *a, const void *b)
134 {
135 const VLCcode *sa=a, *sb=b;
136 return (sa->code >> 1) - (sb->code >> 1);
137 }
138
139 /**
140 * Build VLC decoding tables suitable for use with get_vlc().
141 *
142 * @param vlc the context to be initted
143 *
144 * @param table_nb_bits max length of vlc codes to store directly in this table
145 * (Longer codes are delegated to subtables.)
146 *
147 * @param nb_codes number of elements in codes[]
148 *
149 * @param codes descriptions of the vlc codes
150 * These must be ordered such that codes going into the same subtable are contiguous.
151 * Sorting by VLCcode.code is sufficient, though not necessary.
152 */
build_table(VLC * vlc,int table_nb_bits,int nb_codes,VLCcode * codes,int flags)153 static int build_table(VLC *vlc, int table_nb_bits, int nb_codes,
154 VLCcode *codes, int flags)
155 {
156 int table_size, table_index, index, symbol, subtable_bits;
157 int i, j, k, n, nb, inc;
158 uint32_t code, code_prefix;
159 VLC_TYPE (*table)[2];
160
161 table_size = 1 << table_nb_bits;
162 table_index = alloc_table(vlc, table_size, flags & INIT_VLC_USE_NEW_STATIC);
163 #ifdef DEBUG_VLC
164 av_log(NULL,AV_LOG_DEBUG,"new table index=%d size=%d\n",
165 table_index, table_size);
166 #endif
167 if (table_index < 0)
168 return -1;
169 table = &vlc->table[table_index];
170
171 for (i = 0; i < table_size; i++) {
172 table[i][1] = 0; //bits
173 table[i][0] = -1; //codes
174 }
175
176 /* first pass: map codes and compute auxillary table sizes */
177 for (i = 0; i < nb_codes; i++) {
178 n = codes[i].bits;
179 code = codes[i].code;
180 symbol = codes[i].symbol;
181 #if defined(DEBUG_VLC) && 0
182 av_log(NULL,AV_LOG_DEBUG,"i=%d n=%d code=0x%x\n", i, n, code);
183 #endif
184 if (n <= table_nb_bits) {
185 /* no need to add another table */
186 j = code >> (32 - table_nb_bits);
187 nb = 1 << (table_nb_bits - n);
188 inc = 1;
189 /* if (flags & INIT_VLC_LE) {
190 j = bitswap_32(code);
191 inc = 1 << n;
192 } */
193 for (k = 0; k < nb; k++) {
194 #ifdef DEBUG_VLC
195 av_log(NULL, AV_LOG_DEBUG, "%4x: code=%d n=%d\n",
196 j, i, n);
197 #endif
198 if (table[j][1] /*bits*/ != 0) {
199 av_log(NULL, AV_LOG_ERROR, "incorrect codes\n");
200 return -1;
201 }
202 table[j][1] = n; //bits
203 table[j][0] = symbol;
204 j += inc;
205 }
206 } else {
207 /* fill auxiliary table recursively */
208 n -= table_nb_bits;
209 code_prefix = code >> (32 - table_nb_bits);
210 subtable_bits = n;
211 codes[i].bits = n;
212 codes[i].code = code << table_nb_bits;
213 for (k = i+1; k < nb_codes; k++) {
214 n = codes[k].bits - table_nb_bits;
215 if (n <= 0)
216 break;
217 code = codes[k].code;
218 if (code >> (32 - table_nb_bits) != code_prefix)
219 break;
220 codes[k].bits = n;
221 codes[k].code = code << table_nb_bits;
222 subtable_bits = FFMAX(subtable_bits, n);
223 }
224 subtable_bits = FFMIN(subtable_bits, table_nb_bits);
225 j = /*(flags & INIT_VLC_LE) ? bitswap_32(code_prefix) >> (32 - table_nb_bits) :*/ code_prefix;
226 table[j][1] = -subtable_bits;
227 #ifdef DEBUG_VLC
228 av_log(NULL,AV_LOG_DEBUG,"%4x: n=%d (subtable)\n",
229 j, codes[i].bits + table_nb_bits);
230 #endif
231 index = build_table(vlc, subtable_bits, k-i, codes+i, flags);
232 if (index < 0)
233 return -1;
234 /* note: realloc has been done, so reload tables */
235 table = &vlc->table[table_index];
236 table[j][0] = index; //code
237 i = k-1;
238 }
239 }
240 return table_index;
241 }
242
243
244 /* Build VLC decoding tables suitable for use with get_vlc().
245
246 'nb_bits' set thee decoding table size (2^nb_bits) entries. The
247 bigger it is, the faster is the decoding. But it should not be too
248 big to save memory and L1 cache. '9' is a good compromise.
249
250 'nb_codes' : number of vlcs codes
251
252 'bits' : table which gives the size (in bits) of each vlc code.
253
254 'codes' : table which gives the bit pattern of of each vlc code.
255
256 'symbols' : table which gives the values to be returned from get_vlc().
257
258 'xxx_wrap' : give the number of bytes between each entry of the
259 'bits' or 'codes' tables.
260
261 'xxx_size' : gives the number of bytes of each entry of the 'bits'
262 or 'codes' tables.
263
264 'wrap' and 'size' allows to use any memory configuration and types
265 (byte/word/long) to store the 'bits', 'codes', and 'symbols' tables.
266
267 'use_static' should be set to 1 for tables, which should be freed
268 with av_free_static(), 0 if free_vlc() will be used.
269 */
270
271 /* Rockbox: support for INIT_VLC_LE is currently disabled since none of our
272 codecs use it, there's a LUT based bit reverse function for this commented
273 out above (bitswap_32) and an inline asm version in libtremor/codebook.c
274 if we ever want this */
275
276 static VLCcode buf[1336+1]; /* worst case is wma, which has one table with 1336 entries */
277
init_vlc_sparse(VLC * vlc,int nb_bits,int nb_codes,const void * bits,int bits_wrap,int bits_size,const void * codes,int codes_wrap,int codes_size,const void * symbols,int symbols_wrap,int symbols_size,int flags)278 int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,
279 const void *bits, int bits_wrap, int bits_size,
280 const void *codes, int codes_wrap, int codes_size,
281 const void *symbols, int symbols_wrap, int symbols_size,
282 int flags)
283 {
284 if (nb_codes+1 > (int)(sizeof (buf)/ sizeof (VLCcode)))
285 {
286 DEBUGF("Table is larger than temp buffer!\n");
287 return -1;
288 }
289
290 int i, j, ret;
291
292 vlc->bits = nb_bits;
293 if(flags & INIT_VLC_USE_NEW_STATIC){
294 if(vlc->table_size && vlc->table_size == vlc->table_allocated){
295 return 0;
296 }else if(vlc->table_size){
297 DEBUGF("fatal error, we are called on a partially initialized table\n");
298 return -1;
299 // abort(); // fatal error, we are called on a partially initialized table
300 }
301 }else {
302 vlc->table = NULL;
303 vlc->table_allocated = 0;
304 vlc->table_size = 0;
305 }
306
307 #ifdef DEBUG_VLC
308 av_log(NULL,AV_LOG_DEBUG,"build table nb_codes=%d\n", nb_codes);
309 #endif
310
311 // buf = av_malloc((nb_codes+1)*sizeof(VLCcode));
312
313 // assert(symbols_size <= 2 || !symbols);
314 j = 0;
315 #define COPY(condition)\
316 for (i = 0; i < nb_codes; i++) {\
317 GET_DATA(buf[j].bits, bits, i, bits_wrap, bits_size);\
318 if (!(condition))\
319 continue;\
320 GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size);\
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 // av_free(buf);
340 if (ret < 0) {
341 // av_freep(&vlc->table);
342 return -1;
343 }
344 if((flags & INIT_VLC_USE_NEW_STATIC) && vlc->table_size != vlc->table_allocated) {
345 av_log(NULL, AV_LOG_ERROR, "needed %d had %d\n", vlc->table_size, vlc->table_allocated);
346 }
347 return 0;
348 }
349
350 /* not used in rockbox
351 void free_vlc(VLC *vlc)
352 {
353 av_freep(&vlc->table);
354 }
355 */
356
357