apps/codecs/libcook/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 libavcodec/bitstream.c
  27  * bitstream api.
  28  */
  29
  30 #include "bitstream.h"
  31
  32 const uint8_t ff_log2_run[32]={
  33  0, 0, 0, 0, 1, 1, 1, 1,
  34  2, 2, 2, 2, 3, 3, 3, 3,
  35  4, 4, 5, 5, 6, 6, 7, 7,
  36  8, 9,10,11,12,13,14,15
  37 };
  38
  39 /**
  40  * Same as av_mallocz_static(), but does a realloc.
  41  *
  42  * @param[in] ptr The block of memory to reallocate.
  43  * @param[in] size The requested size.
  44  * @return Block of memory of requested size.
  45  * @deprecated. Code which uses ff_realloc_static is broken/misdesigned
  46  * and should correctly use static arrays
  47  */
  48
  49 #if 0
  50 attribute_deprecated av_alloc_size(2)
  51 static void *ff_realloc_static(void *ptr, unsigned int size);
  52
  53 static void *ff_realloc_static(void *ptr, unsigned int size)
  54 {
  55     return av_realloc(ptr, size);
  56 }
  57
  58 void align_put_bits(PutBitContext *s)
  59 {
  60 #ifdef ALT_BITSTREAM_WRITER
  61     put_bits(s,(  - s->index) & 7,0);
  62 #else
  63     put_bits(s,s->bit_left & 7,0);
  64 #endif
  65 }
  66 #endif
  67
  68 void ff_put_string(PutBitContext * pbc, const char *s, int put_zero)
  69 {
  70     while(*s){
  71         put_bits(pbc, 8, *s);
  72         s++;
  73     }
  74     if(put_zero)
  75         put_bits(pbc, 8, 0);
  76 }
  77
  78 #if 0
  79 void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length)
  80 {
  81     const uint16_t *srcw= (const uint16_t*)src;
  82     int words= length>>4;
  83     int bits= length&15;
  84     int i;
  85
  86     if(length==0) return;
  87
  88     if(CONFIG_SMALL || words < 16 || put_bits_count(pb)&7){
  89         for(i=0; i<words; i++) put_bits(pb, 16, AV_RB16(&srcw[i]));
  90     }else{
  91         for(i=0; put_bits_count(pb)&31; i++)
  92             put_bits(pb, 8, src[i]);
  93         flush_put_bits(pb);
  94         memcpy(pbBufPtr(pb), src+i, 2*words-i);
  95         skip_put_bytes(pb, 2*words-i);
  96     }
  97
  98     put_bits(pb, bits, AV_RB16(&srcw[words])>>(16-bits));
  99 }
 100 #endif
 101
 102 /* VLC decoding */
 103
 104 //#define DEBUG_VLC
 105
 106 #define GET_DATA(v, table, i, wrap, size) \
 107 {\
 108     const uint8_t *ptr = (const uint8_t *)table + i * wrap;\
 109     switch(size) {\
 110     case 1:\
 111         v = *(const uint8_t *)ptr;\
 112         break;\
 113     case 2:\
 114         v = *(const uint16_t *)ptr;\
 115         break;\
 116     default:\
 117         v = *(const uint32_t *)ptr;\
 118         break;\
 119     }\
 120 }
 121
 122
 123 static int alloc_table(VLC *vlc, int size, int use_static)
 124 {
 125     int index;
 126     index = vlc->table_size;
 127     vlc->table_size += size;
 128     if (vlc->table_size > vlc->table_allocated) {
 129         if(use_static>1){
 130             printf("init_vlc() used with too little memory : table_size > allocated_memory\n");
 131             abort(); //cant do anything, init_vlc() is used with too little memory
 132         }
 133
 134         if (!vlc->table)
 135             return -1;
 136     }
 137     return index;
 138 }
 139
 140 static int build_table(VLC *vlc, int table_nb_bits,
 141                        int nb_codes,
 142                        const void *bits, int bits_wrap, int bits_size,
 143                        const void *codes, int codes_wrap, int codes_size,
 144                        const void *symbols, int symbols_wrap, int symbols_size,
 145                        uint32_t code_prefix, int n_prefix, int flags)
 146 {
 147     int i, j, k, n, table_size, table_index, nb, n1, index, code_prefix2, symbol;
 148     uint32_t code;
 149     VLC_TYPE (*table)[2];
 150
 151     table_size = 1 << table_nb_bits;
 152     table_index = alloc_table(vlc, table_size, flags & (INIT_VLC_USE_STATIC|INIT_VLC_USE_NEW_STATIC));
 153 #ifdef DEBUG_VLC
 154     printf("new table index=%d size=%d code_prefix=%x n=%d\n",
 155            table_index, table_size, code_prefix, n_prefix);
 156 #endif
 157     if (table_index < 0)
 158         return -1;
 159     table = &vlc->table[table_index];
 160
 161     for(i=0;i<table_size;i++) {
 162         table[i][1] = 0; //bits
 163         table[i][0] = -1; //codes
 164     }
 165
 166     /* first pass: map codes and compute auxillary table sizes */
 167     for(i=0;i<nb_codes;i++) {
 168         GET_DATA(n, bits, i, bits_wrap, bits_size);
 169         GET_DATA(code, codes, i, codes_wrap, codes_size);
 170         /* we accept tables with holes */
 171         if (n <= 0)
 172             continue;
 173         if (!symbols)
 174             symbol = i;
 175         else
 176             GET_DATA(symbol, symbols, i, symbols_wrap, symbols_size);
 177 #if defined(DEBUG_VLC) && 0
 178         printf("i=%d n=%d code=0x%x\n", i, n, code);
 179 #endif
 180         /* if code matches the prefix, it is in the table */
 181         n -= n_prefix;
 182         if(flags & INIT_VLC_LE)
 183             code_prefix2= code & (n_prefix>=32 ? 0xffffffff : (1 << n_prefix)-1);
 184         else
 185             code_prefix2= code >> n;
 186         if (n > 0 && code_prefix2 == code_prefix) {
 187             if (n <= table_nb_bits) {
 188                 /* no need to add another table */
 189                 j = (code << (table_nb_bits - n)) & (table_size - 1);
 190                 nb = 1 << (table_nb_bits - n);
 191                 for(k=0;k<nb;k++) {
 192                     if(flags & INIT_VLC_LE)
 193                         j = (code >> n_prefix) + (k<<n);
 194 #ifdef DEBUG_VLC
 195                     printf("%4x: code=%d n=%d\n",
 196                            j, i, n);
 197 #endif
 198                     if (table[j][1] /*bits*/ != 0) {
 199                         printf("incorrect codes\n");
 200                         return -1;
 201                     }
 202                     table[j][1] = n; //bits
 203                     table[j][0] = symbol;
 204                     j++;
 205                 }
 206             } else {
 207                 n -= table_nb_bits;
 208                 j = (code >> ((flags & INIT_VLC_LE) ? n_prefix : n)) & ((1 << table_nb_bits) - 1);
 209 #ifdef DEBUG_VLC
 210                 printf("%4x: n=%d (subtable)\n",
 211                        j, n);
 212 #endif
 213                 /* compute table size */
 214                 n1 = -table[j][1]; //bits
 215                 if (n > n1)
 216                     n1 = n;
 217                 table[j][1] = -n1; //bits
 218             }
 219         }
 220     }
 221
 222     /* second pass : fill auxillary tables recursively */
 223     for(i=0;i<table_size;i++) {
 224         n = table[i][1]; //bits
 225         if (n < 0) {
 226             n = -n;
 227             if (n > table_nb_bits) {
 228                 n = table_nb_bits;
 229                 table[i][1] = -n; //bits
 230             }
 231             index = build_table(vlc, n, nb_codes,
 232                                 bits, bits_wrap, bits_size,
 233                                 codes, codes_wrap, codes_size,
 234                                 symbols, symbols_wrap, symbols_size,
 235                                 (flags & INIT_VLC_LE) ? (code_prefix | (i << n_prefix)) : ((code_prefix << table_nb_bits) | i),
 236                                 n_prefix + table_nb_bits, flags);
 237             if (index < 0)
 238                 return -1;
 239             /* note: realloc has been done, so reload tables */
 240             table = &vlc->table[table_index];
 241             table[i][0] = index; //code
 242         }
 243     }
 244     return table_index;
 245 }
 246
 247
 248 /* Build VLC decoding tables suitable for use with get_vlc().
 249
 250    'nb_bits' set thee decoding table size (2^nb_bits) entries. The
 251    bigger it is, the faster is the decoding. But it should not be too
 252    big to save memory and L1 cache. '9' is a good compromise.
 253
 254    'nb_codes' : number of vlcs codes
 255
 256    'bits' : table which gives the size (in bits) of each vlc code.
 257
 258    'codes' : table which gives the bit pattern of of each vlc code.
 259
 260    'symbols' : table which gives the values to be returned from get_vlc().
 261
 262    'xxx_wrap' : give the number of bytes between each entry of the
 263    'bits' or 'codes' tables.
 264
 265    'xxx_size' : gives the number of bytes of each entry of the 'bits'
 266    or 'codes' tables.
 267
 268    'wrap' and 'size' allows to use any memory configuration and types
 269    (byte/word/long) to store the 'bits', 'codes', and 'symbols' tables.
 270
 271    'use_static' should be set to 1 for tables, which should be freed
 272    with av_free_static(), 0 if free_vlc() will be used.
 273 */
 274 int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,
 275              const void *bits, int bits_wrap, int bits_size,
 276              const void *codes, int codes_wrap, int codes_size,
 277              const void *symbols, int symbols_wrap, int symbols_size,
 278              int flags)
 279 {
 280     vlc->bits = nb_bits;
 281     if(flags & INIT_VLC_USE_NEW_STATIC){
 282         if(vlc->table_size && vlc->table_size == vlc->table_allocated){
 283             return 0;
 284         }else if(vlc->table_size){
 285             abort(); // fatal error, we are called on a partially initialized table
 286         }
 287     }else if(!(flags & INIT_VLC_USE_STATIC)) {
 288         vlc->table = NULL;
 289         vlc->table_allocated = 0;
 290         vlc->table_size = 0;
 291     } else {
 292         /* Static tables are initially always NULL, return
 293            if vlc->table != NULL to avoid double allocation */
 294         if(vlc->table)
 295             return 0;
 296     }
 297
 298 #ifdef DEBUG_VLC
 299     printf("build table nb_codes=%d\n", nb_codes);
 300 #endif
 301
 302     if (build_table(vlc, nb_bits, nb_codes,
 303                     bits, bits_wrap, bits_size,
 304                     codes, codes_wrap, codes_size,
 305                     symbols, symbols_wrap, symbols_size,
 306                     0, 0, flags) < 0) {
 307         free(&vlc->table);
 308         return -1;
 309     }
 310     /* Changed the following condition to be true if table_size > table_allocated. *
 311      * This would be more sensible for static tables since we want warnings for    *
 312      * memory shortages only.                                                      */
 313     if((flags & INIT_VLC_USE_NEW_STATIC) && vlc->table_size > vlc->table_allocated)
 314         printf("needed %d had %d\n", vlc->table_size, vlc->table_allocated);
 315     return 0;
 316 }
 317
 318
 319 void free_vlc(VLC *vlc)
 320 {
 321     free(&vlc->table);
 322 }
 323