hvirtual/quicktime/libavcodec/common.c

   1 /*
   2  * Common bit i/o utils
   3  * Copyright (c) 2000, 2001 Fabrice Bellard.
   4  *
   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.
   9  *
  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.
  14  *
  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
  18  *
  19  * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
  20  */
  21 #include "avcodec.h"
  22
  23 const UINT8 ff_sqrt_tab[128]={
  24         0, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5,
  25         5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
  26         8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
  27         9, 9, 9, 9,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,11,11,11,11,11,11,11
  28 };
  29
  30 void init_put_bits(PutBitContext *s,
  31                    UINT8 *buffer, int buffer_size,
  32                    void *opaque,
  33                    void (*write_data)(void *, UINT8 *, int))
  34 {
  35     s->buf = buffer;
  36     s->buf_end = s->buf + buffer_size;
  37     s->data_out_size = 0;
  38     if(write_data!=NULL)
  39     {
  40         fprintf(stderr, "write Data callback is not supported\n");
  41     }
  42 #ifdef ALT_BITSTREAM_WRITER
  43     s->index=0;
  44     ((uint32_t*)(s->buf))[0]=0;
  45 //    memset(buffer, 0, buffer_size);
  46 #else
  47     s->buf_ptr = s->buf;
  48     s->bit_left=32;
  49     s->bit_buf=0;
  50 #endif
  51 }
  52
  53 /* return the number of bits output */
  54 INT64 get_bit_count(PutBitContext *s)
  55 {
  56 #ifdef ALT_BITSTREAM_WRITER
  57     return s->data_out_size * 8 + s->index;
  58 #else
  59     return (s->buf_ptr - s->buf + s->data_out_size) * 8 + 32 - (INT64)s->bit_left;
  60 #endif
  61 }
  62
  63 void align_put_bits(PutBitContext *s)
  64 {
  65 #ifdef ALT_BITSTREAM_WRITER
  66     put_bits(s,(  - s->index) & 7,0);
  67 #else
  68     put_bits(s,s->bit_left & 7,0);
  69 #endif
  70 }
  71
  72 /* pad the end of the output stream with zeros */
  73 void flush_put_bits(PutBitContext *s)
  74 {
  75 #ifdef ALT_BITSTREAM_WRITER
  76     align_put_bits(s);
  77 #else
  78     s->bit_buf<<= s->bit_left;
  79     while (s->bit_left < 32) {
  80         /* XXX: should test end of buffer */
  81         *s->buf_ptr++=s->bit_buf >> 24;
  82         s->bit_buf<<=8;
  83         s->bit_left+=8;
  84     }
  85     s->bit_left=32;
  86     s->bit_buf=0;
  87 #endif
  88 }
  89
  90 void put_string(PutBitContext * pbc, char *s)
  91 {
  92     while(*s){
  93         put_bits(pbc, 8, *s);
  94         s++;
  95     }
  96     put_bits(pbc, 8, 0);
  97 }
  98
  99 /* bit input functions */
 100
 101 void init_get_bits(GetBitContext *s,
 102                    UINT8 *buffer, int buffer_size)
 103 {
 104     s->buffer= buffer;
 105     s->size= buffer_size;
 106     s->buffer_end= buffer + buffer_size;
 107 #ifdef ALT_BITSTREAM_READER
 108     s->index=0;
 109 #elif defined LIBMPEG2_BITSTREAM_READER
 110     s->buffer_ptr = buffer;
 111     s->bit_count = 16;
 112     s->cache = 0;
 113 #elif defined A32_BITSTREAM_READER
 114     s->buffer_ptr = (uint32_t*)buffer;
 115     s->bit_count = 32;
 116     s->cache0 = 0;
 117     s->cache1 = 0;
 118 #endif
 119     {
 120         OPEN_READER(re, s)
 121         UPDATE_CACHE(re, s)
 122 //        UPDATE_CACHE(re, s)
 123         CLOSE_READER(re, s)
 124     }
 125 #ifdef A32_BITSTREAM_READER
 126     s->cache1 = 0;
 127 #endif
 128 }
 129
 130 void align_get_bits(GetBitContext *s)
 131 {
 132     int n= (-get_bits_count(s)) & 7;
 133     if(n) skip_bits(s, n);
 134 }
 135
 136 int check_marker(GetBitContext *s, const char *msg)
 137 {
 138     int bit= get_bits1(s);
 139     if(!bit) printf("Marker bit missing %s\n", msg);
 140
 141     return bit;
 142 }
 143
 144 /* VLC decoding */
 145
 146 //#define DEBUG_VLC
 147
 148 #define GET_DATA(v, table, i, wrap, size) \
 149 {\
 150     const UINT8 *ptr = (UINT8 *)table + i * wrap;\
 151     switch(size) {\
 152     case 1:\
 153         v = *(UINT8 *)ptr;\
 154         break;\
 155     case 2:\
 156         v = *(UINT16 *)ptr;\
 157         break;\
 158     default:\
 159         v = *(UINT32 *)ptr;\
 160         break;\
 161     }\
 162 }
 163
 164
 165 static int alloc_table(VLC *vlc, int size)
 166 {
 167     int index;
 168     index = vlc->table_size;
 169     vlc->table_size += size;
 170     if (vlc->table_size > vlc->table_allocated) {
 171         vlc->table_allocated += (1 << vlc->bits);
 172         vlc->table = realloc(vlc->table,
 173                              sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
 174         if (!vlc->table)
 175             return -1;
 176     }
 177     return index;
 178 }
 179
 180 static int build_table(VLC *vlc, int table_nb_bits,
 181                        int nb_codes,
 182                        const void *bits, int bits_wrap, int bits_size,
 183                        const void *codes, int codes_wrap, int codes_size,
 184                        UINT32 code_prefix, int n_prefix)
 185 {
 186     int i, j, k, n, table_size, table_index, nb, n1, index;
 187     UINT32 code;
 188     VLC_TYPE (*table)[2];
 189
 190     table_size = 1 << table_nb_bits;
 191     table_index = alloc_table(vlc, table_size);
 192 #ifdef DEBUG_VLC
 193     printf("new table index=%d size=%d code_prefix=%x n=%d\n",
 194            table_index, table_size, code_prefix, n_prefix);
 195 #endif
 196     if (table_index < 0)
 197         return -1;
 198     table = &vlc->table[table_index];
 199
 200     for(i=0;i<table_size;i++) {
 201         table[i][1] = 0; //bits
 202         table[i][0] = -1; //codes
 203     }
 204
 205     /* first pass: map codes and compute auxillary table sizes */
 206     for(i=0;i<nb_codes;i++) {
 207         GET_DATA(n, bits, i, bits_wrap, bits_size);
 208         GET_DATA(code, codes, i, codes_wrap, codes_size);
 209         /* we accept tables with holes */
 210         if (n <= 0)
 211             continue;
 212 #if defined(DEBUG_VLC) && 0
 213         printf("i=%d n=%d code=0x%x\n", i, n, code);
 214 #endif
 215         /* if code matches the prefix, it is in the table */
 216         n -= n_prefix;
 217         if (n > 0 && (code >> n) == code_prefix) {
 218             if (n <= table_nb_bits) {
 219                 /* no need to add another table */
 220                 j = (code << (table_nb_bits - n)) & (table_size - 1);
 221                 nb = 1 << (table_nb_bits - n);
 222                 for(k=0;k<nb;k++) {
 223 #ifdef DEBUG_VLC
 224                     printf("%4x: code=%d n=%d\n",
 225                            j, i, n);
 226 #endif
 227                     if (table[j][1] /*bits*/ != 0) {
 228                         fprintf(stderr, "incorrect codes\n");
 229                         exit(1);
 230                     }
 231                     table[j][1] = n; //bits
 232                     table[j][0] = i; //code
 233                     j++;
 234                 }
 235             } else {
 236                 n -= table_nb_bits;
 237                 j = (code >> n) & ((1 << table_nb_bits) - 1);
 238 #ifdef DEBUG_VLC
 239                 printf("%4x: n=%d (subtable)\n",
 240                        j, n);
 241 #endif
 242                 /* compute table size */
 243                 n1 = -table[j][1]; //bits
 244                 if (n > n1)
 245                     n1 = n;
 246                 table[j][1] = -n1; //bits
 247             }
 248         }
 249     }
 250
 251     /* second pass : fill auxillary tables recursively */
 252     for(i=0;i<table_size;i++) {
 253         n = table[i][1]; //bits
 254         if (n < 0) {
 255             n = -n;
 256             if (n > table_nb_bits) {
 257                 n = table_nb_bits;
 258                 table[i][1] = -n; //bits
 259             }
 260             index = build_table(vlc, n, nb_codes,
 261                                 bits, bits_wrap, bits_size,
 262                                 codes, codes_wrap, codes_size,
 263                                 (code_prefix << table_nb_bits) | i,
 264                                 n_prefix + table_nb_bits);
 265             if (index < 0)
 266                 return -1;
 267             /* note: realloc has been done, so reload tables */
 268             table = &vlc->table[table_index];
 269             table[i][0] = index; //code
 270         }
 271     }
 272     return table_index;
 273 }
 274
 275
 276 /* Build VLC decoding tables suitable for use with get_vlc().
 277
 278    'nb_bits' set thee decoding table size (2^nb_bits) entries. The
 279    bigger it is, the faster is the decoding. But it should not be too
 280    big to save memory and L1 cache. '9' is a good compromise.
 281
 282    'nb_codes' : number of vlcs codes
 283
 284    'bits' : table which gives the size (in bits) of each vlc code.
 285
 286    'codes' : table which gives the bit pattern of of each vlc code.
 287
 288    'xxx_wrap' : give the number of bytes between each entry of the
 289    'bits' or 'codes' tables.
 290
 291    'xxx_size' : gives the number of bytes of each entry of the 'bits'
 292    or 'codes' tables.
 293
 294    'wrap' and 'size' allows to use any memory configuration and types
 295    (byte/word/long) to store the 'bits' and 'codes' tables.
 296 */
 297 int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
 298              const void *bits, int bits_wrap, int bits_size,
 299              const void *codes, int codes_wrap, int codes_size)
 300 {
 301     vlc->bits = nb_bits;
 302     vlc->table = NULL;
 303     vlc->table_allocated = 0;
 304     vlc->table_size = 0;
 305 #ifdef DEBUG_VLC
 306     printf("build table nb_codes=%d\n", nb_codes);
 307 #endif
 308
 309     if (build_table(vlc, nb_bits, nb_codes,
 310                     bits, bits_wrap, bits_size,
 311                     codes, codes_wrap, codes_size,
 312                     0, 0) < 0) {
 313         av_free(vlc->table);
 314         return -1;
 315     }
 316     return 0;
 317 }
 318
 319
 320 void free_vlc(VLC *vlc)
 321 {
 322     av_free(vlc->table);
 323 }
 324
 325 int ff_gcd(int a, int b){
 326     if(b) return ff_gcd(b, a%b);
 327     else  return a;
 328 }
 329
 330 void ff_float2fraction(int *nom_arg, int *denom_arg, double f, int max){
 331     double best_diff=1E10, diff;
 332     int best_denom=1, best_nom=1;
 333     int nom, denom, gcd;
 334
 335     //brute force here, perhaps we should try continued fractions if we need large max ...
 336     for(denom=1; denom<=max; denom++){
 337         nom= (int)(f*denom + 0.5);
 338         if(nom<=0 || nom>max) continue;
 339
 340         diff= ABS( f - (double)nom / (double)denom );
 341         if(diff < best_diff){
 342             best_diff= diff;
 343             best_nom= nom;
 344             best_denom= denom;
 345         }
 346     }
 347
 348     gcd= ff_gcd(best_nom, best_denom);
 349     best_nom   /= gcd;
 350     best_denom /= gcd;
 351
 352     *nom_arg= best_nom;
 353     *denom_arg= best_denom;
 354 }