apps/codecs/libwmapro/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 libavcodec/bitstream.c
  28  * bitstream api.
  29  */
  30
  31 #include "avcodec.h"
  32 #include "get_bits.h"
  33 #include "put_bits.h"
  34
  35 #define av_log(...)
  36
  37 const uint8_t ff_log2_run[32]={
  38  0, 0, 0, 0, 1, 1, 1, 1,
  39  2, 2, 2, 2, 3, 3, 3, 3,
  40  4, 4, 5, 5, 6, 6, 7, 7,
  41  8, 9,10,11,12,13,14,15
  42 };
  43
  44 void align_put_bits(PutBitContext *s)
  45 {
  46 #ifdef ALT_BITSTREAM_WRITER
  47     put_bits(s,(  - s->index) & 7,0);
  48 #else
  49     put_bits(s,s->bit_left & 7,0);
  50 #endif
  51 }
  52
  53 void ff_put_string(PutBitContext *pb, const char *string, 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 ff_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) return;
  70 /* The following define was just added to make the codec (wma pro) compile */
  71 #define CONFIG_SMALL 0
  72     if(CONFIG_SMALL || words < 16 || put_bits_count(pb)&7){
  73         for(i=0; i<words; i++) put_bits(pb, 16, AV_RB16(src + 2*i));
  74     }else{
  75         for(i=0; put_bits_count(pb)&31; i++)
  76             put_bits(pb, 8, src[i]);
  77         flush_put_bits(pb);
  78         memcpy(put_bits_ptr(pb), src+i, 2*words-i);
  79         skip_put_bytes(pb, 2*words-i);
  80     }
  81
  82     put_bits(pb, bits, AV_RB16(src + 2*words)>>(16-bits));
  83 }
  84
  85 /* VLC decoding */
  86
  87 //#define DEBUG_VLC
  88
  89 #define GET_DATA(v, table, i, wrap, size) \
  90 {\
  91     const uint8_t *ptr = (const uint8_t *)table + i * wrap;\
  92     switch(size) {\
  93     case 1:\
  94         v = *(const uint8_t *)ptr;\
  95         break;\
  96     case 2:\
  97         v = *(const uint16_t *)ptr;\
  98         break;\
  99     default:\
 100         v = *(const uint32_t *)ptr;\
 101         break;\
 102     }\
 103 }
 104
 105
 106 static int alloc_table(VLC *vlc, int size, int use_static)
 107 {
 108     int index;
 109     index = vlc->table_size;
 110     vlc->table_size += size;
 111     if (vlc->table_size > vlc->table_allocated) {
 112         if(use_static)
 113             return -1; //cant do anything, init_vlc() is used with too little memory
 114         vlc->table_allocated += (1 << vlc->bits);
 115         //vlc->table = av_realloc(vlc->table,
 116         //                        sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
 117         if (!vlc->table)
 118             return -1;
 119     }
 120     return index;
 121 }
 122
 123 static av_always_inline uint32_t bitswap_32(uint32_t x) {
 124     return av_reverse[x&0xFF]<<24
 125          | av_reverse[(x>>8)&0xFF]<<16
 126          | av_reverse[(x>>16)&0xFF]<<8
 127          | av_reverse[x>>24];
 128 }
 129
 130 typedef struct {
 131     uint8_t bits;
 132     uint16_t symbol;
 133     /** codeword, with the first bit-to-be-read in the msb
 134      * (even if intended for a little-endian bitstream reader) */
 135     uint32_t code;
 136 } VLCcode;
 137
 138 static int compare_vlcspec(const void *a, const void *b)
 139 {
 140     const VLCcode *sa=a, *sb=b;
 141     return (sa->code >> 1) - (sb->code >> 1);
 142 }
 143
 144 /**
 145  * Build VLC decoding tables suitable for use with get_vlc().
 146  *
 147  * @param vlc            the context to be initted
 148  *
 149  * @param table_nb_bits  max length of vlc codes to store directly in this table
 150  *                       (Longer codes are delegated to subtables.)
 151  *
 152  * @param nb_codes       number of elements in codes[]
 153  *
 154  * @param codes          descriptions of the vlc codes
 155  *                       These must be ordered such that codes going into the same subtable are contiguous.
 156  *                       Sorting by VLCcode.code is sufficient, though not necessary.
 157  */
 158 static int build_table(VLC *vlc, int table_nb_bits, int nb_codes,
 159                        VLCcode *codes, int flags)
 160 {
 161     int table_size, table_index, index, code_prefix, symbol, subtable_bits;
 162     int i, j, k, n, nb, inc;
 163     uint32_t code;
 164     VLC_TYPE (*table)[2];
 165
 166     table_size = 1 << table_nb_bits;
 167     table_index = alloc_table(vlc, table_size, flags & INIT_VLC_USE_NEW_STATIC);
 168 #ifdef DEBUG_VLC
 169     av_log(NULL,AV_LOG_DEBUG,"new table index=%d size=%d\n",
 170            table_index, table_size);
 171 #endif
 172     if (table_index < 0)
 173         return -1;
 174     table = &vlc->table[table_index];
 175
 176     for (i = 0; i < table_size; i++) {
 177         table[i][1] = 0; //bits
 178         table[i][0] = -1; //codes
 179     }
 180
 181     /* first pass: map codes and compute auxillary table sizes */
 182     for (i = 0; i < nb_codes; i++) {
 183         n = codes[i].bits;
 184         code = codes[i].code;
 185         symbol = codes[i].symbol;
 186 #if defined(DEBUG_VLC) && 0
 187         av_log(NULL,AV_LOG_DEBUG,"i=%d n=%d code=0x%x\n", i, n, code);
 188 #endif
 189         if (n <= table_nb_bits) {
 190             /* no need to add another table */
 191             j = code >> (32 - table_nb_bits);
 192             nb = 1 << (table_nb_bits - n);
 193             inc = 1;
 194             if (flags & INIT_VLC_LE) {
 195                 j = bitswap_32(code);
 196                 inc = 1 << n;
 197             }
 198             for (k = 0; k < nb; k++) {
 199 #ifdef DEBUG_VLC
 200                 av_log(NULL, AV_LOG_DEBUG, "%4x: code=%d n=%d\n",
 201                        j, i, n);
 202 #endif
 203                 if (table[j][1] /*bits*/ != 0) {
 204                     av_log(NULL, AV_LOG_ERROR, "incorrect codes\n");
 205                     return -1;
 206                 }
 207                 table[j][1] = n; //bits
 208                 table[j][0] = symbol;
 209                 j += inc;
 210             }
 211         } else {
 212             /* fill auxiliary table recursively */
 213             n -= table_nb_bits;
 214             code_prefix = code >> (32 - table_nb_bits);
 215             subtable_bits = n;
 216             codes[i].bits = n;
 217             codes[i].code = code << table_nb_bits;
 218             for (k = i+1; k < nb_codes; k++) {
 219                 n = codes[k].bits - table_nb_bits;
 220                 if (n <= 0)
 221                     break;
 222                 code = codes[k].code;
 223                 if (code >> (32 - table_nb_bits) != (unsigned)code_prefix)
 224                     break;
 225                 codes[k].bits = n;
 226                 codes[k].code = code << table_nb_bits;
 227                 subtable_bits = FFMAX(subtable_bits, n);
 228             }
 229             subtable_bits = FFMIN(subtable_bits, table_nb_bits);
 230             j = (flags & INIT_VLC_LE) ? bitswap_32(code_prefix) >> (32 - table_nb_bits) : (unsigned)code_prefix;
 231             table[j][1] = -subtable_bits;
 232 #ifdef DEBUG_VLC
 233             av_log(NULL,AV_LOG_DEBUG,"%4x: n=%d (subtable)\n",
 234                    j, codes[i].bits + table_nb_bits);
 235 #endif
 236             index = build_table(vlc, subtable_bits, k-i, codes+i, 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[j][0] = index; //code
 242             i = k-1;
 243         }
 244     }
 245     return table_index;
 246 }
 247
 248
 249 /* Build VLC decoding tables suitable for use with get_vlc().
 250
 251    'nb_bits' set thee decoding table size (2^nb_bits) entries. The
 252    bigger it is, the faster is the decoding. But it should not be too
 253    big to save memory and L1 cache. '9' is a good compromise.
 254
 255    'nb_codes' : number of vlcs codes
 256
 257    'bits' : table which gives the size (in bits) of each vlc code.
 258
 259    'codes' : table which gives the bit pattern of of each vlc code.
 260
 261    'symbols' : table which gives the values to be returned from get_vlc().
 262
 263    'xxx_wrap' : give the number of bytes between each entry of the
 264    'bits' or 'codes' tables.
 265
 266    'xxx_size' : gives the number of bytes of each entry of the 'bits'
 267    or 'codes' tables.
 268
 269    'wrap' and 'size' allows to use any memory configuration and types
 270    (byte/word/long) to store the 'bits', 'codes', and 'symbols' tables.
 271
 272    'use_static' should be set to 1 for tables, which should be freed
 273    with av_free_static(), 0 if free_vlc() will be used.
 274 */
 275 int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,
 276              const void *bits, int bits_wrap, int bits_size,
 277              const void *codes, int codes_wrap, int codes_size,
 278              const void *symbols, int symbols_wrap, int symbols_size,
 279              int flags)
 280 {
 281     VLCcode buf[nb_codes];
 282     int i, j;
 283
 284     vlc->bits = nb_bits;
 285     if(flags & INIT_VLC_USE_NEW_STATIC){
 286         if(vlc->table_size && vlc->table_size == vlc->table_allocated){
 287             return 0;
 288         }else if(vlc->table_size){
 289             return -1; // fatal error, we are called on a partially initialized table
 290         }
 291     }else {
 292         vlc->table = NULL;
 293         vlc->table_allocated = 0;
 294         vlc->table_size = 0;
 295     }
 296
 297 #ifdef DEBUG_VLC
 298     av_log(NULL,AV_LOG_DEBUG,"build table nb_codes=%d\n", nb_codes);
 299 #endif
 300
 301     //assert(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         GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size);\
 309         if (flags & INIT_VLC_LE)\
 310             buf[j].code = bitswap_32(buf[j].code);\
 311         else\
 312             buf[j].code <<= 32 - buf[j].bits;\
 313         if (symbols)\
 314             GET_DATA(buf[j].symbol, symbols, i, symbols_wrap, symbols_size)\
 315         else\
 316             buf[j].symbol = i;\
 317         j++;\
 318     }
 319     COPY(buf[j].bits > nb_bits);
 320     // qsort is the slowest part of init_vlc, and could probably be improved or avoided
 321     qsort(buf, j, sizeof(VLCcode), compare_vlcspec);
 322     COPY(buf[j].bits && buf[j].bits <= nb_bits);
 323     nb_codes = j;
 324
 325     if (build_table(vlc, nb_bits, nb_codes, buf, flags) < 0) {
 326         //av_freep(&vlc->table);
 327         return -1;
 328     }
 329     //if((flags & INIT_VLC_USE_NEW_STATIC) && vlc->table_size != vlc->table_allocated)
 330      //   av_log(NULL, AV_LOG_ERROR, "needed %d had %d\n", vlc->table_size, vlc->table_allocated);
 331     return 0;
 332 }
 333