apps/codecs/libwma/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  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  *
  22  * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
  23  */
  24
  25 /**
  26  * @file bitstream.c
  27  * bitstream api.
  28  */
  29
  30 #include "bitstream.h"
  31 #include <codecs/lib/codeclib.h>
  32
  33 /* this stuff is unused */
  34 #if 0
  35 /**
  36  * Same as av_mallocz_static(), but does a realloc.
  37  *
  38  * @param[in] ptr The block of memory to reallocate.
  39  * @param[in] size The requested size.
  40  * @return Block of memory of requested size.
  41  * @deprecated. Code which uses ff_realloc_static is broken/missdesigned
  42  * and should correctly use static arrays
  43  */
  44 attribute_deprecated void *ff_realloc_static(void *ptr, unsigned int size);
  45
  46
  47 const uint8_t ff_sqrt_tab[128]={
  48         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,
  49         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,
  50         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,
  51         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
  52 };
  53
  54 const uint8_t ff_log2_tab[256]={
  55         0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
  56         5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
  57         6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
  58         6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
  59         7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
  60         7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
  61         7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
  62         7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
  63 };
  64
  65
  66 void align_put_bits(PutBitContext *s)
  67 {
  68 #ifdef ALT_BITSTREAM_WRITER
  69     put_bits(s,(  - s->index) & 7,0);
  70 #else
  71     put_bits(s,s->bit_left & 7,0);
  72 #endif
  73 }
  74
  75 void ff_put_string(PutBitContext * pbc, char *s, int put_zero)
  76 {
  77     while(*s){
  78         put_bits(pbc, 8, *s);
  79         s++;
  80     }
  81     if(put_zero)
  82         put_bits(pbc, 8, 0);
  83 }
  84 #endif
  85
  86 /* VLC decoding */
  87
  88 //#define DEBUG_VLC
  89
  90 #define GET_DATA(v, table, i, wrap, size) \
  91 {\
  92     const uint8_t *ptr = (const uint8_t *)table + i * wrap;\
  93     switch(size) {\
  94     case 1:\
  95         v = *(const uint8_t *)ptr;\
  96         break;\
  97     case 2:\
  98         v = *(const uint16_t *)ptr;\
  99         break;\
 100     default:\
 101         v = *(const uint32_t *)ptr;\
 102         break;\
 103     }\
 104 }
 105
 106
 107 static int alloc_table(VLC *vlc, int size)
 108 {
 109     int index;
 110     index = vlc->table_size;
 111     vlc->table_size += size;
 112     if (vlc->table_size > vlc->table_allocated) {
 113         DEBUGF("Tried to allocate past the end of a Huffman table: %d/%d\n",
 114             vlc->table_allocated, vlc->table_allocated+(1 << vlc->bits));
 115         vlc->table_allocated += (1 << vlc->bits);
 116         if (!vlc->table)
 117             return -1;
 118     }
 119     return index;
 120 }
 121
 122 static int build_table(VLC *vlc, int table_nb_bits,
 123                        int nb_codes,
 124                        const void *bits, int bits_wrap, int bits_size,
 125                        const void *codes, int codes_wrap, int codes_size,
 126                        uint32_t code_prefix, int n_prefix)
 127 {
 128     int i, j, k, n, table_size, table_index, nb, n1, index, code_prefix2;
 129     uint32_t code;
 130     int flags = 0;
 131     VLC_TYPE (*table)[2];
 132
 133     table_size = 1 << table_nb_bits;
 134     table_index = alloc_table(vlc, table_size);
 135 #ifdef DEBUG_VLC
 136     printf("new table index=%d size=%d code_prefix=%x n=%d\n",
 137            table_index, table_size, code_prefix, n_prefix);
 138 #endif
 139     if (table_index < 0)
 140         return -1;
 141     table = &vlc->table[table_index];
 142
 143     for(i=0;i<table_size;i++) {
 144         table[i][1] = 0; //bits
 145         table[i][0] = -1; //codes
 146     }
 147
 148     /* first pass: map codes and compute auxillary table sizes */
 149     for(i=0;i<nb_codes;i++) {
 150         GET_DATA(n, bits, i, bits_wrap, bits_size);
 151         GET_DATA(code, codes, i, codes_wrap, codes_size);
 152         /* we accept tables with holes */
 153         if (n <= 0)
 154             continue;
 155 #if defined(DEBUG_VLC) && 0
 156         printf("i=%d n=%d code=0x%x\n", i, n, code);
 157 #endif
 158         /* if code matches the prefix, it is in the table */
 159         n -= n_prefix;
 160         if(flags & INIT_VLC_LE)
 161             code_prefix2= code & (n_prefix>=32 ? 0xffffffff : (uint32_t)(1 << n_prefix)-1);
 162         else
 163             code_prefix2= code >> n;
 164         if (n > 0 && (int)code_prefix2 == (int)code_prefix) {
 165             if (n <= table_nb_bits) {
 166                 /* no need to add another table */
 167                 j = (code << (table_nb_bits - n)) & (table_size - 1);
 168                 nb = 1 << (table_nb_bits - n);
 169                 for(k=0;k<nb;k++) {
 170                     if(flags & INIT_VLC_LE)
 171                         j = (code >> n_prefix) + (k<<n);
 172 #ifdef DEBUG_VLC
 173                     av_log(NULL, 0, "%4x: code=%d n=%d\n",
 174                            j, i, n);
 175 #endif
 176                     if (table[j][1] /*bits*/ != 0) {
 177                         return -1;
 178                     }
 179                     table[j][1] = n; //bits
 180                     table[j][0] = i; //code
 181                     j++;
 182                 }
 183             } else {
 184                 n -= table_nb_bits;
 185                 j = (code >> ((flags & INIT_VLC_LE) ? n_prefix : n)) & ((1 << table_nb_bits) - 1);
 186 #ifdef DEBUG_VLC
 187                 av_log(NULL, 0,"%4x: n=%d (subtable)\n",
 188                        j, n);
 189 #endif
 190                 /* compute table size */
 191                 n1 = -table[j][1]; //bits
 192                 if (n > n1)
 193                     n1 = n;
 194                 table[j][1] = -n1; //bits
 195             }
 196         }
 197     }
 198
 199     /* second pass : fill auxillary tables recursively */
 200     for(i=0;i<table_size;i++) {
 201         n = table[i][1]; //bits
 202         if (n < 0) {
 203             n = -n;
 204             if (n > table_nb_bits) {
 205                 n = table_nb_bits;
 206                 table[i][1] = -n; //bits
 207             }
 208             index = build_table(vlc, n, nb_codes,
 209                                 bits, bits_wrap, bits_size,
 210                                 codes, codes_wrap, codes_size,
 211                                 (flags & INIT_VLC_LE) ? (code_prefix | (i << n_prefix)) : ((code_prefix << table_nb_bits) | i),
 212                                 n_prefix + table_nb_bits);
 213             if (index < 0)
 214                 return -1;
 215             /* note: realloc has been done, so reload tables */
 216             table = &vlc->table[table_index];
 217             table[i][0] = index; //code
 218         }
 219     }
 220     return table_index;
 221 }
 222
 223
 224 /* Build VLC decoding tables suitable for use with get_vlc().
 225
 226    'nb_bits' set thee decoding table size (2^nb_bits) entries. The
 227    bigger it is, the faster is the decoding. But it should not be too
 228    big to save memory and L1 cache. '9' is a good compromise.
 229
 230    'nb_codes' : number of vlcs codes
 231
 232    'bits' : table which gives the size (in bits) of each vlc code.
 233
 234    'codes' : table which gives the bit pattern of of each vlc code.
 235
 236    'xxx_wrap' : give the number of bytes between each entry of the
 237    'bits' or 'codes' tables.
 238
 239    'xxx_size' : gives the number of bytes of each entry of the 'bits'
 240    or 'codes' tables.
 241
 242    'wrap' and 'size' allows to use any memory configuration and types
 243    (byte/word/long) to store the 'bits' and 'codes' tables.
 244
 245    'use_static' should be set to 1 for tables, which should be freed
 246    with av_free_static(), 0 if free_vlc() will be used.
 247 */
 248 int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
 249              const void *bits, int bits_wrap, int bits_size,
 250              const void *codes, int codes_wrap, int codes_size,
 251              int flags)
 252 {
 253     vlc->bits = nb_bits;
 254     vlc->table_size = 0;
 255
 256 #ifdef DEBUG_VLC
 257     printf("build table nb_codes=%d\n", nb_codes);
 258 #endif
 259
 260     if (build_table(vlc, nb_bits, nb_codes,
 261                     bits, bits_wrap, bits_size,
 262                     codes, codes_wrap, codes_size,
 263                     0, 0) < 0) {
 264         //av_free(vlc->table);
 265         return -1;
 266     }
 267     /* return flags to block gcc warning while allowing us to keep
 268      * consistent with ffmpeg's function parameters
 269      */
 270     return flags;
 271 }
 272
 273