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 /**
  34  * Same as av_mallocz_static(), but does a realloc.
  35  *
  36  * @param[in] ptr The block of memory to reallocate.
  37  * @param[in] size The requested size.
  38  * @return Block of memory of requested size.
  39  * @deprecated. Code which uses ff_realloc_static is broken/missdesigned
  40  * and should correctly use static arrays
  41  */
  42 attribute_deprecated void *ff_realloc_static(void *ptr, unsigned int size);
  43
  44
  45 const uint8_t ff_sqrt_tab[128]={
  46         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,
  47         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,
  48         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,
  49         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
  50 };
  51
  52 const uint8_t ff_log2_tab[256]={
  53         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,
  54         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,
  55         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,
  56         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,
  57         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,
  58         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,
  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 };
  62
  63
  64 void align_put_bits(PutBitContext *s)
  65 {
  66 #ifdef ALT_BITSTREAM_WRITER
  67     put_bits(s,(  - s->index) & 7,0);
  68 #else
  69     put_bits(s,s->bit_left & 7,0);
  70 #endif
  71 }
  72
  73 void ff_put_string(PutBitContext * pbc, char *s, int put_zero)
  74 {
  75     while(*s){
  76         put_bits(pbc, 8, *s);
  77         s++;
  78     }
  79     if(put_zero)
  80         put_bits(pbc, 8, 0);
  81 }
  82
  83 /* VLC decoding */
  84
  85 //#define DEBUG_VLC
  86
  87 #define GET_DATA(v, table, i, wrap, size) \
  88 {\
  89     const uint8_t *ptr = (const uint8_t *)table + i * wrap;\
  90     switch(size) {\
  91     case 1:\
  92         v = *(const uint8_t *)ptr;\
  93         break;\
  94     case 2:\
  95         v = *(const uint16_t *)ptr;\
  96         break;\
  97     default:\
  98         v = *(const uint32_t *)ptr;\
  99         break;\
 100     }\
 101 }
 102
 103
 104 static int alloc_table(VLC *vlc, int size)
 105 {
 106     int index;
 107     index = vlc->table_size;
 108     vlc->table_size += size;
 109     if (vlc->table_size > vlc->table_allocated) {
 110         DEBUGF("Tried to allocate past the end of a Huffman table: %d/%d\n",
 111             vlc->table_allocated, vlc->table_allocated+(1 << vlc->bits));
 112         vlc->table_allocated += (1 << vlc->bits);
 113         if (!vlc->table)
 114             return -1;
 115     }
 116     return index;
 117 }
 118
 119 static int build_table(VLC *vlc, int table_nb_bits,
 120                        int nb_codes,
 121                        const void *bits, int bits_wrap, int bits_size,
 122                        const void *codes, int codes_wrap, int codes_size,
 123                        uint32_t code_prefix, int n_prefix)
 124 {
 125     int i, j, k, n, table_size, table_index, nb, n1, index, code_prefix2;
 126     uint32_t code;
 127     int flags = 0;
 128     VLC_TYPE (*table)[2];
 129
 130     table_size = 1 << table_nb_bits;
 131     table_index = alloc_table(vlc, table_size);
 132 #ifdef DEBUG_VLC
 133     printf("new table index=%d size=%d code_prefix=%x n=%d\n",
 134            table_index, table_size, code_prefix, n_prefix);
 135 #endif
 136     if (table_index < 0)
 137         return -1;
 138     table = &vlc->table[table_index];
 139
 140     for(i=0;i<table_size;i++) {
 141         table[i][1] = 0; //bits
 142         table[i][0] = -1; //codes
 143     }
 144
 145     /* first pass: map codes and compute auxillary table sizes */
 146     for(i=0;i<nb_codes;i++) {
 147         GET_DATA(n, bits, i, bits_wrap, bits_size);
 148         GET_DATA(code, codes, i, codes_wrap, codes_size);
 149         /* we accept tables with holes */
 150         if (n <= 0)
 151             continue;
 152 #if defined(DEBUG_VLC) && 0
 153         printf("i=%d n=%d code=0x%x\n", i, n, code);
 154 #endif
 155         /* if code matches the prefix, it is in the table */
 156         n -= n_prefix;
 157         if(flags & INIT_VLC_LE)
 158             code_prefix2= code & (n_prefix>=32 ? 0xffffffff : (uint32_t)(1 << n_prefix)-1);
 159         else
 160             code_prefix2= code >> n;
 161         if (n > 0 && (int)code_prefix2 == (int)code_prefix) {
 162             if (n <= table_nb_bits) {
 163                 /* no need to add another table */
 164                 j = (code << (table_nb_bits - n)) & (table_size - 1);
 165                 nb = 1 << (table_nb_bits - n);
 166                 for(k=0;k<nb;k++) {
 167                     if(flags & INIT_VLC_LE)
 168                         j = (code >> n_prefix) + (k<<n);
 169 #ifdef DEBUG_VLC
 170                     av_log(NULL, 0, "%4x: code=%d n=%d\n",
 171                            j, i, n);
 172 #endif
 173                     if (table[j][1] /*bits*/ != 0) {
 174                         return -1;
 175                     }
 176                     table[j][1] = n; //bits
 177                     table[j][0] = i; //code
 178                     j++;
 179                 }
 180             } else {
 181                 n -= table_nb_bits;
 182                 j = (code >> ((flags & INIT_VLC_LE) ? n_prefix : n)) & ((1 << table_nb_bits) - 1);
 183 #ifdef DEBUG_VLC
 184                 av_log(NULL, 0,"%4x: n=%d (subtable)\n",
 185                        j, n);
 186 #endif
 187                 /* compute table size */
 188                 n1 = -table[j][1]; //bits
 189                 if (n > n1)
 190                     n1 = n;
 191                 table[j][1] = -n1; //bits
 192             }
 193         }
 194     }
 195
 196     /* second pass : fill auxillary tables recursively */
 197     for(i=0;i<table_size;i++) {
 198         n = table[i][1]; //bits
 199         if (n < 0) {
 200             n = -n;
 201             if (n > table_nb_bits) {
 202                 n = table_nb_bits;
 203                 table[i][1] = -n; //bits
 204             }
 205             index = build_table(vlc, n, nb_codes,
 206                                 bits, bits_wrap, bits_size,
 207                                 codes, codes_wrap, codes_size,
 208                                 (flags & INIT_VLC_LE) ? (code_prefix | (i << n_prefix)) : ((code_prefix << table_nb_bits) | i),
 209                                 n_prefix + table_nb_bits);
 210             if (index < 0)
 211                 return -1;
 212             /* note: realloc has been done, so reload tables */
 213             table = &vlc->table[table_index];
 214             table[i][0] = index; //code
 215         }
 216     }
 217     return table_index;
 218 }
 219
 220
 221 /* Build VLC decoding tables suitable for use with get_vlc().
 222
 223    'nb_bits' set thee decoding table size (2^nb_bits) entries. The
 224    bigger it is, the faster is the decoding. But it should not be too
 225    big to save memory and L1 cache. '9' is a good compromise.
 226
 227    'nb_codes' : number of vlcs codes
 228
 229    'bits' : table which gives the size (in bits) of each vlc code.
 230
 231    'codes' : table which gives the bit pattern of of each vlc code.
 232
 233    'xxx_wrap' : give the number of bytes between each entry of the
 234    'bits' or 'codes' tables.
 235
 236    'xxx_size' : gives the number of bytes of each entry of the 'bits'
 237    or 'codes' tables.
 238
 239    'wrap' and 'size' allows to use any memory configuration and types
 240    (byte/word/long) to store the 'bits' and 'codes' tables.
 241
 242    'use_static' should be set to 1 for tables, which should be freed
 243    with av_free_static(), 0 if free_vlc() will be used.
 244 */
 245 int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
 246              const void *bits, int bits_wrap, int bits_size,
 247              const void *codes, int codes_wrap, int codes_size,
 248              int flags)
 249 {
 250
 251     vlc->bits = nb_bits;
 252      vlc->table_size = 0;
 253
 254 #ifdef DEBUG_VLC
 255     printf("build table nb_codes=%d\n", nb_codes);
 256 #endif
 257
 258     if (build_table(vlc, nb_bits, nb_codes,
 259                     bits, bits_wrap, bits_size,
 260                     codes, codes_wrap, codes_size,
 261                     0, 0) < 0) {
 262         //av_free(vlc->table);
 263         return -1;
 264     }
 265     /* return flags to block gcc warning while allowing us to keep
 266      * consistent with ffmpeg's function parameters
 267      */
 268     return flags;
 269 }
 270
 271