modules/codec/wmafixed/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
  32 #include <stdio.h>
  33
  34 #define DEBUGF printf
  35
  36 /**
  37  * Same as av_mallocz_static(), but does a realloc.
  38  *
  39  * @param[in] ptr The block of memory to reallocate.
  40  * @param[in] size The requested size.
  41  * @return Block of memory of requested size.
  42  * @deprecated. Code which uses ff_realloc_static is broken/missdesigned
  43  * and should correctly use static arrays
  44  */
  45 attribute_deprecated void *ff_realloc_static(void *ptr, unsigned int size);
  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 void align_put_bits(PutBitContext *s)
  66 {
  67 #ifdef ALT_BITSTREAM_WRITER
  68     put_bits(s,(  - s->index) & 7,0);
  69 #else
  70     put_bits(s,s->bit_left & 7,0);
  71 #endif
  72 }
  73
  74 void ff_put_string(PutBitContext * pbc, char *s, int put_zero)
  75 {
  76     while(*s){
  77         put_bits(pbc, 8, *s);
  78         s++;
  79     }
  80     if(put_zero)
  81         put_bits(pbc, 8, 0);
  82 }
  83
  84 /* VLC decoding */
  85 #define GET_DATA(v, table, i, wrap, size) \
  86 {\
  87     const uint8_t *ptr = (const uint8_t *)table + i * wrap;\
  88     switch(size) {\
  89     case 1:\
  90         v = *(const uint8_t *)ptr;\
  91         break;\
  92     case 2:\
  93         v = *(const uint16_t *)ptr;\
  94         break;\
  95     default:\
  96         v = *(const uint32_t *)ptr;\
  97         break;\
  98     }\
  99 }
 100
 101 static int alloc_table(VLC *vlc, int size)
 102 {
 103     int index;
 104     index = vlc->table_size;
 105     vlc->table_size += size;
 106     if (vlc->table_size > vlc->table_allocated) {
 107         DEBUGF("Tried to allocate past the end of a Huffman table: %d/%d\n",
 108             vlc->table_allocated, vlc->table_allocated+(1 << vlc->bits));
 109         vlc->table_allocated += (1 << vlc->bits);
 110         if (!vlc->table)
 111             return -1;
 112     }
 113     return index;
 114 }
 115
 116 static int build_table(VLC *vlc, int table_nb_bits,
 117                        int nb_codes,
 118                        const void *bits, int bits_wrap, int bits_size,
 119                        const void *codes, int codes_wrap, int codes_size,
 120                        uint32_t code_prefix, int n_prefix)
 121 {
 122     int i, j, k, n, table_size, table_index, nb, n1, index, code_prefix2;
 123     uint32_t code;
 124     int flags = 0;
 125     VLC_TYPE (*table)[2];
 126
 127     table_size = 1 << table_nb_bits;
 128     table_index = alloc_table(vlc, table_size);
 129 #ifdef DEBUG_VLC
 130     printf("new table index=%d size=%d code_prefix=%x n=%d\n",
 131            table_index, table_size, code_prefix, n_prefix);
 132 #endif
 133     if (table_index < 0)
 134         return -1;
 135     table = &vlc->table[table_index];
 136
 137     for(i=0;i<table_size;i++) {
 138         table[i][1] = 0; //bits
 139         table[i][0] = -1; //codes
 140     }
 141
 142     /* first pass: map codes and compute auxillary table sizes */
 143     for(i=0;i<nb_codes;i++) {
 144         GET_DATA(n, bits, i, bits_wrap, bits_size);
 145         GET_DATA(code, codes, i, codes_wrap, codes_size);
 146         /* we accept tables with holes */
 147         if (n <= 0)
 148             continue;
 149 #if defined(DEBUG_VLC) && 0
 150         printf("i=%d n=%d code=0x%x\n", i, n, code);
 151 #endif
 152         /* if code matches the prefix, it is in the table */
 153         n -= n_prefix;
 154         if(flags & INIT_VLC_LE)
 155             code_prefix2= code & (n_prefix>=32 ? 0xffffffff : (uint32_t)(1 << n_prefix)-1);
 156         else
 157             code_prefix2= code >> n;
 158         if (n > 0 && (int)code_prefix2 == (int)code_prefix) {
 159             if (n <= table_nb_bits) {
 160                 /* no need to add another table */
 161                 j = (code << (table_nb_bits - n)) & (table_size - 1);
 162                 nb = 1 << (table_nb_bits - n);
 163                 for(k=0;k<nb;k++) {
 164                     if(flags & INIT_VLC_LE)
 165                         j = (code >> n_prefix) + (k<<n);
 166 #ifdef DEBUG_VLC
 167                     av_log(NULL, 0, "%4x: code=%d n=%d\n",
 168                            j, i, n);
 169 #endif
 170                     if (table[j][1] /*bits*/ != 0) {
 171                         return -1;
 172                     }
 173                     table[j][1] = n; //bits
 174                     table[j][0] = i; //code
 175                     j++;
 176                 }
 177             } else {
 178                 n -= table_nb_bits;
 179                 j = (code >> ((flags & INIT_VLC_LE) ? n_prefix : n)) & ((1 << table_nb_bits) - 1);
 180 #ifdef DEBUG_VLC
 181                 av_log(NULL, 0,"%4x: n=%d (subtable)\n",
 182                        j, n);
 183 #endif
 184                 /* compute table size */
 185                 n1 = -table[j][1]; //bits
 186                 if (n > n1)
 187                     n1 = n;
 188                 table[j][1] = -n1; //bits
 189             }
 190         }
 191     }
 192
 193     /* second pass : fill auxillary tables recursively */
 194     for(i=0;i<table_size;i++) {
 195         n = table[i][1]; //bits
 196         if (n < 0) {
 197             n = -n;
 198             if (n > table_nb_bits) {
 199                 n = table_nb_bits;
 200                 table[i][1] = -n; //bits
 201             }
 202             index = build_table(vlc, n, nb_codes,
 203                                 bits, bits_wrap, bits_size,
 204                                 codes, codes_wrap, codes_size,
 205                                 (flags & INIT_VLC_LE) ? (code_prefix | (i << n_prefix)) : ((code_prefix << table_nb_bits) | i),
 206                                 n_prefix + table_nb_bits);
 207             if (index < 0)
 208                 return -1;
 209             /* note: realloc has been done, so reload tables */
 210             table = &vlc->table[table_index];
 211             table[i][0] = index; //code
 212         }
 213     }
 214     return table_index;
 215 }
 216
 217 /* Build VLC decoding tables suitable for use with get_vlc().
 218
 219    'nb_bits' set thee decoding table size (2^nb_bits) entries. The
 220    bigger it is, the faster is the decoding. But it should not be too
 221    big to save memory and L1 cache. '9' is a good compromise.
 222
 223    'nb_codes' : number of vlcs codes
 224
 225    'bits' : table which gives the size (in bits) of each vlc code.
 226
 227    'codes' : table which gives the bit pattern of of each vlc code.
 228
 229    'xxx_wrap' : give the number of bytes between each entry of the
 230    'bits' or 'codes' tables.
 231
 232    'xxx_size' : gives the number of bytes of each entry of the 'bits'
 233    or 'codes' tables.
 234
 235    'wrap' and 'size' allows to use any memory configuration and types
 236    (byte/word/long) to store the 'bits' and 'codes' tables.
 237
 238    'use_static' should be set to 1 for tables, which should be freed
 239    with av_free_static(), 0 if free_vlc() will be used.
 240 */
 241 int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
 242              const void *bits, int bits_wrap, int bits_size,
 243              const void *codes, int codes_wrap, int codes_size,
 244              int flags)
 245 {
 246
 247     vlc->bits = nb_bits;
 248      vlc->table_size = 0;
 249
 250 #ifdef DEBUG_VLC
 251     printf("build table nb_codes=%d\n", nb_codes);
 252 #endif
 253
 254     if (build_table(vlc, nb_bits, nb_codes,
 255                     bits, bits_wrap, bits_size,
 256                     codes, codes_wrap, codes_size,
 257                     0, 0) < 0) {
 258         //av_free(vlc->table);
 259         return -1;
 260     }
 261     /* return flags to block gcc warning while allowing us to keep
 262      * consistent with ffmpeg's function parameters
 263      */
 264     return flags;
 265 }