reactos/sdk/lib/3rdparty/libmpg123/layer1.c

   1 /*
   2         layer1.c: the layer 1 decoder
   3
   4         copyright 1995-2009 by the mpg123 project - free software under the terms of the LGPL 2.1
   5         see COPYING and AUTHORS files in distribution or http://mpg123.org
   6         initially written by Michael Hipp
   7
   8         may have a few bugs after last optimization ...
   9 */
  10
  11 #include "mpg123lib_intern.h"
  12 #include "getbits.h"
  13 #include "debug.h"
  14
  15 /*
  16         Allocation value is not allowed to be 15. Initially, libmad showed me the
  17         error that mpg123 used to ignore. Then, I found a quote on that in
  18         Shlien, S. (1994): Guide to MPEG-1 Audio Standard.
  19         IEEE Transactions on Broadcasting 40, 4
  20
  21         "To avoid conflicts with the synchronization code, code '1111' is defined
  22         to be illegal."
  23 */
  24 static int check_balloc(mpg123_handle *fr, unsigned int *balloc, unsigned int *end)
  25 {
  26         unsigned int *ba;
  27         for(ba=balloc; ba != end; ++ba)
  28         if(*ba == 15)
  29         {
  30                 if(NOQUIET) error("Illegal bit allocation value.");
  31                 return -1;
  32         }
  33
  34         return 0;
  35 }
  36
  37 static int I_step_one(unsigned int balloc[], unsigned int scale_index[2][SBLIMIT],mpg123_handle *fr)
  38 {
  39         unsigned int *ba=balloc;
  40         unsigned int *sca = (unsigned int *) scale_index;
  41
  42         if(fr->stereo == 2)
  43         {
  44                 int i;
  45                 int jsbound = fr->jsbound;
  46                 for(i=0;i<jsbound;i++)
  47                 {
  48                         *ba++ = getbits(fr, 4);
  49                         *ba++ = getbits(fr, 4);
  50                 }
  51                 for(i=jsbound;i<SBLIMIT;i++) *ba++ = getbits(fr, 4);
  52
  53                 if(check_balloc(fr, balloc, ba)) return -1;
  54
  55                 ba = balloc;
  56
  57                 for(i=0;i<jsbound;i++)
  58                 {
  59                         if ((*ba++))
  60                                 *sca++ = getbits(fr, 6);
  61                         if ((*ba++))
  62                                 *sca++ = getbits(fr, 6);
  63                 }
  64                 for (i=jsbound;i<SBLIMIT;i++)
  65                 if((*ba++))
  66                 {
  67                         *sca++ =  getbits(fr, 6);
  68                         *sca++ =  getbits(fr, 6);
  69                 }
  70         }
  71         else
  72         {
  73                 int i;
  74                 for(i=0;i<SBLIMIT;i++) *ba++ = getbits(fr, 4);
  75
  76                 if(check_balloc(fr, balloc, ba)) return -1;
  77
  78                 ba = balloc;
  79                 for (i=0;i<SBLIMIT;i++)
  80                 if ((*ba++))
  81                 *sca++ = getbits(fr, 6);
  82         }
  83
  84         return 0;
  85 }
  86
  87 static void I_step_two(real fraction[2][SBLIMIT],unsigned int balloc[2*SBLIMIT], unsigned int scale_index[2][SBLIMIT],mpg123_handle *fr)
  88 {
  89         int i,n;
  90         int smpb[2*SBLIMIT]; /* values: 0-65535 */
  91         int *sample;
  92         register unsigned int *ba;
  93         register unsigned int *sca = (unsigned int *) scale_index;
  94
  95         if(fr->stereo == 2)
  96         {
  97                 int jsbound = fr->jsbound;
  98                 register real *f0 = fraction[0];
  99                 register real *f1 = fraction[1];
 100                 ba = balloc;
 101                 for(sample=smpb,i=0;i<jsbound;i++)
 102                 {
 103                         if((n = *ba++)) *sample++ = getbits(fr, n+1);
 104
 105                         if((n = *ba++)) *sample++ = getbits(fr, n+1);
 106                 }
 107                 for(i=jsbound;i<SBLIMIT;i++)
 108                 if((n = *ba++))
 109                 *sample++ = getbits(fr, n+1);
 110
 111                 ba = balloc;
 112                 for(sample=smpb,i=0;i<jsbound;i++)
 113                 {
 114                         if((n=*ba++))
 115                         *f0++ = REAL_MUL_SCALE_LAYER12(DOUBLE_TO_REAL_15( ((-1)<<n) + (*sample++) + 1), fr->muls[n+1][*sca++]);
 116                         else *f0++ = DOUBLE_TO_REAL(0.0);
 117
 118                         if((n=*ba++))
 119                         *f1++ = REAL_MUL_SCALE_LAYER12(DOUBLE_TO_REAL_15( ((-1)<<n) + (*sample++) + 1), fr->muls[n+1][*sca++]);
 120                         else *f1++ = DOUBLE_TO_REAL(0.0);
 121                 }
 122                 for(i=jsbound;i<SBLIMIT;i++)
 123                 {
 124                         if((n=*ba++))
 125                         {
 126                                 real samp = DOUBLE_TO_REAL_15( ((-1)<<n) + (*sample++) + 1);
 127                                 *f0++ = REAL_MUL_SCALE_LAYER12(samp, fr->muls[n+1][*sca++]);
 128                                 *f1++ = REAL_MUL_SCALE_LAYER12(samp, fr->muls[n+1][*sca++]);
 129                         }
 130                         else *f0++ = *f1++ = DOUBLE_TO_REAL(0.0);
 131                 }
 132                 for(i=fr->down_sample_sblimit;i<32;i++)
 133                 fraction[0][i] = fraction[1][i] = 0.0;
 134         }
 135         else
 136         {
 137                 register real *f0 = fraction[0];
 138                 ba = balloc;
 139                 for(sample=smpb,i=0;i<SBLIMIT;i++)
 140                 if ((n = *ba++))
 141                 *sample++ = getbits(fr, n+1);
 142
 143                 ba = balloc;
 144                 for(sample=smpb,i=0;i<SBLIMIT;i++)
 145                 {
 146                         if((n=*ba++))
 147                         *f0++ = REAL_MUL_SCALE_LAYER12(DOUBLE_TO_REAL_15( ((-1)<<n) + (*sample++) + 1), fr->muls[n+1][*sca++]);
 148                         else *f0++ = DOUBLE_TO_REAL(0.0);
 149                 }
 150                 for(i=fr->down_sample_sblimit;i<32;i++)
 151                 fraction[0][i] = DOUBLE_TO_REAL(0.0);
 152         }
 153 }
 154
 155 int do_layer1(mpg123_handle *fr)
 156 {
 157         int clip=0;
 158         int i,stereo = fr->stereo;
 159         unsigned int balloc[2*SBLIMIT];
 160         unsigned int scale_index[2][SBLIMIT];
 161         real (*fraction)[SBLIMIT] = fr->layer1.fraction; /* fraction[2][SBLIMIT] */
 162         int single = fr->single;
 163
 164         fr->jsbound = (fr->mode == MPG_MD_JOINT_STEREO) ? (fr->mode_ext<<2)+4 : 32;
 165
 166         if(stereo == 1 || single == SINGLE_MIX) /* I don't see mixing handled here */
 167         single = SINGLE_LEFT;
 168
 169         if(I_step_one(balloc,scale_index,fr))
 170         {
 171                 if(NOQUIET) error("Aborting layer I decoding after step one.\n");
 172                 return clip;
 173         }
 174
 175         for(i=0;i<SCALE_BLOCK;i++)
 176         {
 177                 I_step_two(fraction,balloc,scale_index,fr);
 178
 179                 if(single != SINGLE_STEREO)
 180                 clip += (fr->synth_mono)(fraction[single], fr);
 181                 else
 182                 clip += (fr->synth_stereo)(fraction[0], fraction[1], fr);
 183         }
 184
 185         return clip;
 186 }
 187
 188