dlls/winemp3.acm/layer1.c

   1 /*
   2  * Mpeg Layer-1 audio decoder
   3  * --------------------------
   4  * copyright (c) 1995 by Michael Hipp, All rights reserved. See also 'README'
   5  * This file has been copied from mpglib.
   6  * near unoptimzed ...
   7  *
   8  * may have a few bugs after last optimization ...
   9  *
  10  * This library is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU Lesser General Public
  12  * License as published by the Free Software Foundation; either
  13  * version 2.1 of the License, or (at your option) any later version.
  14  *
  15  * This library is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * Lesser General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU Lesser General Public
  21  * License along with this library; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  23  */
  24
  25 #include "mpg123.h"
  26
  27 static void I_step_one(unsigned int balloc[], unsigned int scale_index[2][SBLIMIT],struct frame *fr)
  28 {
  29   unsigned int *ba=balloc;
  30   unsigned int *sca = (unsigned int *) scale_index;
  31
  32   if(fr->stereo) {
  33     int i;
  34     int jsbound = fr->jsbound;
  35     for (i=0;i<jsbound;i++) {
  36       *ba++ = getbits(4);
  37       *ba++ = getbits(4);
  38     }
  39     for (i=jsbound;i<SBLIMIT;i++)
  40       *ba++ = getbits(4);
  41
  42     ba = balloc;
  43
  44     for (i=0;i<jsbound;i++) {
  45       if ((*ba++))
  46         *sca++ = getbits(6);
  47       if ((*ba++))
  48         *sca++ = getbits(6);
  49     }
  50     for (i=jsbound;i<SBLIMIT;i++)
  51       if ((*ba++)) {
  52         *sca++ =  getbits(6);
  53         *sca++ =  getbits(6);
  54       }
  55   }
  56   else {
  57     int i;
  58     for (i=0;i<SBLIMIT;i++)
  59       *ba++ = getbits(4);
  60     ba = balloc;
  61     for (i=0;i<SBLIMIT;i++)
  62       if ((*ba++))
  63         *sca++ = getbits(6);
  64   }
  65 }
  66
  67 static void I_step_two(real fraction[2][SBLIMIT],unsigned int balloc[2*SBLIMIT],
  68                        unsigned int scale_index[2][SBLIMIT],struct frame *fr)
  69 {
  70   int i,n;
  71   int smpb[2*SBLIMIT]; /* values: 0-65535 */
  72   int *sample;
  73   register unsigned int *ba;
  74   register unsigned int *sca = (unsigned int *) scale_index;
  75
  76   if(fr->stereo) {
  77     int jsbound = fr->jsbound;
  78     register real *f0 = fraction[0];
  79     register real *f1 = fraction[1];
  80     ba = balloc;
  81     for (sample=smpb,i=0;i<jsbound;i++)  {
  82       if ((n = *ba++))
  83         *sample++ = getbits(n+1);
  84       if ((n = *ba++))
  85         *sample++ = getbits(n+1);
  86     }
  87     for (i=jsbound;i<SBLIMIT;i++)
  88       if ((n = *ba++))
  89         *sample++ = getbits(n+1);
  90
  91     ba = balloc;
  92     for (sample=smpb,i=0;i<jsbound;i++) {
  93       if((n=*ba++))
  94         *f0++ = (real) ( ((-1)<<n) + (*sample++) + 1) * muls[n+1][*sca++];
  95       else
  96         *f0++ = 0.0;
  97       if((n=*ba++))
  98         *f1++ = (real) ( ((-1)<<n) + (*sample++) + 1) * muls[n+1][*sca++];
  99       else
 100         *f1++ = 0.0;
 101     }
 102     for (i=jsbound;i<SBLIMIT;i++) {
 103       if ((n=*ba++)) {
 104         real samp = ( ((-1)<<n) + (*sample++) + 1);
 105         *f0++ = samp * muls[n+1][*sca++];
 106         *f1++ = samp * muls[n+1][*sca++];
 107       }
 108       else
 109         *f0++ = *f1++ = 0.0;
 110     }
 111   }
 112   else {
 113     register real *f0 = fraction[0];
 114     ba = balloc;
 115     for (sample=smpb,i=0;i<SBLIMIT;i++)
 116       if ((n = *ba++))
 117         *sample++ = getbits(n+1);
 118     ba = balloc;
 119     for (sample=smpb,i=0;i<SBLIMIT;i++) {
 120       if((n=*ba++))
 121         *f0++ = (real) ( ((-1)<<n) + (*sample++) + 1) * muls[n+1][*sca++];
 122       else
 123         *f0++ = 0.0;
 124     }
 125   }
 126 }
 127
 128 int do_layer1(struct frame *fr,unsigned char *pcm_sample,int *pcm_point)
 129 {
 130   int clip=0;
 131   int i,stereo = fr->stereo;
 132   unsigned int balloc[2*SBLIMIT];
 133   unsigned int scale_index[2][SBLIMIT];
 134   real fraction[2][SBLIMIT];
 135   int single = fr->single;
 136
 137   fr->jsbound = (fr->mode == MPG_MD_JOINT_STEREO) ? (fr->mode_ext<<2)+4 : 32;
 138
 139   if(stereo == 1 || single == 3)
 140     single = 0;
 141
 142   I_step_one(balloc,scale_index,fr);
 143
 144   for (i=0;i<SCALE_BLOCK;i++)
 145   {
 146     I_step_two(fraction,balloc,scale_index,fr);
 147
 148       if(single >= 0) {
 149         clip += synth_1to1_mono(fr->mp,(real*)fraction[single],pcm_sample,pcm_point);
 150       }
 151       else {
 152         int p1 = *pcm_point;
 153         clip += synth_1to1(fr->mp,(real*)fraction[0],0,pcm_sample,&p1);
 154         clip += synth_1to1(fr->mp,(real*)fraction[1],1,pcm_sample,pcm_point);
 155       }
 156   }
 157
 158   return clip;
 159 }