workbench/classes/datatypes/wav/wave_pcm.c

   1 /*
   2  *      wave.datatype
   3  *      (c) Fredrik Wikstrom (fredrik@a500.org)
   4  */
   5
   6 #include "wave_pcm.h"
   7
   8 DEC_SETUPPROTO(SetupPCM) {
   9         struct WaveFormatEx * fmt;
  10         fmt = data->fmt;
  11
  12         /* check bitsPerSample */
  13         if (fmt->bitsPerSample < 1) {
  14                 return NOTOK;
  15         }
  16         /* owervrite, in case these are corrupt */
  17         fmt->blockAlign = ((fmt->bitsPerSample+7)>>3) * fmt->numChannels;
  18         data->blockFrames = 1;
  19         return OK;
  20 }
  21
  22 DECODERPROTO(DecodePCM) {
  23         LONG mod = (fmt->bitsPerSample+7) >> 3;
  24         LONG chan, frame;
  25
  26         Src += (mod-1); /* set to MSB */
  27         if (mod == 1) {
  28                 for (frame=0;frame<numFrames;frame++) {
  29                         for (chan=0;chan<fmt->numChannels;chan++) {
  30                                 *Dst[chan]++ = (*Src++)+128; /* convert unsigned -> signed */
  31                         }
  32                 }
  33         } else {
  34                 for (frame=0;frame<numFrames;frame++) {
  35                         for (chan=0;chan<fmt->numChannels;chan++) {
  36                                 *Dst[chan]++ = *Src; Src += mod;
  37                         }
  38                 }
  39         }
  40
  41         return numFrames;
  42 }