lib/tone.c

   1 #include <stdlib.h>
   2 #include <stdio.h>
   3 #include <math.h>
   4 #include <string.h>
   5
   6 void usage(){
   7   fprintf(stderr,"tone <frequency_Hz>,[<amplitude>] [<frequency_Hz>,[<amplitude>]...]\n");
   8   exit(1);
   9 }
  10
  11 int main (int argc,char *argv[]){
  12   int i,j;
  13   double *f;
  14   double *amp;
  15
  16   if(argc<2)usage();
  17
  18   f=alloca(sizeof(*f)*(argc-1));
  19   amp=alloca(sizeof(*amp)*(argc-1));
  20
  21   i=0;
  22   while(argv[i+1]){
  23     char *pos=strchr(argv[i+1],',');
  24
  25     f[i]=atof(argv[i+1]);
  26     if(pos)
  27       amp[i]=atof(pos+1)*32767.f;
  28     else
  29       amp[i]=32767.f;
  30
  31     fprintf(stderr,"%g Hz, %g amp\n",f[i],amp[i]);
  32
  33     i++;
  34   }
  35
  36   for(i=0;i<44100*10;i++){
  37     float val=0;
  38     int ival;
  39     for(j=0;j<argc-1;j++)
  40       val+=amp[j]*sin(i/44100.f*f[j]*2*M_PI);
  41     ival=rint(val);
  42
  43     if(ival>32767.f)ival=32767.f;
  44     if(ival<-32768.f)ival=-32768.f;
  45
  46     fprintf(stdout,"%c%c%c%c",
  47             (char)(ival&0xff),
  48             (char)((ival>>8)&0xff),
  49             (char)(ival&0xff),
  50             (char)((ival>>8)&0xff));
  51   }
  52   return(0);
  53 }
  54