1 #include <stdlib.h>
2 #include <stdio.h>
3 #include <math.h>
4 #include <string.h>
5 
usage()6 void usage(){
7   fprintf(stderr,"tone <frequency_Hz>,[<amplitude>] [<frequency_Hz>,[<amplitude>]...]\n");
8   exit(1);
9 }
10 
main(int argc,char * argv[])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 
55