//
// Generate sine waves to test ADEV, FFT, or PSD tools.
//
// 27-Nov-2009 tvb
//

#include <math.h>
#include <stdio.h>
#include <stdlib.h>

double pi = 3.14159265358979323;

void main (int argc, char *argv[])
{
    double secs, sps, a[100], f[100];
    long terms, j, k;

    // Usage message.

    if (argc < 4) {
        fprintf(stderr, "Usage:\n");
        fprintf(stderr, "  %s [secs] [sps] [ampl,freq]*\n", argv[0]);
        fprintf(stderr, "\nExample:\n");
        fprintf(stderr, "  %s 1 1000 1,60\n", argv[0]);
        fprintf(stderr, "  %s 1 44100 1,440\n", argv[0]);
        fprintf(stderr, "  %s 5 1200 1,60 0.5,120 2,150\n", argv[0]);
        exit(1);
    }

    // Get user arguments.

    secs = atof(argv[1]);
    sps = atof(argv[2]);
    if (secs < 1 || sps < 1) {
        fprintf(stderr, "invalid seconds or samples-per-second\n");
        exit(1);
    }
    for (terms = 0; argc > 3; terms += 1, argc -= 1, argv += 1) {
        if (2 != sscanf(argv[3], "%lg,%lg", &a[terms], &f[terms])) {
            fprintf(stderr, "invalid amplitude,frequency pair: %s\n", argv[3]);
            exit(1);
        }
    }

    // Echo user arguments.

    fprintf(stderr, "%lg seconds at %lg Hz (samples per second)\n", secs, sps);
    fprintf(stderr, "output =");
    for (j = 0; j < terms; j += 1) {
        fprintf(stderr, "%s %lg*sin(%lg*wt)", j ? " +" : "", a[j], f[j]);
    }
    fprintf(stderr, "\n");

    // Generate composite sine wave output.

    for (k = 0; k <= secs * sps; k += 1) {
        double t = k / sps;
        double a_sum = 0.0;
        for (j = 0; j < terms; j += 1) {
            double w = 2 * pi * f[j];
            a_sum += a[j] * sin(w * t);
        }
        printf("%.12lf\n", a_sum);
    }
}