Subversion Repositories eco32

/*

 * genbell.c -- 2-operator bell sound

 */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <math.h>

#define NUM_SEC         8               /* duration */

#define CLK             50000000        /* clock rate */

#define DIV             1024            /* clock divisor */

#define SAMPLE_RATE     (CLK / DIV)     /* in samples/sec */

#define PI              M_PI

void prolog(void) {

  printf("\t.export\tsamples\n");

  printf("\t.export\tendsmpl\n");

  printf("\n");

  printf("samples:\n");

}

void epilog(void) {

  printf("endsmpl:\n");

}

void wrtsample(short sample) {

  static int n = 0;

  unsigned w = (((unsigned) sample << 16) & 0xFFFF0000) |

               (((unsigned) sample <<  0) & 0x0000FFFF);

  if (n % 4 == 0) {

    printf("\t.word\t");

    n = 0;

  }

  printf("0x%08X", w);

  if (n % 4 == 3) {

    printf("\n");

  } else {

    printf(", ");

  }

  n++;

}

int main(int argc, char *argv[]) {

  double f0;

  int n, m;

  double a, alpha;

  double b, beta;

  double t;

  double modAmpl;

  double modulator;

  double carrAmpl;

  double carrier;

  short sample;

  int i;

  if (argc != 1) {

    printf("usage: %s\n", argv[0]);

    exit(1);

  }

  f0 = 49.0;

  n = 5;

  m = 7;

  a = 16000.0;

  alpha = 0.6140;

  b = 10.0;

  beta = 0.4605;

  prolog();

  for (i = 0; i < NUM_SEC * SAMPLE_RATE; i++) {

    t = i * (1.0 / SAMPLE_RATE);

    modAmpl = b * exp(-beta * t);

    modulator = modAmpl * sin(2.0 * PI * m * f0 * t);

    carrAmpl = a * exp(-alpha * t);

    carrier = carrAmpl * sin(2.0 * PI * n * f0 * t + modulator);

    sample = floor(carrier + 0.5);

    wrtsample(sample);

  }

  epilog();

  return 0;

}