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

int order = 8, factor = 64, bits = 24;

/*
 * convert double to fixed-point integer
 */
int
mkfp(double x)
{
	long long r, unit;

	unit = 1LL << (bits - 1);
	r = x * unit + ((x >= 0) ? 0.5 : -0.5);
	if (r < -unit || r >= unit) {
		fprintf(stderr, "%g: sample out of range\n", x);
		exit(1);
	}
	return r;
}

/*
 * Blackman window function
 */
double
win_blackman(double a, double x)
{
	if (x < 0)
		x = -x;
	return (x >= 0.5) ? 0 :
		0.5 * (1 - a) +
		0.5 * cos(2 * M_PI * x) +
		0.5 * a * cos(4 * M_PI * x);
}

/*
 * Ideal low-pass filter response
 */
double
lowpass_sinc(double cutoff, double t)
{
	double arg;

	if (t == 0)
		return cutoff;
	arg = M_PI * t;
	return sin(cutoff * arg) / arg;
}

/*
 * Convert table index to time
 */
double
timeof(int i)
{
	return (double)(i - order * factor / 2) / factor;
}

int
main(void)
{
	double t;
	double h;
	double cutoff = 3. / 4.;
	double param = 0.16;
	int i;

	printf("{");
	for (i = 0; i <= order * factor; i++) {
		t = timeof(i);
		h = lowpass_sinc(cutoff, t) * win_blackman(param, t / order);
		if (i != 0)
			printf(",");
		printf("%s", (i % 8 == 0) ? "\n\t" : " ");
		printf("%7d", mkfp(h));
	}
	printf("\n};\n");

	return 0;
}