#include <sys/types.h> /* next 3 lines for open */
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h> /* malloc */
#include <unistd.h> /* read()/write() */
#include <sys/ioctl.h> /* For IOCTL calls */
#include <linux/soundcard.h> /* For Audio Defs */
#include <stdio.h>
#include <math.h> /* for cos() */

#define QUANTIZE 16
#define CHANNELS 1

int main(void)
{
	int n;
	unsigned long int i;
	int sound_fd, status;
	unsigned long int bufsize, arg;
	unsigned short int *buf;

	unsigned int samplerate = 32000;
	unsigned long int samples = samplerate * .330;

	sound_fd = open("/dev/dsp", O_RDWR);
	if (sound_fd < 0) {
		perror("/dev/dsp"); exit(1);
	}

	bufsize = samples * sizeof(unsigned short int);

	buf = (unsigned short int *) malloc(bufsize);
	
	arg = QUANTIZE;
	status = ioctl(sound_fd, SOUND_PCM_WRITE_BITS, &arg);
	if (status == -1) {
		perror("SOUND_PCM_WRITE_BITS ioctl failed");
		exit(1);
	}
	if (arg != QUANTIZE) {
		perror("unable to set quantize rate");
		exit(1);
	}
	
	arg = samplerate;
	status = ioctl(sound_fd, SOUND_PCM_WRITE_RATE, &arg);
	if (status == -1) {
		perror("SOUND_PCM_WRITE_RATE ioctl failed");
		exit(1);
	}

	arg = CHANNELS;
	status = ioctl(sound_fd, SOUND_PCM_WRITE_CHANNELS, &arg);
	if (status == -1) {
		perror("SOUND_PCM_WRITE_CHANNELS ioctl failed");
		exit(1);
	}
	
	printf("Bufsize: %i\n", bufsize);
	
	for (i = 0; i < samples; i++) {
		buf[i] = 0;
	}

	for (n = 0; n < 5; n++) {
		for (i = (n * .066 * samplerate); i < (samplerate * (.033 + .066*n)); i++) {
			buf[i] = (unsigned short int) ((cos(2*M_PI*1700*i/samplerate) + cos(2*M_PI*2200*i/samplerate)) * 10000);
		}
	}

	printf("Generating tones...\n");
	status = write(sound_fd, buf, bufsize);
	if (status != bufsize) {
		perror("wrote wrong number of bytes");
	}
	status = ioctl(sound_fd, SOUND_PCM_SYNC, 0);
	if (status == -1) {
		perror("SOUND_PCM_SYNC ioctl failed");
	}

	return 0;
}