#include <string.h>
#include <sys/soundcard.h>
#include <sys/ioctl.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <stdio.h>
#include <math.h>

unsigned char errmsg[256];
int r;
int dsp;
int bits=16;
int channels;
int blocksize;

float left=10000;
float right=10000;
double left_angle=0;
double right_angle=0;
unsigned char buffer[65536];

void hum(void)
{
	int a;
	int val;
	int remains;
	unsigned char *ptr;

	new_buffer:
	ptr=buffer;
	for (a=0;a<sizeof(buffer)/4;a++){
		val=32767*sin(left_angle);
		*ptr++=val&255;
		*ptr++=val>>8;
		val=32767*sin(right_angle);
		*ptr++=val&255;
		*ptr++=val>>8;
		left_angle+=2*M_PI/44100*left;
		if (left_angle>=2*M_PI) left_angle-=2*M_PI;
		right_angle+=2*M_PI/44100*right;
		if (right_angle>=2*M_PI) right_angle-=2*M_PI;
	}
	remains=sizeof(buffer);
	ptr=buffer;
	a2:
	if (!remains) goto new_buffer;
	val=write(dsp,ptr,remains);
	if (val>=0){
		remains-=val;
		ptr+=val;
		goto a2;
	}
	if (errno==EAGAIN||errno==EINTR) goto a2;
	perror("beat");
	exit(1);
}

/*-------------------------------MAIN---------------------------------------*/
int main(int argc, char **argv)
{
	int a;

again:
dsp=open("/dev/dsp",O_WRONLY);
if (dsp<0){
	if (errno==EINTR||errno==EAGAIN) goto again;
}

if (r){
	fprintf(stderr,"Can't open sound device.\n");
	exit(1);
}

r=ioctl(dsp,SNDCTL_DSP_RESET,NULL);
if (r){
	fprintf(stderr,"Can't reset sound device.\n");
	exit(1);
}

a=44100;
r=ioctl(dsp,SNDCTL_DSP_SPEED,&a);
if (r){
	fprintf(stderr,"Can't set 44100.\n");
	exit(1);
}

a=1;
r=ioctl(dsp,SNDCTL_DSP_STEREO,&a);
if (r){
	fprintf(stderr,"Can't set stereo.\n");
	exit(1);
}

a=16;
r=ioctl(dsp,SOUND_PCM_WRITE_BITS,&a);
if (r){
	fprintf(stderr,"Can't set 16bit.\n");
	exit(1);
}

r=ioctl(dsp,SNDCTL_DSP_GETBLKSIZE,&blocksize);
if (r){
	fprintf(stderr,"Can't get blocksize.\n");
	exit(1);
}

r=ioctl(dsp,SNDCTL_DSP_SYNC,NULL);
if (r){
	fprintf(stderr,"Can't sync device.\n");
	exit(1);
}

hum();

return 0;
	
	printf("Error setting up driver\n");
	return 1;
}