#include<stdlib.h>
#include<dos.h>
//using namespace std;

int base,variance,del,repeat,current;

void ascend(int &,int &,int &);	/* The format of the above function is
 * acsend(current value of frequency , amount to ascend , delay in
 * milliseconds)
 */

void descend(int &,int &,int &);
/* The format remains the same , except that instead of amount to ascend ,
 * you give the amount to descend .
 */

int main(int argc , char *argv[])
{
	/* The format of the command-line parameters to pass
	 * to the program is rather simple .
	 *
	 * The 1st argument is the base frequency ( representing the
	 * sine x-axis) .
	 *
	 * The 2nd argument is the variance , or the amplitude of the sine
	 * wave .
	 *
	 * The 3rd argument is the delay ( in milliseconds ) , representing
	 * the delay between frequency change in the ascent and descent
	 * functions .
	 *
	 * The 4th argument is the number of times you want the siren to loop .
	 */

	int i;

	base=atoi(argv[1]);
	variance=atoi(argv[2]);
	del=atoi(argv[3]);
	repeat=atoi(argv[4]);

	/* The following for loop asends to the top , descends to the base ,
	 * then descends to the bottom , and finally ascends to the base .
	 * To do : convert it into an approximation of a sine function from
	 * a linear one .*/

	for(i=0;i<repeat;i++)
	{
		current=base;
		ascend(current,variance,del);
		descend(current,variance,del);
		descend(current,variance,del);
		ascend(current,variance,del);
	}

	return 0;
}

void ascend(int &current,int &variance,int &del)
{
	for(int i=0;i<=variance;i++)
	{
		if(i)
			current++;
		/* The preceding code makes sure that even if the loop loops
		 * (variance+1) times , current is incremented only (variance)
		 * times . It also makes sure that at least one sound is heard
		 * at the base frequency ( or that the value starts from and
		 * returns to the base frequency ) . This same approach is used
		 * in the descend function . */
		sound(current);
		delay(del);
	}

	nosound();
}

void descend(int &current,int &variance,int &del)
{
	for(int i=variance;i>=0;i--)
	{
		if(i)
			current--;
		/* See the previous comment on this topic in the ascend
		 * function . Here , the value of base is devremented on the
		 * first run , too , to ensure that top and base values
		 * are not repeated .
		 */
		sound(current);
		delay(del);
	}

	nosound();
}