#include <stdio.h>
#include <graph.h>

main()
{
	int i,j,k,l,a,b;
	unsigned char *i1,*i0,*j1,*j0,*k1,*k0,*l1,*l0;

	i0=&i; i1=i0+1; /* set i1 & i0 to the high & low bytes of i */
	j0=&j; j1=j0+1; /* ditto for j0 & j1 */
	k0=&k; k1=k0+1; /* set k1 & k0 to the high & low bytes of k */
	l0=&l; l1=l0+1; /* ditto for l0 & l1 */

	_clearscreen(_GCLEARSCREEN);
	printf(" Sum and Difference Program: hit any key to terminate. \n\n\n\r");
	printf("The analog signals input to A/D 0 and A/D 1 are combined to produce \n\r");
	printf("two output signals.  D/A 0 outputs the sum of the 2 signals and \n\r");
	printf("D/A 1 outputs the difference A/D 0 - A/D 1. \n\r");

loop:   outp(0x301,0);  /* select A/D ch. 0, set gain to 1 */
	outp(0x302,0);  /* start conversion */
	outp(0x305,*k0); outp(0x306,*k1);  /* output last value     */
	while(!(inp(0x300) & 0x40));
	*i0=inp(0x303); *i1=inp(0x304);    /* input voltage         */

	outp(0x301,1);  /* select A/D ch. 1, set gain to 1 */
	outp(0x302,0);  /* start conversion */
	outp(0x307,*l0); outp(0x308,*l1);  /* output last value     */
	while(!(inp(0x300) & 0x40));
	*j0=inp(0x303); *j1=inp(0x304);    /* input voltage         */

	k=i+j;
	l=i-j;

/*      printf(" %d ",j); */

	if(!kbhit())goto loop;
}