vxy
int vxy(int *, int *);
vxy(x, y);
vxy(&x, &y); /* verify coordinates are within range */
vxy(&x, &y); /* verify coordinates are within range */
vxy(&x, &y); /* verify coordinates are within range */
vxy(&xx, &yy); /* verify x & y coordinates */
if (!vxy(&i, &j)) { /* if not out of bounds */
vxy(&x, &y);
vxy(&xl, &yl);
vxy(&xh, &yh); /* check bounds */
vxy(&x, &y); /* verify correct x,y coordinates */
vxy(&xl, &yl);
vxy(&xh, &yh);
vxy(&xl, &yl);
vxy(&xh, &yh);