int main() {
	volatile unsigned char* porta=(volatile unsigned char*)0x1000;
	while(1) {
		unsigned char c=*porta; /* read switches PA0 and PA1 */
		c&=0x03;		/* clear all other PA signals */
		c<<=5;			/* shift 5x so PA5=PA0 and PA6=PA1 */
		*porta=c;		/* write LEDs */
	}
	return 0;
}