/* port_test3.c
 * Turns one of the pins PB0,PB1,PB2,PB3 high depending on the inputs PD0 and PD1
 * Can be used for controlling two motors bidirectionally only one motor runs at a time.
 */

#include <avr/io.h> //standard include for ATMega16
#define sbi(x,y) x |= _BV(y) //set bit
#define cbi(x,y) x &= ~(_BV(y)) //clear bit
#define tbi(x,y) x ^= _BV(y) //toggle bit
#define is_high(x,y) ((x & _BV(y)) == _BV(y))

int main(void)
{
	DDRB=0xff; //PORTB as OUTPUT
	PORTB=0x00;
	DDRD=0x00;//PORTD as INPUT
	PORTD=0xff;

	while(1==1) //Infinite loop
	{
		if(is_high(PIND,PD0) && is_high(PIND,PD1))
		{
			cbi(PORTB,PB0); //First motor stopped
			cbi(PORTB,PB1);
			cbi(PORTB,PB2); //Second motor running forward
			sbi(PORTB,PB3);

		}
		else if(is_high(PIND,PD0) && !is_high(PIND,PD1))
		{
			cbi(PORTB,PB0); //First motor running forward
			sbi(PORTB,PB1);
			cbi(PORTB,PB2); //Second motor stopped
			cbi(PORTB,PB3);
		}
		else if(!is_high(PIND,PD0) && is_high(PIND,PD1))
		{
			cbi(PORTB,PB0); //First motor stopped
			cbi(PORTB,PB1);
			sbi(PORTB,PB2); //Second motor running backwards
			cbi(PORTB,PB3);
		}
		else if(!is_high(PIND,PD0) && !is_high(PIND,PD1))
		{
			sbi(PORTB,PB0); //First motor running backwards
			cbi(PORTB,PB1);
			cbi(PORTB,PB2); //Second motor stopped
			cbi(PORTB,PB3);
		}
	}
	return 0;
}