/* port_test4.c
 * This is a program which checks the 0th pin of port D for input and if it is ON, keeps writing 1 to 0th pin of port B 
 * else if pin 0 of port D is set, it toggles pin 0 of port B
 */

#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)) //check if the input pin is high
#define is_low(x,y) ((x & _BV(y)) == 0) //check if the input pin is low

int main(void)
{
	unsigned int i;
	unsigned int j; 	
	DDRB=0xff; //PORTB as OUTPUT
	PORTB=0x00;
	DDRD=0x00; //PORTD as INPUT
	PORTD=0xff; //Enable Pull-up on the input port

	while(1==1) //Infinite loop
	{

		for(i=0;i<2;i++)
		{
			if(i==0)
			{
				sbi(PORTB,PB0); 
			}
			else if(i==1)
			{
				if(is_low(PIND,PD0))
				{
					cbi(PORTB,PB0);
				}
				else
				{
					sbi(PORTB,PB0);
				}
			}
			for(j=0;j<65535;j++); //The 'for' loops are only for delay
			for(j=0;j<65535;j++);
		}
	}
	return 0;
}