//write a code to blink leds one by one from 7-0 by pressing any button 
//hardware is same as 1st exp

#include <stdint.h>

#define PINA   (*(volatile uint8_t*)0x20)
#define DDRA   (*(volatile uint8_t*)0x21)
#define PORTA  (*(volatile uint8_t*)0x22)

#define PINB   (*(volatile uint8_t*)0x23)
#define DDRB   (*(volatile uint8_t*)0x24)
#define PORTB  (*(volatile uint8_t*)0x25)

void delay1sec(void){
    TCNT1  = 0;
    TCCR1A = 0x00;
    TCCR1B = 0x05;          
    while (TCNT1 < 15625);
    TCCR1B = 0x00;
}

int main(void){
    DDRA = 0xFF;      
    DDRB = 0x00;      

    while(1){
        if (PINB != 0x00) {       
            for (int8_t j = 7; j >= 0; j--) {
                PORTA = (1 << j);
                delay1sec();
                PORTA = 0x00;
                delay1sec();
            }
        } else {
            PORTA = 0x00;
        }
    }
}