#define ddrb 0x37;
#define portb 0x38;
#define ddrd 0x31;
#define inputd 0x30;

void print_led(char value)
{
    char* led = portb;
    *led = value;
}

int main(void) {
    int i;
    char* io_dirb = ddrb;
    *io_dirb = 0xff;
    char* io_dird = ddrd;
    *io_dird = 0x00;
    char* portd = inputd;
    while(1) 
    {        
        print_led(*portd);
    }
    return 0;
}