/* GROUP I
   DARLAN VIVIAN
   EDUARDO A. P. ALCHIERI
   THIAGO MEREGE PEREIRA */

/* I/O PORT B, DATA DIRECTION REGISTER (0 -> in, 1 -> out) */
#define DDRB    (*(volatile unsigned char *)(0x17 + 0x20))

/* I/O PORT B, DATA REGISTER */
#define PORTB   (*(volatile unsigned char *)(0x18 + 0x20))

/* I/O PORT D, INPUT PINS */
#define PIND   (*(volatile unsigned char *)(0x30))

/* GIMSK, GENERAL INTERRUPT MASK REGISTER */
#define GIMSK   (*(volatile unsigned char *)(0x5B))

/* MCUCR, MCU CONTROL REGISTER */
#define MCUCR (*(volatile unsigned char *)(0x55))

/* SREG, STATUS REGISTER */
#define SREG (*(volatile unsigned char *)(0x5F))

#define IRQ0 __vector_1

#define SIGNAL __attribute__ ((signal))

int main(void) {
     
    /* Enable interrupts */
    SREG = 0x80;

    /* Enable External Interrupt Request 0 */
    GIMSK = 0x40;

    /* Rise edge of INT 0 generates a IRQ */
    MCUCR = 0x03;

    /* Set the whole port (all bits) to "output" */
    DDRB = 0xff;

    while(1) {}
        return 0;

}

void IRQ0 (void) SIGNAL;

void IRQ0 (void) {

    /* Turns on/off all PORTB leds */
    PORTB = ~PORTB;

}