---

.include "m16def.inc"

.cseg
.org 0x000
rjmp reset

.org INT0addr
rjmp ext_int0

ext_int0:
    in r16, SREG
    push r16

    sec
    ror r20
    out PORTB, r20

    pop r16
    out SREG, r16
    reti

reset:
    ldi r16, low(RAMEND)
    out SPL, r16
    ldi r16, high(RAMEND)
    out SPH, r16

    ldi r16, 0xFF
    out DDRB, r16

    ldi r20, 0x7F
    out PORTB, r20

    cbi DDRD, 2
    sbi PORTD, 2

    ldi r16, (1<<ISC01)
    out MCUCR, r16

    ldi r16, (1<<INT0)
    out GICR, r16

    sei

main_loop:
    rjmp main_loop