; count with interrupt

.symbol
	stop 0
	cnt 20

.code 0
:main
	mov r1 #isr1
	st r1 1000     ; set up int vector
	mv r27 #2000   ; set sp
	mov r1 #0
	st r1 cnt      ; cnt = 0
:loop
; this is almost empty loop
        swi
	ld r1 cnt
	eq r2 r1 #10
	jf r2 loop
	trap r0 #stop

;  the counting routine is split into two
:isr1
	ld r3 cnt	
	add r3 r3 #1
	pushm r27
	mov r4 #isr2
	st r4 1000     ; change interrupt vector
	reti
:isr2
	popm r27
	st r3 cnt
	mov r4 #isr1
	st r4 1000     ; change int vec
	reti

.end