IGN_ADV_FIRE:
	bset	#ign_pin, porta	; turn on the SAW, we'll turn it off in the timer int

	lda	rpm		;						28 x100rpm
	ror	a		; divide rpm by 2 to get 200 rpm bins		14 x100rpm
	cmp	#min_adv_tbl	; if rpm < min advance table rpm
	bls	IGN_MIN_RPM	; use the minimum advance bin
	sub	#min_adv_tbl	; 0 reference the RPM to the table 		10 x100rpm bin 10
	cmp	#rpm_tbl_bins	; 0 to 15 bins
	bhi	IGN_MAX_RPM	; use the maximum advance bin
	ldx	a		; set the table offset
	bra	IGN_SET_ADV

	IGN_MIN_RPM:

	ldx	#0		; fallthrough for min rpm
	bra	IGN_SET_ADV

	IGN_MAX_RPM:

	ldx	#adv_tbl_bins	; fallthrough for max rpm

	IGN_SET_ADV:

	lda	adv_rpm_tbl, x	; get advance for rpm
	beq	IGN_ADV_DONE	; if our delay is 0, don't SAW, the module will LOS to 10BTDC

	sta	ign_delay	; set our count in timer ticks (100us per tick)

	IGN_ADV_DONE:

	rts

IGN_ADV_KILL_CHECK:
	lda	ign_delay
	beq	IGN_KILL_DONE	; if it's already 0, then ignore; we get more timer ints than tach

	dec	a
	beq	IGN_KILL_SAW	; we hit 0, so turn off the SAW

	IGN_KILL_DONE:
	rts

	IGN_KILL_SAW:
	bclr	#ign_pin, porta

	rts