PIC Microcontroller Math Method

24 bit binary addition

From: Regulus Berdin

	mov	W, twofour0
	add	prod0, W

	mov	W, twofour1
	snb	C
	movsz	W, ++twofour1
	add	prod1, W

	mov	W, twofour2
	snb	C
	movsz	W, ++twofour2
	add	prod2, W

	mov	W, twofour3
	snb	C
	movsz	W, ++twofour3
	add	prod3, W