; -----------------------
; Code to multiply two numbers using bits and masks
; Fritz Ruehr, Willamette University Computer Science
; -----------------------

    SET J0,#loop	; Set up for jump (label: #loop)
	SET J1,#skip	; Set up for jump (label: #skip)

	READ R0,DD	; Read the first number into R0
	READ R1,DD	; Read the control number into R1
#loop	
	SET R2,1	; Set the mask to 1 in R2
	AND R1,R2	; Mask out the rightmost bit of R1
	JPIF R2,EZ,J1	; Skip around the add on zero bit

	ADD R0,R3	; If 1 bit, add to running total
#skip	
	SHIFT R0,-1	; Shift the first number left
	SHIFT R1,1	; Shift the control number right

	JPIF R1,NZ,J0	; Go around again if necessary
	WRITE R3,DD	; Write out the total
	HALT

; -----------------------
; END PROGRAM mult.asm
; -----------------------