; Program to multiply two numbers
; Fritz and 353 class (28 Sep 2006)

    READ R0,DD      ; R0 = multipli-ee
    READ R1,DD      ; R1 = multiplier

    DATA #skip      ; set up J0 for skipping ADD
    COPY DR,J0
    DATA #multi     ; set up J1 for looping
    COPY DR,J1

    ZERO R2         ; R2 = total
    DATA 1          ; mask bit
    
#multi
    COPY DR,R3      ; ... in R3
    
    AND  R1,R3      ; mask out rightmost bit of R1
    JPIF R3,EZ,J0   ; don't add if bit was 0
    ADD R0,R2       ; increase running total (bit was 1)
    
#skip
    SHIFT R0,-1     ; double the m'ee
    SHIFT R1,1      ; drop least sig bit of m'er
    JPIF R1,NZ,J1   ; loop back when m'er is > 0
    
    WRITE R2,DD     ; print out the answer
    HALT

; HEX listing:
;   C00 C10 30C 9EA 308 9EB 120 301 9E3 813 E38 602 508 510 E1D D20 000