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Greatest Common Divisor Program (Version 2)
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-IAN! Ian! D. Allen - idallen@ncf.ca

        Take two integers.  Put one into "large" and one into "small".
        Repeat until "small" equals "large":
	    If "small" is bigger than "large", swap the numbers.
            Subtract "small" from "large" and put result in "large".
        Output "small".

GCD Pseudocode

        1 input S and L
        2 while S != L
        3     If S > L Then
        4         Set tmp to S
        5         Set S to L
        6         Set L to tmp
	7     Set L to be L - S
        8 Output A
        9 Stop

;Label  Mnem.   Operand Comments.............
;-----  -----   ------- ---------------------
        IN              ; (1) input two numbers
        STO     S
        IN
        STO     L

TEST    LDA     S       ; (2) WHILE S != L
        SUB     L
        SKNZ
        JMP     ENDWH

        LDA     L       ; (3) IF S > L ?
        SUB     S
        SKN
        JMP     ENDIF

        LDA     S       ; (4) TRUE - swap numbers
        STO     TMP
	LDA	L	; (5)
	STO	S
	LDA	TMP	; (6)
	STO	L

ENDIF	LDA	L	; (7) subtract small from large
	SUB	S
	STO	L

        JMP     TEST    ; jump to TEST part of WHILE to repeat

ENDWH   LDA     S       ; (7) output GCD
        OUT

        HLT             ; (8) Stop!

L       DAT     ?
S       DAT     ?
TMP	DAT	?