.TITLE	MG05..	GENERAL PURPOSE REGISTER PROCEDURE
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	.IDENT	/MG05../
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	.PAGE
	.SBTTL	EXCHANGE THE CONTENTS OF REGISTERS R1 TO R3
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R$SWAP::
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;		ENTRY CONDITIONS
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;	CONTENTS OF REGISTERS R1 TO R3 PLACED IN DATA AREA
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;		EXIT CONDITIONS
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;	REGISTERS LOADED WITH PREVIOUS ENTRY CONTENTS
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	SAVE	R5		;PROTECT CONTENTS OF R5
	CALL	20$		;GET STORE ADDRESS POINTER
	COM	10$		;SET SWITCH TO POINT TO ALTERNATE STORE
	MOV @R1,(R5)+		;SAVE CONTENTS OF R1
	MOV @R2,(R5)+		;SAVE CONTENTS OF R2
	MOV @R3,(R5)+		;SAVE CONTENTS OF R3
	CALL	20$		;GET ADDRESS OF ALTERNATE STORE
	MOV (R5)+,@R1		;RESTORE CONTENTS INTO R1
	MOV (R5)+,@R2		;RESTORE CONTENTS INTO R2
	MOV (R5)+,@R3		;RESTORE CONTENTS INTO R3
	UNSAVE	R5		;RESTORE CONTENTS OF R5
	RETURN			;RETURN TO CALLING PROGRAM
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;		DATA AREA
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10$:	.WORD	0		;DATA AREA POINTER FLAG
11$:	.WORD	0,0,0,0		;STORE AREA ONE
12$:	.WORD	0,0,0,0		;STORE AREA TWO
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;		ADDRESS CHANGING ROUTINE
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20$:	MOV #11$,R5		;HOLD START ADDRESS OF DATA STORE
	TST	10$		;IS THIS THE REQUIRED ADDRESS
	BEQ	21$		;J IF CORRECT ADDRESS FOUND
	MOV #12$,R5		;INCREMENT ADDRESS POINTER TO SECOND STORE
21$:	RETURN			;EXIT FROM ADDRESS SWAPPER
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	.END
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