.TITLE	MR09.. STRING PROCEDURES IN MACRO
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	.IDENT	/MR09../
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	.PAGE
	.SBTTL	.		CHARACTER SHIFT LEFT END-AROUND
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R$SHLE::				;SHIFT CHARACTER STRING LEFT END AROUND
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;			ENTRY CONDITIONS
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;		R0 -> CHARACTER STRING ADDRESS
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	SAVE R1,R2,R3,R4	;SAVE REGISTERS R1 TO R4
	MOV @R0,R3		;HOLD LOOP COUNTER +1
	DEC R3			;CORRECT VALUE
	BLE	80$		;J IF STRING LENGTH <=1 CHARACTER
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	MOV R0,R1		;HOLD START ADDRESS OF STRING
	INC R1			;INDEX TO START CHARACTERS -1
	ADD @R0,R1		;END CHARACTER ADDRESS OF STRING
	MOV R1,R2		;HOLD END CHARACTER ADDRESS OF STRING
;
50$:	MOVB (R1),90$		;EXTRACT CHARACTERS
	MOVB -(R1),90$+1
	SWAB 90$		;REVERSE ORDER OF CHARACTERS
	MOVB 90$,(R2)		;REPLACE CHARACTERS
	MOVB 90$+1,-(R2)
	SOB R3,50$		;LOOP THROUGH STRING MOVING
				;LAST CHARACTER TO START
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80$:	UNSAVE R1,R2,R3,R4	;RESTORE REGISTERS R1 TO R4
	RETURN			;EXIT
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90$:	.WORD			;SWAP SPACE WORK AREA
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	.END
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