.TITLE	MR13.. STRING PROCEDURES IN MACRO
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	.IDENT	/MR13../
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	.PAGE
	.SBTTL	.	CLEAR OUT A CHARACTER STRING
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R$CLEAR::			;CLEAR OUT A CHARACTER STRING
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;		ENTRY CONDITIONS
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;		R0	-> ADDRESS OF CHARACTER STRING TO BE CLEARED
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	SAVE R4,R0		;PROTECT REGISTER R4 AND R0
	SETERROR		;ASSUME ERROR CONDITION 'AND WHY NOT ?'
	MOV -2(R0),R4		;HOLD MAXIMUM LENGTH OF STRING
	BLE	100$		;J IF STRING WRITE PROTECTED
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	CMPB (R4)+,(R4)+	;SET UP COUNT OF NUMBER OF LOCATIONS TO CLEAR
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50$:	CLRB (R0)+		;SET LENGTH TO ZERO AND CLEAR ALL CHARACTERS
	SOB R4,50$		;LOOP TO END OF STRING
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	SETSUCCESS		;INDICATE STRING CLEARED AND NO PROBLEMS
100$:	UNSAVE R4,R0		;RESTORE REGISTER FOUR AND GOOD OLD R ZERO
	RETURN			;RETURN TO CALLING PROGRAM
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	.END
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