.TITLE	MR14.. STRING PROCEDURES IN MACRO
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	.IDENT	/MR14../
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	.PAGE
	.SBTTL	.		REGISTER CONTROLED SEGMENT PROCEDURE
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R$SEG::				;EXTRACT SEGMENT OF A CHARACTER STRING
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;		ENTRY CONDITIONS
;		R1 -> INPUT STRING
;		R2 =  START POSITION
;		R3 =  END   POSITION
;		R4 -> OUTPUT STRING
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;		EXIT CONDITIONS
;		R4 -> OUTPUT STRING
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	CLR @R4			;SET OUTPUT STRING LENGTH TO ZERO
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20$:	CMP R3,R2		;? ALL CHARACTERS EXTRACTED
	BLT	30$		;J IF ALL CHARACTERS EXTRACTED
	CALL R$GETC		;GET A CHARACTER INTO R0
	IFERROR	30$		;J IF GET CHARACTER ERROR CONDITION
	INC R2			;POINT TO NEXT CHARACTER POSITION
	CALL R$ADDC		;ADD CHARACTER TO OUTPUT STRING
	BR	20$		;LOOP TO END OF SEGMENT
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30$:	RETURN			;EXIT WITH R2 -> AT LAST CHARACTER
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	.END
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