.TITLE	NULL
;AUTHOR:	MARTY PORTNER
;		WORLD BOOK-CHILDCRAFT, INC.
; FUNCTION TO CREATE A NULL STRING
; CALLING FORMAT:
;
;	 	CALL 	NULL(STR)
;
; DEFAULTS SUPPLIED:		NONE
	.IDENT $NULL2$
 
	.PSECT	$$STRG,RO,I,CON,LCL
NULL::
 
	CMPB	#1,@R5		;IF ARG. IS PRESENT, CONTINUE
	BNE	ND$		;ELSE, EXIT
	CMP	#-1,2(R5)	;
	BEQ	ND$		;
	MOV	2(R5),-(SP)
	CLRB	@(SP)+		;PLACE ZERO BYTE AT POSITION 1 OF 'STR'
	
ND$:	RTS	PC		;RETURN
	.END			;