;	SUBROUTINE SUBSTR(IN,OUT,I{,LEN})
;
; COPIES INTO OUT A SUBSTRING OF IN, STARTING AT THE I'TH CHARACTER.
; IF LEN IS GIVEN, THEN LEN CHARACTERS ARE COPIED, OTHERWISE
; THE WHOLE OF IN TO THE RIGHT OF I IS RETURNED IN OUT.

	.TITLE	SUBSTR
	.IDENT	/V2/
	.PSECT

	.GLOBL	SUBSTR

SUBSTR:	MOV	(R5)+,R3
	MOV	(R5)+,R1
	MOV	(R5)+,R2
	MOV	@(R5)+,R4
	BEQ	SBSTRA 
SBSTRC:	TSTB	(R1)+
	BEQ	SBSTRB 
	DEC	R4
	BNE	SBSTRC 
	DEC	R1
SBSTRA:	CMPB	#4 ,R3
	BHI	SBSTRD 
	MOV	@(R5)+,R4
	BEQ	SBSTRB 
SBSTRF:	MOVB	(R1)+,(R2)+
	BEQ	SBSTRE 
	DEC	R4
	BNE	SBSTRF 
SBSTRB:	CLRB	(R2)+
SBSTRE:	RTS	PC
SBSTRD:	MOVB	(R1)+,(R2)+
	BNE	SBSTRD 
	RTS	PC

	.END