.title	markl
;+
;	subroutine markl(int, addres)
;-
ap=%5
int=2
addres=4
	.psect	$r.roi,con,ro,rel,lcl,i
	.enabl	lsb
markl::
	mov	@int(ap),r0		; rat4 unit
	call	r$gfbk			; RFDB address in r1
	bcs	100$			; c set => invalid unit
	bit	#rf.clo,(r1)		; file open?
	bne	100$			; NO
	mov	r.fdb(r1),r0		; FDB address
	call	.mark			; retrieve next RFA
	mov	addres(ap),r1		; user's buffer address
	mov	r2,(r1)+		; return low block address
	mov	r3,(r1)			; and byte offset
100$:
	return
	.end