; X1EFBY.MAC -- FETCH EOF BLOCK NO. AND FIRST FREE BYTE.
; AUTHOR:  J. LEONARD
; DATE WRITTEN:  02-NOV-78
;
	.NLIST	TOC		;TBL OF CONTENTS NOT WANTED
;
	.TITLE	X1EFBY
	.SBTTL	MODIFY FDB
;
	.ENABL	AMA		;NO PC-REL ADDRS
;
	.MCALL	FDOF$L
;
	.GLOBL	$FCHNL,NAM$	;SUBRS CALLED
	.GLOBL	$OTSV		;OTS IMPURE PTR ADDR
	FDOF$L
;
;
; CALL:
;     CALL X1EFBY (LUN, ILOBLK, IHIBLK, IFBY)
; WHERE:
;	LUN	= FILE'S LOGICAL UNIT
;	ILOBLK	= LOW ORDER WORD OF EOF BLOCK
;	IHIBLK	= HI ORDER WORD OF EOF BLOCK
;	IFBY	= FIRST FREE BYTE
;
D.FDB	=	14		;OFFSET TO FDB FROM FFDB
;
FBY	=	0		;FIRST FREE BYTE IN LAST BLOCK
;
X1EFBY::
	MOV	#X1EFBN,R0	;NAME TO TRACE BK
	MOV	(R0)+,R4
	MOV	(R0)+,-(SP)	;PUSH (R0)+ ONTO STACK
	JSR	R4,NAM$		;TRACEBACK CHAIN
	TST	(R5)+		;DITCH NARGS
	MOV	@(R5)+,R2	;GET LUN
	MOV	@#$OTSV,R3	;OTS IMPURE ADDR
	JSR	PC,$FCHNL	;GET DEVT ENTRY ADDR
	ADD	#D.FDB,R0	;LUN'S FDB ADDR
;
	MOV	F.EFBK+2(R0),@(R5)+	;LOW PART
	MOV	F.EFBK(R0),@(R5)+	;HI PART
	MOV	F.FFBY(R0),@(R5)	;FIRST FREE BYTE
;
	RTS	PC		;RETURN TO CALLER
;
X1EFBN:	.RAD50	/X1EFBY /	;TRACE NAME
;
	.END