.IIF	NDF	RSX	RSX	=	0	;Assume RT11
	.TITLE	FLUSH
	.ident	/000001/
	.NLIST	BEX, CND
	.ENABL	LC, GBL
	.LIST	MEB
;
; Flush clears the buffer and forces it out.  It is a no-op on
; RSX, but is needed in RT11.
;
; FLUSH calling sequence:
;
;	MOV	FDB,R0		;R0 -> file data block
;	CALL	FLUSH		;Do it
;
; On return, all registers are preserved.
;
; Edit history
; 01 01-Aug-79 MM	Original edit
;
.IF NE	RSX
.IFTF
FLUSH::
.IFT
	CLC			;Always good return
	RTS	PC		;Do nothing nicely.
.IFF
	.GLOBL	SAVREG, $PUTC0
	JSR	R5,SAVREG	;Save all registers
	MOV	SP,R5		;So we can mark the stack
	MOV	R0,R1		;Copy the FDB
	TST	(R1)+		;R1 -> free count
	CMP	(R1),#512.	;Empty buffer
	BGE	30$		;How can I flush nothing?
10$:	TST	(R1)+		;Free count equals zero?
	BLE	20$		;Close enough, exit loop
	CLRB	@(R1)+		;Clear the buffer byte
	INC	-(R1)		;Step the buffer pointer
	DEC	-(R1)		;Drop the free count
	BR	10$		;Loop some more

20$:	JSR	PC,$PUTC0	;Do it
30$:	RTS	PC		;and return
.ENDC
	.END