.TITLE	VDPRV	;VDDRV PRIVILEGE CHECK SUBROUTINE
	.IDENT	/V001A/	;G.C. EVERHART
	.GLOBL	S.RSAV,S.RRES
	.GLOBL	VDPRV
;CALLED FROM VDDRV TO TEST FURTHER ACCESS RIGHTS
;ON ENTRY, 
;	R0=VD: UNIT NUMBER (0,1,2,3,4,5,...)
;	R1=IO REQUEST QUEUE (IORQ) NODE ADDRESS
;	R2=VDUIT ADDRESS
;	ALL REGISTERS ARE AVAILABLE
;ON RETURN:
;	CARRY SET = FAIL ACCESS REQUEST
;	Z SET     = ALLOW ACCESS AND DISREGARD UIC OF CALLER REQUEST
;			(BYPASS CHECK IN HANDLER OF TASK UIC)
;	CARRY AND Z CLEAR:
;	          ALLOW ACCESS IF UIC IS IN THE LIST OF PERMITTED UIC'S
;		  BUILT INTO THE HANDLER.
;
;	THIS ROUTINE IS PROVIDED TO ALLOW AN INSTALLATION WITH SPECIAL
;SECURITY REQUIREMENTS TO CODE THEM IN WITHOUT HAVING TO MODIFY THE
;DEVICE HANDLER PER SE.
;	THE VERSION HERE JUST RETURNS AND IS AN EFFECTIVE NO-OP.
;	ONE USES THE ATL ADDRESS IN THE I/O REQUEST QUEUE TO
;LOCATE THE TI OF THE CALLER, TASK UIC, TASK NAME, ETC. IF NON-ZERO.
;(A ZERO ATL ADDRESS MEANS AN EXEC REQUEST...)
;	ROUTINES S.RSAV AND S.RRES ARE AVAILABLE TO SAVE AND RESTORE
;REGISTERS SEMI-INVISIBLY.
;	THEY ARE CALLED BY "JSR PC,S.RSAV" OR "JSR PC,S.RRES"
;AND PUSH ALL REGS ONTO THE STACK. A CALL TO S.RSAV WILL RETURN WITH
;THE STACK CONTAINING THE CALL PC,R5,R4,R3,R2,R1, AND R0 PUSHED IN THAT
;ORDER, AND THE REGISTERS UNCHANGED. S.RRES WILL RESTORE THE REGISTERS
;FROM AN S.RSAV CALL.
VDPRV::	CCC
	RTS	PC
	.END