.TITLE	SMCALL
	.IDENT	/V01/
; FORTRAN SEMAPHORE SUBROUTINE CALLS
; WRITTEN 6/8/77 BY HARRY ATHERTON
;
SEMP::	MOV	(PC)+,R0	;PICK UP APPROPRIATE DIC
	.BYTE	13.,2
	BR	SEMCOM		;USE COMMON CODE
SEMV::	MOV	(PC)+,R0
	.BYTE	15.,2
SEMCOM:	MOV	(R5)+,R1	;GET NUMBER OF ARGUMENTS
	TSTB	R1		;IS IT VALID ?
	BLE	ERROR		;MUST BE AT LEAST ONE ARGUMENT
	MOV	(R5)+,R2	;ADDRESS OF FIRST ARGUMENT
	CMP	#-1,R2		;IS IT NULL ?
	BEQ	ERROR		;TOO BAD IF YES
	MOV	@R2,-(SP)	;PUT SEMAPHORE NUMBER ON STACK
	MOV	R0,-(SP)	;AND APPROPRIATE DIC
	EMT	^O<377>		;CALL EXEC
	;WE HAVE RETURNED, SEE WHAT HAPPENED
	CMPB	#2,R1		;IS THERE A SECOND ARGUMENT ?
	BGT	RET		;BRANCH IF NOT
	MOV	(R5)+,R3	;GET 2ND ARGUMENT ADDRESS
	CMP	#-1,R3		;IS IT NULL ?
	BEQ	RET		;BRANCH IF YES
	;HE WANTS THE DSW
	MOV	@#$DSW,@R3	;KEEP PROGRAM PI
	;NOW RETURN
RET:	RETURN
;
ERROR:	;CALL WITH NO ARGUMENTS IS A FATAL ERROR
	TRAP	228.		;ERROR CODE 100.
	;THAT'S IT !!
	.END