;
;	File:		WaitNextEvent.a
;
;	Contains:	This is the Classic Mac OS version of WaitNextEvent.
;				It is completely replaced in MultiFinder.
;
;	Written by:	Phil Goldman and Ed Tecot
;
;	Copyright:	© 1988-1990, 1992 by Apple Computer, Inc., all rights reserved.
;
;	Change History (most recent first):
;
;		 <3>	 2/11/92	JSM		Moved this file to ToolboxEventMgr folder, keeping all the old
;									revisions.
;		 <2>	  1/4/90	dba		get rid of assembly warning by renaming a local
;	   <1.0>	11/16/88	CCH		Added to EASE.
;	  <S426>	 3/16/88	PYG		Handle overflow for timeout and control of mouse-moved diarrhea
;	  <S380>	  2/4/88	EMT		Fix WaitNextEvent when mouseRgn is nil
;

WaitNextEvent	PROC	EXPORT

mouseMovedMsg	EQU	$FA000000
maxTickCount	EQU	$FFFFFFFF

; Stack Frame
retAddr		EQU		4
mouseRgn	EQU		retAddr+4
timeOutX	EQU		mouseRgn+4
theEvent	EQU		timeOutX+4
eventMask	EQU		theEvent+4
retBool		EQU		eventMask+2

; Locals
; d3:			Tick time to wakeup (i.e. return)
; d4:			Last mouse position

			LINK	A6, #0					; Set up stack frame
			MOVEM.L	D3-d4/A2, -(SP)			; Save registers						<S436/22Mar88> PYG
			moveq.l	#$FFFFFFFF,d4			; pick a supposed invalid first value	<S436/22Mar88> PYG
											; for the previous mouse position
			MOVE.L	Ticks, D3				; Save Ticks on entry
			ADD.L	timeOutX(A6),D3			; D3 is wakeup time
			bcc.s	@WaitTimeOK				; if no (unsigned) overflow, branch		<S426/16Mar88> PYG
			moveq.l	#maxTickCount,d3		; if overflow, peg to max tick count	<S426/16Mar88> PYG
@WaitTimeOK									;										<S426/16Mar88> PYG
			MOVE.L	theEvent(A6), A2		; We'll use this often

@WaitLoop
			_SystemTask

			SUBQ.W	#2, SP					; Make space for return value
			MOVE.W	eventMask(A6), -(SP)
			MOVE.L	A2, -(SP)				; theEvent
			_GetNextEvent
			MOVE.B	(SP)+, retBool(A6)		; Stuff the boolean return value
			BNE.S	@WaitDone				; If non-zero, we're done

; GetNextEvent correctly stuffs evtTicks, evtMouse, evtMeta, and evtMBut fields
			CMP.L	evtTicks(A2), D3		; Time to wake up?
			BLS.S	@WaitDone				; If so, we're done

			MOVE.L	mouseRgn(A6), D0		; Get the mouseRgn							<S380>
			BEQ.S	@WaitLoop				; Loop if nil								<S380>

			cmp.l	evtMouse(A2),d4			; is it the same as the last one?		<S436/22Mar88> PYG
			beq.s	@WaitLoop				; if so, loop							<S426/16Mar88> PYG

			move.l	evtMouse(A2),d4			; and save new value					<S436/22Mar88> PYG

			SUBQ.W	#2, SP					; Make space
			MOVE.L	evtMouse(A2), -(SP)		; pt for PtInRgn						<S426/16Mar88> PYG
			MOVE.L	D0, -(SP)				; rgn for PtInRgn							<S380>
			_PtInRgn
			TST.B	(SP)+					; Is it in the region?
			BNE.S	@WaitLoop				; If it is, loop around

			MOVE.W	eventMask(A6), D0
			BTST	#app4Evt, D0			; Accept app4?
			BEQ.S	@WaitDone				; No, get out

; Manufacture a mouse moved event
			MOVE.W	#app4Evt, evtNum(A2)			; what = app4Evt
			MOVE.L	#mouseMovedMsg, evtMessage(A2)	; message = MouseMoved
			ST.B	retBool(A6)						; return True

@WaitDone
			MOVEM.L	(SP)+, D3-d4/A2			; Restore registers						<S436/22Mar88> PYG
			UNLK	A6
			MOVE.L	(SP), A0				; Get return address
			LEA		retBool-4(SP), SP		; Pop the arguments
			JMP		(A0)					; Return

			ENDPROC