Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!uwvax!oddjob!rfl
From: rfl@oddjob.UChicago.EDU (Bob Loewenstein)
Newsgroups: comp.sys.mac
Subject: vbl queue
Message-ID: <3873@oddjob.UChicago.EDU>
Date: Sat, 4-Jul-87 13:19:04 EDT
Article-I.D.: oddjob.3873
Posted: Sat Jul  4 13:19:04 1987
Date-Received: Sat, 4-Jul-87 20:14:40 EDT
Reply-To: rfl@oddjob.UChicago.EDU (Bob Loewenstein)
Distribution: world
Organization: U of Chicago - Astronomy & Astrophysics
Lines: 56


Here is some code I wrote in Neon that posts a procedure to the vbl
queue. I think it's self explanatory even if you don't know Neon.

:code vinstall 
	move.l (a7)+,a0
	call vinstall
	ext.l	d0
	move.l	d0,-(a7)
;code

:code vremove
	move.l (a7)+,a0
	call vremove
	ext.l	d0
	move.l	d0,-(a7)
;code
	


:CLASS vbl <super object

	var			qlink
	int			qtype
	var			procPtr
	int			vblCount
	int			vblPhase

( 1/60ths of second -- )
  :M SetDelay: put: vblCount ;M

( cfaProc -- errcode)
  :M install: +base put: procptr abs: self vinstall abort" install error" ;M

( -- errcode)
  :M remove: abs: self vremove abort" remove error" ;M

  :M classinit: 1 put: qtype ;M

;class

vbl myTask

\ Now to use this, create a :proc definition which is the background task
\ you want to perform. You can set the delay (in 1/60ths
\ of a second) for periodic execution using the setDelay: method.  The
\ task itself must reset this delay everytime it executes.  The task
\ should ultimately be written in assembly, since all other events
\ are on hold while your word is being executed.

\ example below

\ :Proc beeper 1 beep 120 setdelay: myTask ;proc
\ 120 setdelay: myTask
\ 'c beeper install: myTask
\ to remove, say remove: myTask