Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!olivea!oliveb!isc-br!jimc
From: jimc@isc-br.ISC-BR.COM (Jim Cathey)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Animation
Message-ID: <3021@isc-br.ISC-BR.COM>
Date: 14 Feb 91 00:55:08 GMT
References: <9102030634.AA09598@enuxha.eas.asu.edu> <1991Feb7.093610.12594@ecmwf.co.uk> <1991Feb7.233344.7781@umiami.ir.miami.edu>
Organization: ISC-Bunker Ramo, An Olivetti Company
Lines: 38

In article <1991Feb7.233344.7781@umiami.ir.miami.edu> dweisman@umiami.ir.miami.edu (Ordinary Man) writes:
>[From IM page mumble]:
>"...don't rely on the tick count being incremented to a certain value, such
>as testing whether it has become equal to its old value plus 1; check for
>'greater than or equal to' (since an interrupt task may keep control for
>more than one tick)."
>
>So instead say:
>
>	tmp:=TickCount;
>	repeat until TickCount>=(tmp+1);
>
>	CopyBits.....

Of course even this isn't completely correct (foolproof).  Eventually
(2 years or so isn't it?) TickCount will overflow and you could get
into a place where you would wait forever.  (Yes I know the chances are
small, but it's nice to learn the right way too isn't it?)

The most correct way to hang until TickCount changes is:

>	tmp:=TickCount;
>	repeat until TickCount <> tmp;
>
>	CopyBits.....

This also should generate less code and will always work.  After all, you
don't give a hoot about _which_ value it's moving to, you just want to wait
until it changes.

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