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From: russotto@eng.umd.edu (Matthew T. Russotto)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Mac II retrace manager and Tick Counts
Message-ID: <1990Sep10.212420.15408@eng.umd.edu>
Date: 10 Sep 90 21:24:20 GMT
References: <24126@dartvax.Dartmouth.EDU>
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Organization: College of Engineering, Maryversity of Uniland, College Park
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In article <24126@dartvax.Dartmouth.EDU> thomas@eleazar.dartmouth.edu (Thomas Summerall) writes:

>I can and can't do in an interrupt driven SlotVInstall routine, and I don't
>want to find out by trial and error if I don't have to...

Use SlotVInstall anyway.  All you have to do is increment one of your own
variables as soon as it your routine is called-- there are various tricks
to getting access to global data from an interrupt routine, I think the
easiest way is to stick extra bytes off the end of the VBL header.  Then,
in the main program, use the same logic, but instead of while (TickCount()...,
use while (myvbl.myvar...)