Path: utzoo!utgpu!watserv1!watmath!att!pacbell!pacbell.com!decwrl!apple!stevec
From: stevec@Apple.COM (Steve Christensen)
Newsgroups: comp.sys.mac.programmer
Subject: Re: How Can I install a VBL Task from an INIT?
Message-ID: <10086@goofy.Apple.COM>
Date: 7 Sep 90 02:41:27 GMT
References: <1900@mountn.dec.com> <1990Sep6.182348.567@ux1.cso.uiuc.edu>
Organization: Apple Computer Inc., Cupertino, CA
Lines: 39

In article <1990Sep6.182348.567@ux1.cso.uiuc.edu> jason@ux1.cso.uiuc.edu writes:
>domenikos@emass.enet.dec.com (George Domenikos) writes:
>>I am having problems with installing successfully a VBL Task at INIT time.
>>It seems that I crash when I do 
>
>>myVBL.vblAddr := @DoMyVBLStuff;
>
>>where myVBL is of type VBLTask
>>and DoMyVBLStuff is my procedure name containing the code I want to execute
>>as VBL.
>
>   Did you lock down the VBL code so that it wouldn't be moved or purged?
>A good way to accomplish this is to compile the code for DoMyVBLStuff into a
>resource, say of type 'task'.  Your init should:
>
>	1) Load the 'task' code using GetResource()
>	2) move the code to the top of the heap ( MoveHHi() )
>	3) HLock the code.
>	4) Get a pointer to the code using:
>		myVBL.vblAddr = StripAddress( codeHandle^ );

Assuming the INIT is locked down, was it detached?  If not, as soon as the
INIT file is closed, the code goes away, and so there will be a loud crash
1/60th of a second later.  If your INIT has some code that needs to hang
around, do a DetachResource() on the handle to the INIT resource, which will
make the Resource Manager forget about it and leave it alone...

steve

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  Steve Christensen             Internet:   stevec@goofy.apple.com
  Apple Computer, Inc.          AppleLink:  STEVEC
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