Path: utzoo!attcan!uunet!lll-winken!ames!hc!lanl!opus!ksitze
From: ksitze@nmsu.edu (Kevin Sitze)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Installing a CODE as a VBL
Message-ID: <KSITZE.89May24134646@picuris.nmsu.edu>
Date: 24 May 89 19:46:46 GMT
References: <5586@hubcap.clemson.edu>
Sender: news@nmsu.edu
Organization: NMSU Computer Science
Lines: 58

In article: <mikeoro@hubcap.clemson.edu's message of 24 May 89
02:20:48 GMT> Michael writes:
>I am trying to install a precompiled LSP unit as a VBL task.  I compiled it
>as a CODE resource and all it does is a sysbeep(1).
>
>In the calling program i declare:
>
>HCode : Handle;
>
>HCode := GetResource('OUR ',100); { the type and number of the code rsrc}
>DetachResource(HCode);
>
>then i set the vblAddr field of the vblTask to be ProcPtr(HCode^).
>
>This crashes the machine every time.  What's up?

You might want to lock the handle, if the memory manager is in the
middle of moving that handle and the VBL occures, then your task
suddenly finds itself running off into nowheres-ville.  To prevent
fragmenting of the heap, find the size of the resource like this:

... {Previous code}
  SetResLoad(False);	{Don't want to load in the resource as of yet}
  HCode := GetResource('OUR ', 100);  {Get a (empty) handle to the resource}
  ResrvMem(SizeResource(HCode));  {Get enough space for the resource}
	{as low in the heap as possible (ResrvMem is used when}
        {allocating ptrs)}
  SetResLoad(True);
  LoadResource(HCode);  {Load the resource info into memory}
  HLock(HCode);		{Lock it in place so it'll stay valid for VBL}
  DetachResource(HCode);
... {Rest of installation code here}

If you don't want to do the previous, then the answer is simple.  Just
set the ResLock flag (Using ResEdit) on the resource you want in
memory and then the program reverts back to:

...
  HCode := GetResource('OUR ', 100);
  DetachResource(HCode);
...

This is because all the rest of the calls given in the first example
are made automatically by the resource manager.  Pretty fun eh?

If your problem of crashing the machine persists, then you'll have to
go back to your VBL code and make sure that you aren't trying to use
handles anywhere in it's code.

Have fun....			-Kelesi
--

+--------------------------------------------------------------------+
| From the Macintosh of: Kevin L. Sitze. This is ME: ksitze@NMSU.edu |
+------------------------------------------------------+-------------+
| The difference between intelligence and stupidity is |   Is this   |
| that intelligence has a limit.          -- anonymous |   better?   |
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