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From: hartkopf@spot.Colorado.EDU (Jeff Hartkopf)
Newsgroups: comp.sys.apple2
Subject: Stack problems with IIGS code resources
Keywords: Apple IIGS, programming, code resources
Message-ID: <1991May11.022741.25916@colorado.edu>
Date: 11 May 91 02:27:41 GMT
Sender: news@colorado.edu (The Daily Planet)
Organization: University of Colorado, Boulder
Lines: 31
Nntp-Posting-Host: spot.colorado.edu



Is there anything weird to know about the stack when using code resources?  
I ask because I'm having some strange problems using them from an NDA and 
I'm not sure what's causing the problems.  Here's what I'm doing and 
what's going wrong:

I write the code resource function with ORCA/C, and it takes several
various sized parameters (ints, pointers, etc.).  I then copy the compiled
and linked function into my resource fork using the Genesys Import option.  
In my NDA (also written with ORCA/C) I do the required stuff to load the 
code resource, lock it in place, and call it.  Generally the call to the 
code resource function works smoothly.  However, sometimes if I change 
the number of parameters to the code resource function, or add or take 
away some local variables in the code resource function, some things 
don't work quite right.  Sometimes the function's return value isn't 
returned properly (e.g., I return an int value 0 but get back a garbage 
value).  Other times if I modify the contents of a variable pointed to by a 
pointer parameter to the function, it doesn't get modified properly.  
Usually, adding a new local variable or parameter to the function fixes the 
problem.  So it seems like the problem has something to do with the stack 
getting messed up.  Very strange problem.

Any ideas, anyone?

Thanks!


Jeff Hartkopf
University of Colorado at Boulder
Internet: hartkopf@spot.colorado.edu