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From: pittenger-laurence@cs.yale.edu (Laurence Arthur Pittenger)
Newsgroups: comp.sys.mac.programmer
Subject: Think C Debugger woes: stack ptr?
Message-ID: <1991Jun5.014018.18321@cs.yale.edu>
Date: 5 Jun 91 01:40:18 GMT
References: <1991Jun2.144751.1@csc.anu.edu.au> <25099@unix.SRI.COM>
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My program is making the debugger do *very* odd things.  After only a
few seconds of running, it crashes, usually with an "illegal
instruction" msg, sometimes with an "odd address".  It's failing at a
call to a cdef, though the cdef is accessed fine earlier in the
initial setting up and drawing.

One part of the code parses a list of objects, drawing them.
Basically it goes:

-get next element
-if it's not NULL
-draw it
-recurs until NULL.

The draw command calls another routine, which works fine.  If I
comment out this bit of code, thus deactivating the "multi draw"
capacity, the code works fine.  Yet it still uses the drawing code;
the only part which has been made inaccessable is the list parsing,
which is itself error free.  (Easy enough to check; it's the most
*basic* of code...)

Furthermore, when I don't run my program under the Debugger, it works
fine!!!  I've had it go for several minutes w/ narry a peep, whereas
the exact same code under the debugger crashes w/i 2 or 3 seconds.

I can't for the life of me (or of my program at any rate) figure out
any logical explanation for this behavior.  Is it possible that the
stack's starting address is pushed up by the debugger and so runs into
the application memory?

If anyone out there has any ideas (especially any Symantec people who
might see this), *please* pass them along.

Thanks,
LP

-- 

Laurence A. Pittenger
CSNET  : pittenger-laurence@cs.yale.edu
BITNET : pitlaua@yalevm ,  pittenger-laurence@yalecs