Date:	Sat, 28 Dec 1996 12:09:04 +0000
From:	Bill Currie <billc AT blackmagic DOT tait DOT co DOT nz>
Subject:	Debuggers and mouse hooking (or maybe dpmi memory allocation).
To:	djgpp-workers AT delorie DOT com
Reply-to:	billc AT blackmagic DOT tait DOT co DOT nz
Message-id:	<32C50DE0.2D19@blackmagic.tait.co.nz>
Organization:	Tait Electronics NZ
MIME-version:	1.0

I'm having some problems with v2.01 debuggers locking up with my 
editor and I would like some advice on what mods were made to 
dbgcom.c so I can work out what's going on (the story is below).

---

(This is under dos/cwsdpmi r3 with emm386 running, everything works 
fine under windows (or the 2.00 debuggers))

I have an application (an editor, a tad large to post sample code) 
that I can't debug using the v2.01 versions of the debuggers due 
to the computer locking up and needing a reset as soon as I start 
my code running (usually, some times I can move the mouse, but as 
soon as I click a button, the pc locks up).

The unusual things my editor does are:
 hooks the keyboard (I know, doesn't work under the debuggers, not a
  problem)
 hooks the mouse callback
  (all code and data for the above functions IS locked otherwise 
  cwsdpmi would spit the dummy (thanks Charles! EXCELENT debugging 
  tool))
 allocates/resizes additional dpmi memory blocks (on top of any done 
  by sbrk)
 2 or 3 selectors pointing to the screen (wastefull, but the code is 
  in separate libraries)
 frequent calls to int 2f/1680
 a couple of calls to dos via int 21 (rather that dpmi int, general 
  registers only)
 calls to the network broadcast message collection function (21/f215)
  but via __dpmi_int
 the Python interpreter is embedded in my editor but this problem was
  occurring before I did that.

As the v2.00 debuggers work with my editor, that is my workaround, 
but I decuded to try to fix the problem by looking at 
src/debug/common/dbgcom.c.  Doing a diff on the two versions of 
the file, I noticed a lot of additional code that intercepts the
dpmi memory allocation functions (which I make heavy use of, but 
none are called by my code before my pc locks up).  I'me wandering if
this or some of the other mods are conflicting with what I'm doing in 
my editor.

Thanks in advance for any help and when I get things going, I'll post 
the diffs (if any, it may actually be my editor).

Bill
-- 
Leave others their otherness.

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