Date:	Sat, 14 Sep 2002 23:05:38 +0200 (MET DST)
From:	Gisle Vanem <giva AT bgnett DOT no>
To:	djgpp AT delorie DOT com
Subject:	Re: Detecting debugger
In-Reply-To:	<200209141719.01878.pavenis@lanet.lv>
Message-ID:	<Pine.UW2.3.95.1020914230401.17249A-100000@bryggen.bgnett.no>
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Reply-To:	djgpp AT delorie DOT com
Errors-To:	nobody AT delorie DOT com
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On Sat, 14 Sep 2002, Andris wrote:

> On Saturday 14 September 2002 18:53, Gisle Vanem wrote:
> > Hi,
> >
> > I have a strange situation where running a program under a debugger
> > (RHIDE or GDB) will hang the debugger on the call to a particular
> > function. So I need to prevent calling this function when the program
> > is a debugee. How do I detect running under a debugger?
> >
> > For the record, here is that function:
> >
> > static inline void Wait (void)   /* wait until timer changes */
> > {
> >   unsigned long t = _farpeekl (_dos_ds,0x46C);
> >   while (_farpeekl(_dos_ds,0x46C) == t)
> >         ((void)0);
> > }
> >
> 
> It's generally not a good idea to do such wait in so tight loop.
> Such loop perhaps does not touch any memory using DS 
> segment register (only a guess as I did not tried to compile and 
> inspect generated assembler source), so it's not interruptable with Ctrl-Break 
> or Ctrl-C. Therefore I would suggest to call __dpmi_yield() in loop and see 
> whether problem remains instead of trying to detect when a programm is being 
> run under debugger

That worked, thanks. I don't quite see why this should work. Seems the
real-mode timer-handler isn't called to update the timer-tick unless
I do call __dpmi_yield().

Gisle V.

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