Date: Wed, 18 Sep 2002 21:16:29 +0300
From: "Eli Zaretskii" <eliz AT is DOT elta DOT co DOT il>
Sender: halo1 AT zahav DOT net DOT il
To: Gisle Vanem <giva AT bgnett DOT no>
Message-Id: <3405-Wed18Sep2002211628+0300-eliz@is.elta.co.il>
X-Mailer: emacs 21.3.50 (via feedmail 8 I) and Blat ver 1.8.9
CC: djgpp AT delorie DOT com
In-reply-to: <Pine.UW2.3.95.1020914230401.17249A-100000@bryggen.bgnett.no>
	(message from Gisle Vanem on Sat, 14 Sep 2002 23:05:38 +0200 (MET
	DST))
Subject: Re: Detecting debugger
References:  <Pine DOT UW2 DOT 3 DOT 95 DOT 1020914230401 DOT 17249A-100000 AT bryggen DOT bgnett DOT no>
Reply-To: djgpp AT delorie DOT com
Errors-To: nobody AT delorie DOT com
X-Mailing-List: djgpp AT delorie DOT com
X-Unsubscribes-To: listserv AT delorie DOT com
Precedence: bulk

> Date: Sat, 14 Sep 2002 23:05:38 +0200 (MET DST)
> From: Gisle Vanem <giva AT bgnett DOT no>
> 
> 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().

If this is under plain DOS (no Windows) using CWSDPMI, then what you
see is due to a subtle misfeature in the way CWSDPMI implements the
Int 31h interface.  It's a long story, but the bottom line is that
under some circumstances interrupts become disabled.  Insert an
__asm__("sti") into the loop, and I believe the problem will go away.