From: "Alex Oleynikov" <alex AT compuweigh DOT com>
Newsgroups: comp.os.msdos.djgpp
References: <frN89.72711$Pb DOT 3104967 AT news2 DOT east DOT cox DOT net> <7263-Thu22Aug2002105626+0300-eliz AT is DOT elta DOT co DOT il>
Subject: Re: Problem with tight kbhit() loop
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Date: Thu, 22 Aug 2002 13:22:03 GMT
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To: djgpp AT delorie DOT com
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"Eli Zaretskii" <eliz AT is DOT elta DOT co DOT il> wrote in message
news:7263-Thu22Aug2002105626+0300-eliz AT is DOT elta DOT co DOT il...
> > From: "Alex Oleynikov" <alex AT compuweigh DOT com>
> > Newsgroups: comp.os.msdos.djgpp
> >
> > I have a question about using kbhit() function in a tight loop like the
one
> > below:
> > ...
> > while( !kbhit() );
> >
> > ch = getch();
> > ...
> >
> > If I just run the program that contains this code everything works fine.
> > Now, if I run this program under the RHIDE's debugger and have some
> > breakpoints prior to the code listed above, then this loop never quits
and
> > computer locks up completely (only cold re-boot helps to restart it) and
> > sometimes even my CMOS settings are get screwed up, so BIOS loads their
> > default values at start-up making me go nuts restoring them :o).
>
> Is this on plain DOS or on Windows?

No, this is plain DOS.

> If the former, I think it's a known side-effect of the way CWDPMI
> implements the DPMI Interrupt 31 handler: after certain operations
> interrupts are left in disabled state.  Try inserting __asm__("sti")
> inside the loop, and I think the problem will go away.

Yepp, you are right - this takes care of the problem.
Thanks for your help.

Alex