Message-ID: <3421AA22.7C2897D5@utw.com>
Date: Thu, 18 Sep 1997 17:24:34 -0500
From: Kurt Wall <kwall AT utw DOT com>
MIME-Version: 1.0
To: "Salvador Eduardo Tropea (SET)" <salvador AT inti DOT edu DOT ar>
CC: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>, djgpp AT delorie DOT com,
        spector AT EnchantedLearning DOT com
Subject: Re: DJGPP, interprocess communication, and DPMI
References: <m0xBfUB-000S1mC AT inti DOT edu DOT ar>
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Salvador Eduardo Tropea (SET) wrote:

> Eli Zaretskii <eliz AT is DOT elta DOT co DOT il> replied to Mitchell Spector <spector AT EnchantedLearning DOT com>
> > On Wed, 17 Sep 1997, Mitchell Spector wrote:
> >
> > > Can a DJGPP program running in a DOS box under Windows 95
> > > communicate with another currently-running program (either
> > > another DJGPP program in a different DOS box or a regular
> > > Win32 app)?
> >
> > One way that's simple to implement is to use the Windows clipboard.
> > A bunch of functions of Interrupt 2Fh let DOS programs get and put
> > text from and to the Windows clipboard.  Look in Ralf Brown's
> > Interrupt List, under W-2F1700 (WINOLDAP) and thereabouts.
> >
> > For example, the DJGPP port of Emacs uses this interface to support
> > the clipboard cut/paste operation, and as a consequence, you can move
> > text between two instances of Emacs that run on the same machine.
> >
> > This method uses DOS memory, so it's inherently limited to the amount
> > of free DOS memory your program has (usually, at least 500K should be
> > available, but your mileage may vary).
> >
> > The only other way is to write a VxD, I think.  But I'm no expert in
> > the ways of tweaking Windows to do what you need, so don't take this
> > as the definitive opinion.
>
> At least in my system the Windows clipboard seems to be slower than a virtual
> disk or even the HD with enough cache.
> I don't know why but the Win 3.1 clipboard works very slow (I tried coping
> 300Kb from write).
> I think one solution could be a real mode TSR loaded before windows.
>
> SET
> ------------------------------------ 0 --------------------------------
> Visit my home page: http://www.geocities.com/SiliconValley/Vista/6552/
> Salvador Eduardo Tropea (SET). (Electronics Engineer)
> Alternative e-mail: set-sot AT usa DOT net - ICQ: 2951574
> Address: Curapaligue 2124, Caseros, 3 de Febrero
> Buenos Aires, (1678), ARGENTINA
> TE: +(541) 759 0013

Another solution would be to set up a pipe: one app pokes data into an address, the other app
reads data out of the address.  The bookkeeping could get hairy, though.  I know that Win32, at
least, has facilities for IPC such as shared memory and pipes.  Take a look at the SDK, if you can
find it, for the 16-bit versions of Windows.

Kurt