Date:	Wed, 13 Jan 1999 11:41:55 +0200 (IST)
From:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
X-Sender:	eliz AT is
To:	dhensley AT my-dejanews DOT com
cc:	djgpp AT delorie DOT com
Subject:	Re: How to open COM port in DJGPP?
In-Reply-To:	<77g71i$d34$1@nnrp2.dejanews.com>
Message-ID:	<Pine.SUN.3.91.990113114126.27917H-100000@is>
MIME-Version:	1.0
Reply-To:	djgpp AT delorie DOT com

On Tue, 12 Jan 1999 dhensley AT my-dejanews DOT com wrote:

> if I set the COM port attributes through the Control Panel, does DOS (and
> DJGPP) inherit those properties, or does DJGPP set some (other) arbitrary
> attributes?

DJGPP doesn't change any settings inside the call to `open'.  So
whatever properties you have set should be inherited, unless NT has
its own views about what DOS programs should see.  You will have to
check.

> > The filesystem extensions feature is described in the library
> > reference; type "info libc alpha 'File System'" from the DOS prompt
> > (the quotes around File System are important!).
> 
> Will this work under NT?

The filesystem extensions will work on any platform, since this is a
machinery that's entirely internal to DJGPP; the low-level library
calls are intercepted by your handlers *before* they are seen by the
OS.

What you need to establish is this: will NT allow you to change the
settings of the COM port from within your handlers?  If not, then
DJGPP is not your solution, because the handler will be called, but
will be unable to do its job.

It might help if you described what settings does the program you are
porting change (with the calls to termios functions).  Then it can be
estimated how hard would it be to achieve that on an NT.

In general, NT is a very hard platform for such a low-level
programming.  It might be a good idea to switch to another OS.

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