Date: Tue, 18 Nov 1997 10:55:23 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: Mithrandir <434667 AT cepsz DOT unizar DOT es>
cc: djgpp AT delorie DOT com
Subject: Re: Interrupt hooking help, please
In-Reply-To: <347098B8.35F3@cepsz.unizar.es>
Message-ID: <Pine.SUN.3.91.971118105506.5231F-100000@is>
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On Mon, 17 Nov 1997, Mithrandir wrote:

> I need to hook the timer interrupt. I also need have it called 16000
> times a second (a very high rate, I know).

On what machines (hardware and software) should this program run?
Slower machines (486 and less) and some software configurations (e.g.,
EMM386) will not be able to cope with such a high rate, AFAIK.  If you
need this program to run on any platform that supports DJGPP, you will
need to think about a different solution.

> I have read in a document
> called DJGPPASM.DOC that I should use a real mode interrupt. The
> interrupt routine must increment a counter and check if its 0, if so
> increment another counter. Could anybody send me a sample of such a
> routine? Thanks

I suggest that you first write a version which only installs a
protected-mode handler and see how well does it handle the high
interrupt rate.  You will need the PM hook anyway, so this is not a
wasted effort.