From:	"A.Appleyard" <A DOT APPLEYARD AT fs2 DOT mt DOT umist DOT ac DOT uk>
To:	DJGPP AT DELORIE DOT COM
Date:	Wed, 20 Mar 1996 09:42:38 GMT
Subject:	Re: mouse irq
Message-ID:	<8BC0BC7D43@fs2.mt.umist.ac.uk>

  On Tue, 19 Mar 1996, Martynas Kunigelis wrote:
> switches: pm->rm->pm->rm->pm. I thought it would be much better to trap the
> mouse irq and do the driver's job myself. Is it possible? If so, has anyone
> got any docs on that? Any info is very welcome. Thanx.

  Eli Zaretskii <eliz AT is DOT elta DOT co DOT il> replied (Subject: Re: mouse irq):-
> Which mouse IRQ? The serial mouse works with the serial communications IRQ.
> Do you mean you want to hook that and do all the work the mouse driver does,
> like moving the mouse pointer etc.?

  (PM = protected mode, RM = real mode)
  As it is, when the program has a user-writtem mouse interrupt handler, when
the mouse is moved or clicked the PM program must go into RM to obey the mouse
interrupt, which then calls the user's (inevitably compiled by djgpp into RM)
mouse interrupt handler, which then goes back to PM for DOS to return him to
the RM calling program.
  I think what Martynas meant, was that he (and I also) think that it would be
useful for djgpp to be able to be told to compile in real mode if wanted, so
that (1) the user could write real-mode interrupt handler routines and avoid
need for all this repeated switching back and forth between RM and PM at every
e.g. mouse interrupt call; (2) the user can use his djgpp to create short RM
.EXE and .COM program files without having to keep a second compiler
cluttering up his computer's hard disk.

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