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From: mlf@genrad.UUCP (Matt Fichtenbaum)
Newsgroups: comp.os.msdos.programmer
Subject: Interfacing to the Mouse Driver
Message-ID: <39896@genrad.UUCP>
Date: 3 Dec 90 13:12:19 GMT
Distribution: usa
Organization: GenRad, Inc., Concord, Mass.
Lines: 18

Some past articles have discussed difficulties people have had in using
int 33 function 0c to install one's own event handler such that the [Microsoft
and compatibles] mouse driver calls it when a mouse event (button press,
movement) occurs.  Two things to note:

1. The mouse driver calls the handler with the DS register pointing to its -
   the mouse driver's - data segment, not the handler's.  In Turbo C the handler
   can be declared as "huge;" in QuickC some inline assembly is needed.

2. The QuickC debug-mode stack check, in which each routine verifies that there
   is sufficient room on the stack for its local variables, gets confused when
   the user's handler calls the stack-check routine before DS has been
   "corrected."  This can be avoided by using #pragma check_stack(off) to
   suppress stack checking for the handler.  I don't know if Turbo C has a
   corresponding problem.

Matt
"Our job is to rescue fires, not to put out your cat."