Xref: news2.mv.net comp.os.msdos.djgpp:5555
From: Charles Sandmann <sandmann AT clio DOT rice DOT edu>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Help please! protected mode "TSR"'s
Date: Sun, 30 Jun 1996 23:04:10 CDT
Organization: Rice University, Houston, Texas
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Message-ID: <31d74e3a.sandmann@clio.rice.edu>
References: <31D6CE63 DOT 353587C0 AT beattie DOT demon DOT co DOT uk>
Reply-To: sandmann AT clio DOT rice DOT edu
NNTP-Posting-Host: clio.rice.edu
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

> Basically I want to write a program that traps a HW interrupt while a
> DPMI32 program is running.

Two ways.
1) Write your trap program which grabs the HW interrupts, then have it
   system/spawn the program you want to watch.  Nice, simple, and easy
   to unload.  This is similar to the way the debuggers do it - they
   hook Int 31 and watch what the child asks DPMI to do for them.  See
   dbgcom.c for details on the hooking.
2) Write a DJGPP TSR.  This can be done with CWSDPMI and the tools you
   already have.  Basically you hook whatever HW/SW ints you want, then
   you call the simulate interrupt call with the dos TSR call (the 
   amount of memory to keep should be just the PSP plus whatever amount
   of transfer buffer you might need (usually zero, since you can use
   the last 128 bytes of the psp as a mini real mode buffer, if needed).
   You can't unload it, and you have to put up with the entire CWSDPMI
   footprint always resident.  This may also work under other DPMI
   providers but I haven't tested it.  I did test TSRs with CWSDPMI.