Xref:	news2.mv.net comp.os.msdos.djgpp:2353
From:	Charles Sandmann <sandmann AT clio DOT rice DOT edu>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Learning to use DPMI?
Date:	Sun, 31 Mar 1996 16:54:05 CST
Organization:	Rice University, Houston, Texas
Lines:	15
Message-ID:	<315f0d0d.sandmann@clio.rice.edu>
References:	<MAILQUEUE-101 DOT 960328092713 DOT 352 AT merlin DOT e-technik DOT uni-erlangen DOT de>
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

> and do some calulations, but with a frequency of 36kHz. So does 

Let's take a few potential cases:

1) When the HW interrupt comes in, you will (almost) always be in protected
   mode.  In this case, manually hooking the interrupt with GAS code and
   avoiding the wrappers, you should be in good shape, especially if you 
   use a non-ring-switching DPMI like CWSDPR0.  EOI the PIC yourself, don't
   chain.
2) When the HW interrupt comes in, you will frequently be in RM.  If this
   is the case, you need to probably write a RM handler, and hook it after
   the PM one so you have routines which neither forces a mode swap.
3) If case 2) still isn't fast enough for you, there is a copy of Tran's
   PMODE for DJGPP in development which might be a bit faster than CWSDPR0
   in overhead for handling interrupts. 

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