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From: hedley AT inferno DOT cs DOT bris DOT ac DOT uk (David Hedley)
Subject: Re: lots of interrupts per sec with DJGPP
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Reply-To: David DOT Hedley AT bris DOT ac DOT uk
Organization: Computer Science Dept. University of Bristol, England
References: <DFH8HE DOT 7x AT uns DOT bris DOT ac DOT uk> <306712ca DOT sandmann AT clio DOT rice DOT edu>
Date: Tue, 26 Sep 1995 13:38:42 GMT
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To: djgpp AT sun DOT soe DOT clarkson DOT edu
Dj-Gateway: from newsgroup comp.os.msdos.djgpp

Charles Sandmann (sandmann AT clio DOT rice DOT edu) wrote:
: > card. The card generates around 10,000 interrupts per second. I am using a
: > Is this likely to be a problem with djgpp? 

: Maybe. If you stay in protected mode most of the time, don't chain the 
: interrupt, and don't use the wrappers (write your routine in GAS) you 
: should be OK.  You need to lock all of the memory you plan to touch.

OK cheers!

After a little experimentation using the timer interrupt
I discovered the following when run on a PCI 66Mhz 486:

          Using standard go32 PM wrapper      Using simple asm wrapper

Mode

   XMS    3000-4000                           70000-75000


   DPMI   8000-9000                           70000-75000


The numbers give the maximum number of interrupts per second a simple
protected mode interrupt routine could cope with before either
crashing or hanging.

Is there any reason why the standard interrupt wrapper routines are
so slow? It's not terribly important for me as I can get my required
10,000 ints per sec quite happily now using a simple assembler wrapper
cribbed from serial.c!

David
--
 David Hedley (David DOT Hedley AT bris DOT ac DOT uk)
 http://www.cs.bris.ac.uk/~hedley/
 finger hedley AT cs DOT bris DOT ac DOT uk for PGP key
 Computer Graphics Group | University of Bristol | UK                      
 *** All opinions expressed are mine and mine alone ***