From:	mauch AT uni-duisburg DOT de (Michael Mauch)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: timer interrupt - sample code anyone?
Date:	Wed, 23 Apr 1997 18:32:11 +0200
Organization:	Home, sweet home (via Gesamthochschule Duisburg)
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Distribution:	world
Message-ID:	<5jldi9$m5o@h20-hrze.uni-duisburg.de>
References:	<199704221040 DOT MAA11513 AT gilberto DOT physik DOT rwth-aachen DOT de>
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To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

On Tue, 22 Apr 1997 10:40:27 GMT, Christoph Kukulies
<kuku AT gilberto DOT physik DOT rwth-aachen DOT de> wrote:

> I need a (relatively fine grained) time base and I'm thinking of using
> the system timer chip for this purpose. Never programmed that chip 
> before and never dealt with hardware interrupts under djgpp.
> 
> Can anyone point me to some sample code?

The DJGPP FAQ says:

>>>
check out the example of hooking the timer interrupt, e.g.
ftp://ftp.coast.net/Coast/msdos/c/pctime13.zip.
<<<

But first have a look at the uclock() function mentioned in the libc
info file:

>>>
`uclock' is provided for very high-resulution timing.  It is currently
accurate to better than 1 microsecond (actually about 840 nanoseconds).
<<<

> The timer should interrupt at a rate of 10 KHz and the interrupt
> service routine is just supposed to increment a global 32 bit value.
> 
> Hope, the 10KHz doesn't bring down the overall system performance.

10kHz interrupt rate sound very hard - most likely it's easier to call
uclock() just when you need it instead of incrementing a counter all the
time.

Regards...
		Michael

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