Path: utzoo!attcan!uunet!cbmvax!higgin
From: higgin@cbmvax.UUCP (Paul Higginbottom MKT)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Timer question
Message-ID: <5584@cbmvax.UUCP>
Date: 28 Dec 88 18:20:24 GMT
References: <427@tekn01.chalmers.se> <3210@amiga.UUCP> <3137@sugar.uu.net>
Reply-To: higgin@cbmvax.UUCP (Paul Higginbottom MKT)
Organization: Commodore Technology, West Chester, PA
Lines: 45

In article <3137@sugar.uu.net> karl@sugar.uu.net (Karl Lehenbauer) writes:
$In article <3210@amiga.UUCP>, kodiak@amiga.UUCP (Robert R. Burns) writes:
$> ...for CIAB (note that the timers on CIAA are hard allocated, only timers
$> A & B on CIAB are available to allocate).
$You mean there is a CIA timer we can grab that isn't used for the serial
$port or timer.device?
$
$A problem with timer.device is that there isn't a "periodic schedule"; that is,
$I can get a mesage, signal, etc, in a certain number of milliseconds but there
$is no auto-reschedule, consequently I have to reschedule and it induces timing
$delays, even if I'm quick about it.  Compensation is possible if I were to
$count vertical blanks and examine the vertical and horizontal beam position
$to see how late I was, and compute an offset, but this is kludge-city.

Funny you should ask for this, I wrote some code to do this that's included in
Amigamail (not sure which issue, but it's either just been released or will be
shortly).

$The application is a MIDI sequencer and I need more accurate and more precise
$timing than I can currently get through timer.device, too.  

That's why I wrote the code (MIDI applications), and it's fairly obvious
how to modify for timestamping (I use the "autotimer" value in the serial
input handler to timestamp the data "no matter what's going on".

$I am considering timestamping incoming events when recording by reading the 
$video beam's vertical and horizontal positions.  It's a pain to pass this
$through the midi library, though, so I don't know if I'll do recording as
$a "back door" thing or take a certain accuracy hit to gain consistency --
$I currently have a midi module that generates midi clock messages as the
$sequencer timing source and, by not connecting the clock module to the
$sequencer, the sequencer can accept timing clocks from midi in.  blah blah blah

See above.

$-- "We've been following your progress with considerable interest, not to say
$-- contempt."  -- Zaphod Beeblebrox IV
$-- uunet!sugar!karl, Unix BBS (713) 438-5018

The only thing (I know of) possibly wrong with the code I put in Amigamail is
that it's not doing the allocation of a cia as per Matt's recent excellent
example.

	Regards,
	Paul.