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From: koster@cory.Berkeley.EDU.UUCP
Newsgroups: comp.sys.amiga.tech
Subject: Problem with double-buffering and some 1-second interrupt annoyance
Message-ID: <4213@pasteur.Berkeley.Edu>
Date: 1 Jul 88 20:30:12 GMT
Sender: news@pasteur.Berkeley.Edu
Reply-To: koster@cory.Berkeley.EDU.UUCP (Kevin Oster)
Organization: University of California, Berkeley
Lines: 29


   I am doing a double-buffered display just like it says in ROM KERNAL
VOLUME 1. I have created two sets of copper lists and one view structure
and am putting the list I want into the v_LOFcprlist then doing a loadview
when I want the display to switch.
   It may take more than 1/60th of a second to draw the hidden picture, so
I have set up a vertical blank interrupt server that maintains a counter
of fields. When it gets up to 3, it clears the counter and sends the main
program a signal. One mystery is this interrupt. I must AddIntServer a
structure that has priority 127. If I put it at 0 or -60 (Like one of the
examples in RKM1) I get nothing out of it, as if the system servers do not
let the chain continue.
  The main program does as follows: switch the v_LOFcprlist in the view
structure, switch so that I will write to the other bitmap, do a LoadView,
then wait for the above signal sent from the interrupt server. Then I
actually do the writing into the hidden planes, and when that is done
I continue the loop.
  Everything works fine, everything is smooth, except at about one second
intervals I get a little flicker, as if it is displaying the bitmap I am
working on just for a single frame.
  My theory is that at one second intervals the Amiga does some incredibly
lengthy maintainance of say the disk drives, internal clock, whatever, that
takes a long time. What I want to know is how can I fix this problem?
What are these housekeeping functions, and is it ok if I make my server
the end of the chain, such that no one else gets vertical blank timings?
Why do I have to set the VB server's priority at 127?
  Thanks very much in advance, of course.

koster@cory.berkeley.edu