Path: utzoo!utgpu!water!watmath!clyde!att!rutgers!ucsd!ucsdhub!jack!crash!pnet01!haitex
From: haitex@pnet01.cts.com (Wade Bickel)
Newsgroups: comp.sys.amiga.tech
Subject: Re: double buffering via interrupts
Message-ID: <3390@crash.cts.com>
Date: 2 Sep 88 09:56:44 GMT
Sender: news@crash.cts.com
Organization: People-Net [pnet01], El Cajon CA
Lines: 33


        LoadView() works fine inside an interrupt server.  Howerever I think
it is considered unsafe to do so because, while processing the interrupt, the
68000 is in Supervisor mode, and calls to the graphics library are supposed
to be made from the User mode.

        I also believe that LoadView() takes effect durring the VBlank, as
one of the servers on the chain (empirical evidence only).  Thus if your
server sits behind the LoadView() server then the swap will not actually
take effect until the next VBlank.

        As Leo pointed out, you should probably send a message, and have
a software interrupt (soft interrupts are in User mode) handler do the
LoadView().  However, soft interrupts are much slower than hardware
interrupts (if my tests were not flawed in some way), so it's up to you
which way to do it.


                                                Good Luck,


                                                        Wade.

PS:  I hope this information is valid, but please experiment to confirm this.
   Much of my picture of what is going on is built upon the results of 
   repeated attemts to achieve a goal.  Through these attempts I gain
   information, but rarely have time to confirm it rigorously.  So please
   take all this with a grain of salt.  -W.

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