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From: mercurio@crash.CTS.COM (Phil Mercurio)
Newsgroups: comp.sys.amiga
Subject: Need help: Interrupt servers & Graphics calls
Message-ID: <1089@crash.CTS.COM>
Date: Wed, 6-May-87 04:37:44 EDT
Article-I.D.: crash.1089
Posted: Wed May  6 04:37:44 1987
Date-Received: Sat, 9-May-87 00:39:53 EDT
Reply-To: mercurio@crash.CTS.COM (Phil Mercurio)
Distribution: world
Organization: Crash TS, El Cajon, CA
Lines: 30

[-]

I need help with a function being called by another function attached
to the vertical blanking interval interrupt.  The purpose of the
function is to scroll text onto the screen; it calls ScrollRaster()
and BltBitMap().  

The function works perfectly when not called from within the interrupt
server; it also works when called from within the server with the
ScrollRaster() and BltBitMap() calls removed.  With the graphics calls
in place, it still works if I have the text scroll on infrequently. 
However, if I try to scroll on a couple of lines of text in close
succession, I get a really neat fireworks display and a guru of
0000000B.<very low address, around 2C00>.  Pretty, but not what the
program is supposed to do.  

Is there some trick to calling graphics library routines from within
an interrupt server?  I've tried adding WaitBlit() calls (no effect),
OwnBlitter() and DisownBlitter() calls (hangs the system, requiring 
the old three-finger salute (Ctrl-Amiga-Amiga)), and Disable() -
Enable() pairs (again, no effect).  Any help or suggestions of new
things to try would be greatly appreciated.

Thanks in advance,

Phil Mercurio

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