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From: dillon@CORY.BERKELEY.EDU (Matt Dillon)
Newsgroups: comp.sys.amiga
Subject: Re: Need help: Interrupt servers & Graphics calls
Message-ID: <8705061729.AA22995@cory.Berkeley.EDU>
Date: Wed, 6-May-87 13:29:47 EDT
Article-I.D.: cory.8705061729.AA22995
Posted: Wed May  6 13:29:47 1987
Date-Received: Sat, 9-May-87 00:59:28 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
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>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().  

	Most library calls expect to be called from a task or process, NOT
from an actual interrupt routine.  The reason is simple.... the library
call may have to 'sleep' waiting for access to the layers, blitter, or any
number of things.

	Needless to say, Interrupt service routines are NOT normal tasks,
do NOT get preempted by normal tasks, and consequently you CANNOT sleep
from within them. 

	I believe that you can send a signal to some task/process from the
Interrupt Service Routine, and then have that task/process do the actual
Graphics library calls.

				-Matt