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Path: utzoo!utgpu!water!watmath!clyde!rutgers!cbmvax!phillip
From: phillip@cbmvax.UUCP
Newsgroups: comp.sys.amiga
Subject: Re: Need help: Interrupt servers & Graphics calls
Message-ID: <1842@cbmvax.cbmvax.cbm.UUCP>
Date: Wed, 6-May-87 16:17:30 EDT
Article-I.D.: cbmvax.1842
Posted: Wed May  6 16:17:30 1987
Date-Received: Fri, 8-May-87 05:15:04 EDT
References: <1089@crash.CTS.COM>
Distribution: world
Organization: Commodore Technology, West Chester, PA
Lines: 41

in article <1089@crash.CTS.COM>, mercurio@crash.CTS.COM (Phil Mercurio) says:
> 
> [-]
> 
> 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().  
> 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.
It's not nice to push too many cycles in a interrupt!  
Since ScrollRaster() calls LockLayer() which in turn calls ObtainSemaphore
which calls Wait() you cannot safely use scrollraster() in a interrupt. I
have not checked BltBitMap(), but I would probably come to the same conclusion.
-phil 		BTW, important info follows signature...
==============================================================================
Phillip (Flip)Lindsay - Commodore Business Machines - Amiga Technical Support
  UUCP: {ihnp4|seismo|caip}!cbmvax!phillip      - Phone: (215) 431-9180
  No warranty is implied or otherwise given in the form of suggestion or 
  example. Any opinions found here are of my making.
------------------
Here is something Andy Finkel Posted a while back:

  These Exec functions should never be used from interrupt code:

    SuperState, UserState, SetIntVector, AddIntServer, RemIntServer
    Allocate, Deallocate, AllocMem, AllocAbs, FreeMem, AvailMem
    AllocEntry, FreeEntry, AddTask, RemTask, FindTask(0)
    SetSignal, SetExcept, Wait, AllocSignal, FreeSignal, AllocTrap
    FreeTrap, AddPort, RemPort, WaitPort, FindPort, AddLibrary,
    RemLibrary, OpenLibrary, CloseLibrary, SetFunction, SumLibrary
    AddDevice, RemDevice, OpenDevice, CloseDevice, DoIO, SendIO,
    CheckIO, WaitIO, AbortIO, AddResource, RemResource, OpenResource
 
  Using these in interrupt code may result in a NOP, or in some
  cases, total obliteration.  Don't take any chances; check your
  code. 

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