Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!oliveb!amiga!kodiak
From: kodiak@amiga.UUCP (Robert R. Burns)
Newsgroups: comp.sys.amiga
Subject: Re: Reading the gameport.device
Message-ID: <2431@amiga.UUCP>
Date: 16 Jun 88 18:21:03 GMT
References: <8806151701.AA08881@jade.berkeley.edu>
Reply-To: kodiak@tooter.UUCP (Robert Burns)
Organization: Commodore-Amiga Inc, Los Gatos CA
Lines: 37

In article <8806151701.AA08881@jade.berkeley.edu> BBOURBIN@UMDD.BITNET (Brett S Bourbin) writes:
>
>The program I am using this for is a loop which reads the mouse port, if there
>is a message, processes the mouse movement or triggers, and then updates the
>grapgics according to results.  So I want to be able to READ the gameport each
>time through the loop.  Now, here comes the real question {AT LAST! 8^) }:
>
>   Can I use the GetMsg() call, since it will return a zero if there is no
>   messages waiting, and if I get a result on the first call to the routine,
>   do more until I get a zero?  I want to do this because I only need the
>   latest event.  Is this the best way of doing what I want, or should I do
>   a CheckIO() call and if I get a non-zero return then do a GetMsg()?

    The simple answer is yes, you can just use GetMsg().  The next complication
    is that you can set the MsgPort.mp_Flags to PA_IGNORE so the signal isn't
    sent to you, because you're polling for it.  Furthermore, you will get no
    more messages than you've sent READEVENT commands for (you supplied the
    buffer, remember).  If you've sent only one command, and nothing else
    shares the message port, you know there are only zero or one messages
    at the port.  But this all reeks of a busy loop.  I hope the global context
    of your GetMsg call makes that not so.  If it's in a top of frame interrupt
    list, make it low priority: the gameport is at priority zero so you'ld want
    to be lower than that so you're not getting reports that are already a
    frame old.
>
>Now about the triggers- I set the mouse to report movements >= 2 in any
>direction, also for all up and down mouse buttons.  Can I set the timeout
>value in the trigger structure to some value so it will never timeout?
    
    A timeout value of zero is the special case that never triggers that
    you want to set.

- Kodiak
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