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From: cs162ffl@sdcc18.ucsd.EDU (John Schultz)
Newsgroups: comp.sys.amiga
Subject: Re: Grabbing the mouse port.
Message-ID: <802@sdcc18.ucsd.EDU>
Date: Wed, 11-Nov-87 19:47:09 EST
Article-I.D.: sdcc18.802
Posted: Wed Nov 11 19:47:09 1987
Date-Received: Sat, 14-Nov-87 05:19:35 EST
References: <1041@sugar.UUCP>
Reply-To: cs162ffl@sdcc18.ucsd.edu.UUCP (John Schultz)
Organization: University of California, San Diego
Lines: 22


  I've written a very fast a simple routine that reads 
$DFF00A (port 0), $DFF00C (port 1), $BFE001 (read bit 6 for port 0
and bit 7 for port 1) for the button presses.
  All you have to do is read the appropriate bits (and xor a few).
Just read the Hardware manual Appendix_A Page 13.
  Takes only a couple of lines of C code to implement, more for
Modula-2.
  I used the RKM example and it was quite a bit slower, incurred
more overhead, and took over three pages of C code.  It also would
not work with port 0 while intuition was hooked up.

  I have used this routine in all of my games, which all run
perfectly on the 500, 1000, and 2000.
  I realize that future machines may have a different absolute
memory locations, but since it works with all three of the current
models, I am content with the inherent drawbacks of accessing a
peripheral device directly.
  Of course, if one is just hacking around, then there is no
problem.

  John