Path: utzoo!utgpu!attcan!uunet!lll-winken!ames!ucsd!sdcc6!sdcc10!cs161agc
From: cs161agc@sdcc10.ucsd.EDU (John Schultz)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Simple questions/Modula-2
Message-ID: <48@sdcc10.ucsd.EDU>
Date: 14 Jan 89 04:03:21 GMT
References: <341@csd4.milw.wisc.edu>
Reply-To: cs161agc@sdcc10.ucsd.edu.UUCP (John Schultz)
Organization: University of California, San Diego
Lines: 68

In article <341@csd4.milw.wisc.edu> gregm@csd4.milw.wisc.edu (Gregory Mumm) writes:
>
>   How do you read the Joystick port? The only manual I have is the 

Here is modula-2 example code to read the joystick.  It reads the
hardware directly, and is (was) legal when I wrote it (according to
Bob).    

  This is as fast and concise as I could get, without reverting to assembly...


DEFINITION MODULE joystick;

PROCEDURE readjoystick(VAR x,y           : INTEGER;
                       VAR buttonpressed : BOOLEAN;
                       port              : CARDINAL);

END joystick.


IMPLEMENTATION MODULE joystick;

FROM SYSTEM IMPORT ADDRESS,SHIFT;
FROM CIAHardware IMPORT ciaa,CIABITS;
FROM CustomHardware IMPORT custom;

CONST
  one = BITSET(1);

TYPE
  bitsetptr = POINTER TO BITSET;  

VAR
  buttonloc : POINTER TO CIABITS;
  joydat    : ARRAY[0..1] OF bitsetptr;
  j         : BITSET;  

PROCEDURE readjoystick(VAR x,y           : INTEGER;
                       VAR buttonpressed : BOOLEAN;
                       port              : CARDINAL);

BEGIN

  j := joydat[port]^;

  x := CARDINAL(SHIFT(j,-1) * one) -
       CARDINAL(SHIFT(j,-9) * one); 

  y := CARDINAL(SHIFT(SHIFT(j,1) / j,-1) * one) -
       CARDINAL(SHIFT(SHIFT(j,1) / j,-9) * one);

  buttonpressed := NOT((6+port) IN buttonloc^);

END readjoystick;

BEGIN
  buttonloc := ADDRESS(ciaa^.pra);
  WITH custom^ DO
    joydat[0] := bitsetptr(joy0dat);
    joydat[1] := bitsetptr(joy1dat);
  END; 
END joystick.
 

Hope this helps,


  John Schultz