Path: chuka.playstation.co.uk!scea!peter_alau@playstation.sony.com
From: Elliott Lee <tenchi@jps.net>
Newsgroups: scea.yaroze.beginners
Subject: Re: JOYSTICK FUNCTION
Date: Fri, 17 Jul 1998 11:16:50 -0700
Organization: Cisco Systems
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First of all, you might want to try my pad routine library (other people
have also written some good ones) instead of using the book's, but it
works similar:

        http://www.scea.sony.com/net/yaroze/pages/ftp/elee2/padstuff.zip

(This corrects a #define error in the pad.h file.)

Anyways, what happens is that every frame the controller is polled and
the status stored in a fixed location in memory.  The PadRead() just
references that area.  But what it returns is a 32-bit integer which
looks like this:

	bits:	 31 .. 16          15..0
	use:	Controller1	Controller2

The PadRead() just takes the relevant 2 bytes from the 2 controller
pad status buffers and returns it to you in a form which you can then
do bit testing on.

If you want to see what I mean in real-time, you can do what I first
did: make a simple program that just spits out the bit values to the
screen or to STDOUT (via printf()).

So, the defines you see in the Sony demo's pad.h are for controller 1.
To get the bits for controller 2, just shift the mask over 16 bits to
the left.

Confused?  Did this help?

Michael Briere wrote:
> 
> Hi! I need some explanation on how the joystick function u_long
> PadRead(void) works.
> Here's the complete function:
> 
> u_long PadRead(void)
> {
>     return(~(*(bb0+3) | *(bb0+2) <<8 | *(bb1 +3) << 16 | *(bb1+2)
> <<24));
> }
> 
> I understand that this reads the joystick and returns a value equal to
> the button that was pressed as shown in the yellow manual. However I'd
> love it if someone could show me the math behind this with an example.
> ie. if PADLstart (bit 11) is pressed on joystick #1 which should be put
> in the *bb0 pointer. I could spend hours trying to figure this out for
> myself, but I'd really appreciate your help. I know the function works,
> but I make it a habit of understanding the code I use in my programs.
> Thanks!

-- 
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