# HG changeset patch
# User Sam Lantinga <slouken@libsdl.org>
# Date 1078541886 0
# Node ID e7be95d758e8ba849ca6f13f8824a5e8ce0f01f4
# Parent  9cc9e2462d9a73f4d7fbccc0b080df7af6efd0f5
Date: Fri, 05 Mar 2004 16:08:01 +0000
From: Alan Swanson
Subject: Re: [SDL] Fatal signal when initiaize with USB joystick on 2.6.2 kern

On Fri, 2004-03-05 at 15:09, Sam Lantinga wrote:
> > Fred, how does the attached patch work for you? Do all your axes work?
>
> I think you meant the two lines to be reversed.
> I checked a more robust version of this into CVS.  Fred, can you see if
> it works?

You've misread the code. :-/

For coef[0] and coef[1], it is (values[2]+values[1]) / 2 and then add
or subtract values[4] to the answer.

diff -r 9cc9e2462d9a -r e7be95d758e8 src/joystick/linux/SDL_sysjoystick.c
--- a/src/joystick/linux/SDL_sysjoystick.c	Fri Mar 05 15:09:18 2004 +0000
+++ b/src/joystick/linux/SDL_sysjoystick.c	Sat Mar 06 02:58:06 2004 +0000
@@ -436,17 +436,15 @@
 				    joystick->hwdata->abs_correct[i].used = 0;
 				} else {
 				    joystick->hwdata->abs_correct[i].used = 1;
-				    t = (2 - values[4]);
-				    if ( t != 0 ) {
-				        joystick->hwdata->abs_correct[i].coef[0] = (values[2] + values[1]) / t;
-				    }
-				    t = (2 + values[4]);
-				    if ( t != 0 ) {
-				        joystick->hwdata->abs_correct[i].coef[1] = (values[2] + values[1]) / t;
-				    }
+				    joystick->hwdata->abs_correct[i].coef[0] =
+					(values[2] + values[1]) / 2 - values[4];
+				    joystick->hwdata->abs_correct[i].coef[1] =
+					(values[2] + values[1]) / 2 + values[4];
 				    t = ((values[2] - values[1]) / 2 - 2 * values[4]);
 				    if ( t != 0 ) {
 					joystick->hwdata->abs_correct[i].coef[2] = (1 << 29) / t;
+				    } else {
+					joystick->hwdata->abs_correct[i].coef[2] = 0;
 				    }
 				}
 				++joystick->naxes;