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te: Thu, 17 Apr 2003 11:25:26 -0700 From: "Jim" Subject: [SDL] Frame buffer patches... Would seem that GCC 3.2.2 promotes all signed values to unsigned if any single vlaue is unsigned in an expression... for instance when calculating an elo touch position....evertyhign is an (int) except for cach_vinfo.xres which is unsigned. THerefore if y ou reverse the SDL_ELO_MIN_X and SDL_ELO_MAX_X values the resulging negative value pegs the expression to it's max. Attached it the accumu lated patch to typecast the unsigned values to (int) - *dx = (cache_vinfo.xres - (cache_vinfo.xres * (input_x - ELO_MIN_X)) / width); + *dx = ((int)cache_vinfo.xres - ((int)cache_vinfo.xres * (input_x - ELO_MIN_X)) / width); and also to provide quite failure to operations which have the screen currently locked... The touch screen I'm using the original values were exactly opposite of any position I touched on the screen - evaluating the math the expr ession SHOULD have handled reversing the min and max values - and after casting the unsigned .xres and .yres to a signed int - worked well. .. Jim
author Sam Lantinga <slouken@libsdl.org>
date Tue, 24 Jan 2006 06:36:43 +0000
parents 173c063d4f55
children c9b51268668f
line wrap: on
line source

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2004 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga
    slouken@libsdl.org
*/

#ifdef SAVE_RCSID
static char rcsid =
 "@(#) $Id$";
#endif

/* Macros for determining the byte-order of this platform */

#ifndef _SDL_byteorder_h
#define _SDL_byteorder_h

/* The two types of endianness */
#define SDL_LIL_ENDIAN	1234
#define SDL_BIG_ENDIAN	4321

#ifdef __linux__
# include <endian.h>
# if BYTE_ORDER == LITTLE_ENDIAN
#  define SDL_BYTEORDER SDL_LIL_ENDIAN
# else
#  define SDL_BYTEORDER SDL_BIG_ENDIAN
# endif

#else

/* Pardon the mess, I'm trying to determine the endianness of this host.
   I'm doing it by preprocessor defines rather than some sort of configure
   script so that application code can use this too.  The "right" way would
   be to dynamically generate this file on install, but that's a lot of work.
 */
#if (defined(__i386__) || defined(__i386)) || \
     defined(__ia64__) || defined(WIN32) || \
    (defined(__alpha__) || defined(__alpha)) || \
    (defined(__arm__) || defined(__thumb__)) || \
    (defined(__sh__) || defined(__sh64__)) || \
    (defined(__mips__) && defined(__MIPSEL__)) || \
     defined(__SYMBIAN32__) || defined(__x86_64__) || \
     defined(__OS2__) || defined(__LITTLE_ENDIAN__)
#define SDL_BYTEORDER	SDL_LIL_ENDIAN
#else
#define SDL_BYTEORDER	SDL_BIG_ENDIAN
#endif

#endif /* __linux__ */

#endif /* _SDL_byteorder_h */