oro_system.h

/***************************************************************************
  tag: Peter Soetens  Mon Jan 10 15:59:15 CET 2005  oro_system.h 

                        oro_system.h -  description
                           -------------------
    begin                : Mon January 10 2005
    copyright            : (C) 2005 Peter Soetens
    email                : peter.soetens@mech.kuleuven.ac.be
 
 ***************************************************************************
 *   This library is free software; you can redistribute it and/or         *
 *   modify it under the terms of the GNU General Public                   *
 *   License as published by the Free Software Foundation;                 *
 *   version 2 of the License.                                             *
 *                                                                         *
 *   As a special exception, you may use this file as part of a free       *
 *   software library without restriction.  Specifically, if other files   *
 *   instantiate templates or use macros or inline functions from this     *
 *   file, or you compile this file and link it with other files to        *
 *   produce an executable, this file does not by itself cause the         *
 *   resulting executable to be covered by the GNU General Public          *
 *   License.  This exception does not however invalidate any other        *
 *   reasons why the executable file might be covered by the GNU General   *
 *   Public License.                                                       *
 *                                                                         *
 *   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     *
 *   Lesser General Public License for more details.                       *
 *                                                                         *
 *   You should have received a copy of the GNU General Public             *
 *   License along with this library; if not, write to the Free Software   *
 *   Foundation, Inc., 59 Temple Place,                                    *
 *   Suite 330, Boston, MA  02111-1307  USA                                *
 *                                                                         *
 ***************************************************************************/
 
#include "../../rtt-config.h"

// do not rely on system headers :
// i386 :
#ifndef __ASM_ORO_SYSTEM_H
#define __ASM_ORO_SYSTEM_H

// this is required for multi-core cpus
// Export ORO_LOCK_PREFIX, just like the classical bitops.h does.
#ifndef CONFIG_FORCE_UP
#define ORO_LOCK_PREFIX "lock ; "
#else
#define ORO_LOCK_PREFIX ""
#endif

struct oro__xchg_dummy { unsigned long a[100]; };
#define oro__xg(x) ((struct oro__xchg_dummy *)(x))

static inline unsigned long __oro_cmpxchg(volatile void *ptr, unsigned long old,
                                      unsigned long _new, int size)
{
    unsigned long prev;
    switch (size) {
    case 1:
        __asm__ __volatile__(ORO_LOCK_PREFIX "cmpxchgb %b1,%2"
                     : "=a"(prev)
                     : "q"(_new), "m"(*oro__xg(ptr)), "0"(old)
                     : "memory");
        return prev;
    case 2:
        __asm__ __volatile__(ORO_LOCK_PREFIX "cmpxchgw %w1,%2"
                     : "=a"(prev)
                     : "q"(_new), "m"(*oro__xg(ptr)), "0"(old)
                     : "memory");
        return prev;
    case 4:
        __asm__ __volatile__(ORO_LOCK_PREFIX "cmpxchgl %1,%2"
                     : "=a"(prev)
                     : "q"(_new), "m"(*oro__xg(ptr)), "0"(old)
                     : "memory");
        return prev;
    }
    return old;
}

#define oro_cmpxchg(ptr,o,n)\
    ((__typeof__(*(ptr)))__oro_cmpxchg((ptr),(unsigned long)(o),\
                    (unsigned long)(n),sizeof(*(ptr))))

#endif // __ASM_ORO_SYSTEM_H