/*
 * Copyright (C) 2008 by Marc Boris Duerner
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * 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 Library
 * 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 Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include <cxxtools/atomicity.gcc.x86_64.h>
#include <unistd.h>

namespace cxxtools {


atomic_t atomicGet(volatile atomic_t& val)
{
    asm volatile ("mfence" : : : "memory");
    return val;
}


void atomicSet(volatile atomic_t& val, atomic_t n)
{
    val = n;
    asm volatile ("mfence" : : : "memory");
}


atomic_t atomicIncrement(volatile atomic_t& val)
{
        static const atomic_t d = 1;
        atomic_t tmp;

        asm volatile ("lock; xaddq %0, %1"
                      : "=r" (tmp), "=m" (val)
                      : "0" (d), "m" (val));

        return tmp+1;
}

atomic_t atomicDecrement(volatile atomic_t& val)
{
        static const atomic_t d = -1;
        volatile register atomic_t tmp;

        asm volatile ("lock; xaddq %0, %1"
                      : "=r" (tmp), "=m" (val)
                      : "0" (d), "m" (val));

        return tmp-1;
}


atomic_t atomicExchangeAdd(volatile atomic_t& val, atomic_t add)
{
        volatile register atomic_t ret;

        asm volatile ("lock; xaddq %0, %1"
                      : "=r" (ret), "=m" (val)
                      : "0" (add), "m" (val));

        return ret;
}


atomic_t atomicExchange(volatile atomic_t& val, atomic_t new_val)
{
        volatile register atomic_t ret;

        // using cmpxchg and a loop here on purpose
        asm volatile ("1:; lock; cmpxchgq %2, %0; jne 1b"
                      : "=m" (val), "=a" (ret)
                      : "r" (new_val), "m" (val), "a" (val));

        return ret;
}


void* atomicExchange(void* volatile& val, void* new_val)
{
        void* ret;

        asm volatile ("1:; lock; cmpxchgq %2, %0; jne 1b"
                      : "=m" (val), "=a" (ret)
                      : "r" (new_val), "m" (val), "a" (val));

        return ret;
}


atomic_t atomicCompareExchange(volatile atomic_t& dest, atomic_t exch, atomic_t comp)
{
        volatile register atomic_t old;

        asm volatile ("lock; cmpxchgq %2, %0"
                      : "=m" (dest), "=a" (old)
                      : "r" (exch), "m" (dest), "a" (comp));
        return old;
}


void* atomicCompareExchange(void* volatile& dest, void* exch, void* comp)
{
        void* old;

        asm volatile ("lock; cmpxchgq %2, %0"
                      : "=m" (dest), "=a" (old)
                      : "r" (exch), "m" (dest), "a" (comp));
        return old;
}

} // namespace cxxtools
