interlocked_variable.h

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/*
**  ClanLib SDK
**  Copyright (c) 1997-2009 The ClanLib Team
**
**  This software is provided 'as-is', without any express or implied
**  warranty.  In no event will the authors be held liable for any damages
**  arising from the use of this software.
**
**  Permission is granted to anyone to use this software for any purpose,
**  including commercial applications, and to alter it and redistribute it
**  freely, subject to the following restrictions:
**
**  1. The origin of this software must not be misrepresented; you must not
**     claim that you wrote the original software. If you use this software
**     in a product, an acknowledgment in the product documentation would be
**     appreciated but is not required.
**  2. Altered source versions must be plainly marked as such, and must not be
**     misrepresented as being the original software.
**  3. This notice may not be removed or altered from any source distribution.
**
**  Note: Some of the libraries ClanLib may link to may have additional
**  requirements or restrictions.
**
**  File Author(s):
**
**    Magnus Norddahl
*/


#pragma once

#ifndef WIN32
#include "../IOData/datatypes.h"
#endif

class CL_InterlockedVariable
{
public:
        CL_InterlockedVariable()
        {
                set(0);
        }

#ifdef WIN32
        LONG get()
        {
                return InterlockedCompareExchange(&val, 0, 0);
        }

        void set(LONG new_value)
        {
                InterlockedExchange(&val, new_value);
        }

        LONG increment()
        {
                return InterlockedIncrement(&val);
        }

        LONG decrement()
        {
                return InterlockedDecrement(&val);
        }

        bool compare_and_swap(LONG expected_value, LONG new_value)
        {
                return InterlockedCompareExchange(&val, new_value, expected_value) == expected_value;
        }

private:
        __declspec(align(32)) volatile LONG val;

#else
        int get()
        {
                return __sync_val_compare_and_swap(&val, 0, 0);
        }

        void set(int new_value)
        {
                __sync_lock_test_and_set(&val, new_value);
        }

        int increment()
        {
                return __sync_fetch_and_add(&val, 1) + 1;
        }

        int decrement()
        {
                return __sync_fetch_and_add(&val, -1) - 1;
        }

        bool compare_and_swap(int expected_value, int new_value)
        {
                return __sync_val_compare_and_swap(&val, new_value, expected_value) == expected_value;
        }

private:
        __attribute__ ((aligned(32))) volatile cl_int32 val;

#endif
};

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