atomic_poor_man.h

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/** @file
 *  @author Bram de Greve (bram@cocamware.com)
 *  @author Tom De Muer (tom@cocamware.com)
 *
 *  *** BEGIN LICENSE INFORMATION ***
 *  
 *  The contents of this file are subject to the Common Public Attribution License 
 *  Version 1.0 (the "License"); you may not use this file except in compliance with 
 *  the License. You may obtain a copy of the License at 
 *  http://lass.sourceforge.net/cpal-license. The License is based on the 
 *  Mozilla Public License Version 1.1 but Sections 14 and 15 have been added to cover 
 *  use of software over a computer network and provide for limited attribution for 
 *  the Original Developer. In addition, Exhibit A has been modified to be consistent 
 *  with Exhibit B.
 *  
 *  Software distributed under the License is distributed on an "AS IS" basis, WITHOUT 
 *  WARRANTY OF ANY KIND, either express or implied. See the License for the specific 
 *  language governing rights and limitations under the License.
 *  
 *  The Original Code is LASS - Library of Assembled Shared Sources.
 *  
 *  The Initial Developer of the Original Code is Bram de Greve and Tom De Muer.
 *  The Original Developer is the Initial Developer.
 *  
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 *  Copyright (C) 2004-2022 the Initial Developer.
 *  All Rights Reserved.
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 *
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 *  GNU General Public License Version 2 or later (the GPL), in which case the 
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 *  of your version of this file only under the terms of the GPL and not to allow 
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 *  *** END LICENSE INFORMATION ***
 */
 
#define LASS_UTIL_ATOMIC_HAVE_POOR_MANS_IMPL
 
namespace lass
{
namespace util
{
namespace impl
{
 
class LASS_DLL PoorMansGlobalAtomicLock
{
public:
    PoorMansGlobalAtomicLock();
    ~PoorMansGlobalAtomicLock();
};
 
template <size_t byteSize>
struct AtomicOperations
{
    LASS_META_ASSERT(byteSize == 1 || byteSize == 2 || byteSize == 4 || byteSize == 8, bytesize_should_be_1_2_4_or_8);
    
    template <typename T>
    static bool compareAndSwap(volatile T& dest, T expectedValue, T newValue)
    {
        PoorMansGlobalAtomicLock LASS_UNUSED(lock);
        const T old = dest;
        if (old != expectedValue)
        {
            return false;
        }
        dest = newValue;
        return true;
    }
 
    template <typename T1, typename T2> inline 
    static bool LASS_CALL compareAndSwap(
            volatile T1& dest1, T1 expected1, T2 expected2, T1 new1, T2 new2)
    {
        PoorMansGlobalAtomicLock LASS_UNUSED(lock);
        volatile T2& dest2 = *reinterpret_cast<volatile T2*>((&dest1) + 1);
        if (dest1 != expected1 || dest2 != expected2)
        {
            return false;
        }
        dest1 = new1;
        dest2 = new2;
        return true;
    }
 
    template <typename T> inline
    static void LASS_CALL increment(volatile T& value)
    {
        PoorMansGlobalAtomicLock LASS_UNUSED(lock);
        ++value;
    }
 
    template <typename T> inline
    static void LASS_CALL decrement(volatile T& value)
    {
        PoorMansGlobalAtomicLock LASS_UNUSED(lock);
        --value;
    }
};
 
}
}
}
 
// EOF