Alignment.h   [plain text]

/*
 *  Copyright (C) 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
 *
 *  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; see the file COPYING.LIB.  If not, write to
 *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 *  Boston, MA 02110-1301, USA.
 *
 */

#ifndef WTF_Alignment_h
#define WTF_Alignment_h

#include "Platform.h"
#include <algorithm>

namespace WTF {

#if COMPILER(GCC) || COMPILER(MINGW) || COMPILER(RVCT) || COMPILER(GCCE)
    #define WTF_ALIGN_OF(type) __alignof__(type)
    #define WTF_ALIGNED(variable_type, variable, n) variable_type variable __attribute__((__aligned__(n)))
#elif COMPILER(MSVC)
    #define WTF_ALIGN_OF(type) __alignof(type)
    #define WTF_ALIGNED(variable_type, variable, n) __declspec(align(n)) variable_type variable
#else
    #error WTF_ALIGN macros need alignment control.
#endif

#if COMPILER(GCC) && !COMPILER(INTEL) && (((__GNUC__ * 100) + __GNUC_MINOR__) >= 303)
    typedef char __attribute__((__may_alias__)) AlignedBufferChar; 
#else
    typedef char AlignedBufferChar; 
#endif

    template<size_t size, size_t alignment> struct AlignedBuffer;
    template<size_t size> struct AlignedBuffer<size, 1> { AlignedBufferChar buffer[size]; };
    template<size_t size> struct AlignedBuffer<size, 2> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 2);  };
    template<size_t size> struct AlignedBuffer<size, 4> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 4);  };
    template<size_t size> struct AlignedBuffer<size, 8> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 8);  };
    template<size_t size> struct AlignedBuffer<size, 16> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 16); };
    template<size_t size> struct AlignedBuffer<size, 32> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 32); };
    template<size_t size> struct AlignedBuffer<size, 64> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 64); };

    template <size_t size, size_t alignment>
    void swap(AlignedBuffer<size, alignment>& a, AlignedBuffer<size, alignment>& b)
    {
        for (size_t i = 0; i < size; ++i)
            std::swap(a.buffer[i], b.buffer[i]);
    }

}

#endif // WTF_Alignment_h