ebml/EbmlEndian.h

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/****************************************************************************
** libebml : parse EBML files, see http://embl.sourceforge.net/
**
** <file/class description>
**
** Copyright (C) 2002-2010 Steve Lhomme.  All rights reserved.
**
** This file is part of libebml.
**
** 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.
** 
** 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
**
** See http://www.matroska.org/license/lgpl/ for LGPL licensing information.
**
** Contact license@matroska.org if any conditions of this licensing are
** not clear to you.
**
**********************************************************************/

#ifndef LIBEBML_ENDIAN_H
#define LIBEBML_ENDIAN_H

#include <algorithm>
#include <cstring>

#include "EbmlConfig.h" // contains _ENDIANESS_

START_LIBEBML_NAMESPACE

enum endianess {
    big_endian,   
    little_endian 
};

template<class TYPE, endianess ENDIAN> class Endian
{
    public:
            Endian() {}

            Endian(const TYPE value)
            {
                    memcpy(&platform_value, &value, sizeof(TYPE));
                    process_endian();
            }

            inline Endian & Eval(const binary *endian_buffer)
            {
                //endian_value = *(TYPE *)(endian_buffer);
                memcpy(&endian_value, endian_buffer, sizeof(TYPE));     // Some (all?) RISC processors do not allow reading objects bigger than 1 byte from non-aligned addresses, and endian_buffer may point to a non-aligned address.
                process_platform();
                return *this;
            }

            inline void Fill(binary *endian_buffer) const
            {
                //*(TYPE*)endian_buffer = endian_value;
                memcpy(endian_buffer, &endian_value, sizeof(TYPE)); // See above.
            }

            inline operator const TYPE&() const { return platform_value; }
    //  inline TYPE endian() const   { return endian_value; }
            inline const TYPE &endian() const       { return endian_value; }
            inline size_t size() const   { return sizeof(TYPE); }
            inline bool operator!=(const binary *buffer) const {return *((TYPE*)buffer) == platform_value;}

#if defined(EBML_STRICT_API)
    private:
#else
    protected:
#endif
            TYPE platform_value;
            TYPE endian_value;

            inline void process_endian()
            {
                endian_value = platform_value;
#ifdef WORDS_BIGENDIAN
                if (ENDIAN == little_endian)
#else  // _ENDIANESS_
                if (ENDIAN == big_endian)
#endif // _ENDIANESS_
                    std::reverse(reinterpret_cast<uint8*>(&endian_value),reinterpret_cast<uint8*>(&endian_value+1));
            }

            inline void process_platform()
            {
                platform_value = endian_value;
#ifdef WORDS_BIGENDIAN
                if (ENDIAN == little_endian)
#else  // _ENDIANESS_
                if (ENDIAN == big_endian)
#endif // _ENDIANESS_
                    std::reverse(reinterpret_cast<uint8*>(&platform_value),reinterpret_cast<uint8*>(&platform_value+1));
            }
};

END_LIBEBML_NAMESPACE

#endif // LIBEBML_ENDIAN_H

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