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qendian.h

/****************************************************************************
**
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**
** This file is part of the QtCore module of the Qt Toolkit.
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** License versions 2.0 or 3.0 as published by the Free Software
** Foundation and appearing in the files LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file.  Alternatively you may (at
** your option) use any later version of the GNU General Public
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** (or its successors, if any) and the KDE Free Qt Foundation. In
** addition, as a special exception, Trolltech gives you certain
** additional rights. These rights are described in the Trolltech GPL
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** GPL_EXCEPTION.txt in this package.
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****************************************************************************/

#ifndef QENDIAN_H
#define QENDIAN_H

#include <QtCore/qglobal.h>

QT_BEGIN_HEADER

QT_MODULE(Core)

/*
 * ENDIAN FUNCTIONS
*/
inline void qbswap_helper(const uchar *src, uchar *dest, int size)
{
    for (int i = 0; i < size ; ++i) dest[i] = src[size - 1 - i];
}

/*
 * qbswap(const T src, const uchar *dest);
 * Changes the byte order of \a src from big endian to little endian or vice versa
 * and stores the result in \a dest.
 * There is no alignment requirements for \a dest.
*/
template <typename T> inline void qbswap(const T src, uchar *dest)
{
    qbswap_helper(reinterpret_cast<const uchar *>(&src), dest, sizeof(T));
}

// Used to implement a type-safe and alignment-safe copy operation
// If you want to avoid the memcopy, you must write specializations for this function
template <typename T> inline void qToUnaligned(const T src, uchar *dest)
{
    qMemCopy(dest, &src, sizeof(T));
}

/* T qFromLittleEndian(const uchar *src)
 * This function will read a little-endian encoded value from \a src
 * and return the value in host-endian encoding.
 * There is no requirement that \a src must be aligned.
*/
#if defined Q_CC_MSVC && _MSC_VER < 1300 || defined Q_CC_SUN
inline quint64 qFromLittleEndian_helper(const uchar *src, quint64 *dest)
{
    return 0
        | src[0]
        | src[1] * Q_UINT64_C(0x0000000000000100)
        | src[2] * Q_UINT64_C(0x0000000000010000)
        | src[3] * Q_UINT64_C(0x0000000001000000)
        | src[4] * Q_UINT64_C(0x0000000100000000)
        | src[5] * Q_UINT64_C(0x0000010000000000)
        | src[6] * Q_UINT64_C(0x0001000000000000)
        | src[7] * Q_UINT64_C(0x0100000000000000);
}

inline quint32 qFromLittleEndian_helper(const uchar *src, quint32 *dest)
{
    return 0
        | src[0]
        | src[1] * quint32(0x00000100)
        | src[2] * quint32(0x00010000)
        | src[3] * quint32(0x01000000);
}

inline quint16 qFromLittleEndian_helper(const uchar *src, quint16 *dest)
{
    return 0
        | src[0]
        | src[1] * 0x0100;
}

inline qint64 qFromLittleEndian_helper(const uchar *src, qint64 * dest)
{ return static_cast<qint64>(qFromLittleEndian_helper(src, reinterpret_cast<quint64*>(0))); }
inline qint32 qFromLittleEndian_helper(const uchar *src, qint32 * dest)
{ return static_cast<qint32>(qFromLittleEndian_helper(src, reinterpret_cast<quint32*>(0))); }
inline qint16 qFromLittleEndian_helper(const uchar *src, qint16 * dest)
{ return static_cast<qint16>(qFromLittleEndian_helper(src, reinterpret_cast<quint16*>(0))); }

template <class T> inline T qFromLittleEndian(const uchar *src)
{
    return qFromLittleEndian_helper(src, reinterpret_cast<T*>(0));
}

#else
template <typename T> inline T qFromLittleEndian(const uchar *src);
template <> inline quint64 qFromLittleEndian<quint64>(const uchar *src)
{
    return 0
        | src[0]
        | src[1] * Q_UINT64_C(0x0000000000000100)
        | src[2] * Q_UINT64_C(0x0000000000010000)
        | src[3] * Q_UINT64_C(0x0000000001000000)
        | src[4] * Q_UINT64_C(0x0000000100000000)
        | src[5] * Q_UINT64_C(0x0000010000000000)
        | src[6] * Q_UINT64_C(0x0001000000000000)
        | src[7] * Q_UINT64_C(0x0100000000000000);
}

template <> inline quint32 qFromLittleEndian<quint32>(const uchar *src)
{
    return 0
        | src[0]
        | src[1] * quint32(0x00000100)
        | src[2] * quint32(0x00010000)
        | src[3] * quint32(0x01000000);
}

template <> inline quint16 qFromLittleEndian<quint16>(const uchar *src)
{
    return 0
        | src[0]
        | src[1] * 0x0100;
}

// signed specializations
template <> inline qint64 qFromLittleEndian<qint64>(const uchar *src)
{ return static_cast<qint64>(qFromLittleEndian<quint64>(src)); }

template <> inline qint32 qFromLittleEndian<qint32>(const uchar *src)
{ return static_cast<qint32>(qFromLittleEndian<quint32>(src)); }

template <> inline qint16 qFromLittleEndian<qint16>(const uchar *src)
{ return static_cast<qint16>(qFromLittleEndian<quint16>(src)); }
#endif

/* This function will read a big-endian (also known as network order) encoded value from \a src
 * and return the value in host-endian encoding.
 * There is no requirement that \a src must be aligned.
*/
#if defined Q_CC_MSVC && _MSC_VER < 1300 || defined Q_CC_SUN
inline quint64 qFromBigEndian_helper(const uchar *src, quint64 *dest)
{
    return 0
        | src[7]
        | src[6] * Q_UINT64_C(0x0000000000000100)
        | src[5] * Q_UINT64_C(0x0000000000010000)
        | src[4] * Q_UINT64_C(0x0000000001000000)
        | src[3] * Q_UINT64_C(0x0000000100000000)
        | src[2] * Q_UINT64_C(0x0000010000000000)
        | src[1] * Q_UINT64_C(0x0001000000000000)
        | src[0] * Q_UINT64_C(0x0100000000000000);
}

inline quint32 qFromBigEndian_helper(const uchar *src, quint32 * dest)
{
    return 0
        | src[3]
        | src[2] * quint32(0x00000100)
        | src[1] * quint32(0x00010000)
        | src[0] * quint32(0x01000000);
}

inline quint16 qFromBigEndian_helper(const uchar *src, quint16 * des)
{
    return 0
        | src[1]
        | src[0] * 0x0100;
}


inline qint64 qFromBigEndian_helper(const uchar *src, qint64 * dest)
{ return static_cast<qint64>(qFromBigEndian_helper(src, reinterpret_cast<quint64*>(0))); }
inline qint32 qFromBigEndian_helper(const uchar *src, qint32 * dest)
{ return static_cast<qint32>(qFromBigEndian_helper(src, reinterpret_cast<quint32*>(0))); }
inline qint16 qFromBigEndian_helper(const uchar *src, qint16 * dest)
{ return static_cast<qint16>(qFromBigEndian_helper(src, reinterpret_cast<quint16*>(0))); }

template <class T> inline T qFromBigEndian(const uchar *src)
{
    return qFromBigEndian_helper(src, reinterpret_cast<T*>(0));
}

#else
template <class T> inline T qFromBigEndian(const uchar *src);
template<>
inline quint64 qFromBigEndian<quint64>(const uchar *src)
{
    return 0
        | src[7]
        | src[6] * Q_UINT64_C(0x0000000000000100)
        | src[5] * Q_UINT64_C(0x0000000000010000)
        | src[4] * Q_UINT64_C(0x0000000001000000)
        | src[3] * Q_UINT64_C(0x0000000100000000)
        | src[2] * Q_UINT64_C(0x0000010000000000)
        | src[1] * Q_UINT64_C(0x0001000000000000)
        | src[0] * Q_UINT64_C(0x0100000000000000);
}

template<>
inline quint32 qFromBigEndian<quint32>(const uchar *src)
{
    return 0
        | src[3]
        | src[2] * quint32(0x00000100)
        | src[1] * quint32(0x00010000)
        | src[0] * quint32(0x01000000);
}

template<>
inline quint16 qFromBigEndian<quint16>(const uchar *src)
{
    return 0
        | src[1]
        | src[0] * quint16(0x0100);
}


// signed specializations
template <> inline qint64 qFromBigEndian<qint64>(const uchar *src)
{ return static_cast<qint64>(qFromBigEndian<quint64>(src)); }

template <> inline qint32 qFromBigEndian<qint32>(const uchar *src)
{ return static_cast<qint32>(qFromBigEndian<quint32>(src)); }

template <> inline qint16 qFromBigEndian<qint16>(const uchar *src)
{ return static_cast<qint16>(qFromBigEndian<quint16>(src)); }
#endif
/*
 * T qbswap(T source).
 * Changes the byte order of a value from big endian to little endian or vice versa.
 * This function can be used if you are not concerned about alignment issues,
 * and it is therefore a bit more convenient and in most cases more efficient.
*/
template <typename T> T qbswap(T source);
template <> inline quint64 qbswap<quint64>(quint64 source)
{
    return 0
        | ((source & Q_UINT64_C(0x00000000000000ff)) << 56)
        | ((source & Q_UINT64_C(0x000000000000ff00)) << 40)
        | ((source & Q_UINT64_C(0x0000000000ff0000)) << 24)
        | ((source & Q_UINT64_C(0x00000000ff000000)) << 8)
        | ((source & Q_UINT64_C(0x000000ff00000000)) >> 8)
        | ((source & Q_UINT64_C(0x0000ff0000000000)) >> 24)
        | ((source & Q_UINT64_C(0x00ff000000000000)) >> 40)
        | ((source & Q_UINT64_C(0xff00000000000000)) >> 56);
}

template <> inline quint32 qbswap<quint32>(quint32 source)
{
    return 0
        | ((source & 0x000000ff) << 24)
        | ((source & 0x0000ff00) << 8)
        | ((source & 0x00ff0000) >> 8)
        | ((source & 0xff000000) >> 24);
}

template <> inline quint16 qbswap<quint16>(quint16 source)
{
    return 0
        | ((source & 0x00ff) << 8)
        | ((source & 0xff00) >> 8);
}

// signed specializations
template <> inline qint64 qbswap<qint64>(qint64 source)
{
    return qbswap<quint64>(quint64(source));
}

template <> inline qint32 qbswap<qint32>(qint32 source)
{
    return qbswap<quint32>(quint32(source));
}

template <> inline qint16 qbswap<qint16>(qint16 source)
{
    return qbswap<quint16>(quint16(source));
}

#if Q_BYTE_ORDER == Q_BIG_ENDIAN

template <typename T> inline T qToBigEndian(T source)
{ return source; }
template <typename T> inline T qFromBigEndian(T source)
{ return source; }
template <typename T> inline T qToLittleEndian(T source)
{ return qbswap<T>(source); }
template <typename T> inline T qFromLittleEndian(T source)
{ return qbswap<T>(source); }
template <typename T> inline void qToBigEndian(T src, uchar *dest)
{ qToUnaligned<T>(src, dest); }
template <typename T> inline void qToLittleEndian(T src, uchar *dest)
{ qbswap<T>(src, dest); }
#else // Q_LITTLE_ENDIAN

template <typename T> inline T qToBigEndian(T source)
{ return qbswap<T>(source); }
template <typename T> inline T qFromBigEndian(T source)
{ return qbswap<T>(source); }
template <typename T> inline T qToLittleEndian(T source)
{ return source; }
template <typename T> inline T qFromLittleEndian(T source)
{ return source; }
template <typename T> inline void qToBigEndian(T src, uchar *dest)
{ qbswap<T>(src, dest); }
template <typename T> inline void qToLittleEndian(T src, uchar *dest)
{ qToUnaligned<T>(src, dest); }

#endif // Q_BYTE_ORDER == Q_BIG_ENDIAN

QT_END_HEADER

#endif // QENDIAN_H

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