qdatastream.cpp

奇趣公司比较新的qt/emd版本

bool QDataStream::atEnd() const
{
    return dev ? dev->atEnd() : true;
}

/*!
    Returns the status of the data stream.

    \sa Status setStatus() resetStatus()
*/

QDataStream::Status QDataStream::status() const
{
    return q_status;
}

/*!
    Resets the status of the data stream.

    \sa Status status() setStatus()
*/
void QDataStream::resetStatus()
{
    q_status = Ok;
}

/*!
    Sets the status of the data stream to the \a status given.

    \sa Status status() resetStatus()
*/
void QDataStream::setStatus(Status status)
{
    if (q_status == Ok)
        q_status = status;
}

/*!\fn bool QDataStream::eof() const

    Use atEnd() instead.
*/

/*!
    \fn int QDataStream::byteOrder() const

    Returns the current byte order setting -- either BigEndian or
    LittleEndian.

    \sa setByteOrder()
*/

/*!
    Sets the serialization byte order to \a bo.

    The \a bo parameter can be QDataStream::BigEndian or
    QDataStream::LittleEndian.

    The default setting is big endian. We recommend leaving this
    setting unless you have special requirements.

    \sa byteOrder()
*/

void QDataStream::setByteOrder(ByteOrder bo)
{
    byteorder = bo;
    if (QSysInfo::ByteOrder == QSysInfo::BigEndian)
        noswap = (byteorder == BigEndian);
    else
        noswap = (byteorder == LittleEndian);
}


/*!
    \fn bool QDataStream::isPrintableData() const

    In Qt 4, this function always returns false.

    \sa setPrintableData()
*/

/*!
    \fn void QDataStream::setPrintableData(bool enable)

    In Qt 3, this function enabled output in a human-readable
    format if \a enable was false.

    In Qt 4, QDataStream no longer provides a human-readable output.
    This function does nothing.
*/

/*!
    \enum QDataStream::Version

    This enum provides symbolic synonyms for the data serialization
    format version numbers.

    \value Qt_1_0 Version 1 (Qt 1.x)
    \value Qt_2_0 Version 2 (Qt 2.0)
    \value Qt_2_1 Version 3 (Qt 2.1, 2.2, 2.3)
    \value Qt_3_0 Version 4 (Qt 3.0)
    \value Qt_3_1 Version 5 (Qt 3.1, 3.2)
    \value Qt_3_3 Version 6 (Qt 3.3)
    \value Qt_4_0 Version 7 (Qt 4.0, Qt 4.1)
    \value Qt_4_1 Version 7 (Qt 4.0, Qt 4.1)
    \value Qt_4_2 Version 8 (Qt 4.2)
    \value Qt_4_3 Version 9 (Qt 4.3)

    \sa setVersion(), version()
*/

/*!
    \fn int QDataStream::version() const

    Returns the version number of the data serialization format.

    \sa setVersion(), Version
*/

/*!
    \fn void QDataStream::setVersion(int v)

    Sets the version number of the data serialization format to \a v.

    You don't \e have to set a version if you are using the current
    version of Qt, but for your own custom binary formats we
    recommend that you do; see \l{Versioning} in the Detailed
    Description.

    In order to accommodate new functionality, the datastream
    serialization format of some Qt classes has changed in some
    versions of Qt. If you want to read data that was created by an
    earlier version of Qt, or write data that can be read by a
    program that was compiled with an earlier version of Qt, use this
    function to modify the serialization format used by QDataStream.

    \table
    \header \i Qt Version       \i QDataStream Version
    \row \i Qt 4.2              \i 8
    \row \i Qt 4.0              \i 7
    \row \i Qt 3.3              \i 6
    \row \i Qt 3.1, 3.2         \i 5
    \row \i Qt 3.0              \i 4
    \row \i Qt 2.1, 2.2, 2.3    \i 3
    \row \i Qt 2.0              \i 2
    \row \i Qt 1.x              \i 1
    \endtable

    The \l Version enum provides symbolic constants for the different
    versions of Qt. For example:

    \code
        QDataStream out(file);
        out.setVersion(QDataStream::Qt_4_0);
    \endcode

    \sa version(), Version
*/

/*****************************************************************************
  QDataStream read functions
 *****************************************************************************/

/*!
    \fn QDataStream &QDataStream::operator>>(quint8 &i)
    \overload

    Reads an unsigned byte from the stream into \a i, and returns a
    reference to the stream.
*/

/*!
    Reads a signed byte from the stream into \a i, and returns a
    reference to the stream.
*/

QDataStream &QDataStream::operator>>(qint8 &i)
{
    i = 0;
    CHECK_STREAM_PRECOND(*this)
    char c;
    if (!dev->getChar(&c))
        setStatus(ReadPastEnd);
    else
        i = qint8(c);
    return *this;
}


/*!
    \fn QDataStream &QDataStream::operator>>(quint16 &i)
    \overload

    Reads an unsigned 16-bit integer from the stream into \a i, and
    returns a reference to the stream.
*/

/*!
    \overload

    Reads a signed 16-bit integer from the stream into \a i, and
    returns a reference to the stream.
*/

QDataStream &QDataStream::operator>>(qint16 &i)
{
    i = 0;
    CHECK_STREAM_PRECOND(*this)
    if (noswap) {
        if (dev->read((char *)&i, 2) != 2) {
            i = 0;
            setStatus(ReadPastEnd);
        }
    } else {
        register uchar *p = (uchar *)(&i);
        char b[2];
        if (dev->read(b, 2) == 2) {
            *p++ = b[1];
            *p = b[0];
        } else {
            setStatus(ReadPastEnd);
        }
    }
    return *this;
}


/*!
    \fn QDataStream &QDataStream::operator>>(quint32 &i)
    \overload

    Reads an unsigned 32-bit integer from the stream into \a i, and
    returns a reference to the stream.
*/

/*!
    \overload

    Reads a signed 32-bit integer from the stream into \a i, and
    returns a reference to the stream.
*/

QDataStream &QDataStream::operator>>(qint32 &i)
{
    i = 0;
    CHECK_STREAM_PRECOND(*this)
    if (noswap) {
        if (dev->read((char *)&i, 4) != 4) {
            i = 0;
            setStatus(ReadPastEnd);
        }
    } else {                                        // swap bytes
        uchar *p = (uchar *)(&i);
        char b[4];
        if (dev->read(b, 4) == 4) {
            *p++ = b[3];
            *p++ = b[2];
            *p++ = b[1];
            *p   = b[0];
        } else {
            setStatus(ReadPastEnd);
        }
    }
    return *this;
}

/*!
    \fn QDataStream &QDataStream::operator>>(quint64 &i)
    \overload

    Reads an unsigned 64-bit integer from the stream, into \a i, and
    returns a reference to the stream.
*/

/*!
    \overload

    Reads a signed 64-bit integer from the stream into \a i, and
    returns a reference to the stream.
*/

QDataStream &QDataStream::operator>>(qint64 &i)
{
    i = qint64(0);
    CHECK_STREAM_PRECOND(*this)
    if (version() < 6) {
        quint32 i1, i2;
        *this >> i2 >> i1;
        i = ((quint64)i1 << 32) + i2;
    } else if (noswap) {                        // no conversion needed
        if (dev->read((char *)&i, 8) != 8) {
            i = qint64(0);
            setStatus(ReadPastEnd);
        }
    } else {                                        // swap bytes
        uchar *p = (uchar *)(&i);
        char b[8];
        if (dev->read(b, 8) == 8) {
            *p++ = b[7];
            *p++ = b[6];
            *p++ = b[5];
            *p++ = b[4];
            *p++ = b[3];
            *p++ = b[2];
            *p++ = b[1];
            *p   = b[0];
        } else {
            setStatus(ReadPastEnd);
        }
    }
    return *this;
}

/*!
    Reads a boolean value from the stream into \a i. Returns a
    reference to the stream.
*/
QDataStream &QDataStream::operator>>(bool &i)
{
    qint8 v;
    *this >> v;
    i = !!v;
    return *this;
}

/*!
    \overload

    Reads a 32-bit floating point number from the stream into \a f,
    using the standard IEEE 754 format. Returns a reference to the
    stream.
*/

QDataStream &QDataStream::operator>>(float &f)
{
    f = 0.0f;
    CHECK_STREAM_PRECOND(*this)
    if (noswap) {
        if (dev->read((char *)&f, 4) != 4) {
            f = 0.0f;
            setStatus(ReadPastEnd);
        }
    } else {                                        // swap bytes
        uchar *p = (uchar *)(&f);
        char b[4];
        if (dev->read(b, 4) == 4) {
            *p++ = b[3];
            *p++ = b[2];
            *p++ = b[1];
            *p = b[0];
        } else {
            setStatus(ReadPastEnd);
        }
    }
    return *this;
}

#if defined(Q_DOUBLE_FORMAT)
#define Q_DF(x) Q_DOUBLE_FORMAT[(x)] - '0'
#endif

/*!
    \overload

    Reads a 64-bit floating point number from the stream into \a f,
    using the standard IEEE 754 format. Returns a reference to the
    stream.
*/

QDataStream &QDataStream::operator>>(double &f)
{
    f = 0.0;
    CHECK_STREAM_PRECOND(*this)
#ifndef Q_DOUBLE_FORMAT
    if (noswap) {
        if (dev->read((char *)&f, 8) != 8) {
            f = 0.0;
            setStatus(ReadPastEnd);
        }
    } else {                                        // swap bytes
        register uchar *p = (uchar *)(&f);
        char b[8];
        if (dev->read(b, 8) == 8) {
            *p++ = b[7];
            *p++ = b[6];
            *p++ = b[5];
            *p++ = b[4];
            *p++ = b[3];
            *p++ = b[2];
            *p++ = b[1];
            *p   = b[0];
        } else {
            setStatus(ReadPastEnd);
        }
    }
#else
    //non-standard floating point format
    register uchar *p = (uchar *)(&f);
    char b[8];
    if (dev->read(b, 8) == 8) {
        if (noswap) {
            *p++ = b[Q_DF(0)];
            *p++ = b[Q_DF(1)];
            *p++ = b[Q_DF(2)];
            *p++ = b[Q_DF(3)];
            *p++ = b[Q_DF(4)];
            *p++ = b[Q_DF(5)];
            *p++ = b[Q_DF(6)];
            *p = b[Q_DF(7)];
        } else {
            *p++ = b[Q_DF(7)];
            *p++ = b[Q_DF(6)];
            *p++ = b[Q_DF(5)];
            *p++ = b[Q_DF(4)];
            *p++ = b[Q_DF(3)];
            *p++ = b[Q_DF(2)];
            *p++ = b[Q_DF(1)];
            *p = b[Q_DF(0)];
        }
    } else {
        setStatus(ReadPastEnd);
    }
#endif
    return *this;