qdatastream.cpp

奇趣公司比较新的qt/emd版本

}


/*!
    \overload

    Reads the '\0'-terminated string \a s from the stream and returns
    a reference to the stream.

    Space for the string is allocated using \c new -- the caller must
    destroy it with \c{delete[]}.
*/

QDataStream &QDataStream::operator>>(char *&s)
{
    uint len = 0;
    return readBytes(s, len);
}


/*!
    Reads the buffer \a s from the stream and returns a reference to
    the stream.

    The buffer \a s is allocated using \c new. Destroy it with the \c
    delete[] operator.

    The \a l parameter is set to the length of the buffer. If the
    string read is empty, \a l is set to 0 and \a s is set to
    a null pointer.

    The serialization format is a quint32 length specifier first,
    then \a l bytes of data.

    \sa readRawData(), writeBytes()
*/

QDataStream &QDataStream::readBytes(char *&s, uint &l)
{
    s = 0;
    l = 0;
    CHECK_STREAM_PRECOND(*this)

    quint32 len;
    *this >> len;
    if (len == 0)
        return *this;

    const quint32 Step = 1024 * 1024;
    quint32 allocated = 0;
    char *prevBuf = 0;
    char *curBuf = 0;

    do {
        int blockSize = qMin(Step, len - allocated);
        prevBuf = curBuf;
        curBuf = new char[allocated + blockSize + 1];
        if (prevBuf) {
            memcpy(curBuf, prevBuf, allocated);
            delete [] prevBuf;
        }
        if (dev->read(curBuf + allocated, blockSize) != blockSize) {
            delete [] curBuf;
            setStatus(ReadPastEnd);
            return *this;
        }
        allocated += blockSize;
    } while (allocated < len);

    s = curBuf;
    s[len] = '\0';
    l = (uint)len;
    return *this;
}

/*!
    Reads at most \a len bytes from the stream into \a s and returns the number of
    bytes read. If an error occurs, this function returns -1.

    The buffer \a s must be preallocated. The data is \e not encoded.

    \sa readBytes(), QIODevice::read(), writeRawData()
*/

int QDataStream::readRawData(char *s, int len)
{
    CHECK_STREAM_PRECOND(-1)
    return dev->read(s, len);
}


/*****************************************************************************
  QDataStream write functions
 *****************************************************************************/


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

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

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

QDataStream &QDataStream::operator<<(qint8 i)
{
    CHECK_STREAM_PRECOND(*this)
    dev->putChar(i);
    return *this;
}


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

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

/*!
    \overload

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

QDataStream &QDataStream::operator<<(qint16 i)
{
    CHECK_STREAM_PRECOND(*this)
    if (noswap) {
        dev->write((char *)&i, sizeof(qint16));
    } else {                                        // swap bytes
        register uchar *p = (uchar *)(&i);
        char b[2];
        b[1] = *p++;
        b[0] = *p;
        dev->write(b, 2);
    }
    return *this;
}

/*!
    \overload

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

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

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

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

/*!
    \overload

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

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

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

    Writes an unsigned integer, \a i, to the stream as a 32-bit
    unsigned integer (quint32). Returns a reference to the stream.
*/

/*!
    Writes a boolean value, \a i, to the stream. Returns a reference
    to the stream.
*/

QDataStream &QDataStream::operator<<(bool i)
{
    CHECK_STREAM_PRECOND(*this)
    dev->putChar(qint8(i));
    return *this;
}

/*!
    \overload

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

QDataStream &QDataStream::operator<<(float f)
{
    CHECK_STREAM_PRECOND(*this)
    float g = f;                                // fixes float-on-stack problem
    if (noswap) {                                // no conversion needed
        dev->write((char *)&g, sizeof(float));
    } else {                                // swap bytes
        register uchar *p = (uchar *)(&g);
        char b[4];
        b[3] = *p++;
        b[2] = *p++;
        b[1] = *p++;
        b[0] = *p;
        dev->write(b, 4);
    }
    return *this;
}


/*!
    \overload

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

QDataStream &QDataStream::operator<<(double f)
{
    CHECK_STREAM_PRECOND(*this)
#ifndef Q_DOUBLE_FORMAT
    if (noswap) {
        dev->write((char *)&f, sizeof(double));
    } else {
        register uchar *p = (uchar *)(&f);
        char b[8];
        b[7] = *p++;
        b[6] = *p++;
        b[5] = *p++;
        b[4] = *p++;
        b[3] = *p++;
        b[2] = *p++;
        b[1] = *p++;
        b[0] = *p;
        dev->write(b, 8);
    }
#else
    register uchar *p = (uchar *)(&f);
    char b[8];
    if (noswap) {
        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)] = *p;
    } else {
        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)] = *p;
    }
    dev->write(b, 8);
#endif
    return *this;
}


/*!
    \overload

    Writes the '\0'-terminated string \a s to the stream and returns a
    reference to the stream.

    The string is serialized using writeBytes().
*/

QDataStream &QDataStream::operator<<(const char *s)
{
    if (!s) {
        *this << (quint32)0;
        return *this;
    }
    uint len = qstrlen(s) + 1;                        // also write null terminator
    *this << (quint32)len;                        // write length specifier
    writeRawData(s, len);
    return *this;
}


/*!
    Writes the length specifier \a len and the buffer \a s to the
    stream and returns a reference to the stream.

    The \a len is serialized as a quint32, followed by \a len bytes
    from \a s. Note that the data is \e not encoded.

    \sa writeRawData(), readBytes()
*/

QDataStream &QDataStream::writeBytes(const char *s, uint len)
{
    CHECK_STREAM_PRECOND(*this)
    *this << (quint32)len;                        // write length specifier
    if (len)
        writeRawData(s, len);
    return *this;
}


/*!
    Writes \a len bytes from \a s to the stream. Returns the
    number of bytes actually written, or -1 on error.
    The data is \e not encoded.

    \sa writeBytes(), QIODevice::write(), readRawData()
*/

int QDataStream::writeRawData(const char *s, int len)
{
    CHECK_STREAM_PRECOND(-1)
    return dev->write(s, len);
}

/*!
    \since 4.1

    Skips \a len bytes from the device. Returns the number of bytes
    actually skipped, or -1 on error.

    This is equivalent to calling readRawData() on a buffer of length
    \a len and ignoring the buffer.

    \sa QIODevice::seek()
*/
int QDataStream::skipRawData(int len)
{
    CHECK_STREAM_PRECOND(-1)

    if (dev->isSequential()) {
        char buf[4096];
        int sumRead = 0;

        while (len > 0) {
            int blockSize = qMin(len, (int)sizeof(buf));
            int n = dev->read(buf, blockSize);
            if (n == -1)
                return -1;
            if (n == 0)
                return sumRead;

            sumRead += n;
            len -= blockSize;
        }
        return sumRead;
    } else {
        quint64 pos = dev->pos();
        len = qMin(int(dev->size() - pos), len);
        if (!dev->seek(pos + len))
            return -1;
        return len;
    }
}

#ifdef QT3_SUPPORT
/*!
    \fn QDataStream &QDataStream::readRawBytes(char *str, uint len)

    Use readRawData() instead.
*/

/*!
    \fn QDataStream &QDataStream::writeRawBytes(const char *str, uint len)

    Use writeRawData() instead.
*/
#endif

#endif // QT_NO_DATASTREAM