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katie/src/core/io/qdatastream.cpp
Ivailo Monev 5564b9feb0 list all current data stream versions in documentation 
Signed-off-by: Ivailo Monev <xakepa10@gmail.com>
2016-04-22 20:21:16 +00:00

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/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
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**
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** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 or version 3 as published by the Free
** Software Foundation and appearing in the file LICENSE.LGPLv21 and
** LICENSE.LGPLv3 included in the packaging of this file. Please review the
** following information to ensure the GNU Lesser General Public License
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** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
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****************************************************************************/
#include "qdatastream.h"
#include "qdatastream_p.h"
#if !defined(QT_NO_DATASTREAM) || defined(QT_BOOTSTRAPPED)
#include "qbuffer.h"
#include "qstring.h"
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include "qendian.h"
QT_BEGIN_NAMESPACE
/*!
\class QDataStream
\reentrant
\brief The QDataStream class provides serialization of binary data
to a QIODevice.
\ingroup io
A data stream is a binary stream of encoded information which is
100% independent of the host computer's operating system, CPU or
byte order. For example, a data stream that is written by a PC
under Windows can be read by a Sun SPARC running Solaris.
You can also use a data stream to read/write \l{raw}{raw
unencoded binary data}. If you want a "parsing" input stream, see
QTextStream.
The QDataStream class implements the serialization of C++'s basic
data types, like \c char, \c short, \c int, \c{char *}, etc.
Serialization of more complex data is accomplished by breaking up
the data into primitive units.
A data stream cooperates closely with a QIODevice. A QIODevice
represents an input/output medium one can read data from and write
data to. The QFile class is an example of an I/O device.
Example (write binary data to a stream):
\snippet doc/src/snippets/code/src_corelib_io_qdatastream.cpp 0
Example (read binary data from a stream):
\snippet doc/src/snippets/code/src_corelib_io_qdatastream.cpp 1
Each item written to the stream is written in a predefined binary
format that varies depending on the item's type. Supported Qt
types include QBrush, QColor, QDateTime, QFont, QPixmap, QString,
QVariant and many others. For the complete list of all Qt types
supporting data streaming see \l{Serializing Qt Data Types}.
For integers it is best to always cast to a Qt integer type for
writing, and to read back into the same Qt integer type. This
ensures that you get integers of the size you want and insulates
you from compiler and platform differences.
To take one example, a \c{char *} string is written as a 32-bit
integer equal to the length of the string including the '\\0' byte,
followed by all the characters of the string including the
'\\0' byte. When reading a \c{char *} string, 4 bytes are read to
create the 32-bit length value, then that many characters for the
\c {char *} string including the '\\0' terminator are read.
The initial I/O device is usually set in the constructor, but can be
changed with setDevice(). If you've reached the end of the data
(or if there is no I/O device set) atEnd() will return true.
\section1 Versioning
QDataStream's binary format has evolved since Qt 1.0, and is
likely to continue evolving to reflect changes done in Qt. When
inputting or outputting complex types, it's very important to
make sure that the same version of the stream (version()) is used
for reading and writing. If you need both forward and backward
compatibility, you can hardcode the version number in the
application:
\snippet doc/src/snippets/code/src_corelib_io_qdatastream.cpp 2
If you are producing a new binary data format, such as a file
format for documents created by your application, you could use a
QDataStream to write the data in a portable format. Typically, you
would write a brief header containing a magic string and a version
number to give yourself room for future expansion. For example:
\snippet doc/src/snippets/code/src_corelib_io_qdatastream.cpp 3
Then read it in with:
\snippet doc/src/snippets/code/src_corelib_io_qdatastream.cpp 4
You can select which byte order to use when serializing data. The
default setting is big endian (MSB first). Changing it to little
endian breaks the portability (unless the reader also changes to
little endian). We recommend keeping this setting unless you have
special requirements.
\target raw
\section1 Reading and writing raw binary data
You may wish to read/write your own raw binary data to/from the
data stream directly. Data may be read from the stream into a
preallocated \c{char *} using readRawData(). Similarly data can be
written to the stream using writeRawData(). Note that any
encoding/decoding of the data must be done by you.
A similar pair of functions is readBytes() and writeBytes(). These
differ from their \e raw counterparts as follows: readBytes()
reads a quint32 which is taken to be the length of the data to be
read, then that number of bytes is read into the preallocated
\c{char *}; writeBytes() writes a quint32 containing the length of the
data, followed by the data. Note that any encoding/decoding of
the data (apart from the length quint32) must be done by you.
\section1 Reading and writing Qt collection classes
The Qt container classes can also be serialized to a QDataStream.
These include QList, QLinkedList, QVector, QSet, QHash, and QMap.
The stream operators are declared as non-members of the classes.
\target Serializing Qt Classes
\section1 Reading and writing other Qt classes.
In addition to the overloaded stream operators documented here,
any Qt classes that you might want to serialize to a QDataStream
will have appropriate stream operators declared as non-member of
the class:
\code
QDataStream &operator<<(QDataStream &, const QXxx &);
QDataStream &operator>>(QDataStream &, QXxx &);
\endcode
For example, here are the stream operators declared as non-members
of the QImage class:
\code
QDataStream & operator<< (QDataStream& stream, const QImage& image);
QDataStream & operator>> (QDataStream& stream, QImage& image);
\endcode
To see if your favorite Qt class has similar stream operators
defined, check the \bold {Related Non-Members} section of the
class's documentation page.
\sa QTextStream QVariant
*/
/*!
\enum QDataStream::ByteOrder
The byte order used for reading/writing the data.
\value BigEndian Most significant byte first (the default)
\value LittleEndian Least significant byte first
*/
/*!
\enum QDataStream::FloatingPointPrecision
The precision of floating point numbers used for reading/writing the data. This will only have
an effect if the version of the data stream is Qt_4_6 or higher.
\warning The floating point precision must be set to the same value on the object that writes
and the object that reads the data stream.
\value SinglePrecision All floating point numbers in the data stream have 32-bit precision.
\value DoublePrecision All floating point numbers in the data stream have 64-bit precision.
\sa setFloatingPointPrecision(), floatingPointPrecision()
*/
/*!
\enum QDataStream::Status
This enum describes the current status of the data stream.
\value Ok The data stream is operating normally.
\value ReadPastEnd The data stream has read past the end of the
data in the underlying device.
\value ReadCorruptData The data stream has read corrupt data.
\value WriteFailed The data stream cannot write to the underlying device.
*/
/*****************************************************************************
QDataStream member functions
*****************************************************************************/
#undef CHECK_STREAM_PRECOND
#ifndef QT_NO_DEBUG
#define CHECK_STREAM_PRECOND(retVal) \
if (!dev) { \
qWarning("QDataStream: No device"); \
return retVal; \
}
#else
#define CHECK_STREAM_PRECOND(retVal) \
if (!dev) { \
return retVal; \
}
#endif
#define CHECK_STREAM_WRITE_PRECOND(retVal) \
CHECK_STREAM_PRECOND(retVal) \
if (q_status != Ok) \
return retVal;
// ### 5.0: when streaming invalid QVariants, just the type should
// be written, no "data" after it
/*!
Constructs a data stream that has no I/O device.
\sa setDevice()
*/
QDataStream::QDataStream()
{
dev = 0;
owndev = false;
byteorder = BigEndian;
ver = QDataStream::Qt_Default;
noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian;
q_status = Ok;
}
/*!
Constructs a data stream that uses the I/O device \a d.
\warning If you use QSocket or QSocketDevice as the I/O device \a d
for reading data, you must make sure that enough data is available
on the socket for the operation to successfully proceed;
QDataStream does not have any means to handle or recover from
short-reads.
\sa setDevice(), device()
*/
QDataStream::QDataStream(QIODevice *d)
{
dev = d; // set device
owndev = false;
byteorder = BigEndian; // default byte order
ver = QDataStream::Qt_Default;
noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian;
q_status = Ok;
}
/*!
\fn QDataStream::QDataStream(QByteArray *a, QIODevice::OpenMode mode)
Constructs a data stream that operates on a byte array, \a a. The
\a mode describes how the device is to be used.
Alternatively, you can use QDataStream(const QByteArray &) if you
just want to read from a byte array.
Since QByteArray is not a QIODevice subclass, internally a QBuffer
is created to wrap the byte array.
*/
QDataStream::QDataStream(QByteArray *a, QIODevice::OpenMode flags)
{
QBuffer *buf = new QBuffer(a);
#ifndef QT_NO_QOBJECT
buf->blockSignals(true);
#endif
buf->open(flags);
dev = buf;
owndev = true;
byteorder = BigEndian;
ver = QDataStream::Qt_Default;
noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian;
q_status = Ok;
}
/*!
Constructs a read-only data stream that operates on byte array \a a.
Use QDataStream(QByteArray*, int) if you want to write to a byte
array.
Since QByteArray is not a QIODevice subclass, internally a QBuffer
is created to wrap the byte array.
*/
QDataStream::QDataStream(const QByteArray &a)
{
QBuffer *buf = new QBuffer;
#ifndef QT_NO_QOBJECT
buf->blockSignals(true);
#endif
buf->setData(a);
buf->open(QIODevice::ReadOnly);
dev = buf;
owndev = true;
byteorder = BigEndian;
ver = QDataStream::Qt_Default;
noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian;
q_status = Ok;
}
/*!
Destroys the data stream.
The destructor will not affect the current I/O device, unless it is
an internal I/O device (e.g. a QBuffer) processing a QByteArray
passed in the \e constructor, in which case the internal I/O device
is destroyed.
*/
QDataStream::~QDataStream()
{
if (owndev)
delete dev;
}
/*!
\fn QIODevice *QDataStream::device() const
Returns the I/O device currently set, or 0 if no
device is currently set.
\sa setDevice()
*/
/*!
void QDataStream::setDevice(QIODevice *d)
Sets the I/O device to \a d, which can be 0
to unset to current I/O device.
\sa device()
*/
void QDataStream::setDevice(QIODevice *d)
{
if (owndev) {
delete dev;
owndev = false;
}
dev = d;
}
/*!
\fn bool QDataStream::atEnd() const
Returns true if the I/O device has reached the end position (end of
the stream or file) or if there is no I/O device set; otherwise
returns false.
\sa QIODevice::atEnd()
*/
bool QDataStream::atEnd() const
{
return dev ? dev->atEnd() : true;
}
/*!
Returns the floating point precision of the data stream.
\since 4.6
\sa FloatingPointPrecision setFloatingPointPrecision()
*/
QDataStream::FloatingPointPrecision QDataStream::floatingPointPrecision() const
{
return d == 0 ? QDataStream::DoublePrecision : d->floatingPointPrecision;
}
/*!
Sets the floating point precision of the data stream to \a precision. If the floating point precision is
DoublePrecision and the version of the data stream is Qt_4_6 or higher, all floating point
numbers will be written and read with 64-bit precision. If the floating point precision is
SinglePrecision and the version is Qt_4_6 or higher, all floating point numbers will be written
and read with 32-bit precision.
For versions prior to Qt_4_6, the precision of floating point numbers in the data stream depends
on the stream operator called.
The default is DoublePrecision.
\warning This property must be set to the same value on the object that writes and the object
that reads the data stream.
\since 4.6
*/
void QDataStream::setFloatingPointPrecision(QDataStream::FloatingPointPrecision precision)
{
if (d == 0)
d.reset(new QDataStreamPrivate());
d->floatingPointPrecision = precision;
}
/*!
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.
Subsequent calls to setStatus() are ignored until resetStatus()
is called.
\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);
}
/*!
\enum QDataStream::Version
This enum provides symbolic synonyms for the data serialization
format version numbers.
\value Qt_4_0 Version 1 (Qt 4.0, Qt 4.1)
\value Qt_4_1 Version 1 (Qt 4.0, Qt 4.1)
\value Qt_4_2 Version 2 (Qt 4.2)
\value Qt_4_3 Version 3 (Qt 4.3)
\value Qt_4_4 Version 4 (Qt 4.4)
\value Qt_4_5 Version 5 (Qt 4.5)
\value Qt_4_6 Version 6 (Qt 4.6, Qt 4.7, Qt 4.8, Katie 4.9)
\value Qt_4_7 Same as Qt_4_6.
\value Qt_4_8 Same as Qt_4_6.
\value Qt_4_9 Same as Qt_4_6.
\value Qt_Default
\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.
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 4.9 \i 12
\row \i Qt 4.8 \i 12
\row \i Qt 4.7 \i 12
\row \i Qt 4.6 \i 12
\row \i Qt 4.5 \i 11
\row \i Qt 4.4 \i 10
\row \i Qt 4.3 \i 9
\row \i Qt 4.2 \i 8
\row \i Qt 4.0, 4.1 \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:
\snippet doc/src/snippets/code/src_corelib_io_qdatastream.cpp 5
\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 (dev->read((char *)&i, 2) != 2) {
i = 0;
setStatus(ReadPastEnd);
} else {
if (!noswap) {
i = qbswap(i);
}
}
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 (dev->read((char *)&i, 4) != 4) {
i = 0;
setStatus(ReadPastEnd);
} else {
if (!noswap) {
i = qbswap(i);
}
}
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 (dev->read((char *)&i, 8) != 8) {
i = qint64(0);
setStatus(ReadPastEnd);
} else {
if (!noswap) {
i = qbswap(i);
}
}
}
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 floating point number from the stream into \a f,
using the standard IEEE 754 format. Returns a reference to the
stream.
\sa setFloatingPointPrecision()
*/
QDataStream &QDataStream::operator>>(float &f)
{
if (version() >= QDataStream::Qt_4_6
&& floatingPointPrecision() == QDataStream::DoublePrecision) {
double d;
*this >> d;
f = d;
return *this;
}
f = 0.0f;
CHECK_STREAM_PRECOND(*this)
if (dev->read((char *)&f, 4) != 4) {
f = 0.0f;
setStatus(ReadPastEnd);
} else {
if (!noswap) {
union {
float val1;
quint32 val2;
} x;
x.val2 = qbswap(*reinterpret_cast<quint32 *>(&f));
f = x.val1;
}
}
return *this;
}
#if defined(Q_DOUBLE_FORMAT)
#define Q_DF(x) Q_DOUBLE_FORMAT[(x)] - '0'
#endif
/*!
\overload
Reads a floating point number from the stream into \a f,
using the standard IEEE 754 format. Returns a reference to the
stream.
\sa setFloatingPointPrecision()
*/
QDataStream &QDataStream::operator>>(double &f)
{
if (version() >= QDataStream::Qt_4_6
&& floatingPointPrecision() == QDataStream::SinglePrecision) {
float d;
*this >> d;
f = d;
return *this;
}
f = 0.0;
CHECK_STREAM_PRECOND(*this)
#ifndef Q_DOUBLE_FORMAT
if (dev->read((char *)&f, 8) != 8) {
f = 0.0;
setStatus(ReadPastEnd);
} else {
if (!noswap) {
union {
double val1;
quint64 val2;
} x;
x.val2 = qbswap(*reinterpret_cast<quint64 *>(&f));
f = x.val1;
}
}
#else
//non-standard floating point format
union {
double val1;
char val2[8];
} x;
char *p = x.val2;
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)];
}
f = x.val1;
} else {
setStatus(ReadPastEnd);
}
#endif
return *this;
}
/*!
\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_WRITE_PRECOND(*this)
if (!dev->putChar(i))
q_status = WriteFailed;
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_WRITE_PRECOND(*this)
if (!noswap) {
i = qbswap(i);
}
if (dev->write((char *)&i, sizeof(qint16)) != sizeof(qint16))
q_status = WriteFailed;
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_WRITE_PRECOND(*this)
if (!noswap) {
i = qbswap(i);
}
if (dev->write((char *)&i, sizeof(qint32)) != sizeof(qint32))
q_status = WriteFailed;
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_WRITE_PRECOND(*this)
if (version() < 6) {
quint32 i1 = i & 0xffffffff;
quint32 i2 = i >> 32;
*this << i2 << i1;
} else {
if (!noswap) {
i = qbswap(i);
}
if (dev->write((char *)&i, sizeof(qint64)) != sizeof(qint64))
q_status = WriteFailed;
}
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_WRITE_PRECOND(*this)
if (!dev->putChar(qint8(i)))
q_status = WriteFailed;
return *this;
}
/*!
\overload
Writes a floating point number, \a f, to the stream using
the standard IEEE 754 format. Returns a reference to the stream.
\sa setFloatingPointPrecision()
*/
QDataStream &QDataStream::operator<<(float f)
{
if (version() >= QDataStream::Qt_4_6
&& floatingPointPrecision() == QDataStream::DoublePrecision) {
*this << double(f);
return *this;
}
CHECK_STREAM_WRITE_PRECOND(*this)
float g = f; // fixes float-on-stack problem
if (!noswap) {
union {
float val1;
quint32 val2;
} x;
x.val1 = g;
x.val2 = qbswap(x.val2);
if (dev->write((char *)&x.val2, sizeof(float)) != sizeof(float))
q_status = WriteFailed;
return *this;
}
if (dev->write((char *)&g, sizeof(float)) != sizeof(float))
q_status = WriteFailed;
return *this;
}
/*!
\overload
Writes a floating point number, \a f, to the stream using
the standard IEEE 754 format. Returns a reference to the stream.
\sa setFloatingPointPrecision()
*/
QDataStream &QDataStream::operator<<(double f)
{
if (version() >= QDataStream::Qt_4_6
&& floatingPointPrecision() == QDataStream::SinglePrecision) {
*this << float(f);
return *this;
}
CHECK_STREAM_WRITE_PRECOND(*this)
#ifndef Q_DOUBLE_FORMAT
if (noswap) {
if (dev->write((char *)&f, sizeof(double)) != sizeof(double))
q_status = WriteFailed;
} else {
union {
double val1;
quint64 val2;
} x;
x.val1 = f;
x.val2 = qbswap(x.val2);
if (dev->write((char *)&x.val2, sizeof(double)) != sizeof(double))
q_status = WriteFailed;
}
#else
union {
double val1;
char val2[8];
} x;
x.val1 = f;
char *p = x.val2;
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;
}
if (dev->write(b, 8) != 8)
q_status = WriteFailed;
#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_WRITE_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_WRITE_PRECOND(-1)
int ret = dev->write(s, len);
if (ret != len)
q_status = WriteFailed;
return ret;
}
/*!
\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 {
qint64 pos = dev->pos();
qint64 size = dev->size();
if (pos + len > size)
len = size - pos;
if (!dev->seek(pos + len))
return -1;
return len;
}
}
QT_END_NAMESPACE
#endif // QT_NO_DATASTREAM
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