qserialport.cpp

/****************************************************************************
**
** Copyright (C) 2011-2012 Denis Shienkov <denis.shienkov@gmail.com>
** Copyright (C) 2011 Sergey Belyashov <Sergey.Belyashov@gmail.com>
** Copyright (C) 2012 Laszlo Papp <lpapp@kde.org>
** Copyright (C) 2012 Andre Hartmann <aha_1980@gmx.de>
** Contact: http://www.qt-project.org/legal
**
** This file is part of the QtSerialPort module of the Qt Toolkit.
**
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** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
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#include "qserialport.h"
#include "qserialportinfo.h"

#ifdef Q_OS_WIN
#include "qserialport_win_p.h"
#elif defined (Q_OS_SYMBIAN)
#include "qserialport_symbian_p.h"
#elif defined (Q_OS_UNIX)
#include "qserialport_unix_p.h"
#else
#error Unsupported OS
#endif

#ifndef SERIALPORT_BUFFERSIZE
#  define SERIALPORT_BUFFERSIZE 16384
#endif

QT_BEGIN_NAMESPACE

QSerialPortPrivateData::QSerialPortPrivateData(QSerialPort *q)
    : readBufferMaxSize(0)
    , readBuffer(SERIALPORT_BUFFERSIZE)
    , writeBuffer(SERIALPORT_BUFFERSIZE)
    , error(QSerialPort::NoError)
    , inputBaudRate(0)
    , outputBaudRate(0)
    , dataBits(QSerialPort::UnknownDataBits)
    , parity(QSerialPort::UnknownParity)
    , stopBits(QSerialPort::UnknownStopBits)
    , flow(QSerialPort::UnknownFlowControl)
    , policy(QSerialPort::IgnorePolicy)
    , settingsRestoredOnClose(true)
    , q_ptr(q)
{
}

int QSerialPortPrivateData::timeoutValue(int msecs, int elapsed)
{
    if (msecs == -1)
        return msecs;
    msecs -= elapsed;
    return qMax(msecs, 0);
}

/*!
    \class QSerialPort

    \brief Provides functions to access serial ports.

    \reentrant
    \ingroup serialport-main
    \inmodule QtSerialPort
    \since 5.1

    You can get information about the available serial ports using the
    QSerialPortInfo helper class, which allows an enumeration of all the serial
    ports in the system. This is useful to obtain the correct name of the
    serial port you want to use. You can pass an object
    of the helper class as an argument to the setPort() or setPortName()
    methods to assign the desired serial device.

    After setting the port, you can open it in read-only (r/o), write-only
    (w/o), or read-write (r/w) mode using the open() method.

    \note The serial port is always opened with exclusive access
    (that is, no other process or thread can access an already opened serial port).

    Having successfully opened, QSerialPort tries to determine the current
    configuration of the port and initializes itself. You can reconfigure the
    port to the desired setting using the setBaudRate(), setDataBits(),
    setParity(), setStopBits(), and setFlowControl() methods.

    The status of the control pinout signals is determined with the
    isDataTerminalReady(), isRequestToSend, and pinoutSignals() methods. To
    change the control line status, use the setDataTerminalReady(), and
    setRequestToSend() methods.

    Once you know that the ports are ready to read or write, you can
    use the read() or write() methods. Alternatively the
    readLine() and readAll() convenience methods can also be invoked.
    If not all the data is read at once, the remaining data will
    be available for later as new incoming data is appended to the
    QSerialPort's internal read buffer. You can limit the size of the read
    buffer using setReadBufferSize().

    Use the close() method to close the port and cancel the I/O operations.

    See the following example:

    \code
     int numRead = 0, numReadTotal = 0;
     char buffer[50];

     forever {
         numRead  = serial.read(buffer, 50);

         // Do whatever with the array

         numReadTotal += numRead;
         if (numRead == 0 && !serial.waitForReadyRead())
             break;
     }
    \endcode

    If \l{QIODevice::}{waitForReadyRead()} returns false, the
    connection has been closed or an error has occurred.

    Programming with a blocking serial port is radically different from
    programming with a non-blocking serial port. A blocking serial port
    does not require an event loop and typically leads to simpler code.
    However, in a GUI application, blocking serial port should only be
    used in non-GUI threads, to avoid freezing the user interface.

    For more details about these approaches, refer to the
    \l {Examples}{example} applications.

    The QSerialPort class can also be used with QTextStream and QDataStream's
    stream operators (operator<<() and operator>>()). There is one issue to be
    aware of, though: make sure that enough data is available before attempting
    to read by using the operator>>() overloaded operator.

    \sa QSerialPortInfo
*/

/*!
    \enum QSerialPort::Direction

    This enum describes the possible directions of the data transmission.

    \note This enumeration is used for setting the baud rate of the device
    separately for each direction on some operating systems (for example,
    POSIX-like).

    \value Input            Input direction.
    \value Output           Output direction.
    \value AllDirections    Simultaneously in two directions.
*/

/*!
    \enum QSerialPort::BaudRate

    This enum describes the baud rate which the communication device operates
    with. Note: only the most common standard baud rates are listed in this
    enum.

    \value Baud1200     1200 baud.
    \value Baud2400     2400 baud.
    \value Baud4800     4800 baud.
    \value Baud9600     9600 baud.
    \value Baud19200    19200 baud.
    \value Baud38400    38400 baud.
    \value Baud57600    57600 baud.
    \value Baud115200   115200 baud.
    \value UnknownBaud  Unknown baud.

    \sa QSerialPort::baudRate
*/

/*!
    \enum QSerialPort::DataBits

    This enum describes the number of data bits used.

    \value Data5            Five bits.
    \value Data6            Six bits.
    \value Data7            Seven bits
    \value Data8            Eight bits.
    \value UnknownDataBits  Unknown number of bits.

    \sa QSerialPort::dataBits
*/

/*!
    \enum QSerialPort::Parity

    This enum describes the parity scheme used.

    \value NoParity No parity.
    \value EvenParity Even parity.
    \value OddParity Odd parity.
    \value SpaceParity Space parity.
    \value MarkParity Mark parity.
    \value UnknownParity Unknown parity.

    \sa QSerialPort::parity
*/

/*!
    \enum QSerialPort::StopBits

    This enum describes the number of stop bits used.

    \value OneStop 1 stop bit.
    \value OneAndHalfStop 1.5 stop bits.
    \value TwoStop 2 stop bits.
    \value UnknownStopBits Unknown number of stop bit.

    \sa QSerialPort::stopBits
*/

/*!
    \enum QSerialPort::FlowControl

    This enum describes the flow control used.

    \value NoFlowControl No flow control.
    \value HardwareControl Hardware flow control (RTS/CTS).
    \value SoftwareControl Software flow control (XON/XOFF).
    \value UnknownFlowControl Unknown flow control.

    \sa QSerialPort::flowControl
*/

/*!
    \enum QSerialPort::PinoutSignal

    This enum describes the possible RS-232 pinout signals.

    \value NoSignal                       No line active
    \value TransmittedDataSignal          TxD (Transmitted Data).
    \value ReceivedDataSignal             RxD (Received Data).
    \value DataTerminalReadySignal        DTR (Data Terminal Ready).
    \value DataCarrierDetectSignal        DCD (Data Carrier Detect).
    \value DataSetReadySignal             DSR (Data Set Ready).
    \value RingIndicatorSignal            RNG (Ring Indicator).
    \value RequestToSendSignal            RTS (Request To Send).
    \value ClearToSendSignal              CTS (Clear To Send).
    \value SecondaryTransmittedDataSignal STD (Secondary Transmitted Data).
    \value SecondaryReceivedDataSignal    SRD (Secondary Received Data).

    \sa pinoutSignals(), QSerialPort::dataTerminalReady,
    QSerialPort::requestToSend
*/

/*!
    \enum QSerialPort::DataErrorPolicy

    This enum describes the policies for the received symbols
    while parity errors were detected.

    \value SkipPolicy           Skips the bad character.
    \value PassZeroPolicy       Replaces bad character to zero.
    \value IgnorePolicy         Ignores the error for a bad character.
    \value StopReceivingPolicy  Stops data reception on error.
    \value UnknownPolicy        Unknown policy.

    \sa QSerialPort::dataErrorPolicy
*/

/*!
    \enum QSerialPort::SerialPortError

    This enum describes the errors that may be contained by the
    QSerialPort::error property.

    \value NoError              No error occurred.
    \value DeviceNotFoundError  An error occurred while attempting to
                                open an non-existing device.
    \value PermissionError      An error occurred while attempting to
           open an already opened device by another process or a user not
           having enough permission and credentials to open.
    \value OpenError            An error occurred while attempting to
           open an already opened device in this object.
    \value ParityError Parity error detected by the hardware while reading data.
    \value FramingError Framing error detected by the hardware while reading data.
    \value BreakConditionError Break condition detected by the hardware on
           the input line.
    \value WriteError An I/O error occurred while writing the data.
    \value ReadError An I/O error occurred while reading the data.
    \value ResourceError An I/O error occurred when a resource becomes unavailable,
           e.g. when the device is unexpectedly removed from the system.
    \value UnsupportedOperationError The requested device operation is
           not supported or prohibited by the running operating system.
    \value UnknownError         An unidentified error occurred.

    \sa QSerialPort::error
*/



/*!
    Constructs a new serial port object with the given \a parent.
*/
QSerialPort::QSerialPort(QObject *parent)
    : QIODevice(parent)
    , d_ptr(new QSerialPortPrivate(this))
{}

/*!
    Constructs a new serial port object with the given \a parent
    to represent the serial port with the specified \a name.

    The name should have a specific format; see the setPort() method.
*/
QSerialPort::QSerialPort(const QString &name, QObject *parent)
    : QIODevice(parent)
    , d_ptr(new QSerialPortPrivate(this))
{
    setPortName(name);
}

/*!
    Constructs a new serial port object with the given \a parent
    to represent the serial port with the specified helper class
    \a serialPortInfo.
*/
QSerialPort::QSerialPort(const QSerialPortInfo &serialPortInfo, QObject *parent)
    : QIODevice(parent)
    , d_ptr(new QSerialPortPrivate(this))
{
    setPort(serialPortInfo);
}

/*!
    Closes the serial port, if necessary, and then destroys object.
*/
QSerialPort::~QSerialPort()
{
    /**/
    close();
    delete d_ptr;
}

/*!
    Sets the \a name of the serial port.

    The name of the serial port can be passed on as either a short name or
    the long system location if necessary.

    \sa portName(), QSerialPortInfo
*/
void QSerialPort::setPortName(const QString &name)
{
    Q_D(QSerialPort);
    d->systemLocation = QSerialPortPrivate::portNameToSystemLocation(name);
}

/*!
    Sets the port stored in the serial port info instance \a serialPortInfo.

    \sa portName(), QSerialPortInfo
*/
void QSerialPort::setPort(const QSerialPortInfo &serialPortInfo)
{
    Q_D(QSerialPort);
    d->systemLocation = QSerialPortPrivate::portNameToSystemLocation(serialPortInfo.systemLocation());
}

/*!
    Returns the name set by setPort() or to the QSerialPort constructors.
    This name is short, i.e. it extract and convert out from the internal
    variable system location of the device. Conversion algorithm is
    platform specific:
    \table
    \header
        \li Platform
        \li Brief Description
    \row
        \li Windows
        \li Removes the prefix "\\\\.\\" from the system location
           and returns the remainder of the string.
    \row
        \li Windows CE
        \li Removes the postfix ":" from the system location
           and returns the remainder of the string.
    \row
        \li Symbian
        \li Returns the system location as it is,
           as it is equivalent to the port name.
    \row
        \li GNU/Linux
        \li Removes the prefix "/dev/" from the system location
           and returns the remainder of the string.
    \row
        \li Mac OSX
        \li Removes the prefix "/dev/cu." and "/dev/tty." from the
           system location and returns the remainder of the string.
    \row
        \li Other *nix
        \li  The same as for GNU/Linux.
    \endtable

    \sa setPort(), QSerialPortInfo::portName()
*/
QString QSerialPort::portName() const
{
    Q_D(const QSerialPort);
    return QSerialPortPrivate::portNameFromSystemLocation(d->systemLocation);
}

/*!
    \reimp

    Opens the serial port using OpenMode \a mode, and then returns true if
    successful; otherwise returns false with and sets an error code which can be
    obtained by calling the error() method.

    \warning The \a mode has to be QIODevice::ReadOnly, QIODevice::WriteOnly,
    or QIODevice::ReadWrite. Other modes are unsupported.

    \sa QIODevice::OpenMode, setPort()
*/
bool QSerialPort::open(OpenMode mode)
{
    Q_D(QSerialPort);

    if (isOpen()) {
        setError(QSerialPort::OpenError);
        return false;
    }

    // Define while not supported modes.
    static const OpenMode unsupportedModes = Append | Truncate | Text | Unbuffered;
    if ((mode & unsupportedModes) || mode == NotOpen) {
        setError(QSerialPort::UnsupportedOperationError);
        return false;
    }

    clearError();
    if (d->open(mode)) {
        QIODevice::open(mode);

        d->dataTerminalReady = isDataTerminalReady();
        d->requestToSend = isRequestToSend();

        return true;
    }
    return false;
}

/*!
    \reimp

    \sa QIODevice::close()
*/
void QSerialPort::close()
{
    Q_D(QSerialPort);
    if (!isOpen()) {
        return;
    }

    QIODevice::close();
    d->close();
}

/*!
    \property QSerialPort::settingsRestoredOnClose
    \brief the flag which allows to restore the previous settings while closing
    the serial port.

    If this flag is true, the settings will be restored; otherwise not.
    The default state of the QSerialPort class is configured to restore the
    settings.
*/
void QSerialPort::setSettingsRestoredOnClose(bool restore)
{
    Q_D(QSerialPort);

    if (d->settingsRestoredOnClose != restore) {
        d->settingsRestoredOnClose = restore;
        emit settingsRestoredOnCloseChanged(d->settingsRestoredOnClose);
    }
}

bool QSerialPort::settingsRestoredOnClose() const
{
    Q_D(const QSerialPort);
    return d->settingsRestoredOnClose;
}

/*!
    \fn void QSerialPort::settingsRestoredOnCloseChanged(bool restore)

    This signal is emitted after the flag which allows to restore the
    previous settings while closing the serial port has been changed. The new
    flag which allows to restore the previous settings while closing the serial
    port is passed as \a restore.

    \sa QSerialPort::settingsRestoredOnClose
*/

/*!
    \property QSerialPort::baudRate
    \brief the data baud rate for the desired direction

    If the setting is successful, returns true; otherwise returns false and sets
    an error code which can be obtained by accessing the value of the
    QSerialPort::error property. To set the baud rate, use the enumeration
    QSerialPort::BaudRate or any positive qint32 value.

    \warning Only the AllDirections flag is support for setting this property on
    Windows, Windows CE, and Symbian.

    \warning Returns equal baud rate in any direction on Windows, Windows CE, and
    Symbian.
*/
bool QSerialPort::setBaudRate(qint32 baudRate, Directions dir)
{
    Q_D(QSerialPort);

    if (d->setBaudRate(baudRate, dir)) {
        if (dir & QSerialPort::Input) {
            if (d->inputBaudRate != baudRate)
                d->inputBaudRate = baudRate;
            else
                dir &= ~QSerialPort::Input;
        }

        if (dir & QSerialPort::Output) {
            if (d->outputBaudRate != baudRate)
                d->outputBaudRate = baudRate;
            else
                dir &= ~QSerialPort::Output;
        }

        if (dir)
            emit baudRateChanged(baudRate, dir);

        return true;
    }

    return false;
}

qint32 QSerialPort::baudRate(Directions dir) const
{
    Q_D(const QSerialPort);
    if (dir == QSerialPort::AllDirections)
        return d->inputBaudRate == d->outputBaudRate ?
                    d->inputBaudRate : QSerialPort::UnknownBaud;
    return dir & QSerialPort::Input ? d->inputBaudRate : d->outputBaudRate;
}

/*!
    \fn void QSerialPort::baudRateChanged(qint32 baudRate, Directions dir)

    This signal is emitted after the baud rate has been changed. The new baud
    rate is passed as \a baudRate and directions as \a dir.

    \sa QSerialPort::baudRate
*/

/*!
    \property QSerialPort::dataBits
    \brief the data bits in a frame

    If the setting is successful, returns true; otherwise returns false and sets
    an error code which can be obtained by accessing the value of the
    QSerialPort::error property.
*/
bool QSerialPort::setDataBits(DataBits dataBits)
{
    Q_D(QSerialPort);

    if (d->setDataBits(dataBits)) {
        if (d->dataBits != dataBits) {
            d->dataBits = dataBits;
            emit dataBitsChanged(d->dataBits);
        }
        return true;
    }

    return false;
}

QSerialPort::DataBits QSerialPort::dataBits() const
{
    Q_D(const QSerialPort);
    return d->dataBits;
}

/*!
    \fn void QSerialPort::dataBitsChanged(DataBits dataBits)

    This signal is emitted after the data bits in a frame has been changed. The
    new data bits in a frame is passed as \a dataBits.

    \sa QSerialPort::dataBits
*/


/*!
    \property QSerialPort::parity
    \brief the parity checking mode

    If the setting is successful, returns true; otherwise returns false and sets
    an error code which can be obtained by accessing the value of the
    QSerialPort::error property.
*/
bool QSerialPort::setParity(Parity parity)
{
    Q_D(QSerialPort);

    if (d->setParity(parity)) {
        if (d->parity != parity) {
            d->parity = parity;
            emit parityChanged(d->parity);
        }
        return true;
    }

    return false;
}

QSerialPort::Parity QSerialPort::parity() const
{
    Q_D(const QSerialPort);
    return d->parity;
}

/*!
    \fn void QSerialPort::parityChanged(Parity parity)

    This signal is emitted after the parity checking mode has been changed. The
    new parity checking mode is passed as \a parity.

    \sa QSerialPort::parity
*/

/*!
    \property QSerialPort::stopBits
    \brief the number of stop bits in a frame

    If the setting is successful, returns true; otherwise returns false and
    sets an error code which can be obtained by accessing the value of the
    QSerialPort::error property.
*/
bool QSerialPort::setStopBits(StopBits stopBits)
{
    Q_D(QSerialPort);

    if (d->setStopBits(stopBits)) {
        if (d->stopBits != stopBits) {
            d->stopBits = stopBits;
            emit stopBitsChanged(d->stopBits);
        }
        return true;
    }

    return false;
}

QSerialPort::StopBits QSerialPort::stopBits() const
{
    Q_D(const QSerialPort);
    return d->stopBits;
}

/*!
    \fn void QSerialPort::stopBitsChanged(StopBits stopBits)

    This signal is emitted after the number of stop bits in a frame has been
    changed. The new number of stop bits in a frame is passed as \a stopBits.

    \sa QSerialPort::stopBits
*/

/*!
    \property QSerialPort::flowControl
    \brief the desired flow control mode

    If the setting is successful, returns true; otherwise returns false and sets
    an error code which can be obtained by accessing the value of the
    QSerialPort::error property.
*/
bool QSerialPort::setFlowControl(FlowControl flow)
{
    Q_D(QSerialPort);

    if (d->setFlowControl(flow)) {
        if (d->flow != flow) {
            d->flow = flow;
            emit flowControlChanged(d->flow);
        }
        return true;
    }

    return false;
}

QSerialPort::FlowControl QSerialPort::flowControl() const
{
    Q_D(const QSerialPort);
    return d->flow;
}

/*!
    \fn void QSerialPort::flowControlChanged(FlowControl flow)

    This signal is emitted after the flow control mode has been changed. The
    new flow control mode is passed as \a flow.

    \sa QSerialPort::flowControl
*/

/*!
    \property QSerialPort::dataTerminalReady
    \brief the state (high or low) of the line signal DTR

    If the setting is successful, returns true; otherwise returns false.
    If the flag is true then the DTR signal is set to high; otherwise low.

    \sa pinoutSignals()
*/
bool QSerialPort::setDataTerminalReady(bool set)
{
    Q_D(QSerialPort);

    bool retval = d->setDataTerminalReady(set);
    if (retval && (d->dataTerminalReady != set)) {
        d->dataTerminalReady = set;
        emit dataTerminalReadyChanged(set);
    }

    return retval;
}

bool QSerialPort::isDataTerminalReady()
{
    Q_D(const QSerialPort);
    return d->pinoutSignals() & QSerialPort::DataTerminalReadySignal;
}

/*!
    \fn void QSerialPort::dataTerminalReadyChanged(bool set)

    This signal is emitted after the state (high or low) of the line signal DTR
    has been changed. The new the state (high or low) of the line signal DTR is
    passed as \a set.

    \sa QSerialPort::dataTerminalReady
*/

/*!
    \property QSerialPort::requestToSend
    \brief the state (high or low) of the line signal RTS

    If the setting is successful, returns true; otherwise returns false.
    If the flag is true then the RTS signal is set to high; otherwise low.

    \sa pinoutSignals()
*/
bool QSerialPort::setRequestToSend(bool set)
{
    Q_D(QSerialPort);

    bool retval = d->setRequestToSend(set);
    if (retval && (d->requestToSend != set)) {
        d->requestToSend = set;
        emit requestToSendChanged(set);
    }

    return retval;
}

bool QSerialPort::isRequestToSend()
{
    Q_D(const QSerialPort);
    return d->pinoutSignals() & QSerialPort::RequestToSendSignal;
}

/*!
    \fn void QSerialPort::requestToSendChanged(bool set)

    This signal is emitted after the state (high or low) of the line signal RTS
    has been changed. The new the state (high or low) of the line signal RTS is
    passed as \a set.

    \sa QSerialPort::requestToSend
*/

/*!
    Returns the state of the line signals in a bitmap format.

    From this result, it is possible to allocate the state of the
    desired signal by applying a mask "AND", where the mask is
    the desired enumeration value from QSerialPort::PinoutSignals.

    Note that, this method performs a system call, thus ensuring that the line
    signal states are returned properly. This is necessary when the underlying
    operating systems cannot provide proper notifications about the changes.

    \sa isDataTerminalReady(), isRequestToSend, setDataTerminalReady(),
    setRequestToSend()
*/
QSerialPort::PinoutSignals QSerialPort::pinoutSignals()
{
    Q_D(const QSerialPort);
    return d->pinoutSignals();
}

/*!
    This function writes as much as possible from the internal write
    buffer to the underlying serial port without blocking. If any data
    was written, this function returns true; otherwise returns false.

    Call this function for sending the buffered data immediately to the serial
    port. The number of bytes successfully written depends on the operating
    system. In most cases, this function does not need to be called, because the
    QSerialPort class will start sending data automatically once control is
    returned to the event loop. In the absence of an event loop, call
    waitForBytesWritten() instead.

    \sa write(), waitForBytesWritten()
*/
bool QSerialPort::flush()
{
    Q_D(QSerialPort);
    return d->flush();
}

/*!
    Discards all characters from the output or input buffer, depending on
    a given direction \a dir. Including clear an internal class buffers and
    the UART (driver) buffers. Also terminate pending read or write operations.
    If successful, returns true; otherwise returns false.
*/
bool QSerialPort::clear(Directions dir)
{
    Q_D(QSerialPort);
    if (dir & Input)
        d->readBuffer.clear();
    if (dir & Output)
        d->writeBuffer.clear();
    return d->clear(dir);
}

/*!
    \reimp

    Returns true if no more data is currently available for reading; otherwise
    returns false.

    This function is most commonly used when reading data from the
    serial port in a loop. For example:

    \code
    // This slot is connected to QSerialPort::readyRead()
    void QSerialPortClass::readyReadSlot()
    {
        while (!port.atEnd()) {
            QByteArray data = port.read(100);
            ....
        }
    }
    \endcode

     \sa bytesAvailable(), readyRead()
 */
bool QSerialPort::atEnd() const
{
    Q_D(const QSerialPort);
    return QIODevice::atEnd() && (!isOpen() || (d->bytesAvailable() == 0));
}

/*!
    \property QSerialPort::dataErrorPolicy
    \brief the error policy how the process receives the character in case of
    parity error detection.

    If the setting is successful, returns true; otherwise returns false. The
    default policy set is IgnorePolicy.
*/
bool QSerialPort::setDataErrorPolicy(DataErrorPolicy policy)
{
    Q_D(QSerialPort);

    const bool ret = d->policy == policy || d->setDataErrorPolicy(policy);
    if (ret && (d->policy != policy)) {
        d->policy = policy;
        emit dataErrorPolicyChanged(d->policy);
    }

    return ret;
}

QSerialPort::DataErrorPolicy QSerialPort::dataErrorPolicy() const
{
    Q_D(const QSerialPort);
    return d->policy;
}

/*!
    \fn void QSerialPort::dataErrorPolicyChanged(DataErrorPolicy policy)

    This signal is emitted after the error policy how the process receives the
    character in case of parity error detection has been changed. The new error
    policy how the process receives the character in case of parity error
    detection is passed as \a policy.

    \sa QSerialPort::dataErrorPolicy
*/

/*!
    \property QSerialPort::error
    \brief the error status of the serial port

    The I/O device status returns an error code. For example, if open()
    returns false, or a read/write operation returns -1, this property can
    be used to figure out the reason why the operation failed.

    The error code is set to the default QSerialPort::NoError after a call to
    clearError()
*/
QSerialPort::SerialPortError QSerialPort::error() const
{
    Q_D(const QSerialPort);
    return d->error;
}

void QSerialPort::clearError()
{
    setError(QSerialPort::NoError);
}

/*!
    \fn void QSerialPort::error(SerialPortError error)

    This signal is emitted after the error has been changed. The new erroris
    passed as \a error.

    \sa QSerialPort::error
*/

/*!
    Returns the size of the internal read buffer. This limits the
    amount of data that the client can receive before calling the read()
    or readAll() methods.

    A read buffer size of 0 (the default) means that the buffer has
    no size limit, ensuring that no data is lost.

    \sa setReadBufferSize(), read()
*/
qint64 QSerialPort::readBufferSize() const
{
    Q_D(const QSerialPort);
    return d->readBufferMaxSize;
}

/*!
    Sets the size of QSerialPort's internal read buffer to be \a
    size bytes.

    If the buffer size is limited to a certain size, QSerialPort
    will not buffer more than this size of data. Exceptionally, a buffer
    size of 0 means that the read buffer is unlimited and all
    incoming data is buffered. This is the default.

    This option is useful if the data is only read at certain points
    in time (for instance in a real-time streaming application) or if the serial
    port should be protected against receiving too much data, which may
    eventually causes that the application runs out of memory.

    \sa readBufferSize(), read()