portmanager.cpp

#include "portmanager.h"

#include <QtEndian>
#include <QCoreApplication>
#include <QDebug>
#include <QElapsedTimer>

static constexpr char
    END_SLIP_OCTET = -64, // 0xC0
    END_SUBS_OCTET = -36, // 0xDC
    ESC_SLIP_OCTET = -37, // 0xDB
    ESC_SUBS_OCTET = -35; // 0xDD

static constexpr int MIN_FRAME_SIZE = sizeof(quint8) + sizeof(quint16) + 1;

static const quint16 _crc_ccitt_lut[] = {
    0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7, 0x8108,
    0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef, 0x1231, 0x0210,
    0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6, 0x9339, 0x8318, 0xb37b,
    0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de, 0x2462, 0x3443, 0x0420, 0x1401,
    0x64e6, 0x74c7, 0x44a4, 0x5485, 0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee,
    0xf5cf, 0xc5ac, 0xd58d, 0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6,
    0x5695, 0x46b4, 0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d,
    0xc7bc, 0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
    0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b, 0x5af5,
    0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12, 0xdbfd, 0xcbdc,
    0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a, 0x6ca6, 0x7c87, 0x4ce4,
    0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41, 0xedae, 0xfd8f, 0xcdec, 0xddcd,
    0xad2a, 0xbd0b, 0x8d68, 0x9d49, 0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13,
    0x2e32, 0x1e51, 0x0e70, 0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a,
    0x9f59, 0x8f78, 0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e,
    0xe16f, 0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
    0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e, 0x02b1,
    0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256, 0xb5ea, 0xa5cb,
    0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d, 0x34e2, 0x24c3, 0x14a0,
    0x0481, 0x7466, 0x6447, 0x5424, 0x4405, 0xa7db, 0xb7fa, 0x8799, 0x97b8,
    0xe75f, 0xf77e, 0xc71d, 0xd73c, 0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657,
    0x7676, 0x4615, 0x5634, 0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9,
    0xb98a, 0xa9ab, 0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882,
    0x28a3, 0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
    0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92, 0xfd2e,
    0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9, 0x7c26, 0x6c07,
    0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1, 0xef1f, 0xff3e, 0xcf5d,
    0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8, 0x6e17, 0x7e36, 0x4e55, 0x5e74,
    0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
};

static inline void _encodeSymbol(QByteArray &buffer, char ch) Q_DECL_NOTHROW
{
    switch (ch)
    {
        case END_SLIP_OCTET:
            buffer.append(ESC_SLIP_OCTET);
            buffer.append(END_SUBS_OCTET);
            break;

        case ESC_SLIP_OCTET:
            buffer.append(ESC_SLIP_OCTET);
            buffer.append(ESC_SUBS_OCTET);
            break;

        default:
            buffer.append(ch);
    }
}

static int _restTime(int timeout, int elapsed)
{
    if (timeout < 0)
        return -1;

    timeout = timeout - elapsed;

    return timeout < 0 ? 0 : timeout;
}

PortManager::PortManager(QObject *parent) : QObject(parent), _serial(this)
{
}

void PortManager::setPort(const QString &name, qint32 baudRate, QSerialPort::DataBits dataBits, QSerialPort::Parity parity, QSerialPort::StopBits stopBits, QSerialPort::FlowControl flowControl)
{
    _serial.setPortName(name);

    bool res = _serial.setBaudRate(baudRate)
        && _serial.setDataBits(dataBits)
        && _serial.setParity(parity)
        && _serial.setStopBits(stopBits)
        && _serial.setFlowControl(flowControl);

    if (!res)
        qCritical() << "Serial port set() error:" << getSerialError();
}

bool PortManager::open()
{
    if (_serial.isOpen())
        _serial.close();

    if (!_serial.open(QSerialPort::ReadWrite))
    {
        qCritical() << "An error occures when opening serial port: " << _serial.errorString();

        return false;
    }

    return true;
}

void PortManager::close()
{
    if (_serial.isOpen())
        _serial.close();
}

QStringList PortManager::slipCommand(const QByteArray &frame, int msecs)
{
    if (!_serial.isOpen())
    {
        qCritical() << "Serial is closed:" << _serial.portName();

        return QStringList();
    }

    if (frame.size() < (int)sizeof(MB_Packet_t))
        return QStringList();

    QElapsedTimer stopWatch;

    QCoreApplication::processEvents();
    _serial.clear();
    sendFrame(0, frame);
    for (stopWatch.start(); _restTime(msecs, stopWatch.elapsed()) > 0;)
    {
        QByteArray reply = waitForFrame(_restTime(msecs, stopWatch.elapsed()));

        // Timeout when no reply received.
        if (reply.isEmpty())
            break;

        int channel;
        QByteArray message;

        if (decodeFrame(reply, channel, message)
                && 0 == channel
                && message.size() >= (int)sizeof(MB_GeneralResult_t)
                && frame.at(2) == message.at(2))
        {
            const MB_GeneralResult_t *gr = (const MB_GeneralResult_t*)message.constData();

            if (MB_GENERAL_RESULT == qFromBigEndian(gr->header.type))
            {
                QCoreApplication::processEvents();

                return QStringList() << QString::number(qFromBigEndian(gr->errorCode));
            }
        }
    }

    QCoreApplication::processEvents();

    return QStringList();
}

QStringList PortManager::railtestCommand(int channel, const QByteArray &cmd, int msecs)
{
    if (!_serial.isOpen())
    {
        qCritical() << "Serial is closed:" << _serial.portName();

        return QStringList();
    }

    if (channel < 1 || channel > 3)
        return QStringList();

    bool startPrefixFound = false;
    QByteArray startPrefix = "{{(" + cmd.trimmed().split(' ').at(0) + ")}";
    QString response;
    QElapsedTimer stopWatch;

    QCoreApplication::processEvents();
    _serial.clear();
    sendFrame(channel, cmd + "\r\n\r\n");
    for (stopWatch.start(); _restTime(msecs, stopWatch.elapsed()) > 0;)
    {
        QByteArray reply = waitForFrame(_restTime(msecs, stopWatch.elapsed()));

        // Timeout when no reply received.
        if (reply.isEmpty())
            break;

        int ch;
        QByteArray part;

        if (decodeFrame(reply, ch, part) && ch == channel)
        {
            int idx;

            response += part;
            if (startPrefixFound)
            {
                idx = response.indexOf("\r\n> ", 0, Qt::CaseInsensitive);
                if (idx >= 0)
                {
                    response = response.left(idx);
                    break;
                }
            }
            else
            {
                idx = response.indexOf(startPrefix, 0, Qt::CaseInsensitive);
                if (idx >= 0)
                {
                    startPrefixFound = true;
                    response = response.mid(idx);
                }
            }
        }
    }

    QCoreApplication::processEvents();

    return startPrefixFound ?
          response
              .replace(QChar('{'), QChar(' '))
              .replace(QChar('}'), QChar(' '))
              .replace(QChar('\n'), QChar(' '))
              .replace(QChar('\r'), QChar(' '))
              .replace(QChar('>'), QChar(' '))
              .simplified()
              .split(' ')
        : QStringList();
}

void PortManager::sendFrame(int channel, const QByteArray &frame) Q_DECL_NOTHROW
{
    QByteArray encodedBuffer;
    quint16 frameCrc = 0xFFFF;

    // Write UART wake up symbols and SLIP frame start.
    encodedBuffer.reserve((frame.size() + 3) * 2 + 2);
    encodedBuffer.append(END_SLIP_OCTET);

    // Write escaped channel number.
    quint8 index = channel ^ (frameCrc >> 8);

    _encodeSymbol(encodedBuffer, channel);
    frameCrc = _crc_ccitt_lut[index] ^ (frameCrc << 8);

    // Write escaped frame and calculate CRC.
    foreach (char ch, frame)
    {
        quint8 index = (quint8)ch ^ (frameCrc >> 8);

        _encodeSymbol(encodedBuffer, ch);
        frameCrc = _crc_ccitt_lut[index] ^ (frameCrc << 8);
    }

    // Write escaped CRC.
    _encodeSymbol(encodedBuffer, frameCrc >> 8);
    _encodeSymbol(encodedBuffer, frameCrc & 0xFF);

    // Write SLIP frame end.
    encodedBuffer.append(END_SLIP_OCTET);

    // Write encoded frame to serial port.
    _serial.write(encodedBuffer);
    _serial.flush();
    _serial.flush();
}

QByteArray PortManager::waitForFrame(int msecs)
{
    bool started = false;
    QByteArray frame;
    QElapsedTimer stopWatch;

    for (stopWatch.start(); _restTime(msecs, stopWatch.elapsed()) > 0;)
    {
        // Timeout when no response received.
        if (!_serial.waitForReadyRead(_restTime(msecs, stopWatch.elapsed())))
        {
            if (_serial.error())
                qCritical() << "Serial waitForReadyRead() error:" << getSerialError();
            break;
        }

        QByteArray buffer = _serial.readAll();

        if (buffer.isEmpty() && _serial.error())
        {
            qCritical() << "Serial readAll() error:" << getSerialError();
            break;
        }

        foreach (char ch, buffer)
        {
            if (ch == END_SLIP_OCTET)
                if (started)
                {
                    if (frame.size() >= MIN_FRAME_SIZE)
                        return frame;                      // Full frame reached.

                    frame.clear();
                }
                else
                {
                    started = true;
                    frame.clear();
                }
            else
                if (started)
                    frame.append(ch);
        }
    }

    return QByteArray();
}

bool PortManager::decodeFrame(const QByteArray &frame, int &channel, QByteArray &message)
{
    QByteArray decodedBuffer;

    // Write unescaped buffer.
    decodedBuffer.reserve(frame.size());
    for (int i = 0; i < frame.size(); ++i)
    {
        char ch = frame.at(i);

        if (ch == ESC_SLIP_OCTET)
        {
            ++i;
            if (i >= frame.size())
            {
                qWarning() << "SLIP. Decode frame. Unfinished escape sequence.";

                return false;
            }
            switch (frame.at(i))
            {
                case END_SUBS_OCTET:
                    decodedBuffer.append(END_SLIP_OCTET);
                    break;

                case ESC_SUBS_OCTET:
                    decodedBuffer.append(ESC_SLIP_OCTET);
                    break;

                default:
                    qWarning() << "SLIP. Decode frame. Invalid escape sequence.";

                    return false;
            }
        }
        else
            decodedBuffer.append(ch);
    }
    if (decodedBuffer.size() < MIN_FRAME_SIZE)
    {
        qWarning() << "SLIP. Decode frame. Frame too short.";

        return false;
    }

    // Calculate CRC.
    int frameSize = decodedBuffer.size() - 2;
    quint16
        frameCrc = 0xFFFF,
        bufferCrc = (quint8)decodedBuffer.at(frameSize + 1) | ((quint16)decodedBuffer.at(frameSize) << 8);

    for (int i = 0; i < frameSize; ++i)
    {
        quint8 index = (quint8)decodedBuffer.at(i) ^ (frameCrc >> 8);

        frameCrc = _crc_ccitt_lut[index] ^ (frameCrc << 8);
    }

    // Check CRC.
    if (frameCrc != bufferCrc)
    {
        qWarning() << "SLIP. Decode frame. Invalid Frame CRC.";

        return false;
    }

    // Frame received successfully.
    channel = decodedBuffer.at(0);
    message = decodedBuffer.mid(1, frameSize - 1);

    return true;
}

QString PortManager::getSerialError()
{
    QString ret = _serial.portName() + " " + _serial.errorString() + " (" + _serial.error() + ")";

    _serial.clearError();

    return ret;
}