Implement spiWriteRead()

[samuelfmlourenco]

This function is to be implemented in the upcoming version 2.2.0. Its purpose is to write to the SPI bus while reading back.

[samuelfmlourenco]

Implemented in version 2.2.0. Code as follows:

// Writes to the SPI bus while reading back, returning a vector of the same size as the one given
// This is the prefered method of writing and reading, if both endpoint addresses are known
QVector<quint8> CP2130::spiWriteRead(const QVector<quint8> &data, quint8 endpointInAddr, quint8 endpointOutAddr, int &errcnt, QString &errstr)
{
    size_t bytesToWriteRead = static_cast<size_t>(data.size());
    size_t bytesLeft = bytesToWriteRead;
    QVector<quint8> retdata;
    while (bytesLeft > 0) {
        int payload = bytesLeft > 56 ? 56 : bytesLeft;
        int bufsize = payload + 8;
        unsigned char *writeReadCommandBuffer = new unsigned char[bufsize] {
            0x00, 0x00,         // Reserved
            CP2130::WRITEREAD,  // WriteRead command
            0x00,               // Reserved
            static_cast<quint8>(payload),
            static_cast<quint8>(payload >> 8),
            static_cast<quint8>(payload >> 16),
            static_cast<quint8>(payload >> 24)
        };
        for (int i = 0; i < payload; ++i) {
            writeReadCommandBuffer[i + 8] = data[bytesToWriteRead - bytesLeft + i];
        }
#if LIBUSB_API_VERSION >= 0x01000105
        bulkTransfer(endpointOutAddr, writeReadCommandBuffer, bufsize, nullptr, errcnt, errstr);
#else
        int bytesWritten;
        bulkTransfer(endpointOutAddr, writeReadCommandBuffer, bufsize, &bytesWritten, errcnt, errstr);
#endif
        delete[] writeReadCommandBuffer;
        unsigned char *writeReadInputBuffer = new unsigned char[payload];
        int bytesRead = 0;  // Important!
        bulkTransfer(endpointInAddr, writeReadInputBuffer, payload, &bytesRead, errcnt, errstr);
        for (int i = 0; i < bytesRead; ++i) {
            retdata += writeReadInputBuffer[i];
        }
        delete[] writeReadInputBuffer;
        bytesLeft -= payload;
    }
    return retdata;
}

// This function is a shorthand version of the previous one (both endpoint addresses are automatically deduced, at the cost of decreased speed)
QVector<quint8> CP2130::spiWriteRead(const QVector<quint8> &data, int &errcnt, QString &errstr)
{
    return spiWriteRead(data, getEndpointInAddr(errcnt, errstr), getEndpointOutAddr(errcnt, errstr), errcnt, errstr);
}