Unnecessary append operations in "cp2130.cpp", line 937

[samuelfmlourenco]

Inside the file "cp2130.cpp", in line 937, there is an instance where values from writeReadInputBuffer are appended to retdata. An excerpt of spiWriteRead(), the function which contains said line, 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;
...
        int bytesRead = 0;  // Important!
        bulkTransfer(endpointInAddr, writeReadInputBuffer, payload, &bytesRead, errcnt, errstr);
        for (int i = 0; i < bytesRead; ++i) {
            retdata += writeReadInputBuffer[i];
        }
...
    return retdata;
}

However, appending to a QVector is slower than just assigning a value to an element that already exists. Once the number of bytes read is known, retdata could be resized and then the values assigned to it:

// 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;
...
        int bytesRead = 0;  // Important!
        bulkTransfer(endpointInAddr, writeReadInputBuffer, payload, &bytesRead, errcnt, errstr);
        retdata.resize(bytesRead);
        for (int i = 0; i < bytesRead; ++i) {
            retdata[i] = writeReadInputBuffer[i];
        }
...
    return retdata;
}

[samuelfmlourenco]

Implemented in version 2.2.2.