Reimplementing QSerialPort canReadLine() and readLine() methods

Question

I am trying to receive custom framed raw bytes via QSerialPort using value 0 as delimiter in asynchronous mode (using signals instead of polling).

The inconvenience is that QSerialPort doesn't seem to have a method that can read serial data until a specified byte value is encountered e.g. read_until (delimiter_value) in pyserial.

I was wondering if it's possible to reimplement QSerialPort's readLine() function in Python so that it reads until 0 byte value is encountered instead of '\n'. Similarly, it would be handy to reimplement canReadLine() as well.

I know that it is possible to use readAll() method and then parse the data for delimiter value. But this approach likely implies more code and decrease in efficiency. I would like to have the lowest overhead possible when processing the frames (serial baud rate and number of incoming bytes are large). However, if you know a fast approach to do it, I would like to take a look.

Answer 1

I ended up parsing the frame, it seems to work well enough. Below is a method extract from my script which receives and parses serial data asynchronously. self.serial_buffer is a QByteArray array initialized inside a custom class init method. You can also use a globally declared bytearray but you will have to check for your delimiter value in another way.

@pyqtSlot()
def receive(self):
    self.serial_buffer += self.serial.readAll()   # Read all data from serial buffer

    start_pos, del_pos = 0, 0
    while True:
        del_pos = self.serial_buffer.indexOf(b'\x00', start_pos)   # b'\x00' is delimiter byte
        if del_pos == -1: break   # del_pos is -1 if b'\x00' is not found
        frame = self.serial_buffer[start_pos: del_pos]   # Copy data until delimiter
        start_pos = del_pos + 1   # Exclude old delimiter from your search
        self.serial_buffer = self.serial_buffer[start_pos:]   # Copy remaining data excluding frame
        self.process_frame(frame)   # Process frame