BrickPi.Brick.BrickPiRx C# (CSharp) Method

        private async Task<byte[]> BrickPiRx(int timeout, int cancelAfter = CancelAfter)
        {
            // clean token
            if (ReadCancellationTokenSource == null)
                ReadCancellationTokenSource = new CancellationTokenSource();
            ReadCancellationTokenSource.CancelAfter(timeout + cancelAfter);
            //read from the serial port
            byte[] rx_buffer = await ReadAsync(timeout, ReadCancellationTokenSource.Token);
            if (ReadCancellationTokenSource != null)
            {
                ReadCancellationTokenSource.Dispose();
                ReadCancellationTokenSource = null;
            }
            // check if data are valids
            if (rx_buffer == null)
                return null;
            if (rx_buffer.Length < 2)
                return null;
            if (rx_buffer.Length < (rx_buffer[1] + 2))
                return null;
            long CheckSum = (sum(1, rx_buffer.Length - 1, rx_buffer) % 256);
            if (CheckSum != rx_buffer[0])
                return null;
            byte[] retval = new byte[rx_buffer.Length - 2];
            //create the returned buffer, remove the message lenght and checksum
            for (int i = 0; i < (rx_buffer.Length - 2); i++)
                retval[i] = rx_buffer[i + 2];
            return retval;
        }