private void sendYmodemClosingPacket(byte STX, int packetNumber, int invertedPacketNumber, byte[] data, int dataSize, byte[] CRC, int crcSize)
        {
            /* calculate CRC */
            Crc16Ccitt crc16Ccitt = new Crc16Ccitt(InitialCrcValue.Zeros);

            CRC = crc16Ccitt.ComputeChecksumBytes(data);

            /* send the packet */
            sendYmodemPacket(STX, packetNumber, invertedPacketNumber, data, dataSize, CRC, crcSize);
        }
        private void sendYmodemInitialPacket(byte STX, int packetNumber, int invertedPacketNumber, byte[] data, int dataSize, string path, FileStream fileStream, byte[] CRC, int crcSize)
        {
            string fileName = System.IO.Path.GetFileName(path);
            string fileSize = fileStream.Length.ToString();

            /* add filename to data */
            int i;

            for (i = 0; i < fileName.Length && (fileName.ToCharArray()[i] != 0); i++)
            {
                data[i] = (byte)fileName.ToCharArray()[i];
            }
            data[i] = 0;

            /* add filesize to data */
            int j;

            for (j = 0; j < fileSize.Length && (fileSize.ToCharArray()[j] != 0); j++)
            {
                data[(i + 1) + j] = (byte)fileSize.ToCharArray()[j];
            }
            data[(i + 1) + j] = 0;

            /* fill the remaining data bytes with 0 */
            for (int k = ((i + 1) + j) + 1; k < dataSize; k++)
            {
                data[k] = 0;
            }

            /* calculate CRC */
            Crc16Ccitt crc16Ccitt = new Crc16Ccitt(InitialCrcValue.Zeros);

            CRC = crc16Ccitt.ComputeChecksumBytes(data);

            /* send the packet */
            sendYmodemPacket(STX, packetNumber, invertedPacketNumber, data, dataSize, CRC, crcSize);
        }
        public bool YmodemUploadFile()
        {
            /* control signals */
            const byte STX = 2;  // Start of TeXt
            const byte EOT = 4;  // End Of Transmission
            const byte ACK = 6;  // Positive ACknowledgement
            const byte C   = 67; // capital letter C
            /* sizes */
            const int dataSize = 1024;
            const int crcSize  = 2;
            /* THE PACKET: 1029 bytes */
            /* header: 3 bytes */
            // STX
            int invertedPacketNumber = 255;

            /* data: 1024 bytes */
            byte[] data = new byte[dataSize];
            /* footer: 2 bytes */
            byte[] CRC = new byte[crcSize];
            /* get the file */
            FileStream fileStream = new FileStream(@path, FileMode.Open, FileAccess.Read);
            DateTime   dt         = DateTime.Now;

            byte[] ack;
            ack = new byte[] { 0x31 };
            try
            {
                serialPort.Write(ack, 0, 1);
            }
            catch
            {
                MessageBox.Show("Exception");
            }
            Thread.Sleep(300);
            try
            {
                sendYmodemInitialPacket(STX, packetNumber, invertedPacketNumber, data, dataSize, path, fileStream, CRC, crcSize);
                if (serialPort.ReadByte() != ACK)
                {
                    MessageBox.Show("Can't send the initial packet.");
                    return(false);
                }

                if (serialPort.ReadByte() != C)
                {
                    return(false);
                }

                /* send packets with a cycle until we send the last byte */
                int fileReadCount;
                do
                {
                    /* if this is the last packet fill the remaining bytes with 0 */

                    fileReadCount = fileStream.Read(data, 0, dataSize);

                    if (fileReadCount == 0)
                    {
                        break;
                    }
                    if (fileReadCount != dataSize)
                    {
                        for (int i = fileReadCount; i < dataSize; i++)
                        {
                            data[i] = 0;
                        }
                    }
                    /* calculate packetNumber */
                    packetNumber++;
                    if (packetNumber > 255)
                    {
                        packetNumber -= 256;
                    }
                    ThreadFunction();
                    Console.WriteLine(packetNumber);

                    /* calculate invertedPacketNumber */
                    invertedPacketNumber = 255 - packetNumber;

                    /* calculate CRC */
                    Crc16Ccitt crc16Ccitt = new Crc16Ccitt(InitialCrcValue.Zeros);
                    CRC = crc16Ccitt.ComputeChecksumBytes(data);

                    /* send the packet */
                    sendYmodemPacket(STX, packetNumber, invertedPacketNumber, data, dataSize, CRC, crcSize);

                    /* wait for ACK */
                    if (serialPort.ReadByte() != ACK)
                    {
                        Console.WriteLine("Couldn't send a packet.");
                        return(false);
                    }
                } while (dataSize == fileReadCount);

                /* send EOT (tell the downloader we are finished) */
                serialPort.Write(new byte[] { EOT }, 0, 1);
                /* send closing packet */
                packetNumber         = 0;
                invertedPacketNumber = 255;
                data = new byte[dataSize];
                CRC  = new byte[crcSize];
                sendYmodemClosingPacket(STX, packetNumber, invertedPacketNumber, data, dataSize, CRC, crcSize);
                /* get ACK (downloader acknowledge the EOT) */
                if (serialPort.ReadByte() != ACK)
                {
                    Console.WriteLine("Can't complete the transfer.");
                    return(false);
                }
            }
            catch (TimeoutException)
            {
                throw new Exception("Eductor does not answering");
            }
            finally
            {
                fileStream.Close();
            }
            Console.WriteLine("File transfer is succesful");
            TimeSpan span = DateTime.Now - dt;

            ButtonDownload.Invoke(
                new MethodInvoker
                (
                    delegate
            {
                ButtonDownload.Text = "Download Completed";
            }
                )
                );

            MessageBox.Show("Download time: " + span.ToString(@"hh\:mm\:ss\.ff"), "Download successful", MessageBoxButtons.OK, MessageBoxIcon.None);

            ButtonDownload.Invoke
            (
                new MethodInvoker
                (
                    delegate
            {
                ButtonDownload.Text = "Download";
            }
                )
            );

            RunNewApplication();

            return(true);
        }