/// <summary>
/// Creates the HDLC frame and stores it into buffer
/// </summary>
public void CreateHDLC()
{
byte temp;
List <byte> tmpBuffer = new List <byte>();
List <byte> tmpBuffer2 = new List <byte>();
// Clear buffer
tmpBuffer.Clear();
// Add cmd
tmpBuffer.Add(cmd);
// Add Length
Length = (byte)Data.Count;
tmpBuffer.Add((byte)Data.Count);
// Add Data
for (byte i = 0; i < Length; i++)
{
tmpBuffer.Add(Data[i]);
}
// Add CRC
crc = DPA_UTILS.CalcCRC(tmpBuffer);
tmpBuffer.Add(crc);
// Make a HDLC frame
tmpBuffer2.Clear();
tmpBuffer2.Add((byte)0x7E); // Flag sequence
foreach (byte tmp in tmpBuffer)
{
temp = tmp;
// If there is Flag sequence or Control escape
if ((temp == (byte)0x7D) || (temp == (byte)0x7E))
{
tmpBuffer2.Add((byte)0x7D);
tmpBuffer2.Add((byte)(temp ^ 0x20));
}
else
{
tmpBuffer2.Add((byte)temp);
}
}
tmpBuffer2.Add((byte)0x7E); // Flag sequence
// Copy result to Buffer
Buffer = new byte[tmpBuffer2.Count];
tmpBuffer2.CopyTo(Buffer);
}
/// <summary>
/// Method to parse through incoming bytes and create a HDLC frame
/// </summary>
/// <param name="character">the byte to check</param>
/// <returns>Returns the state of the HDLC frame after checking one character</returns>
public DPA_RX_STATE DPA_RX_Parse(byte character)
{
int i = 0;
DPA_RX_STATE ret_val = DPA_RX_STATE.DPA_RX_NOERR;
if (character == HDLC_FLAG_SEQUENCE) // flag sequence
{
// first Flag sequnce
if (Buffer.Count == 0)
{
Buffer.Add((byte)character);
HDLC_CE = false;
}
else
{
// It is error state - too short message
if (Buffer.Count < (HDLC_MIN_LEN - 1))
{
// Maybe it is start of new frame...
Buffer.Clear(); Buffer.Add(character);
return(DPA_RX_STATE.DPA_RX_FE);
}
// Correct length
else
{
// Check CRC
Buffer.RemoveAt(0); // remove first Flag sequnce
byte crc = DPA_UTILS.CalcCRC(Buffer);
// CRC is OK
if (crc == 0)
{
byte[] tmpBuffer = new byte[Buffer.Count];
Buffer.CopyTo(tmpBuffer);
cmd = tmpBuffer[0];
Length = tmpBuffer[1];
for (i = 0; i < Length; i++)
{
Data.Add(tmpBuffer[i + 2]); //exception
}
CRC = tmpBuffer[Length + 2];
Buffer.Clear();
return(DPA_RX_STATE.DPA_RX_OK);
}
// CRC is no OK
else
{
// Maybe it is start of new frame...
Buffer.Clear(); Buffer.Add((byte)0x7E);
return(DPA_RX_STATE.DPA_RX_CRCERR);
}
}
}
}
else // if another character received
{
// if it is not the first character and length is within borders
if ((Buffer.Count > 0) && (Buffer.Count < HDLC_MAX_LEN))
{
// if Control Esape received
if (character == HDLC_CONTROL_ESCAPE)
{
HDLC_CE = true;
}
else
{ // else insert character
if (HDLC_CE == false)
{
Buffer.Add((byte)character);
}
else
{
HDLC_CE = false;
Buffer.Add((byte)((byte)character ^ (byte)HDLC_ESCAPE_BIT));
}
}
}
}
return(ret_val);
}