public ushort GetChecksum()
{
List <byte> bytes = new List <byte>();
bytes.AddRange(BitConverter.GetBytes(MessageType));
bytes.AddRange(BitConverter.GetBytes(SenderID));
bytes.Add(Length);
bytes.AddRange(Payload.Data);
return(Crc16CcittKermit.ComputeChecksum(bytes.ToArray()));
}
public bool ValidateCheckSum()
{
if (ReceicevedChecksum.HasValue)
{
List <byte> bytes = new List <byte>();
bytes.AddRange(BitConverter.GetBytes((ushort)(int)MessageType.Value));
bytes.AddRange(BitConverter.GetBytes(SenderID.Value));
bytes.Add(Length.Value);
bytes.AddRange(Payload);
return(Crc16CcittKermit.ComputeChecksum(bytes.ToArray()) == ReceicevedChecksum.Value);
}
else
{
return(false);
}
}
protected override void ProcessReading(bool restart)
{
if (restart)
{
_preambleFound = false;
_messageBytes.Clear();
}
if (!_preambleFound)
{
while (_receivedBytes.Count > 0)
{
if (_receivedBytes[0] == PREAMBLE)
{
_preambleFound = true;
_receivedBytes.RemoveAt(0);
break;
}
else
{
_receivedBytes.RemoveAt(0);
}
}
}
if (_preambleFound)
{
if (_messageBytes.Count == 0)
{
_messageBytes.Add(PREAMBLE);
}
if (_messageBytes.Count < 6 && _receivedBytes.Count >= 5)
{
_messageBytes.AddRange(_receivedBytes.GetRange(0, 5));
_messageBytes.RemoveRange(0, 5);
}
int messageLength = -1;
if (_messageBytes.Count >= 6)
{
messageLength = (int)_messageBytes[5];
}
if (messageLength > 0)
{
if (_receivedBytes.Count > messageLength + 2)
{
_messageBytes.AddRange(_receivedBytes.GetRange(0, messageLength + 2));
_receivedBytes.RemoveRange(0, messageLength + 2);
List <byte> crcBytes = new List <byte>();
for (int i = 1; i < _messageBytes.Count - 2; i++)
{
crcBytes.Add(_messageBytes[i]);
}
ushort crc = Crc16CcittKermit.ComputeChecksum(crcBytes.ToArray());
byte[] crcSumBytes = new byte[2] {
_messageBytes[_messageBytes.Count - 2], _messageBytes[_messageBytes.Count - 1]
};
ushort crcInMessage = BitConverter.ToUInt16(crcSumBytes, 0);
if (crc == crcInMessage)
{
lock (_syncobject)
_messageQueue.Enqueue(_messageBytes.ToArray());
}
else
{
lock (_syncobject)
_readExceptionQueue.Enqueue(new SBPReadExceptionEventArgs(new Exception("CRC not valid")));
}
_messageBytes.Clear();
_preambleFound = false;
}
}
}
}
