//DecodeMessage input event
public void DecodeMessage(object sender, DataReceivedArgs e)
{
foreach (byte c in e.Data)
{
if (rcvState == StateReception.Waiting)
{
messageAvailable = false;
}
switch (rcvState)
{
case StateReception.Waiting:
if (c == 0xFE)
{
rcvState = StateReception.FunctionMSB;
}
break;
case StateReception.FunctionMSB:
msgDecodedFunction = (ushort)(c << 8);
rcvState = StateReception.FunctionLSB;
break;
case StateReception.FunctionLSB:
msgDecodedFunction += (ushort)(c << 0);
rcvState = StateReception.PayloadLengthMSB;
break;
case StateReception.PayloadLengthMSB:
msgDecodedPayloadLength = (ushort)(c << 8);
rcvState = StateReception.PayloadLengthLSB;
break;
case StateReception.PayloadLengthLSB:
msgDecodedPayloadLength += (ushort)(c << 0);
if (msgDecodedPayloadLength > 0)
{
msgDecodedPayloadIndex = 0;
msgDecodedPayload = new byte[msgDecodedPayloadLength];
rcvState = StateReception.Payload;
}
else
{
rcvState = StateReception.CheckSum; //if no payload, skip to CheckSum state
}
break;
case StateReception.Payload:
if (msgDecodedPayloadIndex < msgDecodedPayloadLength)
{
msgDecodedPayload[msgDecodedPayloadIndex] = c;
msgDecodedPayloadIndex++;
if (msgDecodedPayloadIndex == msgDecodedPayloadLength)
{
rcvState = StateReception.CheckSum;
}
}
break;
case StateReception.CheckSum:
receivedCheckSum = c;
calculatedCheckSum = mesEncoder.CalculateChecksum(msgDecodedFunction, msgDecodedPayloadLength, msgDecodedPayload);
messageAvailable = true;
if (calculatedCheckSum == receivedCheckSum)
{
//Console.WriteLine("checksum ok received: " + receivedCheckSum.ToString("X2") +
// " calculated: " + calculatedCheckSum.ToString("X2"));
CheckSumErrorOccured = false;
}
else
{
// Console.WriteLine("checksum error received: " + receivedCheckSum.ToString("X2") +
// " calculated: " + calculatedCheckSum.ToString("X2"));
CheckSumErrorOccured = true;
}
OnDataDecoded(msgDecodedFunction, msgDecodedPayloadLength, msgDecodedPayload, receivedCheckSum, CheckSumErrorOccured);
rcvState = StateReception.Waiting;
break;
default:
rcvState = StateReception.Waiting;
break;
}
}
}