bool ProcessReceivedCharacter(char currentCharacter, CBusStateMachine state)
{
switch (state.ParserState)
{
case CBusStateMachine.StateMachineState.MESSAGE_COMPLETE:
case CBusStateMachine.StateMachineState.NONE:
{
if (currentCharacter != STX_CHAR)
{
//Serial interface seems to strip leading '\' character
//so just assume that the STX was received and that this is the first data character.
//So the next received character will be data 2
if (IsValidCharacter(currentCharacter))
{
state.ParserState = CBusStateMachine.StateMachineState.DATA2;
}
else
{
state.ParserState = CBusStateMachine.StateMachineState.ACK_RECEIVED;
}
}
else
{
state.ParserState = CBusStateMachine.StateMachineState.STX_FOUND;
}
break;
}
case CBusStateMachine.StateMachineState.ACK_RECEIVED:
{
switch (currentCharacter)
{
case ACK_CHAR:
//Store the ack character...
state.ACK_Character = state.PreviousRxCharacter;
state.MessageType = CBusMessageType.ACK;
return(true);
//NAK Responses
case NAK:
state.MessageType = CBusMessageType.NAK;
return(true);
case NAK_CORRUPTED:
state.MessageType = CBusMessageType.NAK_CORRUPTED;
return(true);
case NAK_NO_CLOCK:
state.MessageType = CBusMessageType.NAK_NO_CLOCK;
return(true);
case NAK_MSG_TOO_LONG:
state.MessageType = CBusMessageType.NAK_MESSAGE_TOO_LONG;
return(true);
default:
//Unexpected character
state.Reset();
break;
}
break;
}
case CBusStateMachine.StateMachineState.DATA1:
{
if (currentCharacter == ETX_CHAR_1)
{
state.ParserState = CBusStateMachine.StateMachineState.MESSAGE_COMPLETE;
state.CalculatedChecksum = CBusSALCommand.CalculateChecksum(state.CommandBytes, state.CommandLength);
state.MessageType = CBusMessageType.SAL_MESSAGE_RECEIVED;
return(true);
}
else
{
if (IsValidCharacter(currentCharacter))
{
state.ParserState = CBusStateMachine.StateMachineState.DATA2;
}
else
{
state.Reset();
}
}
break;
}
case CBusStateMachine.StateMachineState.DATA2:
{
var hex = string.Format("{0}{1}", state.PreviousRxCharacter, currentCharacter);
byte data;
if (byte.TryParse(hex, System.Globalization.NumberStyles.HexNumber, System.Globalization.CultureInfo.InvariantCulture, out data))
{
state.CommandBytes[state.CommandLength++] = data;
state.ParserState = CBusStateMachine.StateMachineState.DATA1;
}
else
{
state.Reset();
}
break;
}
}
if (state.ParserState != CBusStateMachine.StateMachineState.NONE)
{
state.MessageType = CBusMessageType.MESSAGE_PENDING;
}
return(false);
}
public bool TryProcessReceivedBytes(char[] RxData, int rxDataLength, ref int DataPositionPointer, CBusStateMachine state)
{
state.BytesProcessed = 0;
for (int i = DataPositionPointer; i < rxDataLength; ++i)
{
var currentCharacter = RxData[i];
state.BytesProcessed++;
DataPositionPointer++;
var result = ProcessReceivedCharacter(currentCharacter, state);
state.PreviousRxCharacter = currentCharacter;
if (result)
{
//If we have a valid check sum and message terminated by ETX_CHAR_1 & ETX_CHAR_2 then trat as a monitored SAL
if (/*state.CalculatedChecksum == 0 &&*/ state.MessageType == CBusMessageType.SAL_MESSAGE_RECEIVED)
{
//Has Valid check sum so could be a monitored SAL message
if ((i + 1) < rxDataLength)
{
if (RxData[i + 1] == ETX_CHAR_2)
{
DataPositionPointer++;
state.BytesProcessed++;
state.MessageType = CBusMessageType.MONITORED_SAL_MESSAGE_RECEIVED;
}
}
}
return(true);
}
}
return(false);
}
