/**
* This function decodes a message into either the NegotiationData or GuessData structs depending
* on what the type of message is. This function receives the message one byte at a time, where the
* messages are in the format defined by MESSAGE_TEMPLATE, with payloads of the format defined by
* the PAYLOAD_TEMPLATE_* macros. It returns the type of message that was decoded and also places
* the decoded data into either the `nData` or `gData` structs depending on what the message held.
* The onus is on the calling function to make sure the appropriate structs are available (blame the
* lack of function overloading in C for this ugliness).
*
* PROTOCOL_PARSING_FAILURE is returned if there was an error of any kind (though this excludes
* checking for NULL pointers), while
*
* @param parser The struct holding the data for this instance of the parser. Allows for multiple
* protocol decoding streams.
* @param in The next character in the NMEA0183 message to be decoded.
* @param nData A struct used for storing data if a message is decoded that stores NegotiationData.
* @param gData A struct used for storing data if a message is decoded that stores GuessData.
* @return A value from the UnpackageDataEnum enum.
*/
ProtocolParserStatus ProtocolDecode(char in, NegotiationData *nData, GuessData *gData) {
static int i;
static uint8_t expSum;
switch (p.state)
{
//WATING case
case (WAITING) :
{
//Recycle WAITING
if (in != '$') {
p.state = WAITING;
return PROTOCOL_WAITING;
}
//Enter RECORDING
else if (in == '$') {
i = 0;
p.state = RECORDING;
return PROTOCOL_PARSING_GOOD;
}
break;
}
//RECORDING case
case (RECORDING) :
{
//Recycle RECORDING
if (in != '*') {
sentence[i] = in;
i += 1;
p.state = RECORDING;
return PROTOCOL_PARSING_GOOD;
}
//Enter FIRSTCHECKSUMHALF
else if (in == '*') {
p.state = FIRST_CHECKSUM_HALF;
return PROTOCOL_PARSING_GOOD;
}
break;
}
//FIRSTCHECKSUMHALF case
case (FIRST_CHECKSUM_HALF) :
{
//If given valid Hex Data continue accordingly
if (((in >= 'A') && (in <= 'F')) || ((in >= 'a') && (in <= 'f')) ||
((in >= '0') && (in <= '9'))) {
p.checkSum = (ConvertAscii(in) << 4);
p.state = SECOND_CHECKSUM_HALF;
return PROTOCOL_PARSING_GOOD;
}
//Given invalid hex data enter WAITING
else {
p.state = WAITING;
return PROTOCOL_PARSING_FAILURE;
}
break;
}
//SECONDCHECKSUM case
case (SECOND_CHECKSUM_HALF) :
{
//Calculate the expected checkSum
expSum = CreateCheckSum(i, sentence);
//If given VALID hex data and continue
if (((in >= 'A') && (in <= 'F')) || ((in >= 'a') && (in <= 'f')) ||
((in >= '0') && (in <= '9'))) {
//Finish assembling the Checksum thats read
p.checkSum |= ConvertAscii(in);
printf("Checksum is: %x\nExpChecksum is: %x\n", p.checkSum, expSum);
//If the two checkSums ARE equal pass GOOD and enter NEWLINE
if (p.checkSum == expSum) {
sentence[i] = '\0';
p.state = NEWLINE;
return PROTOCOL_PARSING_GOOD;
}
//If they ARENT equal then pass failure and enter WAITING
else {
p.state = WAITING;
return PROTOCOL_PARSING_FAILURE;
}
}
//Given INVALID hex data return FAILURE and enter WAITING
else {
p.state = WAITING;
return PROTOCOL_PARSING_FAILURE;
}
break;
}
//NEWINE case
case (NEWLINE) :
{
//If GIVEN a newline terminated string then evalauate the message
//Check what kind of message it is
if (in == '\n') {
//Check which C message it is
if (sentence[0] == 'C') {
//return CHA_MESSAGE and enter WAITING
if (sentence[1] == 'H') {
sscanf(sentence, PAYLOAD_TEMPLATE_CHA, &(nData->encryptedGuess),
&(nData->hash));
p.state = WAITING;
return PROTOCOL_PARSED_CHA_MESSAGE;
}
//return COO_MESSAGE and enter WAITING
else {
sscanf(sentence, PAYLOAD_TEMPLATE_COO, &(gData->row), &(gData->col));
p.state = WAITING;
return PROTOCOL_PARSED_COO_MESSAGE;
}
}
//return DET_MESSAGE and enter WAITING
else if (sentence[0] == 'D') {
sscanf(sentence, PAYLOAD_TEMPLATE_DET, &(nData->guess),
&(nData->encryptionKey));
p.state = WAITING;
return PROTOCOL_PARSED_DET_MESSAGE;
}
//return HIT_MESSAGE and enter WAITING
else if (sentence[0] == 'H') {
sscanf(sentence, PAYLOAD_TEMPLATE_HIT, &(gData->row), &(gData->col),
&(gData->hit));
p.state = WAITING;
return PROTOCOL_PARSED_HIT_MESSAGE;
}
}
//If NOT GIVEN a newline terminated string then evalauate the message
//return FAILURE and enter WAITING
else {
p.state = WAITING;
return PROTOCOL_PARSING_FAILURE;
}
break;
}
//Default to waiting just in case of failure
default :
{
p.state = WAITING;
return PROTOCOL_PARSING_FAILURE;
break;
}
}
//In case it didnt hit anything then indicate a failure
return PROTOCOL_PARSING_FAILURE;
}
SqlVal GetCsAsciiVal(const SqlVal& val)
{
return ConvertAscii(GetCsVal(val));
}
