public static NmeaSentence From(string sentence)
{
NmeaSentence nmeaSentence = new NmeaSentence();
int length1 = !string.IsNullOrEmpty(sentence) ? sentence.LastIndexOf('*') : throw new ArgumentException("Empty sentence. Nothing to parse.");
string str1 = length1 > 0 ? sentence.Substring(length1 + 1) : throw new ArgumentException("No checksum found. Invalid data.");
string str2 = sentence.Substring(0, length1);
byte num1 = ChecksumCalculator.XOR(str2.Substring(1));
byte num2;
try
{
num2 = byte.Parse(str1.Trim());//, 16);
}
catch (Exception ex)
{
throw new ArgumentException("Checksum failed to parse, error: " + ex.Message);
}
if ((int)num1 != (int)num2)
{
throw new ArgumentException("Checksum does not match data. Invalid data.");
}
int length2 = str2.IndexOf(',') - 1 == 5 ? 2 : 1;
int startIndex = length2 == 2 ? 3 : 2;
nmeaSentence.StartingDelimiter = str2.Substring(0, 1);
nmeaSentence.TalkerID = str2.Substring(1, length2);
nmeaSentence.Prefix = str2.Substring(startIndex, 3);
var span1 = str2.Split(',');//new string[]{((M0[]) );
if (span1.Length <= 0)
{
throw new ArgumentException("No data in sentence.");
}
nmeaSentence.DataElements.Clear();
ArrayList dataElements = nmeaSentence.DataElements;
var span2 = new string[span1.Length - 1];
for (int i = 1; i < span1.Length; i++)
{
span2[i - 1] = span1[i];
}
for (int i = 0; i < span2.Length; i++)
{
dataElements.Add(span2[i]);
}
return(nmeaSentence);
}
private static (byte[] tag, RfidValidationStatus status) GetValidatedRfidTag(Span <byte> data)
{
// Valid format is as follows:
// STX, 0-F x10 tag, 0-F x2 checksum, CR, LF, ETX
// example:
// STX 7 C 0 0 5 5 F 8 C 4 1 5 CR LF ETX
const int validLength = 16;
const int startByte = 0;
const int endByte = 15;
const int tagStartByte = 1;
const int tagLength = 10;
const int checksumStartByte = 11;
const int checksumLength = 2;
if (data.Length != validLength)
{
Debug.WriteLine(
$"Serial data is not of expected length for RFID tag format. Expected {validLength}, actual {data.Length}");
return(tag : null, status : RfidValidationStatus.InvalidDataFormat);
}
if (data[startByte] != StartToken)
{
Debug.WriteLine(
$"Invalid start byte in serial data for RFID tag format. Expected '{StartToken}', actual '{data[startByte]}'");
return(tag : null, status : RfidValidationStatus.InvalidDataFormat);
}
if (data[endByte] != EndToken)
{
Debug.WriteLine(
$"Invalid end byte in serial data for RFID tag format. Expected '{EndToken}', actual '{data[endByte]}'");
return(tag : null, status : RfidValidationStatus.InvalidDataFormat);
}
// verify tag is hexadecimal
var tagSlice = data.Slice(tagStartByte, tagLength);
if (!IsHexChars(tagSlice))
{
Debug.WriteLine(
"Invalid end byte in serial data for RFID tag format. Expected hex ASCII character (48-57, 65-70)");
return(tag : null, status : RfidValidationStatus.InvalidDataFormat);
}
// verify checksum is hexadecimal
var checksumSlice = data.Slice(checksumStartByte, checksumLength);
if (!IsHexChars(checksumSlice))
{
Debug.WriteLine(
"Invalid end byte in serial data for RFID tag format. Expected hex ASCII character (48-57, 65-70)");
return(tag : null, status : RfidValidationStatus.InvalidDataFormat);
}
var tag = AsciiHexByteArrayToBytes(tagSlice);
var checkSum = AsciiHexByteArrayToBytes(checksumSlice)[0];
return((ChecksumCalculator.XOR(tag) == checkSum)
? (tag, status : RfidValidationStatus.Ok)
: (tag, status : RfidValidationStatus.ChecksumFailed));
}
public override string ToString()
{
string dataString = this.GetDataString();
return(dataString + "*" + ChecksumCalculator.XOR(dataString).ToString());
}
