/// <summary>
/// </summary>
/// <param name="sixState"></param>
/// <exception cref="SixbitsExhaustedException"></exception>
/// <exception cref="AisMessageException"></exception>
public override void Parse(Sixbit sixState)
{
if (sixState.BitLength != 168)
{
throw new AisMessageException($"Message {MsgId} wrong length");
}
base.Parse(sixState);
/* Parse the Message 1 */
NavStatus = (int)sixState.Get(4);
Rot = (int)sixState.Get(8);
Sog = (int)sixState.Get(10);
PosAcc = (int)sixState.Get(1);
Pos = new Position {
Longitude = sixState.Get(28),
Latitude = sixState.Get(27)
};
Cog = (int)sixState.Get(12);
TrueHeading = (int)sixState.Get(9);
UtcSec = (int)sixState.Get(6);
Regional = (int)sixState.Get(4);
Spare = (int)sixState.Get(1);
Raim = (int)sixState.Get(1);
SyncState = (int)sixState.Get(2);
}
/// <summary>
/// Assemble AIVDM/VDO sentences
/// This function handles re-assembly and extraction of the 6-bit data
/// from AIVDM/AIVDO sentences.
/// Because the NMEA standard limits the length of a line to 80 characters
/// some AIS messages, such as message 5, are output as a multipart VDM
/// messages.
/// This routine collects the 6-bit encoded data from these parts and
/// returns a 1 when all pieces have been reassembled.
/// It expects the sentences to:
/// - Be in order, part 1, part 2, etc.
/// - Be from a single sequence
/// It will return an error if it receives a piece out of order or from
/// a new sequence before the previous one is finished.
/// </summary>
/// <returns>
/// - 0 Complete packet
/// - 1 Incomplete packet
/// - 2 NMEA 0183 checksum failed
/// - 3 Not an AIS message
/// - 4 Error with nmea_next_field
/// - 5 Out of sequence packet
/// </returns>
/// <exception cref="ChecksumFailedException"></exception>
/// <exception cref="StartNotFoundException"></exception>
/// <exception cref="VDMSentenceException"></exception>
public VdmStatus Add(string str)
{
int total;
int num;
int sequence;
if (Nmea.CheckChecksum(str) != 0)
{
throw new ChecksumFailedException();
}
var ptr = Nmea.FindStart(str);
// Allow any sender type for VDM and VDO messages
//if (!str.regionMatches(ptr + 3, "VDM", 0, 3) && !str.regionMatches(ptr + 3, "VDO", 0, 3))
var tag = str.Substring(ptr + 3, 3);
if (!tag.Equals("VDM") && !tag.Equals("VDO"))
{
throw new VDMSentenceException("Not a VDM or VDO message");
}
var fields = FieldSpliter.Split(str); //str.Split(",|\\*", true);
if (fields.Length != 8)
{
throw new VDMSentenceException("Does not have 8 fields");
}
// Get the message info for multipart messages
try {
total = int.Parse(fields[1]);
num = int.Parse(fields[2]);
} catch (FormatException) {
throw new VDMSentenceException("total or num field is not an integer");
}
if (!int.TryParse(fields[3], out sequence))
{
sequence = 0;
}
// Are we looking for more message parts?
if (Total > 0)
{
if (Sequence != sequence || Num != num - 1)
{
Total = 0;
Sequence = 0;
Num = 0;
return((VdmStatus)5);
//throw new VDMSentenceException("Out of sequence sentence");
}
Num++;
}
else
{
Total = total;
Num = num;
Sequence = sequence;
SixState = new Sixbit();
}
Channel = fields[4].FirstOrDefault();//[0];
SixState.Add(fields[5]);
if (total == 0 || Total == num)
{
Total = 0;
Num = 0;
Sequence = 0;
// Get the message id
try {
MsgId = (int)SixState.Get(6);
} catch (SixbitsExhaustedException) {
throw new VDMSentenceException("Not enough bits for msgid");
}
// Adjust bit count
SixState.PadBits(int.Parse(fields[6]));
// Found a complete packet
return(0);
}
// No complete message yet
return((VdmStatus)1);
}
