NMEA 4.0 tag block

Author: jvde-github

Source/IO/File.h

@@ -68,6 +68,16 @@ namespace IO
 					}
 				}
 			}
+			else if (fmt == MessageFormat::NMEA_TAG)
+			{
+				for (int i = 0; i < len; i++)
+				{
+					if (!filter.include(data[i]))
+						continue;
+
+					file << data[i].getNMEATagBlock();
+				}
+			}
 			else if (fmt == MessageFormat::BINARY_NMEA)
 			{
 				for (int i = 0; i < len; i++)

Source/IO/Network.cpp

@@ -390,6 +390,16 @@ namespace IO
 					SendTo((s + "\r\n").c_str());
 			}
 		}
+		else if (fmt == MessageFormat::NMEA_TAG)
+		{
+			for (int i = 0; i < len; i++)
+			{
+				if (!filter.include(data[i]))
+					continue;
+
+				SendTo(data[i].getNMEATagBlock());
+			}
+		}
 		else if (fmt == MessageFormat::BINARY_NMEA)
 		{
 			for (int i = 0; i < len; i++)
@@ -626,6 +636,26 @@ namespace IO
 				}
 			}
 		}
+		else if (fmt == MessageFormat::NMEA_TAG)
+		{
+			for (int i = 0; i < len; i++)
+			{
+				if (!filter.include(data[i]))
+					continue;
+
+				if (SendTo(data[i].getNMEATagBlock()) < 0)
+				{
+					first_message = true;
+					if (!persistent)
+					{
+						Error() << "TCP feed: requesting termination.";
+						StopRequest();
+					}
+				}
+				else
+					first_message = false;
+			}
+		}
 		else if ((fmt == MessageFormat::COMMUNITY_HUB && !first_message) || fmt == MessageFormat::BINARY_NMEA)
 		{
 			for (int i = 0; i < len; i++)
@@ -851,6 +881,16 @@ namespace IO
 				}
 			}
 		}
+		else if (fmt == MessageFormat::NMEA_TAG)
+		{
+			for (int i = 0; i < len; i++)
+			{
+				if (!filter.include(data[i]))
+					continue;
+
+				SendAllDirect(data[i].getNMEATagBlock());
+			}
+		}
 		else if (fmt == MessageFormat::BINARY_NMEA)
 		{
 			for (int i = 0; i < len; i++)

Source/IO/Screen.cpp

@@ -56,10 +56,12 @@ namespace IO
 				switch (fmt)
 				{
 				case MessageFormat::NMEA:
-				case MessageFormat::NMEA_TAG:
 					for (const auto &s : data[i].NMEA)
 						std::cout << s << std::endl;
 					break;
+				case MessageFormat::NMEA_TAG:
+					std::cout << data[i].getNMEATagBlock();
+					break;
 				case MessageFormat::FULL:
 					for (const auto &s : data[i].NMEA)
 					{

Source/Marine/Message.cpp

@@ -132,6 +132,39 @@ namespace AIS
 		return ss.str();
 	}
 
+	std::string Message::getNMEATagBlock() const
+	{
+		static int groupId = 0;
+		groupId = (groupId % 9999) + 1;  // Recycle 1-9999
+
+		std::string result;
+		int total = NMEA.size();
+		int seq = 1;
+
+		// Use station ID with 's' prefix as source
+		std::string src = "s" + std::to_string(station);
+
+		for (const auto &nmea : NMEA)
+		{
+			std::stringstream tb;
+			tb << "s:" << src << ",c:" << rxtime << ",g:" << seq << "-" << total << "-" << groupId;
+
+			// Calculate checksum for tag block
+			std::string tbs = tb.str();
+			int check = 0;
+			for (char c : tbs)
+				check ^= c;
+
+			std::stringstream ss;
+			ss << "\\" << tbs << "*" << std::hex << std::uppercase << std::setfill('0') << std::setw(2) << check << "\\" << nmea << "\r\n";
+
+			result += ss.str();
+			seq++;
+		}
+
+		return result;
+	}
+
 	std::string Message::getBinaryNMEA(const TAG &tag, bool crc) const
 	{
 		std::string packet;

Source/Marine/Message.h

@@ -76,6 +76,7 @@ namespace AIS
 		}
 
 		std::string getNMEAJSON(unsigned mode, float level, float ppm, int status, const std::string &hardware, int version, Type driver, bool include_ss = false, uint32_t ipv4 = 0, const std::string &uid = "") const;
+		std::string getNMEATagBlock() const;
 		std::string getBinaryNMEA(const TAG &tag, bool crc = false) const;
 
 		std::string getRxTime() const