added getter function

tmtcpacket/pus/TcPacketBase.cpp

@@ -23,6 +23,10 @@ uint8_t TcPacketBase::getSubService() {
 	return tcData->dataField.service_subtype;
 }
 
+uint8_t TcPacketBase::getSourceId() {
+    return tcData->dataField.source_id;
+}
+
 uint8_t TcPacketBase::getAcknowledgeFlags() {
 	return tcData->dataField.version_type_ack & 0b00001111;
 }

tmtcpacket/pus/TcPacketBase.h

@@ -108,6 +108,13 @@ public:
 	 * @return	The packet's PUS Service Subtype.
 	 */
 	uint8_t getSubService();
+	/**
+	 * The source ID can be used to have an additional identifier, e.g. for different ground
+	 * station.
+	 * @return
+	 */
+	uint8_t getSourceId();
+
 	/**
 	 * This is a getter for a pointer to the packet's Application data.
 	 *