Rename 'src' directory to 'ndn-cxx'

Change-Id: I14394023680901a86977313ca87fb017333614dd
Refs: #3084
diff --git a/ndn-cxx/packet-base.cpp b/ndn-cxx/packet-base.cpp
new file mode 100644
index 0000000..31540c9
--- /dev/null
+++ b/ndn-cxx/packet-base.cpp
@@ -0,0 +1,52 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2013-2018 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "packet-base.hpp"
+#include "lp/tags.hpp"
+
+namespace ndn {
+
+uint64_t
+PacketBase::getCongestionMark() const
+{
+  auto mark = this->getTag<lp::CongestionMarkTag>();
+
+  if (mark == nullptr) {
+    return 0;
+  }
+  else {
+    return *mark;
+  }
+}
+
+void
+PacketBase::setCongestionMark(uint64_t mark)
+{
+  if (mark != 0) {
+    auto tag = make_shared<lp::CongestionMarkTag>(mark);
+    this->setTag(std::move(tag));
+  }
+  else {
+    this->removeTag<lp::CongestionMarkTag>();
+  }
+}
+
+} // namespace ndn