tlv: avoid misaligned memory access

They cause unit test crashing on ARM platform.

refs: #4609

Change-Id: Ifdb0401529de48b5c08ebcf6938d80ba87ff883d
diff --git a/tests/tlv/test-nlsr.cpp b/tests/tlv/test-nlsr.cpp
new file mode 100644
index 0000000..43d1487
--- /dev/null
+++ b/tests/tlv/test-nlsr.cpp
@@ -0,0 +1,57 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014-2018,  The University of Memphis,
+ *                           Regents of the University of California,
+ *                           Arizona Board of Regents.
+ *
+ * This file is part of NLSR (Named-data Link State Routing).
+ * See AUTHORS.md for complete list of NLSR authors and contributors.
+ *
+ * NLSR is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * NLSR 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * NLSR, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+#include "tlv/tlv-nlsr.hpp"
+
+#include "../boost-test.hpp"
+
+#include <ndn-cxx/encoding/estimator.hpp>
+#include <ndn-cxx/encoding/encoding-buffer.hpp>
+#include <ndn-cxx/encoding/block-helpers.hpp>
+
+namespace nlsr {
+namespace tlv {
+namespace test {
+
+BOOST_AUTO_TEST_SUITE(TlvTestNlsr)
+
+BOOST_AUTO_TEST_CASE(TestDouble)
+{
+  ndn::Block block = ndn::encoding::makeNonNegativeIntegerBlock(0x01, 1);
+  BOOST_CHECK_THROW(ndn::tlv::nlsr::readDouble(block), ndn::tlv::Error);
+
+  double value = 1.65;
+  uint32_t type = 0x251;
+
+  ndn::encoding::EncodingEstimator estimator;
+  size_t totalLength = ndn::tlv::nlsr::prependDouble(estimator, type, value);
+
+  ndn::encoding::EncodingBuffer encoder(totalLength, 0);
+  ndn::tlv::nlsr::prependDouble(encoder, type, value);
+
+  BOOST_CHECK_CLOSE(value, ndn::tlv::nlsr::readDouble(encoder.block()), 0.001);
+}
+
+BOOST_AUTO_TEST_SUITE_END()
+
+} // namespace test
+} // namespace tlv
+} // namespace nlsr