replace FastCDR and serialise straight into a serdata to avoid an extra copy

rmw_cyclonedds_cpp/src/serdes.cpp

@@ -0,0 +1,53 @@
+#include "rmw_cyclonedds_cpp/serdes.hpp"
+
+cycser::cycser(struct sertopic *topic)
+{
+    st = ddsi_serstate_new(topic);
+    sd = nullptr;
+}
+
+cycser::~cycser()
+{
+    if (sd == nullptr) {
+        ddsi_serstate_release(st);
+    } else {
+        ddsi_serdata_unref(sd);
+    }
+}
+
+cycser& cycser::ref()
+{
+    assert(sd != nullptr);
+    ddsi_serdata_ref(sd);
+    return *this;
+}
+
+void cycser::unref()
+{
+    assert(sd != nullptr);
+    ddsi_serdata_unref(sd);
+}
+
+cycser& cycser::fix()
+{
+    assert(sd == nullptr);
+    sd = ddsi_serstate_fix(st);
+    return *this;
+}
+
+struct serdata *cycser::data()
+{
+    assert(sd != nullptr);
+    return sd;
+}
+
+cycdeser::cycdeser(const void *data_, size_t size_)
+{
+    data = static_cast<const char *>(data_);
+    lim = size_;
+    pos = 0;
+}
+
+cycdeser::~cycdeser()
+{
+}