1 files changed, 119 insertions, 0 deletions
diff --git a/src/fig/TransitionHandler.h b/src/fig/TransitionHandler.h
new file mode 100644
index 0000000..59bbe3c
--- /dev/null
+++ b/src/fig/TransitionHandler.h
@@ -0,0 +1,119 @@
+/*
+   Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
+   2011, 2012 Her Majesty the Queen in Right of Canada (Communications
+   Research Center Canada)
+
+   Copyright (C) 2016
+   Matthias P. Braendli, matthias.braendli@mpb.li
+   */
+/*
+   This file is part of ODR-DabMux.
+
+   ODR-DabMux 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.
+
+   ODR-DabMux 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 ODR-DabMux.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#pragma once
+
+#include <cstdint>
+#include <map>
+#include <set>
+#include <vector>
+#include <memory>
+
+namespace FIC {
+
+// Some FIGs need to adapt their rate or their contents depending
+// on if some data entries are stable or currently undergoing a
+// change. The TransitionHandler keeps track of which entries
+// are in what state.
+template<class T>
+class TransitionHandler {
+    public:
+        // update_state must be called once per ETI frame, and will
+        // move entries from new to repeated to disabled depending
+        // on their is_active() return value.
+        void update_state(int timeout, std::vector<std::shared_ptr<T> > all_entries)
+        {
+            for (const auto& entry : all_entries) {
+                if (entry->is_active()) {
+                    if (repeated_entries.count(entry) > 0) {
+                        // We are currently announcing this entry
+                        continue;
+                    }
+
+                    if (new_entries.count(entry) > 0) {
+                        // We are currently announcing this entry at a
+                        // fast rate. Handle timeout:
+                        new_entries[entry] -= 1;
+                        if (new_entries[entry] <= 0) {
+                            repeated_entries.insert(entry);
+                            new_entries.erase(entry);
+                        }
+                        continue;
+                    }
+
+                    // unlikely
+                    if (disabled_entries.count(entry) > 0) {
+                        new_entries[entry] = timeout;
+                        disabled_entries.erase(entry);
+                        continue;
+                    }
+
+                    // It's a new entry!
+                    new_entries[entry] = timeout;
+                }
+                else { // Not active
+                    if (disabled_entries.count(entry) > 0) {
+                        disabled_entries[entry] -= 1;
+                        if (disabled_entries[entry] <= 0) {
+                            disabled_entries.erase(entry);
+                        }
+                        continue;
+                    }
+
+                    if (repeated_entries.count(entry) > 0) {
+                        // We are currently announcing this entry
+                        disabled_entries[entry] = timeout;
+                        repeated_entries.erase(entry);
+                        continue;
+                    }
+
+                    // unlikely
+                    if (new_entries.count(entry) > 0) {
+                        // We are currently announcing this entry at a
+                        // fast rate. We must stop announcing it
+                        disabled_entries[entry] = timeout;
+                        new_entries.erase(entry);
+                        continue;
+                    }
+                }
+            }
+        }
+        // The FIG that needs the information about what state an entry is in
+        // can read from the following data structures. It shall not modify them.
+
+        /* Map to frame count */
+        std::map<
+            std::shared_ptr<T>,int> new_entries;
+
+        std::set<
+            std::shared_ptr<T> > repeated_entries;
+
+        /* Map to frame count */
+        std::map<
+            std::shared_ptr<T>,int> disabled_entries;
+};
+
+} // namespace FIC
+