--- /dev/null
+/*
+ Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+ Copyright (C) 2004-2020 The Stockfish developers (see AUTHORS file)
+
+ Stockfish 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.
+
+ Stockfish 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 this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+//Common header of input features of NNUE evaluation function
+
+#ifndef NNUE_FEATURES_COMMON_H_INCLUDED
+#define NNUE_FEATURES_COMMON_H_INCLUDED
+
+#include "../../evaluate.h"
+#include "../nnue_common.h"
+
+namespace Eval::NNUE::Features {
+
+ class IndexList;
+
+ template <typename... FeatureTypes>
+ class FeatureSet;
+
+ // Trigger to perform full calculations instead of difference only
+ enum class TriggerEvent {
+ kFriendKingMoved // calculate full evaluation when own king moves
+ };
+
+ enum class Side {
+ kFriend // side to move
+ };
+
+} // namespace Eval::NNUE::Features
+
+#endif // #ifndef NNUE_FEATURES_COMMON_H_INCLUDED