--- /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/>.
+*/
+
+//Definition of input features HalfKP of NNUE evaluation function
+
+#ifndef NNUE_FEATURES_HALF_KP_H_INCLUDED
+#define NNUE_FEATURES_HALF_KP_H_INCLUDED
+
+#include "../../evaluate.h"
+#include "features_common.h"
+
+namespace Eval::NNUE::Features {
+
+ // Feature HalfKP: Combination of the position of own king
+ // and the position of pieces other than kings
+ template <Side AssociatedKing>
+ class HalfKP {
+
+ public:
+ // Feature name
+ static constexpr const char* kName = "HalfKP(Friend)";
+ // Hash value embedded in the evaluation file
+ static constexpr std::uint32_t kHashValue =
+ 0x5D69D5B9u ^ (AssociatedKing == Side::kFriend);
+ // Number of feature dimensions
+ static constexpr IndexType kDimensions =
+ static_cast<IndexType>(SQUARE_NB) * static_cast<IndexType>(PS_END);
+ // Maximum number of simultaneously active features
+ static constexpr IndexType kMaxActiveDimensions = PIECE_ID_KING;
+ // Trigger for full calculation instead of difference calculation
+ static constexpr TriggerEvent kRefreshTrigger = TriggerEvent::kFriendKingMoved;
+
+ // Get a list of indices for active features
+ static void AppendActiveIndices(const Position& pos, Color perspective,
+ IndexList* active);
+
+ // Get a list of indices for recently changed features
+ static void AppendChangedIndices(const Position& pos, Color perspective,
+ IndexList* removed, IndexList* added);
+
+ // Index of a feature for a given king position and another piece on some square
+ static IndexType MakeIndex(Square sq_k, PieceSquare p);
+
+ private:
+ // Get pieces information
+ static void GetPieces(const Position& pos, Color perspective,
+ PieceSquare** pieces, Square* sq_target_k);
+ };
+
+} // namespace Eval::NNUE::Features
+
+#endif // #ifndef NNUE_FEATURES_HALF_KP_H_INCLUDED