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stockfish/src/nnue/features/half_kp.h

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/*
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