2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2020 The Stockfish developers (see AUTHORS file)
5 Stockfish is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation, either version 3 of the License, or
8 (at your option) any later version.
10 Stockfish is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>.
19 //Definition of input features HalfKP of NNUE evaluation function
22 #include "index_list.h"
24 namespace Eval::NNUE::Features {
26 // Orient a square according to perspective (rotates by 180 for black)
27 inline Square orient(Color perspective, Square s) {
28 return Square(int(s) ^ (bool(perspective) * 63));
31 // Find the index of the feature quantity from the king position and PieceSquare
32 template <Side AssociatedKing>
33 inline IndexType HalfKP<AssociatedKing>::MakeIndex(
34 Color perspective, Square s, Piece pc, Square ksq) {
36 return IndexType(orient(perspective, s) + kpp_board_index[pc][perspective] + PS_END * ksq);
39 // Get a list of indices for active features
40 template <Side AssociatedKing>
41 void HalfKP<AssociatedKing>::AppendActiveIndices(
42 const Position& pos, Color perspective, IndexList* active) {
44 Square ksq = orient(perspective, pos.square<KING>(perspective));
45 Bitboard bb = pos.pieces() & ~pos.pieces(KING);
47 Square s = pop_lsb(&bb);
48 active->push_back(MakeIndex(perspective, s, pos.piece_on(s), ksq));
52 // Get a list of indices for recently changed features
53 template <Side AssociatedKing>
54 void HalfKP<AssociatedKing>::AppendChangedIndices(
55 const Position& pos, const DirtyPiece& dp, Color perspective,
56 IndexList* removed, IndexList* added) {
58 Square ksq = orient(perspective, pos.square<KING>(perspective));
59 for (int i = 0; i < dp.dirty_num; ++i) {
60 Piece pc = dp.piece[i];
61 if (type_of(pc) == KING) continue;
62 if (dp.from[i] != SQ_NONE)
63 removed->push_back(MakeIndex(perspective, dp.from[i], pc, ksq));
64 if (dp.to[i] != SQ_NONE)
65 added->push_back(MakeIndex(perspective, dp.to[i], pc, ksq));
69 template class HalfKP<Side::kFriend>;
71 } // namespace Eval::NNUE::Features