2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2021 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 // A class template that represents the input feature set of the NNUE evaluation function
21 #ifndef NNUE_FEATURE_SET_H_INCLUDED
22 #define NNUE_FEATURE_SET_H_INCLUDED
24 #include "features_common.h"
27 namespace Stockfish::Eval::NNUE::Features {
29 // Class template that represents a list of values
30 template <typename T, T... Values>
31 struct CompileTimeList;
33 template <typename T, T First, T... Remaining>
34 struct CompileTimeList<T, First, Remaining...> {
35 static constexpr bool Contains(T value) {
36 return value == First || CompileTimeList<T, Remaining...>::Contains(value);
38 static constexpr std::array<T, sizeof...(Remaining) + 1>
39 kValues = {{First, Remaining...}};
42 // Base class of feature set
43 template <typename Derived>
44 class FeatureSetBase {
48 // Class template that represents the feature set
49 template <typename FeatureType>
50 class FeatureSet<FeatureType> : public FeatureSetBase<FeatureSet<FeatureType>> {
53 // Hash value embedded in the evaluation file
54 static constexpr std::uint32_t kHashValue = FeatureType::kHashValue;
55 // Number of feature dimensions
56 static constexpr IndexType kDimensions = FeatureType::kDimensions;
57 // Maximum number of simultaneously active features
58 static constexpr IndexType kMaxActiveDimensions =
59 FeatureType::kMaxActiveDimensions;
60 // Trigger for full calculation instead of difference calculation
61 using SortedTriggerSet =
62 CompileTimeList<TriggerEvent, FeatureType::kRefreshTrigger>;
63 static constexpr auto kRefreshTriggers = SortedTriggerSet::kValues;
67 } // namespace Stockfish::Eval::NNUE::Features
69 #endif // #ifndef NNUE_FEATURE_SET_H_INCLUDED