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 // 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 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 {
47 // Get a list of indices for active features
48 template <typename IndexListType>
49 static void AppendActiveIndices(
50 const Position& pos, TriggerEvent trigger, IndexListType active[2]) {
52 for (Color perspective : { WHITE, BLACK }) {
53 Derived::CollectActiveIndices(
54 pos, trigger, perspective, &active[perspective]);
58 // Get a list of indices for recently changed features
59 template <typename PositionType, typename IndexListType>
60 static void AppendChangedIndices(
61 const PositionType& pos, TriggerEvent trigger,
62 IndexListType removed[2], IndexListType added[2], bool reset[2]) {
64 const auto& dp = pos.state()->dirtyPiece;
65 if (dp.dirty_num == 0) return;
67 for (Color perspective : { WHITE, BLACK }) {
68 reset[perspective] = false;
70 case TriggerEvent::kFriendKingMoved:
72 dp.pieceId[0] == PIECE_ID_KING + perspective;
78 if (reset[perspective]) {
79 Derived::CollectActiveIndices(
80 pos, trigger, perspective, &added[perspective]);
82 Derived::CollectChangedIndices(
83 pos, trigger, perspective,
84 &removed[perspective], &added[perspective]);
90 // Class template that represents the feature set
91 template <typename FeatureType>
92 class FeatureSet<FeatureType> : public FeatureSetBase<FeatureSet<FeatureType>> {
95 // Hash value embedded in the evaluation file
96 static constexpr std::uint32_t kHashValue = FeatureType::kHashValue;
97 // Number of feature dimensions
98 static constexpr IndexType kDimensions = FeatureType::kDimensions;
99 // Maximum number of simultaneously active features
100 static constexpr IndexType kMaxActiveDimensions =
101 FeatureType::kMaxActiveDimensions;
102 // Trigger for full calculation instead of difference calculation
103 using SortedTriggerSet =
104 CompileTimeList<TriggerEvent, FeatureType::kRefreshTrigger>;
105 static constexpr auto kRefreshTriggers = SortedTriggerSet::kValues;
108 // Get a list of indices for active features
109 static void CollectActiveIndices(
110 const Position& pos, const TriggerEvent trigger, const Color perspective,
111 IndexList* const active) {
112 if (FeatureType::kRefreshTrigger == trigger) {
113 FeatureType::AppendActiveIndices(pos, perspective, active);
117 // Get a list of indices for recently changed features
118 static void CollectChangedIndices(
119 const Position& pos, const TriggerEvent trigger, const Color perspective,
120 IndexList* const removed, IndexList* const added) {
122 if (FeatureType::kRefreshTrigger == trigger) {
123 FeatureType::AppendChangedIndices(pos, perspective, removed, added);
127 // Make the base class and the class template that recursively uses itself a friend
128 friend class FeatureSetBase<FeatureSet>;
129 template <typename... FeatureTypes>
130 friend class FeatureSet;
133 } // namespace Eval::NNUE::Features
135 #endif // #ifndef NNUE_FEATURE_SET_H_INCLUDED