git.sesse.net Git - stockfish/blob - src/nnue/features/feature_set.h

   1 /*
   2   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   3   Copyright (C) 2004-2020 The Stockfish developers (see AUTHORS file)
   4
   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.
   9
  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.
  14
  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/>.
  17 */
  18
  19 // A class template that represents the input feature set of the NNUE evaluation function
  20
  21 #ifndef NNUE_FEATURE_SET_H_INCLUDED
  22 #define NNUE_FEATURE_SET_H_INCLUDED
  23
  24 #include "features_common.h"
  25 #include <array>
  26
  27 namespace Eval::NNUE::Features {
  28
  29   // Class template that represents a list of values
  30   template <typename T, T... Values>
  31   struct CompileTimeList;
  32
  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);
  37     }
  38     static constexpr std::array<T, sizeof...(Remaining) + 1>
  39         kValues = {{First, Remaining...}};
  40   };
  41
  42   // Base class of feature set
  43   template <typename Derived>
  44   class FeatureSetBase {
  45
  46    public:
  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]) {
  51
  52       for (Color perspective : { WHITE, BLACK }) {
  53         Derived::CollectActiveIndices(
  54             pos, trigger, perspective, &active[perspective]);
  55       }
  56     }
  57
  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]) {
  63
  64       auto collect_for_one = [&](const DirtyPiece& dp) {
  65         for (Color perspective : { WHITE, BLACK }) {
  66           switch (trigger) {
  67             case TriggerEvent::kFriendKingMoved:
  68               reset[perspective] = dp.piece[0] == make_piece(perspective, KING);
  69               break;
  70             default:
  71               assert(false);
  72               break;
  73           }
  74           if (reset[perspective]) {
  75             Derived::CollectActiveIndices(
  76                 pos, trigger, perspective, &added[perspective]);
  77           } else {
  78             Derived::CollectChangedIndices(
  79                 pos, dp, trigger, perspective,
  80                 &removed[perspective], &added[perspective]);
  81           }
  82         }
  83       };
  84
  85       auto collect_for_two = [&](const DirtyPiece& dp1, const DirtyPiece& dp2) {
  86         for (Color perspective : { WHITE, BLACK }) {
  87           switch (trigger) {
  88             case TriggerEvent::kFriendKingMoved:
  89               reset[perspective] = dp1.piece[0] == make_piece(perspective, KING)
  90                                 || dp2.piece[0] == make_piece(perspective, KING);
  91               break;
  92             default:
  93               assert(false);
  94               break;
  95           }
  96           if (reset[perspective]) {
  97             Derived::CollectActiveIndices(
  98                 pos, trigger, perspective, &added[perspective]);
  99           } else {
 100             Derived::CollectChangedIndices(
 101                 pos, dp1, trigger, perspective,
 102                 &removed[perspective], &added[perspective]);
 103             Derived::CollectChangedIndices(
 104                 pos, dp2, trigger, perspective,
 105                 &removed[perspective], &added[perspective]);
 106           }
 107         }
 108       };
 109
 110       if (pos.state()->previous->accumulator.computed_accumulation) {
 111         const auto& prev_dp = pos.state()->dirtyPiece;
 112         if (prev_dp.dirty_num == 0) return;
 113         collect_for_one(prev_dp);
 114       } else {
 115         const auto& prev_dp = pos.state()->previous->dirtyPiece;
 116         if (prev_dp.dirty_num == 0) {
 117           const auto& prev2_dp = pos.state()->dirtyPiece;
 118           if (prev2_dp.dirty_num == 0) return;
 119           collect_for_one(prev2_dp);
 120         } else {
 121           const auto& prev2_dp = pos.state()->dirtyPiece;
 122           if (prev2_dp.dirty_num == 0) {
 123             collect_for_one(prev_dp);
 124           } else {
 125             collect_for_two(prev_dp, prev2_dp);
 126           }
 127         }
 128       }
 129     }
 130   };
 131
 132   // Class template that represents the feature set
 133   template <typename FeatureType>
 134   class FeatureSet<FeatureType> : public FeatureSetBase<FeatureSet<FeatureType>> {
 135
 136    public:
 137     // Hash value embedded in the evaluation file
 138     static constexpr std::uint32_t kHashValue = FeatureType::kHashValue;
 139     // Number of feature dimensions
 140     static constexpr IndexType kDimensions = FeatureType::kDimensions;
 141     // Maximum number of simultaneously active features
 142     static constexpr IndexType kMaxActiveDimensions =
 143         FeatureType::kMaxActiveDimensions;
 144     // Trigger for full calculation instead of difference calculation
 145     using SortedTriggerSet =
 146         CompileTimeList<TriggerEvent, FeatureType::kRefreshTrigger>;
 147     static constexpr auto kRefreshTriggers = SortedTriggerSet::kValues;
 148
 149    private:
 150     // Get a list of indices for active features
 151     static void CollectActiveIndices(
 152         const Position& pos, const TriggerEvent trigger, const Color perspective,
 153         IndexList* const active) {
 154       if (FeatureType::kRefreshTrigger == trigger) {
 155         FeatureType::AppendActiveIndices(pos, perspective, active);
 156       }
 157     }
 158
 159     // Get a list of indices for recently changed features
 160     static void CollectChangedIndices(
 161         const Position& pos, const DirtyPiece& dp, const TriggerEvent trigger, const Color perspective,
 162         IndexList* const removed, IndexList* const added) {
 163
 164       if (FeatureType::kRefreshTrigger == trigger) {
 165         FeatureType::AppendChangedIndices(pos, dp, perspective, removed, added);
 166       }
 167     }
 168
 169     // Make the base class and the class template that recursively uses itself a friend
 170     friend class FeatureSetBase<FeatureSet>;
 171     template <typename... FeatureTypes>
 172     friend class FeatureSet;
 173   };
 174
 175 }  // namespace Eval::NNUE::Features
 176
 177 #endif // #ifndef NNUE_FEATURE_SET_H_INCLUDED