Add a HalfKA architecture (a product of K - king, and A - any piece) along with all required infrastructure. HalfKA doesn't discriminate kings compared to HalfKP. Keep old architecture as the default one.

2025-12-26 20:16:14 +08:00 · 2020-10-28 15:24:29 +01:00
parent 317fda2516
commit ec9e49e875
10 changed files with 573 additions and 0 deletions
--- a/src/nnue/features/half_ka.cpp
+++ b/src/nnue/features/half_ka.cpp
@@ -0,0 +1,89 @@
+/*
+    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 HalfKA of NNUE evaluation function
+
+#include "half_ka.h"
+#include "index_list.h"
+
+namespace Eval::NNUE::Features {
+
+    // Orient a square according to perspective (flip rank for black)
+    inline Square orient(Color perspective, Square s) {
+        return Square(int(s) ^ (bool(perspective) * SQ_A8));
+    }
+
+    // Find the index of the feature quantity from the king position and PieceSquare
+    template <Side AssociatedKing>
+    inline IndexType HalfKA<AssociatedKing>::make_index(
+        Color perspective,
+        Square s,
+        Piece pc,
+        Square ksq) {
+
+        return IndexType(orient(perspective, s) + kpp_board_index[pc][perspective] + PS_END2 * ksq);
+    }
+
+    // Get a list of indices for active features
+    template <Side AssociatedKing>
+    void HalfKA<AssociatedKing>::append_active_indices(
+        const Position& pos,
+        Color perspective,
+        IndexList* active) {
+
+        Square ksq = orient(
+            perspective,
+            pos.square<KING>(
+                AssociatedKing == Side::kFriend ? perspective : ~perspective));
+
+        Bitboard bb = pos.pieces();
+        while (bb) {
+            Square s = pop_lsb(&bb);
+            active->push_back(make_index(perspective, s, pos.piece_on(s), ksq));
+        }
+    }
+
+    // Get a list of indices for recently changed features
+    template <Side AssociatedKing>
+    void HalfKA<AssociatedKing>::append_changed_indices(
+        const Position& pos,
+        Color perspective,
+        IndexList* removed,
+        IndexList* added) {
+
+        Square ksq = orient(
+            perspective,
+            pos.square<KING>(
+                AssociatedKing == Side::kFriend ? perspective : ~perspective));
+
+        const auto& dp = pos.state()->dirtyPiece;
+        for (int i = 0; i < dp.dirty_num; ++i) {
+            Piece pc = dp.piece[i];
+
+            if (dp.from[i] != SQ_NONE)
+                removed->push_back(make_index(perspective, dp.from[i], pc, ksq));
+
+            if (dp.to[i] != SQ_NONE)
+                added->push_back(make_index(perspective, dp.to[i], pc, ksq));
+        }
+    }
+
+    template class HalfKA<Side::kFriend>;
+    template class HalfKA<Side::kEnemy>;
+
+}  // namespace Eval::NNUE::Features