⚖️ Add opponent king buckets to passed pawns bucketed arrays (#1349)

lynx-chess · Jan 14, 2025 · e4163ec · e4163ec
1 parent c7fc722
commit e4163ec
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Showing 3 changed files with 5,818 additions and 5,392 deletions.
diff --git a/src/Lynx/Model/Position.cs b/src/Lynx/Model/Position.cs
@@ -584,7 +584,7 @@ public bool WasProduceByAValidMove()
                     bitboard.ResetLS1B();
 
                     gamePhase += GamePhaseByPiece[pieceIndex];
-                    packedScore += AdditionalPieceEvaluation(whiteBucket, pieceSquareIndex, pieceIndex, (int)Side.White, whiteKing, blackKing, blackPawnAttacks);
+                    packedScore += AdditionalPieceEvaluation(whiteBucket, blackBucket, pieceSquareIndex, pieceIndex, (int)Side.White, whiteKing, blackKing, blackPawnAttacks);
                 }
             }
 
@@ -603,7 +603,7 @@ public bool WasProduceByAValidMove()
                     bitboard.ResetLS1B();
 
                     gamePhase += GamePhaseByPiece[pieceIndex];
-                    packedScore -= AdditionalPieceEvaluation(blackBucket, pieceSquareIndex, pieceIndex, (int)Side.Black, blackKing, whiteKing, whitePawnAttacks);
+                    packedScore -= AdditionalPieceEvaluation(blackBucket, whiteBucket, pieceSquareIndex, pieceIndex, (int)Side.Black, blackKing, whiteKing, whitePawnAttacks);
                 }
             }
         }
@@ -629,7 +629,7 @@ public bool WasProduceByAValidMove()
 
                     gamePhase += GamePhaseByPiece[pieceIndex];
 
-                    packedScore += AdditionalPieceEvaluation(whiteBucket, pieceSquareIndex, pieceIndex, (int)Side.White, whiteKing, blackKing, blackPawnAttacks);
+                    packedScore += AdditionalPieceEvaluation(whiteBucket, blackBucket, pieceSquareIndex, pieceIndex, (int)Side.White, whiteKing, blackKing, blackPawnAttacks);
                 }
             }
 
@@ -652,7 +652,7 @@ public bool WasProduceByAValidMove()
 
                     gamePhase += GamePhaseByPiece[pieceIndex];
 
-                    packedScore -= AdditionalPieceEvaluation(blackBucket, pieceSquareIndex, pieceIndex, (int)Side.Black, blackKing, whiteKing, whitePawnAttacks);
+                    packedScore -= AdditionalPieceEvaluation(blackBucket, whiteBucket, pieceSquareIndex, pieceIndex, (int)Side.Black, blackKing, whiteKing, whitePawnAttacks);
                 }
             }
 
@@ -816,11 +816,11 @@ public static int EvaluateFinalPosition(int ply, bool isInCheck)
     /// Doesn't include <see cref="Piece.K"/> and <see cref="Piece.k"/> evaluation
     /// </summary>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    internal int AdditionalPieceEvaluation(int bucket, int pieceSquareIndex, int pieceIndex, int pieceSide, int sameSideKingSquare, int oppositeSideKingSquare, BitBoard enemyPawnAttacks)
+    internal int AdditionalPieceEvaluation(int bucket, int oppositeSideBucket, int pieceSquareIndex, int pieceIndex, int pieceSide, int sameSideKingSquare, int oppositeSideKingSquare, BitBoard enemyPawnAttacks)
     {
         return pieceIndex switch
         {
-            (int)Piece.P or (int)Piece.p => PawnAdditionalEvaluation(bucket, pieceSquareIndex, pieceIndex, sameSideKingSquare, oppositeSideKingSquare),
+            (int)Piece.P or (int)Piece.p => PawnAdditionalEvaluation(bucket, oppositeSideBucket, pieceSquareIndex, pieceIndex, sameSideKingSquare, oppositeSideKingSquare),
             (int)Piece.R or (int)Piece.r => RookAdditionalEvaluation(pieceSquareIndex, pieceIndex, pieceSide, oppositeSideKingSquare, enemyPawnAttacks),
             (int)Piece.B or (int)Piece.b => BishopAdditionalEvaluation(pieceSquareIndex, pieceIndex, pieceSide, oppositeSideKingSquare, enemyPawnAttacks),
             (int)Piece.N or (int)Piece.n => KnightAdditionalEvaluation(pieceSquareIndex, pieceSide, oppositeSideKingSquare, enemyPawnAttacks),
@@ -830,7 +830,7 @@ internal int AdditionalPieceEvaluation(int bucket, int pieceSquareIndex, int pie
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private int PawnAdditionalEvaluation(int bucket, int squareIndex, int pieceIndex, int sameSideKingSquare, int oppositeSideKingSquare)
+    private int PawnAdditionalEvaluation(int bucket, int oppositeSideBucket, int squareIndex, int pieceIndex, int sameSideKingSquare, int oppositeSideKingSquare)
     {
         int packedBonus = 0;
 
@@ -857,6 +857,7 @@ private int PawnAdditionalEvaluation(int bucket, int squareIndex, int pieceIndex
             if ((passedPawnsMask & OccupancyBitBoards[oppositeSide]) == 0)
             {
                 packedBonus += PassedPawnBonusNoEnemiesAheadBonus[bucket][rank];
+                packedBonus += PassedPawnBonusNoEnemiesAheadEnemyBonus[oppositeSideBucket][rank];
             }
 
             // King distance to passed pawn
@@ -866,6 +867,7 @@ private int PawnAdditionalEvaluation(int bucket, int squareIndex, int pieceIndex
             var enemyKingDistance = Constants.ChebyshevDistance[squareIndex][oppositeSideKingSquare];
 
             packedBonus += PassedPawnBonus[bucket][rank]
+                + PassedPawnEnemyBonus[oppositeSideBucket][rank]
                 + FriendlyKingDistanceToPassedPawnBonus[friendlyKingDistance]
                 + EnemyKingDistanceToPassedPawnPenalty[enemyKingDistance];
         }