Make ZobristTable.CastleHash static

lynx-chess · Jan 5, 2024 · d82af44 · d82af44
1 parent df7077f
commit d82af44
Showing 1 changed file with 35 additions and 21 deletions.
diff --git a/src/Lynx/ZobristTable.cs b/src/Lynx/ZobristTable.cs
@@ -16,6 +16,20 @@ public static class ZobristTable
     private static readonly long BK_Hash = _table[(int)BoardSquare.c8, (int)Piece.p];
     private static readonly long BQ_Hash = _table[(int)BoardSquare.d8, (int)Piece.p];
 
+    private static readonly long WK_Hash_XOR_WQ_Hash = WK_Hash ^ WQ_Hash;
+    private static readonly long WK_Hash_XOR_BK_Hash = WK_Hash ^ BK_Hash;
+    private static readonly long WK_Hash_XOR_BQ_Hash = WK_Hash ^ BQ_Hash;
+    private static readonly long WQ_Hash_XOR_BK_Hash = WQ_Hash ^ BK_Hash;
+    private static readonly long WQ_Hash_XOR_BQ_Hash = WQ_Hash ^ BQ_Hash;
+    private static readonly long BK_Hash_XOR_BQ_Hash = BK_Hash ^ BQ_Hash;
+
+    private static readonly long WK_Hash_XOR_WQ_Hash_XOR_BK_Hash = WK_Hash ^ WQ_Hash ^ BK_Hash;
+    private static readonly long WK_Hash_XOR_WQ_Hash_XOR_BQ_Hash = WK_Hash ^ WQ_Hash ^ BQ_Hash;
+    private static readonly long WK_Hash_XOR_BK_Hash_XOR_BQ_Hash = WK_Hash ^ BK_Hash ^ BQ_Hash;
+    private static readonly long WQ_Hash_XOR_BK_Hash_XOR_BQ_Hash = WQ_Hash ^ BK_Hash ^ BQ_Hash;
+
+    private static readonly long WK_Hash_XOR_WQ_Hash_XOR_BK_Hash_XOR_BQ_Hash = WK_Hash ^ WQ_Hash ^ BK_Hash ^ BQ_Hash;
+
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static long PieceHash(int boardSquare, int piece) => _table[boardSquare, piece];
 
@@ -66,27 +80,27 @@ public static long CastleHash(byte castle)
     {
         return castle switch
         {
-            0 => 0,                                // -    | -
-
-            (byte)CastlingRights.WK => WK_Hash,    // K    | -
-            (byte)CastlingRights.WQ => WQ_Hash,    // Q    | -
-            (byte)CastlingRights.BK => BK_Hash,    // -    | k
-            (byte)CastlingRights.BQ => BQ_Hash,    // -    | q
-
-            (byte)CastlingRights.WK | (byte)CastlingRights.WQ => WK_Hash ^ WQ_Hash,    // KQ   | -
-            (byte)CastlingRights.WK | (byte)CastlingRights.BK => WK_Hash ^ BK_Hash,    // K    | k
-            (byte)CastlingRights.WK | (byte)CastlingRights.BQ => WK_Hash ^ BQ_Hash,    // K    | q
-            (byte)CastlingRights.WQ | (byte)CastlingRights.BK => WQ_Hash ^ BK_Hash,    // Q    | k
-            (byte)CastlingRights.WQ | (byte)CastlingRights.BQ => WQ_Hash ^ BQ_Hash,    // Q    | q
-            (byte)CastlingRights.BK | (byte)CastlingRights.BQ => BK_Hash ^ BQ_Hash,    // -    | kq
-
-            (byte)CastlingRights.WK | (byte)CastlingRights.WQ | (byte)CastlingRights.BK => WK_Hash ^ WQ_Hash ^ BK_Hash,    // KQ   | k
-            (byte)CastlingRights.WK | (byte)CastlingRights.WQ | (byte)CastlingRights.BQ => WK_Hash ^ WQ_Hash ^ BQ_Hash,    // KQ   | q
-            (byte)CastlingRights.WK | (byte)CastlingRights.BK | (byte)CastlingRights.BQ => WK_Hash ^ BK_Hash ^ BQ_Hash,    // K    | kq
-            (byte)CastlingRights.WQ | (byte)CastlingRights.BK | (byte)CastlingRights.BQ => WQ_Hash ^ BK_Hash ^ BQ_Hash,    // Q    | kq
-
-            (byte)CastlingRights.WK | (byte)CastlingRights.WQ | (byte)CastlingRights.BK | (byte)CastlingRights.BQ =>       // KQ   | kq
-                WK_Hash ^ WQ_Hash ^ BK_Hash ^ BQ_Hash,
+            0 => 0,                                                                                                             // -    | -
+
+            (byte)CastlingRights.WK => WK_Hash,                                                                                 // K    | -
+            (byte)CastlingRights.WQ => WQ_Hash,                                                                                 // Q    | -
+            (byte)CastlingRights.BK => BK_Hash,                                                                                 // -    | k
+            (byte)CastlingRights.BQ => BQ_Hash,                                                                                 // -    | q
+
+            (byte)CastlingRights.WK | (byte)CastlingRights.WQ => WK_Hash_XOR_WQ_Hash,                                           // KQ   | -
+            (byte)CastlingRights.WK | (byte)CastlingRights.BK => WK_Hash_XOR_BK_Hash,                                           // K    | k
+            (byte)CastlingRights.WK | (byte)CastlingRights.BQ => WK_Hash_XOR_BQ_Hash,                                           // K    | q
+            (byte)CastlingRights.WQ | (byte)CastlingRights.BK => WQ_Hash_XOR_BK_Hash,                                           // Q    | k
+            (byte)CastlingRights.WQ | (byte)CastlingRights.BQ => WQ_Hash_XOR_BQ_Hash,                                           // Q    | q
+            (byte)CastlingRights.BK | (byte)CastlingRights.BQ => BK_Hash_XOR_BQ_Hash,                                           // -    | kq
+
+            (byte)CastlingRights.WK | (byte)CastlingRights.WQ | (byte)CastlingRights.BK => WK_Hash_XOR_WQ_Hash_XOR_BK_Hash,     // KQ   | k
+            (byte)CastlingRights.WK | (byte)CastlingRights.WQ | (byte)CastlingRights.BQ => WK_Hash_XOR_WQ_Hash_XOR_BQ_Hash,     // KQ   | q
+            (byte)CastlingRights.WK | (byte)CastlingRights.BK | (byte)CastlingRights.BQ => WK_Hash_XOR_BK_Hash_XOR_BQ_Hash,     // K    | kq
+            (byte)CastlingRights.WQ | (byte)CastlingRights.BK | (byte)CastlingRights.BQ => WQ_Hash_XOR_BK_Hash_XOR_BQ_Hash,     // Q    | kq
+
+            (byte)CastlingRights.WK | (byte)CastlingRights.WQ | (byte)CastlingRights.BK | (byte)CastlingRights.BQ =>            // KQ   | kq
+                WK_Hash_XOR_WQ_Hash_XOR_BK_Hash_XOR_BQ_Hash,
 
             _ => throw new($"Unexpected castle encoded number: {castle}")
         };