GameState compression: make Piece (and therefore `GameState.Capture…

…dPiece`) a sbyte enum
lynx-chess · Aug 9, 2023 · 5bcbeae · 5bcbeae
1 parent 5fc56e7
commit 5bcbeae
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Showing 4 changed files with 11 additions and 11 deletions.
diff --git a/src/Lynx.Benchmark/MakeMove.cs b/src/Lynx.Benchmark/MakeMove.cs
@@ -151,12 +151,12 @@ namespace Lynx.Benchmark;
 public class MakeMove : BaseBenchmark
 {
     public static IEnumerable<(string, int)> Data => new[] {
-            //(Constants.InitialPositionFEN, 4),
-            //(Constants.TrickyTestPositionFEN, 4),
-            //("r4rk1/1pp1qppp/p1np1n2/2b1p1B1/2B1P1b1/P1NP1N2/1PP1QPPP/R4RK1 w - - 0 10", 4),
+            (Constants.InitialPositionFEN, 4),
+            (Constants.TrickyTestPositionFEN, 4),
+            ("r4rk1/1pp1qppp/p1np1n2/2b1p1B1/2B1P1b1/P1NP1N2/1PP1QPPP/R4RK1 w - - 0 10", 4),
             ("3K4/8/8/8/8/8/4p3/2k2R2 b - - 0 1", 6),
-            //("2K2r2/4P3/8/8/8/8/8/3k4 w - - 0 1", 6),
-            //("8/p7/8/1P6/K1k3p1/6P1/7P/8 w - -", 6),
+            ("2K2r2/4P3/8/8/8/8/8/3k4 w - - 0 1", 6),
+            ("8/p7/8/1P6/K1k3p1/6P1/7P/8 w - -", 6)
         };
 
     [Benchmark(Baseline = true)]

diff --git a/src/Lynx/Model/GameState.cs b/src/Lynx/Model/GameState.cs
@@ -1,15 +1,15 @@
 namespace Lynx.Model;
 public readonly struct GameState
 {
-    public readonly int CapturedPiece;
+    public readonly sbyte CapturedPiece;
 
     public readonly byte Castle;
 
     public readonly BoardSquare EnPassant;
 
     // TODO: save full Zobrist key?
 
-    public GameState(int capturedPiece, byte castle, BoardSquare enpassant)
+    public GameState(sbyte capturedPiece, byte castle, BoardSquare enpassant)
     {
         CapturedPiece = capturedPiece;
         Castle = castle;

diff --git a/src/Lynx/Model/Piece.cs b/src/Lynx/Model/Piece.cs
@@ -1,6 +1,6 @@
 namespace Lynx.Model;
 
-public enum Piece
+public enum Piece : sbyte
 {
     Unknown = -1,
     P, N, B, R, Q, K,   // White

diff --git a/src/Lynx/Model/Position.cs b/src/Lynx/Model/Position.cs
@@ -209,7 +209,7 @@ public Position(Position position, Move move) : this(position)
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public GameState MakeMove(Move move)
     {
-        int capturedPiece = -1;
+        sbyte capturedPiece = -1;
         byte castleCopy = Castle;
         BoardSquare enpassantCopy = EnPassant;
 
@@ -255,7 +255,7 @@ public GameState MakeMove(Move move)
                 PieceBitBoards[oppositePawnIndex].PopBit(capturedPawnSquare);
                 OccupancyBitBoards[oppositeSide].PopBit(capturedPawnSquare);
                 UniqueIdentifier ^= ZobristTable.PieceHash(capturedPawnSquare, oppositePawnIndex);
-                capturedPiece = oppositePawnIndex;
+                capturedPiece = (sbyte)oppositePawnIndex;
             }
             else
             {
@@ -266,7 +266,7 @@ public GameState MakeMove(Move move)
                     {
                         PieceBitBoards[pieceIndex].PopBit(targetSquare);
                         UniqueIdentifier ^= ZobristTable.PieceHash(targetSquare, pieceIndex);
-                        capturedPiece = pieceIndex;
+                        capturedPiece = (sbyte)pieceIndex;
                         break;
                     }
                 }