Replace Move class with int and use 'Move' pool for MoveGenerator

.gitignore

@@ -355,4 +355,7 @@ global.json
 *.profraw
 
 # Environment files
-*.env
+*.env
+
+# VS diagnostic sessions
+*.diagsession

Directory.Build.props

@@ -7,6 +7,10 @@
  <EnableTrimAnalyzer>true</EnableTrimAnalyzer>
  </PropertyGroup>
 
+ <ItemGroup>
+ <Using Include="System.Int32" Alias="Move" />
+ </ItemGroup >
+
  <PropertyGroup>
  <Version>0.10.0</Version>
  <Authors>Eduardo Cáceres</Authors>

src/Lynx.Benchmark/FENGeneration.cs

@@ -215,7 +215,7 @@ public string Struct_FENCalculatedOnTheFly(string fen)
  var moves = new Position(fen).AllPossibleMoves();
 
  var position = new StructCustomPosition(fen);
- var newPosition = new StructCustomPosition(position, moves[0]);
+ var newPosition = new StructCustomPosition(position, moves.First());
  return newPosition.FEN;
  }
 
@@ -226,7 +226,7 @@ public string Struct_FENCalculatedWithinTheMoveConstructor(string fen)
  var moves = new Position(fen).AllPossibleMoves();
 
  var position = new StructCustomPosition(fen);
- var newPosition = new StructCustomPosition(position, moves[0], default);
+ var newPosition = new StructCustomPosition(position, moves.First(), default);
 
  return newPosition.FEN;
  }
@@ -238,7 +238,7 @@ public string ReadonlyStruct_FENCalculatedOnTheFly(string fen)
  var moves = new Position(fen).AllPossibleMoves();
 
  var position = new ReadonlyStructCustomPosition(fen);
- var newPosition = new ReadonlyStructCustomPosition(position, moves[0]);
+ var newPosition = new ReadonlyStructCustomPosition(position, moves.First());
 
  return newPosition.FEN;
  }
@@ -250,7 +250,7 @@ public string ReadonlyStruct_FENCalculatedWithinTheMoveConstructor(string fen)
  var moves = new Position(fen).AllPossibleMoves();
 
  var position = new ReadonlyStructCustomPosition(fen);
- var newPosition = new ReadonlyStructCustomPosition(position, moves[0], default);
+ var newPosition = new ReadonlyStructCustomPosition(position, moves.First(), default);
 
  return newPosition.FEN;
  }
@@ -262,7 +262,7 @@ public string Class_FENCalculatedOnTheFly(string fen)
  var moves = new Position(fen).AllPossibleMoves();
 
  var position = new ClassCustomPosition(fen);
- var newPosition = new ClassCustomPosition(position, moves[0]);
+ var newPosition = new ClassCustomPosition(position, moves.First());
 
  return newPosition.FEN;
  }
@@ -274,7 +274,7 @@ public string Class_FENCalculatedWithinTheMoveConstructor(string fen)
  var moves = new Position(fen).AllPossibleMoves();
 
  var position = new ClassCustomPosition(fen);
- var newPosition = new ClassCustomPosition(position, moves[0], default);
+ var newPosition = new ClassCustomPosition(position, moves.First(), default);
 
  return newPosition.FEN;
  }
@@ -286,7 +286,7 @@ public string RecordClass_FENCalculatedOnTheFly(string fen)
  var moves = new Position(fen).AllPossibleMoves();
 
  var position = new RecordClassCustomPosition(fen);
- var newPosition = new RecordClassCustomPosition(position, moves[0]);
+ var newPosition = new RecordClassCustomPosition(position, moves.First());
 
  return newPosition.FEN;
  }
@@ -298,7 +298,7 @@ public string RecordClass_FENCalculatedWithinTheMoveConstructor(string fen)
  var moves = new Position(fen).AllPossibleMoves();
 
  var position = new RecordClassCustomPosition(fen);
- var newPosition = new RecordClassCustomPosition(position, moves[0], default);
+ var newPosition = new RecordClassCustomPosition(position, moves.First(), default);
 
  return newPosition.FEN;
  }
@@ -310,7 +310,7 @@ public string RecordStruct_FENCalculatedOnTheFly(string fen)
  var moves = new Position(fen).AllPossibleMoves();
 
  var position = new RecordStructCustomPosition(fen);
- var newPosition = new RecordStructCustomPosition(position, moves[0]);
+ var newPosition = new RecordStructCustomPosition(position, moves.First());
 
  return newPosition.FEN;
  }
@@ -322,7 +322,7 @@ public string RecordStruct_FENCalculatedWithinTheMoveConstructor(string fen)
  var moves = new Position(fen).AllPossibleMoves();
 
  var position = new RecordStructCustomPosition(fen);
- var newPosition = new RecordStructCustomPosition(position, moves[0], default);
+ var newPosition = new RecordStructCustomPosition(position, moves.First(), default);
 
  return newPosition.FEN;
  }

src/Lynx.Benchmark/MoveGeneratorParallel.cs

@@ -1,5 +1,5 @@
 /*
- * 
+ *
  * | Method | fen | Mean | Error | StdDev | Ratio | RatioSD | Gen 0 | Gen 1 | Allocated |
  * |--------------------- |--------------------- |----------:|----------:|----------:|------:|--------:|-------:|-------:|----------:|
  * | SingleThread | r2q1r(...)- 0 9 [68] | 8.650 us | 0.1549 us | 0.1293 us | 1.00 | 0.00 | 2.3346 | - | 5 KB |
@@ -36,7 +36,7 @@
  * | SingleThreadArray | rnbqk(...)- 0 1 [56] | 7.986 us | 0.1455 us | 0.1361 us | 1.13 | 0.02 | 2.3956 | - | 5 KB |
  * | ParallelForEachArray | rnbqk(...)- 0 1 [56] | 20.664 us | 0.1411 us | 0.1251 us | 2.93 | 0.04 | 1.2512 | 0.6104 | 8 KB |
  * | WhenAllArray | rnbqk(...)- 0 1 [56] | 19.929 us | 0.0522 us | 0.0435 us | 2.83 | 0.03 | 3.2959 | - | 7 KB |
- * 
+ *
 */
 
 using BenchmarkDotNet.Attributes;
@@ -222,14 +222,14 @@ internal static IEnumerable<Move> GeneratePawnMoves(Position position, int offse
  var targetRank = (singlePushSquare / 8) + 1;
  if (targetRank == 1 || targetRank == 8) // Promotion
  {
- yield return new Move(sourceSquare, singlePushSquare, piece, promotedPiece: (int)Piece.Q + offset);
- yield return new Move(sourceSquare, singlePushSquare, piece, promotedPiece: (int)Piece.R + offset);
- yield return new Move(sourceSquare, singlePushSquare, piece, promotedPiece: (int)Piece.N + offset);
- yield return new Move(sourceSquare, singlePushSquare, piece, promotedPiece: (int)Piece.B + offset);
+ yield return MoveExtensions.Encode(sourceSquare, singlePushSquare, piece, promotedPiece: (int)Piece.Q + offset);
+ yield return MoveExtensions.Encode(sourceSquare, singlePushSquare, piece, promotedPiece: (int)Piece.R + offset);
+ yield return MoveExtensions.Encode(sourceSquare, singlePushSquare, piece, promotedPiece: (int)Piece.N + offset);
+ yield return MoveExtensions.Encode(sourceSquare, singlePushSquare, piece, promotedPiece: (int)Piece.B + offset);
  }
  else if (!capturesOnly)
  {
- yield return new Move(sourceSquare, singlePushSquare, piece);
+ yield return MoveExtensions.Encode(sourceSquare, singlePushSquare, piece);
  }
 
  // Double pawn push
@@ -240,7 +240,7 @@ internal static IEnumerable<Move> GeneratePawnMoves(Position position, int offse
  if (!position.OccupancyBitBoards[2].GetBit(doublePushSquare)
  && ((sourceRank == 2 && position.Side == Side.Black) || (sourceRank == 7 && position.Side == Side.White)))
  {
- yield return new Move(sourceSquare, doublePushSquare, piece, isDoublePawnPush: TRUE);
+ yield return MoveExtensions.Encode(sourceSquare, doublePushSquare, piece, isDoublePawnPush: TRUE);
  }
  }
  }
@@ -251,7 +251,7 @@ internal static IEnumerable<Move> GeneratePawnMoves(Position position, int offse
  if (position.EnPassant != BoardSquare.noSquare && attacks.GetBit(position.EnPassant))
  // We assume that position.OccupancyBitBoards[oppositeOccupancy].GetBit(targetSquare + singlePush) == true
  {
- yield return new Move(sourceSquare, (int)position.EnPassant, piece, isCapture: TRUE, isEnPassant: TRUE);
+ yield return MoveExtensions.Encode(sourceSquare, (int)position.EnPassant, piece, isCapture: TRUE, isEnPassant: TRUE);
  }
 
  // Captures
@@ -264,14 +264,14 @@ internal static IEnumerable<Move> GeneratePawnMoves(Position position, int offse
  var targetRank = (targetSquare / 8) + 1;
  if (targetRank == 1 || targetRank == 8) // Capture with promotion
  {
- yield return new Move(sourceSquare, targetSquare, piece, promotedPiece: (int)Piece.Q + offset, isCapture: TRUE);
- yield return new Move(sourceSquare, targetSquare, piece, promotedPiece: (int)Piece.R + offset, isCapture: TRUE);
- yield return new Move(sourceSquare, targetSquare, piece, promotedPiece: (int)Piece.N + offset, isCapture: TRUE);
- yield return new Move(sourceSquare, targetSquare, piece, promotedPiece: (int)Piece.B + offset, isCapture: TRUE);
+ yield return MoveExtensions.Encode(sourceSquare, targetSquare, piece, promotedPiece: (int)Piece.Q + offset, isCapture: TRUE);
+ yield return MoveExtensions.Encode(sourceSquare, targetSquare, piece, promotedPiece: (int)Piece.R + offset, isCapture: TRUE);
+ yield return MoveExtensions.Encode(sourceSquare, targetSquare, piece, promotedPiece: (int)Piece.N + offset, isCapture: TRUE);
+ yield return MoveExtensions.Encode(sourceSquare, targetSquare, piece, promotedPiece: (int)Piece.B + offset, isCapture: TRUE);
  }
  else
  {
- yield return new Move(sourceSquare, targetSquare, piece, isCapture: TRUE);
+ yield return MoveExtensions.Encode(sourceSquare, targetSquare, piece, isCapture: TRUE);
  }
  }
  }
@@ -297,7 +297,7 @@ internal static IEnumerable<Move> GenerateCastlingMoves(Position position, int o
  && !Attacks.IsSquaredAttackedBySide((int)BoardSquare.f1, position, oppositeSide)
  && !Attacks.IsSquaredAttackedBySide((int)BoardSquare.g1, position, oppositeSide))
  {
- yield return new Move(sourceSquare, Constants.WhiteShortCastleKingSquare, piece, isShortCastle: TRUE);
+ yield return MoveExtensions.Encode(sourceSquare, Constants.WhiteShortCastleKingSquare, piece, isShortCastle: TRUE);
  }
 
  if (((position.Castle & (int)CastlingRights.WQ) != default)
@@ -308,7 +308,7 @@ internal static IEnumerable<Move> GenerateCastlingMoves(Position position, int o
  && !Attacks.IsSquaredAttackedBySide((int)BoardSquare.d1, position, oppositeSide)
  && !Attacks.IsSquaredAttackedBySide((int)BoardSquare.c1, position, oppositeSide))
  {
- yield return new Move(sourceSquare, Constants.WhiteLongCastleKingSquare, piece, isLongCastle: TRUE);
+ yield return MoveExtensions.Encode(sourceSquare, Constants.WhiteLongCastleKingSquare, piece, isLongCastle: TRUE);
  }
  }
  else
@@ -320,7 +320,7 @@ internal static IEnumerable<Move> GenerateCastlingMoves(Position position, int o
  && !Attacks.IsSquaredAttackedBySide((int)BoardSquare.f8, position, oppositeSide)
  && !Attacks.IsSquaredAttackedBySide((int)BoardSquare.g8, position, oppositeSide))
  {
- yield return new Move(sourceSquare, Constants.BlackShortCastleKingSquare, piece, isShortCastle: TRUE);
+ yield return MoveExtensions.Encode(sourceSquare, Constants.BlackShortCastleKingSquare, piece, isShortCastle: TRUE);
  }
 
  if (((position.Castle & (int)CastlingRights.BQ) != default)
@@ -331,7 +331,7 @@ internal static IEnumerable<Move> GenerateCastlingMoves(Position position, int o
  && !Attacks.IsSquaredAttackedBySide((int)BoardSquare.d8, position, oppositeSide)
  && !Attacks.IsSquaredAttackedBySide((int)BoardSquare.c8, position, oppositeSide))
  {
- yield return new Move(sourceSquare, Constants.BlackLongCastleKingSquare, piece, isLongCastle: TRUE);
+ yield return MoveExtensions.Encode(sourceSquare, Constants.BlackLongCastleKingSquare, piece, isLongCastle: TRUE);
  }
  }
  }
@@ -358,11 +358,11 @@ internal static IEnumerable<Move> GeneratePieceMoves(int piece, Position positio
 
  if (position.OccupancyBitBoards[(int)Side.Both].GetBit(targetSquare))
  {
- yield return new Move(sourceSquare, targetSquare, piece, isCapture: TRUE);
+ yield return MoveExtensions.Encode(sourceSquare, targetSquare, piece, isCapture: TRUE);
  }
  else if (!capturesOnly)
  {
- yield return new Move(sourceSquare, targetSquare, piece);
+ yield return MoveExtensions.Encode(sourceSquare, targetSquare, piece);
  }
  }
  }

src/Lynx.Benchmark/PositionIdGeneration.cs

@@ -62,10 +62,10 @@ public string Id(Position newPosition)
 
  public static IEnumerable<Position> Data => new[] {
  //Constants.EmptyBoardFEN,
- new Position(Positions[0], Positions[0].AllPossibleMoves()[0]),
- new Position(Positions[1], Positions[1].AllPossibleMoves()[0]),
- new Position(Positions[2], Positions[2].AllPossibleMoves()[0]),
- new Position(Positions[3], Positions[3].AllPossibleMoves()[0])
+ new Position(Positions[0], Positions[0].AllPossibleMoves().First()),
+ new Position(Positions[1], Positions[1].AllPossibleMoves().First()),
+ new Position(Positions[2], Positions[2].AllPossibleMoves().First()),
+ new Position(Positions[3], Positions[3].AllPossibleMoves().First())
  };
 }
 

src/Lynx.Dev/Program.cs

@@ -5,7 +5,6 @@
 using System.Numerics;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
-using static Lynx.Model.Move;
 
 //_2_GettingStarted();
 //_3_PawnAttacks();
@@ -394,7 +393,7 @@ static void _23_Castling_Moves()
  var position = new Position("rn2k2r/pppppppp/8/8/8/8/PPPPPPPP/RN2K2R w KQkq - 0 1");
  position.Print();
 
- var moves = MoveGenerator.GenerateCastlingMoves(position, Utils.PieceOffset(position.Side)).ToList();
+ var moves = MoveGenerator.GenerateCastlingMovesForReference(position, Utils.PieceOffset(position.Side)).ToList();
 
  foreach (var move in moves)
  {
@@ -440,16 +439,16 @@ static void _29_Move_List()
 {
  var position = new Position(TrickyPosition);
  var moves = MoveGenerator.GenerateAllMoves(position);
- PrintMoveList(moves);
+ moves.PrintMoveList();
 
  position = new Position(TrickyPositionReversed);
  moves = MoveGenerator.GenerateAllMoves(position);
- PrintMoveList(moves);
+ moves.PrintMoveList();
 
  position = new Position(KillerPosition);
  position.Print();
  moves = MoveGenerator.GenerateAllMoves(position);
- PrintMoveList(moves);
+ moves.PrintMoveList();
 }
 
 static void _32_Make_Move()
@@ -468,13 +467,13 @@ static void _32_Make_Move()
  //CastlingRightsTest(game);
  //CastlingRightsTest(reversedGame);
 
- PrintMoveList(gameWithPromotion.GetAllMoves());
+ MoveGenerator.GenerateAllMoves(gameWithPromotion.CurrentPosition).PrintMoveList();
 
  GeneralMoveTest(gameWithPromotion);
 
  static void GeneralMoveTest(Game game)
  {
- foreach (var move in game.GetAllMoves())
+ foreach (var move in MoveGenerator.GenerateAllMoves(game.CurrentPosition))
  {
  game.CurrentPosition.Print();
 
@@ -494,7 +493,7 @@ static void GeneralMoveTest(Game game)
 
  static void CastlingRightsTest(Game game)
  {
- foreach (var move in game.GetAllMoves())
+ foreach (var move in MoveGenerator.GenerateAllMoves(game.CurrentPosition))
  {
  if (move.Piece() == (int)Piece.R || (move.Piece() == (int)Piece.r)
  || move.Piece() == (int)Piece.K || (move.Piece() == (int)Piece.k))
@@ -678,7 +677,7 @@ static void ZobristTable()
  var pos = new Position(KillerPosition);
  var zobristTable = InitializeZobristTable();
  var hash = CalculatePositionHash(zobristTable, pos);
- var updatedHash = UpdatePositionHash(zobristTable, hash, pos.AllPossibleMoves()[0]);
+ var updatedHash = UpdatePositionHash(zobristTable, hash, pos.AllPossibleMoves().First());
 
  Console.WriteLine(updatedHash);
 }

src/Lynx/Constants.cs

@@ -359,4 +359,11 @@ public static class Constants
  15, 15, 15, 15, 15, 15, 15, 15,
  13, 15, 15, 15, 12, 15, 15, 14
  };
+
+ /// <summary>
+ /// 218 or 224 seems to be the known limit
+ /// https://www.reddit.com/r/chess/comments/9j70dc/position_with_the_most_number_of_legal_moves/
+ /// </summary>
+ public const int MaxNumberOfPossibleMovesInAPosition = 250;
+
 }

src/Lynx/Model/Game.cs

@@ -6,6 +6,8 @@ public sealed class Game
 {
  private static readonly ILogger _logger = LogManager.GetCurrentClassLogger();
 
+ public Move[] MovePool { get; } = new Move[Constants.MaxNumberOfPossibleMovesInAPosition];
+
  public List<Move> MoveHistory { get; }
  public List<Position> PositionHistory { get; }
  public Dictionary<long, int> PositionHashHistory { get; }
@@ -35,7 +37,9 @@ public Game(string fen, List<string> movesUCIString) : this(fen)
  {
  foreach (var moveString in movesUCIString)
  {
- if (!Move.TryParseFromUCIString(moveString, GetAllMoves(), out var parsedMove))
+ var moveList = MoveGenerator.GenerateAllMoves(CurrentPosition, MovePool);
+
+ if (!MoveExtensions.TryParseFromUCIString(moveString, moveList, out var parsedMove))
  {
  _logger.Error($"Error parsing game with fen {fen} and moves {string.Join(' ', movesUCIString)}: error detected in {moveString}");
  break;
@@ -45,9 +49,6 @@ public Game(string fen, List<string> movesUCIString) : this(fen)
  }
  }
 
- public List<Move> GetAllMoves() => MoveGenerator.GenerateAllMoves(CurrentPosition);
- public List<Move> GetAllMovesWithCaptures() => MoveGenerator.GenerateAllMoves(CurrentPosition, capturesOnly: true);
-
  public bool MakeMove(Move moveToPlay)
  {
  PositionHistory.Add(CurrentPosition);