public bool MovePiece(byte srcPosition, byte dstPosition)
{
Piece piece = this.ChessBoard.Squares[(int)srcPosition].Piece;
this.PreviousChessBoard = new Board(this.ChessBoard);
this.UndoChessBoard = new Board(this.ChessBoard);
this.UndoGameBook = new List <OpeningMove>((IEnumerable <OpeningMove>) this.CurrentGameBook);
Board.MovePiece(this.ChessBoard, srcPosition, dstPosition, this.PromoteToPieceType);
this.ChessBoard.LastMove.GeneratePGNString(this.ChessBoard);
PieceValidMoves.GenerateValidMoves(this.ChessBoard);
Evaluation.EvaluateBoardScore(this.ChessBoard);
if (piece.PieceColor == ChessPieceColor.White)
{
if (this.ChessBoard.WhiteCheck)
{
this.ChessBoard = new Board(this.PreviousChessBoard);
PieceValidMoves.GenerateValidMoves(this.ChessBoard);
return(false);
}
}
else if (piece.PieceColor == ChessPieceColor.Black && this.ChessBoard.BlackCheck)
{
this.ChessBoard = new Board(this.PreviousChessBoard);
PieceValidMoves.GenerateValidMoves(this.ChessBoard);
return(false);
}
this.MoveHistory.Push(this.ChessBoard.LastMove);
ChessEngine.Engine.Engine.CheckForMate(this.WhoseMove, ref this.ChessBoard);
this.PieceTakenAdd(this.ChessBoard.LastMove);
if (this.ChessBoard.WhiteMate || this.ChessBoard.BlackMate)
{
this.LastMove.PgnMove += "#";
}
else if (this.ChessBoard.WhiteCheck || this.ChessBoard.BlackCheck)
{
this.LastMove.PgnMove += "+";
}
return(true);
}
public void AiPonderMove()
{
Thinking = true;
/* Fix added to prevent premature declaration of checkmate against computer's king.
*
* The original version only looked at squares that were available for the black king to move to PRIOR to white's latest move.
* So... suppose you had a situation like this:
* r4r2/pppb1p1k/8/3p2Q1/q4P2/2np4/6PP/5RK1/ w - 0 27
* ... and moved the white queen from G5 to H5.
* At the start of white's move, the black king has 5 possible moves... 4 of which are attackable by white, and noted by
* GenerateValidMoves in WhiteAttackBoard[]. When AiPonderMove executes, it immediately eliminates those 4 squares as options
* for the black king, even though 2 of them are now safe because no white piece can attack them. However, square 7 is now
* directly in the queen's attack path, so it's eliminated as an option as well. Boom, premature checkmate... game over.
*/
ChessBoard.BlackMate = false;
ChessBoard.WhiteMate = false;
PieceValidMoves.GenerateValidMoves(ChessBoard);
NodesSearched = 0;
var resultBoards = new ResultBoards();
resultBoards.Positions = new List <Board>();
if (CheckForMate(WhoseMove, ref ChessBoard))
{
Thinking = false;
return;
}
MoveContent bestMove = new MoveContent();
//If there is no playbook move search for the best move
if (FindPlayBookMove(ref bestMove, ChessBoard, OpeningBook) == false ||
ChessBoard.HalfMoveClock > 90 || ChessBoard.RepeatedMove >= 2)
{
if (FindPlayBookMove(ref bestMove, ChessBoard, CurrentGameBook) == false ||
ChessBoard.HalfMoveClock > 90 || ChessBoard.RepeatedMove >= 2)
{
bestMove = Search.IterativeSearch(ChessBoard, PlyDepthSearched, ref NodesSearched, ref NodesQuiessence, ref pvLine, ref PlyDepthReached, ref RootMovesSearched, CurrentGameBook);
}
}
//Make the move
PreviousChessBoard = new Board(ChessBoard);
RootMovesSearched = (byte)resultBoards.Positions.Count;
Board.MovePiece(ChessBoard, bestMove.MovingPiecePrimary.SrcPosition, bestMove.MovingPiecePrimary.DstPosition, ChessPieceType.Queen);
ChessBoard.LastMove.GeneratePGNString(ChessBoard);
FileIO.SaveCurrentGameMove(ChessBoard, PreviousChessBoard, CurrentGameBook, bestMove);
for (byte x = 0; x < 64; x++)
{
Square sqr = ChessBoard.Squares[x];
if (sqr.Piece == null)
{
continue;
}
sqr.Piece.DefendedValue = 0;
sqr.Piece.AttackedValue = 0;
}
PieceValidMoves.GenerateValidMoves(ChessBoard);
Evaluation.EvaluateBoardScore(ChessBoard);
PieceTakenAdd(ChessBoard.LastMove);
MoveHistory.Push(ChessBoard.LastMove);
if (CheckForMate(WhoseMove, ref ChessBoard))
{
Thinking = false;
if (ChessBoard.WhiteMate || ChessBoard.BlackMate)
{
LastMove.PgnMove += "#";
}
return;
}
if (ChessBoard.WhiteCheck || ChessBoard.BlackCheck)
{
LastMove.PgnMove += "+";
}
Thinking = false;
}
public int EvaluateBoardScore()
{
Evaluation.EvaluateBoardScore(ChessBoard);
return(ChessBoard.Score);
}
private static int Quiescence(Board examineBoard, int alpha, int beta, ref int nodesSearched)
{
nodesSearched++;
//Evaluate Score
Evaluation.EvaluateBoardScore(examineBoard);
//Invert Score to support Negamax
examineBoard.Score = SideToMoveScore(examineBoard.Score, examineBoard.WhoseMove);
if (examineBoard.Score >= beta)
{
return(beta);
}
if (examineBoard.Score > alpha)
{
alpha = examineBoard.Score;
}
List <Position> positions;
if (examineBoard.WhiteCheck || examineBoard.BlackCheck)
{
positions = EvaluateMoves(examineBoard, 0);
}
else
{
positions = EvaluateMovesQ(examineBoard);
}
if (positions.Count == 0)
{
return(examineBoard.Score);
}
positions.Sort(Sort);
foreach (Position move in positions)
{
if (StaticExchangeEvaluation(examineBoard.Squares[move.DstPosition]) >= 0)
{
continue;
}
//Make a copy
Board board = examineBoard.FastCopy();
//Move Piece
Board.MovePiece(board, move.SrcPosition, move.DstPosition, ChessPieceType.Queen);
//We Generate Valid Moves for Board
PieceValidMoves.GenerateValidMoves(board);
if (board.BlackCheck)
{
if (examineBoard.WhoseMove == ChessPieceColor.Black)
{
//Invalid Move
continue;
}
}
if (board.WhiteCheck)
{
if (examineBoard.WhoseMove == ChessPieceColor.White)
{
//Invalid Move
continue;
}
}
int value = -Quiescence(board, -beta, -alpha, ref nodesSearched);
if (value >= beta)
{
KillerMove[2, 0].SrcPosition = move.SrcPosition;
KillerMove[2, 0].DstPosition = move.DstPosition;
return(beta);
}
if (value > alpha)
{
alpha = value;
}
}
return(alpha);
}
private static ResultBoards GetSortValidMoves(Board examineBoard)
{
ResultBoards succ = new ResultBoards
{
Positions = new List <Board>(30)
};
piecesRemaining = 0;
for (byte x = 0; x < 64; x++)
{
Square sqr = examineBoard.Squares[x];
//Make sure there is a piece on the square
if (sqr.Piece == null)
{
continue;
}
piecesRemaining++;
//Make sure the color is the same color as the one we are moving.
if (sqr.Piece.PieceColor != examineBoard.WhoseMove)
{
continue;
}
//For each valid move for this piece
foreach (byte dst in sqr.Piece.ValidMoves)
{
//We make copies of the board and move so that we can move it without effecting the parent board
Board board = examineBoard.FastCopy();
//Make move so we can examine it
Board.MovePiece(board, x, dst, ChessPieceType.Queen);
//We Generate Valid Moves for Board
PieceValidMoves.GenerateValidMoves(board);
//Invalid Move
if (board.WhiteCheck && examineBoard.WhoseMove == ChessPieceColor.White)
{
continue;
}
//Invalid Move
if (board.BlackCheck && examineBoard.WhoseMove == ChessPieceColor.Black)
{
continue;
}
//We calculate the board score
Evaluation.EvaluateBoardScore(board);
//Invert Score to support Negamax
board.Score = SideToMoveScore(board.Score, board.WhoseMove);
succ.Positions.Add(board);
}
}
succ.Positions.Sort(Sort);
return(succ);
}
public void AiPonderMove()
{
Thinking = true;
NodesSearched = 0;
var resultBoards = new ResultBoards();
resultBoards.Positions = new List <Board>();
if (CheckForMate(WhoseMove, ref ChessBoard))
{
Thinking = false;
return;
}
MoveContent bestMove = new MoveContent();
//If there is no playbook move search for the best move
if (FindPlayBookMove(ref bestMove, ChessBoard, OpeningBook) == false ||
ChessBoard.FiftyMove > 45 || ChessBoard.RepeatedMove >= 2)
{
if (FindPlayBookMove(ref bestMove, ChessBoard, CurrentGameBook) == false ||
ChessBoard.FiftyMove > 45 || ChessBoard.RepeatedMove >= 2)
{
bestMove = Search.IterativeSearch(ChessBoard, PlyDepthSearched, ref NodesSearched, ref NodesQuiessence, ref pvLine, ref PlyDepthReached, ref RootMovesSearched, CurrentGameBook);
}
}
//Make the move
PreviousChessBoard = new Board(ChessBoard);
RootMovesSearched = (byte)resultBoards.Positions.Count;
Board.MovePiece(ChessBoard, bestMove.MovingPiecePrimary.SrcPosition, bestMove.MovingPiecePrimary.DstPosition, ChessPieceType.Queen);
ChessBoard.LastMove.GeneratePGNString(ChessBoard);
FileIO.SaveCurrentGameMove(ChessBoard, PreviousChessBoard, CurrentGameBook, bestMove);
for (byte x = 0; x < 64; x++)
{
Square sqr = ChessBoard.Squares[x];
if (sqr.Piece == null)
{
continue;
}
sqr.Piece.DefendedValue = 0;
sqr.Piece.AttackedValue = 0;
}
PieceValidMoves.GenerateValidMoves(ChessBoard);
Evaluation.EvaluateBoardScore(ChessBoard);
PieceTakenAdd(ChessBoard.LastMove);
MoveHistory.Push(ChessBoard.LastMove);
if (CheckForMate(WhoseMove, ref ChessBoard))
{
Thinking = false;
if (ChessBoard.WhiteMate || ChessBoard.BlackMate)
{
LastMove.PgnMove += "#";
}
return;
}
if (ChessBoard.WhiteCheck || ChessBoard.BlackCheck)
{
LastMove.PgnMove += "+";
}
Thinking = false;
}
public void AiPonderMove()
{
Thinking = true;
/* Fix added to prevent premature declaration of checkmate against computer's king.
*
* The original version only looked at squares that were available for the black king to move to PRIOR to white's latest move.
* So... suppose you had a situation like this:
* r4r2/pppb1p1k/8/3p2Q1/q4P2/2np4/6PP/5RK1/ w - 0 27
* ... and moved the white queen from G5 to H5.
* At the start of white's move, the black king has 5 possible moves... 4 of which are attackable by white, and noted by
* GenerateValidMoves in WhiteAttackBoard[]. When AiPonderMove executes, it immediately eliminates those 4 squares as options
* for the black king, even though 2 of them are now safe because no white piece can attack them. However, square 7 is now
* directly in the queen's attack path, so it's eliminated as an option as well. Boom, premature checkmate... game over.
*
* The time it takes to regenerate the valid moves is nontrivial under Android. To improve performance,
* my fix regenerates the valid moves ONLY when it might prevent a game-ending premature declaration
* of checkmate, unless the difficulty is set to Hard or VeryHard (in which case it runs every time).
* Even a novice player is likely to get confused if the engine declares checkmate for no apparent reason,
* but the bug's more insidious manifestations at the two easiest difficulty levels help to make the computer a tiny bit easier
* to beat by giving it a blind spot that a player can exploit, the same way HUMAN opponents have blind spots and weaknesses of their own.
*/
if (ChessBoard.BlackMate || ChessBoard.WhiteMate || (GameDifficulty == Difficulty.VeryHard) || (GameDifficulty == Difficulty.Hard))
{
ChessBoard.BlackMate = false;
ChessBoard.WhiteMate = false;
PieceValidMoves.GenerateValidMoves(ChessBoard);
}
NodesSearched = 0;
var resultBoards = new ResultBoards();
resultBoards.Positions = new List <Board>();
if (CheckForMate(WhoseMove, ref ChessBoard))
{
Thinking = false;
return;
}
MoveContent bestMove = new MoveContent();
//If there is no playbook move search for the best move
if (FindPlayBookMove(ref bestMove, ChessBoard, OpeningBook) == false ||
ChessBoard.FiftyMove > 45 || ChessBoard.RepeatedMove >= 2)
{
if (FindPlayBookMove(ref bestMove, ChessBoard, CurrentGameBook) == false ||
ChessBoard.FiftyMove > 45 || ChessBoard.RepeatedMove >= 2)
{
bestMove = Search.IterativeSearch(ChessBoard, PlyDepthSearched, ref NodesSearched, ref NodesQuiessence, ref pvLine, ref PlyDepthReached, ref RootMovesSearched, CurrentGameBook);
}
}
//Make the move
PreviousChessBoard = new Board(ChessBoard);
RootMovesSearched = (byte)resultBoards.Positions.Count;
Board.MovePiece(ChessBoard, bestMove.MovingPiecePrimary.SrcPosition, bestMove.MovingPiecePrimary.DstPosition, ChessPieceType.Queen);
ChessBoard.LastMove.GeneratePGNString(ChessBoard);
FileIO.SaveCurrentGameMove(ChessBoard, PreviousChessBoard, CurrentGameBook, bestMove);
for (byte x = 0; x < 64; x++)
{
Square sqr = ChessBoard.Squares[x];
if (sqr.Piece == null)
{
continue;
}
sqr.Piece.DefendedValue = 0;
sqr.Piece.AttackedValue = 0;
}
PieceValidMoves.GenerateValidMoves(ChessBoard);
Evaluation.EvaluateBoardScore(ChessBoard);
PieceTakenAdd(ChessBoard.LastMove);
MoveHistory.Push(ChessBoard.LastMove);
if (CheckForMate(WhoseMove, ref ChessBoard))
{
Thinking = false;
if (ChessBoard.WhiteMate || ChessBoard.BlackMate)
{
LastMove.PgnMove += "#";
}
return;
}
if (ChessBoard.WhiteCheck || ChessBoard.BlackCheck)
{
LastMove.PgnMove += "+";
}
Thinking = false;
}
/// <summary>
/// Process incoming commands
/// </summary>
/// <param name="input">Incoming string from interface</param>
public void Comunication(string input)
{
string command = input.Split(' ').First();
string messageBody = input.Substring(command.Length).Trim();
switch (command)
{
case "protover":
{
if (messageBody == "2")
{
Console.WriteLine(@"feature setboard=1 usermove=1 colors=0 reuse=1 time=1 myname=""The Turk"" name=1 done=1");
}
break;
}
case "force":
{
force = force ? false : true;
break;
}
case "new":
{
engine.Board.SetUpBoard();
GameHistory.Clear();
force = true;
break;
}
case "setboard":
{
engine.Board.Fen = messageBody;
GameHistory.Clear();
break;
}
case "quit":
{
Environment.Exit(Environment.ExitCode);
break;
}
case "usermove":
{
ReceivedMove(messageBody);
if (force) //Make move after received a move
{
Console.WriteLine("force mode is on");
var result = engine.Search(timer.timeForPerMove);
Console.WriteLine("move " + result.BestLine.First().IONotation());
engine.Board.MakeMove(result.BestLine.First());
GameHistory.Push(result.BestLine.First());
}
break;
}
case "go":
{
force = true;
var result = engine.Search(timer.timeForPerMove);
Console.WriteLine("move " + result.BestLine.First().IONotation());
engine.Board.MakeMove(result.BestLine.First());
GameHistory.Push(result.BestLine.First());
break;
}
case "undo":
{
engine.Board.TakeBackMove(GameHistory.Pop());
break;
}
case "level":
{
timer = new ChessClock(messageBody);
break;
}
case "st":
{
timer = new ChessClock("0 0 " + messageBody);
break;
}
case "fen": //just for testing purposes
{
engine.Board.Fen = "rn4kr/4p1bp/2pp4/1p3P1Q/2P1P3/6R1/PBp3PP/RN4K1 w - - 0 24 ";
GameHistory.Clear();
break;
}
case "score": //just for testing purposes
{
var score = Evaluation.Evaluate(engine.Board);
engine.Board.ShowBoard();
Console.WriteLine("score : " + score);
break;
}
case "show": //just for testing purposes
{
engine.Board.ShowBoard();
break;
}
}
}
