private static ResultBoards GetSortValidMoves(Board examineBoard)
{
ResultBoards resultBoards = new ResultBoards()
{
Positions = new List <Board>(30)
};
Search.piecesRemaining = 0;
for (byte srcPosition = 0; (int)srcPosition < 64; ++srcPosition)
{
Square square = examineBoard.Squares[(int)srcPosition];
if (square.Piece != null)
{
++Search.piecesRemaining;
if (square.Piece.PieceColor == examineBoard.WhoseMove)
{
foreach (byte validMove in square.Piece.ValidMoves)
{
Board board = examineBoard.FastCopy();
Board.MovePiece(board, srcPosition, validMove, ChessPieceType.Queen);
PieceValidMoves.GenerateValidMoves(board);
if ((!board.WhiteCheck || examineBoard.WhoseMove != ChessPieceColor.White) && (!board.BlackCheck || examineBoard.WhoseMove != ChessPieceColor.Black))
{
Evaluation.EvaluateBoardScore(board);
board.Score = Search.SideToMoveScore(board.Score, board.WhoseMove);
resultBoards.Positions.Add(board);
}
}
}
}
}
resultBoards.Positions.Sort(new Comparison <Board>(Search.Sort));
return(resultBoards);
}
private static ResultBoards GetPossibleBoards(ChessPieceColor movingSide, Board examineBoard)
{
//We are going to store our result boards here
resultBoards = new ResultBoards
{
Positions = new List <Board>()
};
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;
}
//Make sure the color is the same color as the one we are moving.
if (sqr.Piece.PieceColor != movingSide)
{
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);
if (board.BlackCheck && movingSide == ChessPieceColor.Black)
{
continue;
}
if (board.WhiteCheck && movingSide == ChessPieceColor.White)
{
continue;
}
//We calculate the board score
Evaluation.EvaluateBoardScore(board);
//Invert Score to support Negamax
board.Score = SideToMoveScore(board.Score, GetOppositeColor(movingSide));
resultBoards.Positions.Add(board);
}
}
return(resultBoards);
}
public void InitiateBoard(string fen)
{
ChessBoard = new Board(fen);
if (!String.IsNullOrEmpty(fen))
{
PieceValidMoves.GenerateValidMoves(ChessBoard);
Evaluation.EvaluateBoardScore(ChessBoard);
}
}
public void InitiateBoard(string fen)
{
this.ChessBoard = new Board(fen);
if (string.IsNullOrEmpty(fen))
{
return;
}
PieceValidMoves.GenerateValidMoves(this.ChessBoard);
Evaluation.EvaluateBoardScore(this.ChessBoard);
}
public bool MovePiece(byte srcPosition, byte dstPosition)
{
Piece piece = ChessBoard.Squares[srcPosition].Piece;
PreviousChessBoard = new Board(ChessBoard);
UndoChessBoard = new Board(ChessBoard);
UndoGameBook = new List <OpeningMove>(CurrentGameBook);
Board.MovePiece(ChessBoard, srcPosition, dstPosition, PromoteToPieceType);
ChessBoard.LastMove.GeneratePGNString(ChessBoard);
PieceValidMoves.GenerateValidMoves(ChessBoard);
Evaluation.EvaluateBoardScore(ChessBoard);
//If there is a check in place, check if this is still true;
if (piece.PieceColor == ChessPieceColor.White)
{
if (ChessBoard.WhiteCheck)
{
//Invalid Move
ChessBoard = new Board(PreviousChessBoard);
PieceValidMoves.GenerateValidMoves(ChessBoard);
return(false);
}
}
else if (piece.PieceColor == ChessPieceColor.Black)
{
if (ChessBoard.BlackCheck)
{
//Invalid Move
ChessBoard = new Board(PreviousChessBoard);
PieceValidMoves.GenerateValidMoves(ChessBoard);
return(false);
}
}
MoveHistory.Push(ChessBoard.LastMove);
FileIO.SaveCurrentGameMove(ChessBoard, PreviousChessBoard, CurrentGameBook, ChessBoard.LastMove);
CheckForMate(WhoseMove, ref ChessBoard);
PieceTakenAdd(ChessBoard.LastMove);
if (ChessBoard.WhiteMate || ChessBoard.BlackMate)
{
LastMove.PgnMove += "#";
}
else if (ChessBoard.WhiteCheck || ChessBoard.BlackCheck)
{
LastMove.PgnMove += "+";
}
return(true);
}
public void AiPonderMove(BackgroundWorker worker)
{
this.Thinking = true;
this.NodesSearched = 0;
ResultBoards resultBoards = new ResultBoards();
resultBoards.Positions = new List <Board>();
if (ChessEngine.Engine.Engine.CheckForMate(this.WhoseMove, ref this.ChessBoard))
{
this.Thinking = false;
}
else
{
MoveContent bestMove = new MoveContent();
if ((!ChessEngine.Engine.Engine.FindPlayBookMove(ref bestMove, this.ChessBoard, (IEnumerable <OpeningMove>) this.OpeningBook) || (int)this.ChessBoard.FiftyMove > 45 || (int)this.ChessBoard.RepeatedMove >= 2) && (!ChessEngine.Engine.Engine.FindPlayBookMove(ref bestMove, this.ChessBoard, (IEnumerable <OpeningMove>) this.CurrentGameBook) || (int)this.ChessBoard.FiftyMove > 45 || (int)this.ChessBoard.RepeatedMove >= 2))
{
bestMove = Search.IterativeSearch(this.ChessBoard, this.PlyDepthSearched, ref this.NodesSearched, ref this.NodesQuiessence, ref this.pvLine, worker, ref this.PlyDepthReached, ref this.RootMovesSearched, this.CurrentGameBook);
}
this.PreviousChessBoard = new Board(this.ChessBoard);
this.RootMovesSearched = (byte)resultBoards.Positions.Count;
Board.MovePiece(this.ChessBoard, bestMove.MovingPiecePrimary.SrcPosition, bestMove.MovingPiecePrimary.DstPosition, ChessPieceType.Queen);
this.ChessBoard.LastMove.GeneratePGNString(this.ChessBoard);
for (byte index = 0; (int)index < 64; ++index)
{
Square square = this.ChessBoard.Squares[(int)index];
if (square.Piece != null)
{
square.Piece.DefendedValue = (short)0;
square.Piece.AttackedValue = (short)0;
}
}
PieceValidMoves.GenerateValidMoves(this.ChessBoard);
Evaluation.EvaluateBoardScore(this.ChessBoard);
this.PieceTakenAdd(this.ChessBoard.LastMove);
this.MoveHistory.Push(this.ChessBoard.LastMove);
if (ChessEngine.Engine.Engine.CheckForMate(this.WhoseMove, ref this.ChessBoard))
{
this.Thinking = false;
if (!this.ChessBoard.WhiteMate && !this.ChessBoard.BlackMate)
{
return;
}
this.LastMove.PgnMove += "#";
}
else
{
if (this.ChessBoard.WhiteCheck || this.ChessBoard.BlackCheck)
{
this.LastMove.PgnMove += "+";
}
this.Thinking = false;
}
}
}
public void Undo()
{
if (this.UndoChessBoard == null)
{
return;
}
this.PieceTakenRemove(this.ChessBoard.LastMove);
this.PieceTakenRemove(this.PreviousChessBoard.LastMove);
this.ChessBoard = new Board(this.UndoChessBoard);
this.CurrentGameBook = new List <OpeningMove>((IEnumerable <OpeningMove>) this.UndoGameBook);
PieceValidMoves.GenerateValidMoves(this.ChessBoard);
Evaluation.EvaluateBoardScore(this.ChessBoard);
}
public void Undo()
{
if (UndoChessBoard != null)
{
PieceTakenRemove(ChessBoard.LastMove);
PieceTakenRemove(PreviousChessBoard.LastMove);
ChessBoard = new Board(UndoChessBoard);
CurrentGameBook = new List <OpeningMove>(UndoGameBook);
PieceValidMoves.GenerateValidMoves(ChessBoard);
Evaluation.EvaluateBoardScore(ChessBoard);
}
}
private static int Quiescence(Board examineBoard, int alpha, int beta, ref int nodesSearched)
{
nodesSearched = nodesSearched + 1;
Evaluation.EvaluateBoardScore(examineBoard);
examineBoard.Score = Search.SideToMoveScore(examineBoard.Score, examineBoard.WhoseMove);
if (examineBoard.Score >= beta)
{
return(beta);
}
if (examineBoard.Score > alpha)
{
alpha = examineBoard.Score;
}
List <Search.Position> positionList = examineBoard.WhiteCheck || examineBoard.BlackCheck ? Search.EvaluateMoves(examineBoard, (byte)0) : Search.EvaluateMovesQ(examineBoard);
if (positionList.Count == 0)
{
return(examineBoard.Score);
}
positionList.Sort(new Comparison <Search.Position>(Search.Sort));
foreach (Search.Position position in positionList)
{
if (Search.StaticExchangeEvaluation(examineBoard.Squares[(int)position.DstPosition]) < 0)
{
Board board = examineBoard.FastCopy();
Board.MovePiece(board, position.SrcPosition, position.DstPosition, ChessPieceType.Queen);
PieceValidMoves.GenerateValidMoves(board);
if ((!board.BlackCheck || examineBoard.WhoseMove != ChessPieceColor.Black) && (!board.WhiteCheck || examineBoard.WhoseMove != ChessPieceColor.White))
{
int num = -Search.Quiescence(board, -beta, -alpha, ref nodesSearched);
if (num >= beta)
{
Search.KillerMove[2, 0].SrcPosition = position.SrcPosition;
Search.KillerMove[2, 0].DstPosition = position.DstPosition;
return(beta);
}
if (num > alpha)
{
alpha = num;
}
}
}
}
return(alpha);
}
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;
}
