public BoardState(Piece[] currentBoardPosition, UInt64[] pieceToBitboard,
CastlingAndEnPassantRights castlingAndEnPassant, int sideToMove, UInt64 zobristHash)
{
CurrentBoardPosition = currentBoardPosition;
PieceToBitboard = pieceToBitboard;
CastlingAndEnPassant = castlingAndEnPassant;
SideToMove = sideToMove;
ZobristHash = zobristHash;
}
public Move(sbyte side, byte startPosition, byte endPosition, Piece promotedPiece)
{
Side = side;
StartPosition = startPosition;
EndPosition = endPosition;
PromotedPiece = promotedPiece;
HashKey = (UInt16)((StartPosition << 8) ^ EndPosition);
}
/// <summary>
/// Sets the move data by parsing in a long algebraic notation as described in
/// this document: http://wbec-ridderkerk.nl/html/UCIProtocol.html (see Move format).
/// </summary>
/// <param name="longAlgebraicNotationMove">The move string, e.g. a8a5.</param>
public void Set(sbyte side, string longAlgebraicNotationMove)
{
Side = side;
string start = longAlgebraicNotationMove.Substring(0, 2);
StartPosition = Constants.AlgebraicToIntegerIndex[start];
string end = longAlgebraicNotationMove.Substring(2, 2);
EndPosition = Constants.AlgebraicToIntegerIndex[end];
// if length is greater than 5, e.g. b7b8q, then it means a pawn promotion.
if (longAlgebraicNotationMove.Length == 5)
{
IsPawnPromotion = true;
string promotedPiece = longAlgebraicNotationMove.Substring(4, 1);
switch (promotedPiece)
{
case "q": PromotedPiece = (Side == Engine.Side.Black) ? Piece.BlackQueen : Piece.WhiteQueen;
break;
case "r": PromotedPiece = (Side == Engine.Side.Black) ? Piece.BlackRook : Piece.WhiteRook;
break;
case "b": PromotedPiece = (Side == Engine.Side.Black) ? Piece.BlackBishop : Piece.WhiteBishop;
break;
case "n": PromotedPiece = (Side == Engine.Side.Black) ? Piece.BlackKnight : Piece.WhiteKnight;
break;
case "p": PromotedPiece = (Side == Engine.Side.Black) ? Piece.BlackPawn : Piece.WhitePawn;
break;
default:
throw new ArgumentException("Invalid promoted piece.");
}
}
else
{
IsPawnPromotion = false;
PromotedPiece = Piece.None;
}
HashKey = (UInt16)((StartPosition << 8) ^ EndPosition);
}
private void GenerateMoves(Piece piece, UInt16[] moves, UInt16[] quietMoves, ref int movesCount, ref int quietMovesCount)
{
UInt64 pieceBitboard = PieceToBitboard[piece.Index];
byte[] startPositions = BitHelper.GetSetBitIndexes2(pieceBitboard);
UInt64 ownBoard = GetBoardForSide(sideToMove);
for (int i = 0; i < startPositions.Length; i++)
{
UInt64 validMoves = GetValidMovesForPiece(piece, startPositions[i], ownBoard);
ExtractPseudoLegalMoves(validMoves, startPositions[i], moves, quietMoves, ref movesCount, ref quietMovesCount);
}
}
private void ReplacePawnWithPromotedPiece(Piece promotedPiece, Piece pawnToReplace, byte promotionSquare)
{
UInt64 pawnQueenMask = (UInt64)1 << promotionSquare;
PieceToBitboard[pawnToReplace.Index] = PieceToBitboard[pawnToReplace.Index] ^ pawnQueenMask;
PieceToBitboard[promotedPiece.Index] = PieceToBitboard[promotedPiece.Index] | pawnQueenMask;
squareToPiece[promotionSquare] = promotedPiece;
// update zobrist hash: XOR out the pawn and XOR in the promoted piece
ZobristHash ^= _zobristKeys[pawnToReplace.ZobristStartingIndex + promotionSquare];
ZobristHash ^= _zobristKeys[promotedPiece.ZobristStartingIndex + promotionSquare];
}
// updates: 1. piece to BB for that piece, 2. zobrist, 3. square to piece array.
private void JustMoveThePiece(Piece movingPiece, byte fromSquare, byte toSquare)
{
/* Update KDFs */
// KDF 1: piece to BB array
UInt64 startEndBitboard = (((UInt64)1) << fromSquare) ^ (((UInt64)1) << toSquare);
PieceToBitboard[movingPiece.Index] ^= startEndBitboard;
// KDF 2: zobrist hash
// update zobrist hash (http://stackoverflow.com/questions/10067514/correctly-implementing-zobrist-hashing)
// remove starting position of moving piece from hash (i.e. XOR out)
ZobristHash ^= _zobristKeys[movingPiece.ZobristStartingIndex + fromSquare];
// include ending position of moving piece into hash (i.e. XOR in)
ZobristHash ^= _zobristKeys[movingPiece.ZobristStartingIndex + toSquare];
// KDF 3: square to piece array
// square to piece array:
squareToPiece[fromSquare] = Piece.None;
squareToPiece[toSquare] = movingPiece;
}
private bool IsSameSide(Piece piece, int side)
{
return ((piece.Number * side) > 0);
}
private UInt64 GetValidMovesForPiece(Piece piece, int square, UInt64 ownBoard)
{
// gets all the spots that this piece can move to assuming that this is the only piece on the board.
switch (piece.Number)
{
case Constants.BlackKingNumber:
case Constants.WhiteKingNumber:
return GetValidMovesForKing(square, ownBoard);
case Constants.BlackKnightNumber:
case Constants.WhiteKnightNumber:
return GetValidMovesForKnight(square, ownBoard);
case Constants.WhitePawnNumber:
return GetValidMovesForWhitePawn(square);
case Constants.BlackPawnNumber:
return GetValidMovesForBlackPawn(square);
case Constants.BlackRookNumber:
case Constants.WhiteRookNumber:
return GetValidMovesForRook(square, ownBoard);
case Constants.BlackBishopNumber:
case Constants.WhiteBishopNumber:
return GetValidMovesForBishop(square, ownBoard);
case Constants.BlackQueenNumber:
case Constants.WhiteQueenNumber:
return GetValidMovesForQueen(square, ownBoard);
default:
throw new ArgumentException("Invalid piece.");
}
}