/*
* A valid move for a knight is 1 square along either the X or Y axes, and
* 2 squares along the axis that wasn't moved 1 along. Every combination of
* adding/subtracting 1 or 2 points along an axis and doing the opposite
* mathematical operation to the other number is accounted for.
*/
/*public override BoardSquare[] getMoveableSquares(short xCoord, short yCoord)
{
possibleMoves[0] = new BoardSquare(xCoord + 2, yCoord + 1);
possibleMoves[1] = new BoardSquare(xCoord + 2, yCoord - 1);
possibleMoves[2] = new BoardSquare(xCoord - 2, yCoord + 1);
possibleMoves[3] = new BoardSquare(xCoord - 2, yCoord - 1);
possibleMoves[4] = new BoardSquare(xCoord - 1, yCoord + 2);
possibleMoves[5] = new BoardSquare(xCoord - 1, yCoord - 2);
possibleMoves[6] = new BoardSquare(xCoord + 1, yCoord + 2);
possibleMoves[7] = new BoardSquare(xCoord + 1, yCoord - 2);
return possibleMoves;
}*/
/*
* Get the bitboard form of all the valid moves for the given board and start position.
*/
internal override BitBoard getAllMoves(Board b, short xCoord, short yCoord)
{
BitBoard bit = BitBoard.Empty;
BoardSquare ownKing = b.GetKingLocation(this.colour == Piece.NOTATION_W ? Game.Sides.white : Game.Sides.black);
BoardSquare potentialPinner = b.ExtrapolateAttack(xCoord, yCoord, (short)ownKing.X, (short)ownKing.Y);
// if piece is not pinned
if (potentialPinner == BoardSquare.Empty)
{
if (b.isValidSquare(xCoord+2, yCoord+1) &&
(b[yCoord + 1, xCoord + 2] == null || b[yCoord + 1, xCoord + 2].Colour != this.colour))
bit.AddPosition(xCoord + 2, yCoord + 1);
if (b.isValidSquare(xCoord + 1, yCoord + 2) &&
(b[yCoord + 2, xCoord + 1] == null || b[yCoord + 2, xCoord + 1].Colour != this.colour))
bit.AddPosition(xCoord + 1, yCoord + 2);
if (b.isValidSquare(xCoord - 2, yCoord - 1) &&
(b[yCoord - 1, xCoord - 2] == null || b[yCoord - 1, xCoord - 2].Colour != this.colour))
bit.AddPosition(xCoord - 2, yCoord - 1);
if (b.isValidSquare(xCoord - 1, yCoord - 2) &&
(b[yCoord - 2, xCoord - 1] == null || b[yCoord - 2, xCoord - 1].Colour != this.colour))
bit.AddPosition(xCoord - 1, yCoord - 2);
if (b.isValidSquare(xCoord + 2, yCoord - 1) &&
(b[yCoord - 1, xCoord + 2] == null || b[yCoord - 1, xCoord + 2].Colour != this.colour))
bit.AddPosition(xCoord +2, yCoord - 1);
if (b.isValidSquare(xCoord + 1, yCoord - 2) &&
(b[yCoord - 2, xCoord + 1] == null || b[yCoord - 2, xCoord + 1].Colour != this.colour))
bit.AddPosition(xCoord + 1, yCoord - 2);
if (b.isValidSquare(xCoord - 2, yCoord + 1) &&
(b[yCoord + 1, xCoord - 2] == null || b[yCoord + 1, xCoord - 2].Colour != this.colour))
bit.AddPosition(xCoord - 2, yCoord + 1);
if (b.isValidSquare(xCoord - 1, yCoord + 2) &&
(b[yCoord + 2, xCoord - 1] == null || b[yCoord + 2, xCoord - 1].Colour != this.colour))
bit.AddPosition(xCoord - 1, yCoord + 2);
}
return bit;
}
/*
* Get the bitboard form of all the valid moves for the given board and start position.
*/
internal override BitBoard getAllMoves(Board b, short xCoord, short yCoord)
{
BitBoard bit = BitBoard.Empty;
BoardSquare ownKing = b.GetKingLocation(this.colour == Piece.NOTATION_W ? Game.Sides.white : Game.Sides.black);
BoardSquare potentialPinner = b.ExtrapolateAttack(xCoord, yCoord, (short)ownKing.X, (short)ownKing.Y);
int sign = this.colour == Piece.NOTATION_W ? 1 : -1;
// if piece is not pinned, check normal movement
if (potentialPinner == BoardSquare.Empty || potentialPinner.X == xCoord)
{
if (b[yCoord + sign, xCoord] == null) {
bit.AddPosition(xCoord, yCoord + sign);
if (yCoord == this.GetStartRow() && b[yCoord + sign * 2, xCoord] == null)
bit.AddPosition(xCoord, yCoord + sign * 2);
}
}
// Check for attacks on either side
if (potentialPinner == BoardSquare.Empty || new BoardSquare(xCoord + 1, yCoord + sign).IsBetweenPoints(potentialPinner, ownKing))
{
if (b.isValidSquare(xCoord + 1, yCoord + sign) &&
(b[yCoord + sign, xCoord + 1] == null ? MayEnPassant(b, xCoord, yCoord, (short)(xCoord + 1), (short)(yCoord + sign)) : b[yCoord + sign, xCoord + 1].Colour != this.colour))
bit.AddPosition(xCoord + 1, yCoord + sign);
}
if (potentialPinner == BoardSquare.Empty || new BoardSquare(xCoord - 1, yCoord + sign).IsBetweenPoints(potentialPinner, ownKing))
{
if (b.isValidSquare(xCoord - 1, yCoord + sign) &&
(b[yCoord + sign, xCoord - 1] == null ? MayEnPassant(b, xCoord, yCoord, (short)(xCoord - 1), (short)(yCoord + sign)) : b[yCoord + sign, xCoord - 1].Colour != this.colour))
bit.AddPosition(xCoord - 1, yCoord + sign);
}
return bit;
}
