// Note that this doesn't check if a pawn can be taken en passant
public bool IsAttacked(int defenderIx, Color defenderColor)
{
// check in roughly descending order of power
// rook and queen
var potentialRookCaptures = RookMoveTable.GetMoves(defenderIx, GetOccupied());
if ((potentialRookCaptures & GetPieceBitboard(defenderColor.Other(), PieceType.Rook)) > 0)
{
return(true);
}
if ((potentialRookCaptures & GetPieceBitboard(defenderColor.Other(), PieceType.Queen)) > 0)
{
return(true);
}
// bishop and queen
var potentialBishopCaptures = BishopMoveTable.GetMoves(defenderIx, GetOccupied());
if ((potentialBishopCaptures & GetPieceBitboard(defenderColor.Other(), PieceType.Bishop)) > 0)
{
return(true);
}
if ((potentialBishopCaptures & GetPieceBitboard(defenderColor.Other(), PieceType.Queen)) > 0)
{
return(true);
}
var potentialKnightCaptures = KnightMoveTable.GetMoves(defenderIx);
if ((potentialKnightCaptures & GetPieceBitboard(defenderColor.Other(), PieceType.Knight)) > 0)
{
return(true);
}
var potentialKingCaptures = KingMoveTable.GetMoves(defenderIx);
if ((potentialKingCaptures & GetPieceBitboard(defenderColor.Other(), PieceType.King)) > 0)
{
return(true);
}
var potentialPawnCaptures = PawnCaptureMoveTable.GetMoves(defenderIx, defenderColor);
if ((potentialPawnCaptures & GetPieceBitboard(defenderColor.Other(), PieceType.Pawn)) > 0)
{
return(true);
}
// we checked all possible attacks by all possible piece types
return(false);
}
private void GeneratePawnMoves(List <Move> moves, Position position, ulong sourceSquares)
{
var color = position.SideToMove;
ulong promotionSourceSquares = sourceSquares & PawnPromotionSourceTable[(int)color];
ulong nonPromotionSourceSquares = sourceSquares & ~promotionSourceSquares;
while (Bits.TryPopLsb(ref nonPromotionSourceSquares, out var sourceIx))
{
// TODO: separate out normal moves from double moves. Normal moves use normal lookup table, double moves use magic lookup table
var quiets = PawnQuietMoveTable.GetMoves(sourceIx, color);
quiets &= ~position.GetOccupied();
var doubles = PawnDoubleMoveTable.GetMoves(sourceIx, position.GetOccupied(), color);
// note: no need to mask double moves; the move table already takes care of that
var captures = PawnCaptureMoveTable.GetMoves(sourceIx, color);
var normalCaptures = captures & position.GetOccupied(color.Other());
var enPassantCaptures = captures & position.EnPassant;
while (Bits.TryPopLsb(ref quiets, out var dstIx))
{
moves.Add(new Move(MoveType.Normal | MoveType.Quiet, sourceIx, dstIx));
}
while (Bits.TryPopLsb(ref doubles, out var dstIx))
{
moves.Add(new Move(MoveType.DoubleMove | MoveType.Quiet, sourceIx, dstIx));
}
while (Bits.TryPopLsb(ref normalCaptures, out var dstIx))
{
moves.Add(new Move(MoveType.Normal | MoveType.Capture, sourceIx, dstIx));
}
while (Bits.TryPopLsb(ref enPassantCaptures, out var dstIx))
{
moves.Add(new Move(MoveType.EnPassant | MoveType.Capture, sourceIx, dstIx));
}
}
while (Bits.TryPopLsb(ref promotionSourceSquares, out var sourceIx))
{
var quiets = PawnQuietMoveTable.GetMoves(sourceIx, color);
quiets &= ~position.GetOccupied();
var captures = PawnCaptureMoveTable.GetMoves(sourceIx, color);
captures &= position.GetOccupied(color.Other());
foreach (var piece in new[] { PieceType.Queen, PieceType.Knight, PieceType.Rook, PieceType.Bishop })
{
var quietsTmp = quiets;
while (Bits.TryPopLsb(ref quietsTmp, out var dstIx))
{
moves.Add(new Move(MoveType.Promotion | MoveType.Quiet, sourceIx, dstIx, piece));
}
var capturesTmp = captures;
while (Bits.TryPopLsb(ref capturesTmp, out var dstIx))
{
moves.Add(new Move(MoveType.Promotion | MoveType.Capture, sourceIx, dstIx, piece));
}
}
}
}