private static void GenerateQuietMoves(this IPosition pos, MoveList moves, Emgf flags)
{
var currentSide = pos.State.SideToMove;
var up = currentSide == PlayerExtensions.White ? EDirection.North : EDirection.South;
var notOccupied = ~pos.Pieces();
var pushed = (pos.Pieces(EPieceType.Pawn, currentSide) & ~currentSide.Rank7()).Shift(up) & notOccupied;
pos.AddPawnMoves(moves, pushed, currentSide.PawnPushDistance(), EMoveType.Quiet, flags);
pushed &= currentSide.Rank3();
pos.AddPawnMoves(moves, pushed.Shift(up) & notOccupied, currentSide.PawnDoublePushDistance(), EMoveType.Doublepush, flags);
pos.AddMoves(moves, notOccupied, flags);
if (pos.InCheck)
{
return;
}
for (var castleType = ECastleling.Short; castleType < ECastleling.CastleNb; castleType++)
{
if (pos.CanCastle(castleType))
{
pos.AddCastleMove(moves, pos.GetKingCastleFrom(currentSide, castleType), castleType.GetKingCastleTo(currentSide), flags);
}
}
}
public static MoveList GenerateMoves(this IPosition pos, Emgf flags = Emgf.Legalmoves, bool useCache = true, bool force = false)
{
pos.State.Pinned = flags.HasFlagFast(Emgf.Legalmoves)
? pos.GetPinnedPieces(pos.GetPieceSquare(EPieceType.King, pos.State.SideToMove), pos.State.SideToMove)
: BitBoards.EmptyBitBoard;
var moves = new MoveList();
pos.GenerateCapturesAndPromotions(moves, flags);
pos.GenerateQuietMoves(moves, flags);
return(moves);
}
public static bool HasFlagFast(this Emgf value, Emgf flag) => (value & flag) != 0;
private static void GenerateCapturesAndPromotions(this IPosition pos, MoveList moves, Emgf flags)
{
var currentSide = pos.State.SideToMove;
var them = ~currentSide;
var occupiedByThem = pos.OccupiedBySide[them.Side];
var(northEast, northWest) = currentSide.GetPawnAttackDirections();
var pawns = pos.Pieces(EPieceType.Pawn, currentSide);
pos.AddPawnMoves(moves, currentSide.PawnPush(pawns & currentSide.Rank7()) & ~pos.Pieces(), currentSide.PawnPushDistance(), EMoveType.Quiet, flags);
pos.AddPawnMoves(moves, pawns.Shift(northEast) & occupiedByThem, currentSide.PawnWestAttackDistance(), EMoveType.Capture, flags);
pos.AddPawnMoves(moves, pawns.Shift(northWest) & occupiedByThem, currentSide.PawnEastAttackDistance(), EMoveType.Capture, flags);
if (pos.State.EnPassantSquare != ESquare.none)
{
pos.AddPawnMoves(moves, pawns.Shift(northEast) & pos.State.EnPassantSquare, currentSide.PawnWestAttackDistance(), EMoveType.Epcapture, flags);
pos.AddPawnMoves(moves, pawns.Shift(northWest) & pos.State.EnPassantSquare, currentSide.PawnEastAttackDistance(), EMoveType.Epcapture, flags);
}
pos.AddMoves(moves, occupiedByThem, flags);
}
private static void AddMove(this IPosition pos, MoveList moves, Piece piece, Square from, Square to, Piece promoted, Emgf flags, EMoveType type = EMoveType.Quiet)
{
Move move;
if (type.HasFlagFast(EMoveType.Capture))
{
move = new Move(piece, pos.GetPiece(to), from, to, type, promoted);
}
else if (type.HasFlagFast(EMoveType.Epcapture))
{
move = new Move(piece, EPieceType.Pawn.MakePiece(~pos.State.SideToMove), from, to, type, promoted);
}
else
{
move = new Move(piece, from, to, type, promoted);
}
// check if move is actual a legal move if the flag is enabled
if (flags.HasFlagFast(Emgf.Legalmoves) && !pos.IsLegal(move, piece, from, type))
{
return;
}
moves.Add(move);
}
private static void AddCastleMove(this IPosition pos, MoveList moves, Square from, Square to, Emgf flags) => pos.AddMove(moves, EPieceType.King.MakePiece(pos.State.SideToMove), from, to, PieceExtensions.EmptyPiece, flags, EMoveType.Castle);
private static void AddPawnMoves(this IPosition pos, MoveList moves, BitBoard targetSquares, Direction direction, EMoveType type, Emgf flags)
{
if (targetSquares.Empty())
{
return;
}
var stm = pos.State.SideToMove;
var piece = EPieceType.Pawn.MakePiece(stm);
var promotionRank = stm.PromotionRank();
var promotionSquares = targetSquares & promotionRank;
var nonPromotionSquares = targetSquares & ~promotionRank;
while (nonPromotionSquares)
{
var to = nonPromotionSquares.Lsb();
var from = to - direction;
pos.AddMove(moves, piece, from, to, PieceExtensions.EmptyPiece, flags, type);
BitBoards.ResetLsb(ref nonPromotionSquares);
}
type |= EMoveType.Promotion;
if (flags.HasFlagFast(Emgf.Queenpromotion))
{
var sqTo = promotionSquares.Lsb();
var sqFrom = sqTo - direction;
pos.AddMove(moves, piece, sqFrom, sqTo, EPieceType.Queen.MakePiece(stm), flags, type);
BitBoards.ResetLsb(ref promotionSquares);
}
else
{
while (promotionSquares)
{
var sqTo = promotionSquares.Lsb();
var sqFrom = sqTo - direction;
for (var promotedPiece = EPieceType.Queen; promotedPiece >= EPieceType.Knight; promotedPiece--)
{
pos.AddMove(moves, piece, sqFrom, sqTo, promotedPiece.MakePiece(stm), flags, type);
}
BitBoards.ResetLsb(ref promotionSquares);
}
}
}
private static void AddMoves(this IPosition pos, MoveList moves, Piece piece, Square from, BitBoard attacks, Emgf flags)
{
var target = pos.Pieces(~pos.State.SideToMove) & attacks;
while (target)
{
var to = target.Lsb();
pos.AddMove(moves, piece, from, to, PieceExtensions.EmptyPiece, flags, EMoveType.Capture);
BitBoards.ResetLsb(ref target);
}
target = ~pos.Pieces() & attacks;
while (target)
{
var to = target.Lsb();
pos.AddMove(moves, piece, from, to, PieceExtensions.EmptyPiece, flags);
BitBoards.ResetLsb(ref target);
}
}
/// <summary>
/// Iterates through the piece types and generates moves based on their attacks.
/// It does not contain any checks for moves that are invalid, as the leaf methods
/// contains implicit denial of move generation if the target bitboard is empty.
/// </summary>
/// <param name="moves">The move list to add potential moves to.</param>
/// <param name="targetSquares">The target squares to move to</param>
private static void AddMoves(this IPosition pos, MoveList moves, BitBoard targetSquares, Emgf flags)
{
var c = pos.State.SideToMove;
var occupied = pos.Pieces();
for (var pt = EPieceType.Knight; pt <= EPieceType.King; ++pt)
{
var pc = pt.MakePiece(c);
var pieces = pos.Pieces(pc);
while (pieces)
{
var from = pieces.Lsb();
pos.AddMoves(moves, pc, from, from.GetAttacks(pt, occupied) & targetSquares, flags);
BitBoards.ResetLsb(ref pieces);
}
}
}
