internal static ExtMoveArrayWrapper generate_castling(
CastlingRight Cr,
bool Checks,
bool Chess960,
Position pos,
ExtMoveArrayWrapper moveList,
ColorT us,
CheckInfo ci)
{
var KingSide = (Cr == CastlingRight.WHITE_OO || Cr == CastlingRight.BLACK_OO);
if (pos.castling_impeded(Cr) || !pos.can_castle(Cr))
{
return moveList;
}
// After castling, the rook and king final positions are the same in Chess960
// as they would be in standard chess.
var kfrom = pos.square(PieceType.KING, us);
var rfrom = pos.castling_rook_square(Cr);
var kto = Square.relative_square(us, KingSide ? Square.SQ_G1 : Square.SQ_C1);
var enemies = pos.pieces_Ct(Color.opposite(us));
Debug.Assert(pos.checkers() == 0);
var K = Chess960 ? kto > kfrom ? Square.DELTA_W : Square.DELTA_E : KingSide ? Square.DELTA_W : Square.DELTA_E;
for (var s = kto; s != kfrom; s += K)
{
if ((pos.attackers_to(s) & enemies) != 0)
{
return moveList;
}
}
// Because we generate only legal castling moves we need to verify that
// when moving the castling rook we do not discover some hidden checker.
// For instance an enemy queen in SQ_A1 when castling rook is in SQ_B1.
if (Chess960
&& ((Utils.attacks_bb_PtSBb(PieceType.ROOK, kto, Bitboard.XorWithSquare(pos.pieces(), rfrom))
& pos.pieces_CtPtPt(Color.opposite(us), PieceType.ROOK, PieceType.QUEEN)))!= 0)
{
return moveList;
}
var m = Move.make(MoveType.CASTLING, kfrom, rfrom);
if (Checks && !pos.gives_check(m, ci))
{
return moveList;
}
moveList.Add(m);
return moveList;
}
// evaluate_pieces() assigns bonuses and penalties to the pieces of a given color
private static ScoreT evaluate_pieces(
PieceTypeT pieceType,
ColorT Us,
bool DoTrace,
Position pos,
EvalInfo ei,
ScoreT[] mobility,
BitboardT[] mobilityArea)
{
int Pt = pieceType;
if (Pt == PieceType.KING)
{
return Score.SCORE_ZERO;
}
var score = Score.SCORE_ZERO;
var NextPt = (Us == Color.WHITE ? pieceType : pieceType + 1);
var Them = (Us == Color.WHITE ? Color.BLACK : Color.WHITE);
ei.attackedBy[Us, Pt] = Bitboard.Create(0);
for(var idx=0; idx<16;idx++)
{
var s = pos.square(pieceType, Us, idx);
if (s == Square.SQ_NONE)
{
break;
}
// Find attacked squares, including x-ray attacks for bishops and rooks
var b = Pt == PieceType.BISHOP
? Utils.attacks_bb_PtSBb(PieceType.BISHOP, s, pos.pieces() ^ pos.pieces_CtPt(Us, PieceType.QUEEN))
: Pt == PieceType.ROOK
? Utils.attacks_bb_PtSBb(
PieceType.ROOK,
s,
pos.pieces() ^ pos.pieces_CtPtPt(Us, PieceType.ROOK, PieceType.QUEEN))
: pos.attacks_from_PtS(pieceType, s);
if (Bitboard.AndWithSquare(ei.pinnedPieces[Us], s)!=0)
{
b &= Utils.LineBB[pos.square(PieceType.KING, Us), s];
}
ei.attackedBy[Us, PieceType.ALL_PIECES] |= ei.attackedBy[Us, Pt] |= b;
if ((b & ei.kingRing[Them])!=0)
{
ei.kingAttackersCount[Us]++;
ei.kingAttackersWeight[Us] += KingAttackWeights[Pt];
var bb = b & ei.attackedBy[Them, PieceType.KING];
if (bb!=0)
{
ei.kingAdjacentZoneAttacksCount[Us] += Bitcount.popcount_Max15(bb);
}
}
if (Pt == PieceType.QUEEN)
{
b &=
~(ei.attackedBy[Them, PieceType.KNIGHT] | ei.attackedBy[Them, PieceType.BISHOP]
| ei.attackedBy[Them, PieceType.ROOK]);
}
var mob = Pt == PieceType.QUEEN
? Bitcount.popcount_Full(b & mobilityArea[Us])
: Bitcount.popcount_Max15(b & mobilityArea[Us]);
mobility[Us] += MobilityBonus[Pt][mob];
if (Pt == PieceType.BISHOP || Pt == PieceType.KNIGHT)
{
// Bonus for outpost square
if (Rank.relative_rank_CtSt(Us, s) >= Rank.RANK_4 && Rank.relative_rank_CtSt(Us, s) <= Rank.RANK_6
&& (pos.pieces_CtPt(Them, PieceType.PAWN) & Utils.pawn_attack_span(Us, s))==0)
{
score +=
Outpost[Pt == PieceType.BISHOP ? 1 : 0][Bitboard.AndWithSquare(ei.attackedBy[Us, PieceType.PAWN], s)!=0 ? 1 : 0];
}
// Bonus when behind a pawn
if (Rank.relative_rank_CtSt(Us, s) < Rank.RANK_5 && Bitboard.AndWithSquare(pos.pieces_Pt(PieceType.PAWN), (s + Square.pawn_push(Us)))!=0)
{
score += MinorBehindPawn;
}
// Penalty for pawns on same color square of bishop
if (Pt == PieceType.BISHOP)
{
score -= BishopPawns*ei.pi.pawns_on_same_color_squares(Us, s);
}
// An important Chess960 pattern: A cornered bishop blocked by a friendly
// pawn diagonally in front of it is a very serious problem, especially
// when that pawn is also blocked.
if (Pt == PieceType.BISHOP && pos.is_chess960()
&& (s == Square.relative_square(Us, Square.SQ_A1) || s == Square.relative_square(Us, Square.SQ_H1)))
{
var d = Square.pawn_push(Us) + (Square.file_of(s) == File.FILE_A ? Square.DELTA_E : Square.DELTA_W);
if (pos.piece_on(s + d) == Piece.make_piece(Us, PieceType.PAWN))
{
score -= !pos.empty(s + d + Square.pawn_push(Us))
? TrappedBishopA1H1*4
: pos.piece_on(s + d + d) == Piece.make_piece(Us, PieceType.PAWN)
? TrappedBishopA1H1*2
: TrappedBishopA1H1;
}
}
}
if (Pt == PieceType.ROOK)
{
// Bonus for aligning with enemy pawns on the same rank/file
if (Rank.relative_rank_CtSt(Us, s) >= Rank.RANK_5)
{
var alignedPawns = pos.pieces_CtPt(Them, PieceType.PAWN) & Utils.PseudoAttacks[PieceType.ROOK, s];
if (alignedPawns!=0)
{
score += Bitcount.popcount_Max15(alignedPawns)*RookOnPawn;
}
}
// Bonus when on an open or semi-open file
if (ei.pi.semiopen_file(Us, Square.file_of(s)) != 0)
{
score += ei.pi.semiopen_file(Them, Square.file_of(s)) != 0 ? RookOnOpenFile : RookOnSemiOpenFile;
}
// Penalize when trapped by the king, even more if king cannot castle
if (mob <= 3 && 0 == ei.pi.semiopen_file(Us, Square.file_of(s)))
{
var ksq = pos.square(PieceType.KING, Us);
if (((Square.file_of(ksq) < File.FILE_E) == (Square.file_of(s) < Square.file_of(ksq)))
&& (Square.rank_of(ksq) == Square.rank_of(s) || Rank.relative_rank_CtSt(Us, ksq) == Rank.RANK_1)
&& 0 == ei.pi.semiopen_side(Us, Square.file_of(ksq), Square.file_of(s) < Square.file_of(ksq)))
{
score -= (TrappedRook - Score.make_score(mob*22, 0))*(1 + (pos.can_castle(Us) == 0 ? 1 : 0));
}
}
}
}
if (DoTrace)
{
add_IdxCtSt(Pt, Us, score);
}
// Recursively call evaluate_pieces() of next piece type until KING excluded
return score - evaluate_pieces(NextPt, Them, DoTrace, pos, ei, mobility, mobilityArea);
}
