/// Mate with KX vs K. This function is used to evaluate positions with
/// king and plenty of material vs a lone king. It simply gives the
/// attacking side a bonus for driving the defending king towards the edge
/// of the board, and for keeping the distance between the two kings small.
public Value KXK(Position pos)
{
Debug.Assert(verify_material(pos, weakSide, ValueS.VALUE_ZERO, 0));
Debug.Assert(0 == pos.checkers()); // Eval is never called when in check
// Stalemate detection with lone king
if (pos.side_to_move() == weakSide && 0 == (new MoveList(pos, GenTypeS.LEGAL)).size())
{
return(ValueS.VALUE_DRAW);
}
Square winnerKSq = pos.king_square(strongSide);
Square loserKSq = pos.king_square(weakSide);
Value result = pos.non_pawn_material(strongSide)
+ pos.count(strongSide, PieceTypeS.PAWN) * ValueS.PawnValueEg
+ PushToEdges[loserKSq]
+ PushClose[BitBoard.square_distance(winnerKSq, loserKSq)];
if (pos.count(strongSide, PieceTypeS.QUEEN) != 0 ||
pos.count(strongSide, PieceTypeS.ROOK) != 0 ||
(pos.count(strongSide, PieceTypeS.BISHOP) != 0 && pos.count(strongSide, PieceTypeS.KNIGHT) != 0) ||
pos.bishop_pair(strongSide))
{
result += ValueS.VALUE_KNOWN_WIN;
}
return(strongSide == pos.side_to_move() ? result : -result);
}
/// TranspositionTable::resize() sets the size of the transposition table,
/// measured in megabytes. Transposition table consists of a power of 2 number
/// of clusters and each cluster consists of ClusterSize number of TTEntry.
public void resize(UInt64 mbSize)
{
Debug.Assert(BitBoard.msb((mbSize << 20) / 16) < 32);
uint size = ClusterSize << BitBoard.msb((mbSize << 20) / 64);
if (hashMask == size - ClusterSize)
{
return;
}
hashMask = size - ClusterSize;
try
{
table = new TTEntry[size];
for (int i = 0; i < table.Length; i++)
{
table[i] = new TTEntry();
}
}
catch (Exception)
{
System.Console.Error.WriteLine("Failed to allocate " + mbSize + "MB for transposition table.");
throw new Exception("Failed to allocate " + mbSize + "MB for transposition table.");
}
}
/// Entry::shelter_storm() calculates shelter and storm penalties for the file
/// the king is on, as well as the two adjacent files.
public Value shelter_storm(Position pos, Square ksq, Color Us)
{
Color Them = (Us == ColorS.WHITE ? ColorS.BLACK : ColorS.WHITE);
Value safety = Pawns.MaxSafetyBonus;
Bitboard b = pos.pieces_piecetype(PieceTypeS.PAWN) & (BitBoard.in_front_bb(Us, Types.rank_of(ksq)) | BitBoard.rank_bb_square(ksq));
Bitboard ourPawns = b & pos.pieces_color(Us);
Bitboard theirPawns = b & pos.pieces_color(Them);
Rank rkUs, rkThem;
File kf = Math.Max(FileS.FILE_B, Math.Min(FileS.FILE_G, Types.file_of(ksq)));
for (File f = kf - 1; f <= kf + 1; ++f)
{
b = ourPawns & BitBoard.file_bb_file(f);
rkUs = b != 0 ? Types.relative_rank_square(Us, BitBoard.backmost_sq(Us, b)) : RankS.RANK_1;
b = theirPawns & BitBoard.file_bb_file(f);
rkThem = b != 0 ? Types.relative_rank_square(Us, BitBoard.frontmost_sq(Them, b)) : RankS.RANK_1;
if ((MiddleEdges & BitBoard.SquareBB[Types.make_square(f, rkThem)]) != 0 &&
Types.file_of(ksq) == f &&
Types.relative_rank_square(Us, ksq) == rkThem - 1)
{
safety += 200;
}
else
{
safety -= ShelterWeakness[rkUs]
+ StormDanger[rkUs == RankS.RANK_1 ? 0 : rkThem == rkUs + 1 ? 2 : 1][rkThem];
}
}
return(safety);
}
public KPKPosition(uint idx)
{
wksq = (Square)((idx >> 0) & 0x3F);
bksq = (Square)((idx >> 6) & 0x3F);
us = (Color)((idx >> 12) & 0x01);
psq = Types.make_square((File)((idx >> 13) & 0x03), (Rank)(RankS.RANK_7 - (idx >> 15)));
result = Result.UNKNOWN;
// Check if two pieces are on the same square or if a king can be captured
if (BitBoard.square_distance(wksq, bksq) <= 1 ||
wksq == psq ||
bksq == psq ||
(us == ColorS.WHITE && (BitBoard.StepAttacksBB[PieceTypeS.PAWN][psq] & BitBoard.SquareBB[bksq]) != 0))
{
result = Result.INVALID;
}
else if (us == ColorS.WHITE)
{
// Immediate win if pawn can be promoted without getting captured
if (Types.rank_of(psq) == RankS.RANK_7 &&
wksq != psq + SquareS.DELTA_N &&
(BitBoard.square_distance(bksq, psq + SquareS.DELTA_N) > 1 ||
(BitBoard.StepAttacksBB[PieceTypeS.KING][wksq] & BitBoard.SquareBB[psq + SquareS.DELTA_N]) != 0))
{
result = Result.WIN;
}
}
// Immediate draw if it is a stalemate or a king captures undefended pawn
else if (0 == (BitBoard.StepAttacksBB[PieceTypeS.KING][bksq] & ~(BitBoard.StepAttacksBB[PieceTypeS.KING][wksq] | BitBoard.StepAttacksBB[PieceTypeS.PAWN][psq])) ||
(BitBoard.StepAttacksBB[PieceTypeS.KING][bksq] & BitBoard.SquareBB[psq] & ~BitBoard.StepAttacksBB[PieceTypeS.KING][wksq]) != 0)
{
result = Result.DRAW;
}
}
// init_eval_info() initializes king bitboards for given color adding
// pawn attacks. To be done at the beginning of the evaluation.
public static void init_eval_info(Position pos, EvalInfo ei, Color Us)
{
Color Them = (Us == ColorS.WHITE ? ColorS.BLACK : ColorS.WHITE);
Square Down = (Us == ColorS.WHITE ? SquareS.DELTA_S : SquareS.DELTA_N);
ei.pinnedPieces[Us] = pos.pinned_pieces(Us);
Bitboard b = ei.attackedBy[Them][PieceTypeS.KING] = pos.attacks_from_square_piecetype(pos.king_square(Them), PieceTypeS.KING);
ei.attackedBy[Us][PieceTypeS.ALL_PIECES] = ei.attackedBy[Us][PieceTypeS.PAWN] = ei.pi.pawn_attacks(Us);
// Init king safety tables only if we are going to use them
if (pos.count(Us, PieceTypeS.QUEEN) != 0 && pos.non_pawn_material(Us) > ValueS.QueenValueMg + ValueS.PawnValueMg)
{
ei.kingRing[Them] = b | BitBoard.shift_bb(b, Down);
b &= ei.attackedBy[Us][PieceTypeS.PAWN];
ei.kingAttackersCount[Us] = (b != 0) ? Bitcount.popcount_Max15(b) : 0;
ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
}
else
{
ei.kingRing[Them] = 0;
ei.kingAttackersCount[Us] = 0;
}
}
// evaluate_outposts() evaluates bishop and knight outpost squares
public static Score evaluate_outposts(Position pos, EvalInfo ei, Square s, PieceType Pt, Color Us)
{
Color Them = (Us == ColorS.WHITE ? ColorS.BLACK : ColorS.WHITE);
Debug.Assert(Pt == PieceTypeS.BISHOP || Pt == PieceTypeS.KNIGHT);
// Initial bonus based on square
Value bonus = Outpost[Pt == PieceTypeS.BISHOP ? 1 : 0][Types.relative_square(Us, s)];
// Increase bonus if supported by pawn, especially if the opponent has
// no minor piece which can trade with the outpost piece.
if (bonus != 0 && (ei.attackedBy[Us][PieceTypeS.PAWN] & BitBoard.SquareBB[s]) != 0)
{
if (0 == pos.pieces_color_piecetype(Them, PieceTypeS.KNIGHT) &&
0 == (BitBoard.squares_of_color(s) & pos.pieces_color_piecetype(Them, PieceTypeS.BISHOP)))
{
bonus += bonus + bonus / 2;
}
else
{
bonus += bonus / 2;
}
}
return(Types.make_score(bonus, bonus));
}
/// generate<QUIET_CHECKS> generates all pseudo-legal non-captures and knight
/// underpromotions that give check. Returns a pointer to the end of the move list.
public static int generate_quiet_checks(Position pos, ExtMove[] mlist, int mPos)
{
Debug.Assert(0 == pos.checkers());
Color us = pos.side_to_move();
CheckInfo ci = new CheckInfo(pos);
Bitboard dc = ci.dcCandidates;
while (dc != 0)
{
Square from = BitBoard.pop_lsb(ref dc);
PieceType pt = Types.type_of_piece(pos.piece_on(from));
if (pt == PieceTypeS.PAWN)
{
continue; // Will be generated togheter with direct checks
}
Bitboard b = pos.attacks_from_piece_square((Piece)pt, from) & ~pos.pieces();
if (pt == PieceTypeS.KING)
{
b &= ~BitBoard.PseudoAttacks[PieceTypeS.QUEEN][ci.ksq];
}
while (b != 0)
{
mlist[mPos++].move = Types.make_move(from, BitBoard.pop_lsb(ref b));
}
}
return(us == ColorS.WHITE ? generate_all(pos, mlist, mPos, ~pos.pieces(), ColorS.WHITE, GenTypeS.QUIET_CHECKS, ci) :
generate_all(pos, mlist, mPos, ~pos.pieces(), ColorS.BLACK, GenTypeS.QUIET_CHECKS, ci));
}
public static int generate_promotions(ExtMove[] mlist, int mPos, Bitboard pawnsOn7, Bitboard target, CheckInfo ci, GenType Type, Square Delta)
{
Bitboard b = BitBoard.shift_bb(pawnsOn7, Delta) & target;
while (b != 0)
{
Square to = BitBoard.pop_lsb(ref b);
if (Type == GenTypeS.CAPTURES || Type == GenTypeS.EVASIONS || Type == GenTypeS.NON_EVASIONS)
{
mlist[mPos++].move = Types.make(to - Delta, to, MoveTypeS.PROMOTION, PieceTypeS.QUEEN);
}
if (Type == GenTypeS.QUIETS || Type == GenTypeS.EVASIONS || Type == GenTypeS.NON_EVASIONS)
{
mlist[mPos++].move = Types.make(to - Delta, to, MoveTypeS.PROMOTION, PieceTypeS.ROOK);
mlist[mPos++].move = Types.make(to - Delta, to, MoveTypeS.PROMOTION, PieceTypeS.BISHOP);
mlist[mPos++].move = Types.make(to - Delta, to, MoveTypeS.PROMOTION, PieceTypeS.KNIGHT);
}
// Knight promotion is the only promotion that can give a direct check
// that's not already included in the queen promotion.
if (Type == GenTypeS.QUIET_CHECKS && (BitBoard.StepAttacksBB[PieceS.W_KNIGHT][to] & BitBoard.SquareBB[ci.ksq]) != 0)
{
mlist[mPos++].move = Types.make(to - Delta, to, MoveTypeS.PROMOTION, PieceTypeS.KNIGHT);
}
}
return(mPos);
}
// polyglot_key() returns the PolyGlot hash key of the given position
public static Key polyglot_key(Position pos)
{
Key key = 0;
Bitboard b = pos.pieces();
while (b != 0)
{
Square s = BitBoard.pop_lsb(ref b);
Piece pc = pos.piece_on(s);
// PolyGlot pieces are: BP = 0, WP = 1, BN = 2, ... BK = 10, WK = 11
int pieceOfs = 2 * (Types.type_of_piece(pc) - 1) + ((Types.color_of(pc) == ColorS.WHITE) ? 1 : 0);
key ^= PG[psq + (64 * pieceOfs + s)];
}
b = (ulong)pos.can_castle_castleright(CastlingRightS.ANY_CASTLING);
while (b != 0)
{
key ^= PG[castle + BitBoard.pop_lsb(ref b)];
}
if (pos.ep_square() != SquareS.SQ_NONE)
{
key ^= PG[enpassant + Types.file_of(pos.ep_square())];
}
if (pos.side_to_move() == ColorS.WHITE)
{
key ^= PG[turn + 0];
}
return(key);
}
/// KBP vs KB. There are two rules: if the defending king is somewhere along the
/// path of the pawn, and the square of the king is not of the same color as the
/// stronger side's bishop, it's a draw. If the two bishops have opposite color,
/// it's almost always a draw.
public ScaleFactor KBPKB(Position pos)
{
Debug.Assert(verify_material(pos, strongSide, ValueS.BishopValueMg, 1));
Debug.Assert(verify_material(pos, weakSide, ValueS.BishopValueMg, 0));
Square pawnSq = pos.list(strongSide, PieceTypeS.PAWN)[0];
Square strongerBishopSq = pos.list(strongSide, PieceTypeS.BISHOP)[0];
Square weakerBishopSq = pos.list(weakSide, PieceTypeS.BISHOP)[0];
Square weakerKingSq = pos.king_square(weakSide);
// Case 1: Defending king blocks the pawn, and cannot be driven away
if (Types.file_of(weakerKingSq) == Types.file_of(pawnSq) &&
Types.relative_rank_square(strongSide, pawnSq) < Types.relative_rank_square(strongSide, weakerKingSq) &&
(Types.opposite_colors(weakerKingSq, strongerBishopSq) ||
Types.relative_rank_square(strongSide, weakerKingSq) <= RankS.RANK_6))
{
return(ScaleFactorS.SCALE_FACTOR_DRAW);
}
// Case 2: Opposite colored bishops
if (Types.opposite_colors(strongerBishopSq, weakerBishopSq))
{
// We assume that the position is drawn in the following three situations:
//
// a. The pawn is on rank 5 or further back.
// b. The defending king is somewhere in the pawn's path.
// c. The defending bishop attacks some square along the pawn's path,
// and is at least three squares away from the pawn.
//
// These rules are probably not perfect, but in practice they work
// reasonably well.
if (Types.relative_rank_square(strongSide, pawnSq) <= RankS.RANK_5)
{
return(ScaleFactorS.SCALE_FACTOR_DRAW);
}
else
{
Bitboard path = BitBoard.forward_bb(strongSide, pawnSq);
if ((path & pos.pieces_color_piecetype(weakSide, PieceTypeS.KING)) != 0)
{
return(ScaleFactorS.SCALE_FACTOR_DRAW);
}
if (((pos.attacks_from_square_piecetype(weakerBishopSq, PieceTypeS.BISHOP) & path) != 0) &&
BitBoard.square_distance(weakerBishopSq, pawnSq) >= 3)
{
return(ScaleFactorS.SCALE_FACTOR_DRAW);
}
}
}
return(ScaleFactorS.SCALE_FACTOR_NONE);
}
// evaluate_unstoppable_pawns() scores the most advanced among the passed and
// candidate pawns. In case opponent has no pieces but pawns, this is somewhat
// related to the possibility that pawns are unstoppable.
public static Score evaluate_unstoppable_pawns(Position pos, Color us, EvalInfo ei)
{
Bitboard b = ei.pi.passed_pawns(us) | ei.pi.candidate_pawns(us);
if (0 == b || pos.non_pawn_material(Types.notColor(us)) != 0)
{
return(ScoreS.SCORE_ZERO);
}
return(Unstoppable * (Types.relative_rank_square(us, BitBoard.frontmost_sq(us, b))));
}
/// KR vs KN. The attacking side has slightly better winning chances than
/// in KR vs KB, particularly if the king and the knight are far apart.
public Value KRKN(Position pos)
{
Debug.Assert(verify_material(pos, strongSide, ValueS.RookValueMg, 0));
Debug.Assert(verify_material(pos, weakSide, ValueS.KnightValueMg, 0));
Square bksq = pos.king_square(weakSide);
Square bnsq = pos.list(weakSide, PieceTypeS.KNIGHT)[0];
Value result = (PushToEdges[bksq] + PushAway[BitBoard.square_distance(bksq, bnsq)]);
return(strongSide == pos.side_to_move() ? result : -result);
}
/// KQ vs KR. This is almost identical to KX vs K: We give the attacking
/// king a bonus for having the kings close together, and for forcing the
/// defending king towards the edge. If we also take care to avoid null move for
/// the defending side in the search, this is usually sufficient to win KQ vs KR.
public Value KQKR(Position pos)
{
Debug.Assert(verify_material(pos, strongSide, ValueS.QueenValueMg, 0));
Debug.Assert(verify_material(pos, weakSide, ValueS.RookValueMg, 0));
Square winnerKSq = pos.king_square(strongSide);
Square loserKSq = pos.king_square(weakSide);
Value result = ValueS.QueenValueEg
- ValueS.RookValueEg
+ PushToEdges[loserKSq]
+ PushClose[BitBoard.square_distance(winnerKSq, loserKSq)];
return(strongSide == pos.side_to_move() ? result : -result);
}
/// KNP vs KB. If knight can block bishop from taking pawn, it's a win.
/// Otherwise the position is drawn.
public ScaleFactor KNPKB(Position pos)
{
Square pawnSq = pos.list(strongSide, PieceTypeS.PAWN)[0];
Square bishopSq = pos.list(weakSide, PieceTypeS.BISHOP)[0];
Square weakerKingSq = pos.king_square(weakSide);
// King needs to get close to promoting pawn to prevent knight from blocking.
// Rules for this are very tricky, so just approximate.
if ((BitBoard.forward_bb(strongSide, pawnSq) & pos.attacks_from_square_piecetype(bishopSq, PieceTypeS.BISHOP)) != 0)
{
return(BitBoard.square_distance(weakerKingSq, pawnSq));
}
return(ScaleFactorS.SCALE_FACTOR_NONE);
}
public static int generate_castling(Position pos, ExtMove[] mlist, int mPos, Color us, CheckInfo ci, CastlingRight Cr, bool Checks, bool Chess960)
{
bool KingSide = (Cr == CastlingRightS.WHITE_OO || Cr == CastlingRightS.BLACK_OO);
if (pos.castling_impeded(Cr) || 0 == pos.can_castle_castleright(Cr))
{
return(mPos);
}
// After castling, the rook and king final positions are the same in Chess960
// as they would be in standard chess.
Square kfrom = pos.king_square(us);
Square rfrom = pos.castling_rook_square(Cr);
Square kto = Types.relative_square(us, KingSide ? SquareS.SQ_G1 : SquareS.SQ_C1);
Bitboard enemies = pos.pieces_color(Types.notColor(us));
Debug.Assert(0 == pos.checkers());
Square K = Chess960 ? kto > kfrom ? SquareS.DELTA_W : SquareS.DELTA_E
: KingSide ? SquareS.DELTA_W : SquareS.DELTA_E;
for (Square s = kto; s != kfrom; s += K)
{
if ((pos.attackers_to(s) & enemies) != 0)
{
return(mPos);
}
}
// 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 && (BitBoard.attacks_bb_SBBPT(kto, pos.pieces() ^ BitBoard.SquareBB[rfrom], PieceTypeS.ROOK) & pos.pieces_color_piecetype(Types.notColor(us), PieceTypeS.ROOK, PieceTypeS.QUEEN)) != 0)
{
return(mPos);
}
Move m = Types.make(kfrom, rfrom, MoveTypeS.CASTLING);
if (Checks && !pos.gives_check(m, ci))
{
return(mPos);
}
mlist[mPos++].move = m;
return(mPos);
}
public ScaleFactor KRPKB(Position pos)
{
Debug.Assert(verify_material(pos, strongSide, ValueS.RookValueMg, 1));
Debug.Assert(verify_material(pos, weakSide, ValueS.BishopValueMg, 0));
// Test for a rook pawn
if ((pos.pieces_piecetype(PieceTypeS.PAWN) & (BitBoard.FileABB | BitBoard.FileHBB)) != 0)
{
Square ksq = pos.king_square(weakSide);
Square bsq = pos.list(weakSide, PieceTypeS.BISHOP)[0];
Square psq = pos.list(strongSide, PieceTypeS.PAWN)[0];
Rank rk = Types.relative_rank_square(strongSide, psq);
Square push = Types.pawn_push(strongSide);
// If the pawn is on the 5th rank and the pawn (currently) is on
// the same color square as the bishop then there is a chance of
// a fortress. Depending on the king position give a moderate
// reduction or a stronger one if the defending king is near the
// corner but not trapped there.
if (rk == RankS.RANK_5 && !Types.opposite_colors(bsq, psq))
{
int d = BitBoard.square_distance(psq + 3 * push, ksq);
if (d <= 2 && !(d == 0 && ksq == pos.king_square(strongSide) + 2 * push))
{
return(24);
}
else
{
return(48);
}
}
// When the pawn has moved to the 6th rank we can be fairly sure
// it's drawn if the bishop attacks the square in front of the
// pawn from a reasonable distance and the defending king is near
// the corner
if (rk == RankS.RANK_6 &&
BitBoard.square_distance(psq + 2 * push, ksq) <= 1 &&
(BitBoard.PseudoAttacks[PieceTypeS.BISHOP][bsq] & BitBoard.SquareBB[(psq + push)]) != 0 &&
BitBoard.file_distance(bsq, psq) >= 2)
{
return(8);
}
}
return(ScaleFactorS.SCALE_FACTOR_NONE);
}
/// KNP vs K. There is a single rule: if the pawn is a rook pawn on the 7th rank
/// and the defending king prevents the pawn from advancing, the position is drawn.
public ScaleFactor KNPK(Position pos)
{
Debug.Assert(verify_material(pos, strongSide, ValueS.KnightValueMg, 1));
Debug.Assert(verify_material(pos, weakSide, ValueS.VALUE_ZERO, 0));
// Assume strongSide is white and the pawn is on files A-D
Square pawnSq = normalize(pos, strongSide, pos.list(strongSide, PieceTypeS.PAWN)[0]);
Square weakKingSq = normalize(pos, strongSide, pos.king_square(weakSide));
if (pawnSq == SquareS.SQ_A7 && BitBoard.square_distance(SquareS.SQ_A8, weakKingSq) <= 1)
{
return(ScaleFactorS.SCALE_FACTOR_DRAW);
}
return(ScaleFactorS.SCALE_FACTOR_NONE);
}
/// KR vs KP. This is a somewhat tricky endgame to evaluate precisely without
/// a bitbase. The function below returns drawish scores when the pawn is
/// far advanced with support of the king, while the attacking king is far
/// away.
public Value KRKP(Position pos)
{
Debug.Assert(verify_material(pos, strongSide, ValueS.RookValueMg, 0));
Debug.Assert(verify_material(pos, weakSide, ValueS.VALUE_ZERO, 1));
Square wksq = Types.relative_square(strongSide, pos.king_square(strongSide));
Square bksq = Types.relative_square(strongSide, pos.king_square(weakSide));
Square rsq = Types.relative_square(strongSide, pos.list(strongSide, PieceTypeS.ROOK)[0]);
Square psq = Types.relative_square(strongSide, pos.list(weakSide, PieceTypeS.PAWN)[0]);
Square queeningSq = Types.make_square(Types.file_of(psq), RankS.RANK_1);
Value result;
// If the stronger side's king is in front of the pawn, it's a win
if (wksq < psq && Types.file_of(wksq) == Types.file_of(psq))
{
result = ValueS.RookValueEg - (BitBoard.square_distance(wksq, psq));
}
// If the weaker side's king is too far from the pawn and the rook,
// it's a win
else if (BitBoard.square_distance(bksq, psq) >= 3 + ((pos.side_to_move() == weakSide)?1:0) &&
BitBoard.square_distance(bksq, rsq) >= 3)
{
result = ValueS.RookValueEg - (BitBoard.square_distance(wksq, psq));
}
// If the pawn is far advanced and supported by the defending king,
// the position is drawish
else if (Types.rank_of(bksq) <= RankS.RANK_3 &&
BitBoard.square_distance(bksq, psq) == 1 &&
Types.rank_of(wksq) >= RankS.RANK_4 &&
BitBoard.square_distance(wksq, psq) > 2 + ((pos.side_to_move() == strongSide)?1:0))
{
result = 80 - 8 * BitBoard.square_distance(wksq, psq);
}
else
{
result = (Value)(200) - 8 * (BitBoard.square_distance(wksq, psq + SquareS.DELTA_S)
- BitBoard.square_distance(bksq, psq + SquareS.DELTA_S)
- BitBoard.square_distance(psq, queeningSq));
}
return(strongSide == pos.side_to_move() ? result : -result);
}
public Engine(string[] args)
{
inOut.WriteLine(Misc.engine_info(), MutexAction.ATOMIC);
Uci.init(Options);
BitBoard.init();
Position.init();
Bitbases.init_kpk();
Search.init();
Pawns.init();
Eval.init();
Threads.init();
TT.resize((ulong)Options["Hash"].getInt());
Uci.loop(args);
Threads.exit();
}
public Result classify(KPKPosition[] db, Color Us)
{
// White to Move: If one move leads to a position classified as WIN, the result
// of the current position is WIN. If all moves lead to positions classified
// as DRAW, the current position is classified as DRAW, otherwise the current
// position is classified as UNKNOWN.
//
// Black to Move: If one move leads to a position classified as DRAW, the result
// of the current position is DRAW. If all moves lead to positions classified
// as WIN, the position is classified as WIN, otherwise the current position is
// classified as UNKNOWN.
Color Them = (Us == ColorS.WHITE ? ColorS.BLACK : ColorS.WHITE);
Result r = Result.INVALID;
Bitboard b = BitBoard.StepAttacksBB[PieceTypeS.KING][Us == ColorS.WHITE ? wksq : bksq];
while (b != 0)
{
r |= (Us == ColorS.WHITE) ? db[Bitbases.index(Them, bksq, BitBoard.pop_lsb(ref b), psq)].result
: db[Bitbases.index(Them, BitBoard.pop_lsb(ref b), wksq, psq)].result;
}
if (Us == ColorS.WHITE && Types.rank_of(psq) < RankS.RANK_7)
{
Square s = (psq + SquareS.DELTA_N);
r |= db[Bitbases.index(ColorS.BLACK, bksq, wksq, s)].result; // Single push
if (Types.rank_of(psq) == RankS.RANK_2 && s != wksq && s != bksq)
{
r |= db[Bitbases.index(ColorS.BLACK, bksq, wksq, s + SquareS.DELTA_N)].result; // Double push
}
}
if (Us == ColorS.WHITE)
{
return(result = (r & Result.WIN) != 0 ? Result.WIN : (r & Result.UNKNOWN) != 0 ? Result.UNKNOWN : Result.DRAW);
}
else
{
return(result = (r & Result.DRAW) != 0 ? Result.DRAW : (r & Result.UNKNOWN) != 0 ? Result.UNKNOWN : Result.WIN);
}
}
// evaluate_threats() assigns bonuses according to the type of attacking piece
// and the type of attacked one.
public static Score evaluate_threats(Position pos, EvalInfo ei, Color Us, bool Trace)
{
Color Them = (Us == ColorS.WHITE ? ColorS.BLACK : ColorS.WHITE);
Bitboard b, weakEnemies;
Score score = ScoreS.SCORE_ZERO;
// Enemies not defended by a pawn and under our attack
weakEnemies = pos.pieces_color(Them)
& ~ei.attackedBy[Them][PieceTypeS.PAWN]
& ei.attackedBy[Us][PieceTypeS.ALL_PIECES];
// Add a bonus according if the attacking pieces are minor or major
if (weakEnemies != 0)
{
b = weakEnemies & (ei.attackedBy[Us][PieceTypeS.PAWN] | ei.attackedBy[Us][PieceTypeS.KNIGHT] | ei.attackedBy[Us][PieceTypeS.BISHOP]);
if (b != 0)
{
score += Threat[0][Types.type_of_piece(pos.piece_on(BitBoard.lsb(b)))];
}
b = weakEnemies & (ei.attackedBy[Us][PieceTypeS.ROOK] | ei.attackedBy[Us][PieceTypeS.QUEEN]);
if (b != 0)
{
score += Threat[1][Types.type_of_piece(pos.piece_on(BitBoard.lsb(b)))];
}
b = weakEnemies & ~ei.attackedBy[Them][PieceTypeS.ALL_PIECES];
if (b != 0)
{
score += BitBoard.more_than_one(b) ? Hanging[Us != pos.side_to_move()?1:0] * Bitcount.popcount_Max15(b)
: Hanging[Us == pos.side_to_move()?1:0];
}
}
if (Trace)
{
Tracing.terms[Us][TermsS.THREAT] = score;
}
return(score);
}
/// KQ vs KP. In general, this is a win for the stronger side, but there are a
/// few important exceptions. A pawn on 7th rank and on the A,C,F or H files
/// with a king positioned next to it can be a draw, so in that case, we only
/// use the distance between the kings.
public Value KQKP(Position pos)
{
Debug.Assert(verify_material(pos, strongSide, ValueS.QueenValueMg, 0));
Debug.Assert(verify_material(pos, weakSide, ValueS.VALUE_ZERO, 1));
Square winnerKSq = pos.king_square(strongSide);
Square loserKSq = pos.king_square(weakSide);
Square pawnSq = pos.list(weakSide, PieceTypeS.PAWN)[0];
Value result = (PushClose[BitBoard.square_distance(winnerKSq, loserKSq)]);
if (Types.relative_rank_square(weakSide, pawnSq) != RankS.RANK_7 ||
BitBoard.square_distance(loserKSq, pawnSq) != 1 ||
0 == ((BitBoard.FileABB | BitBoard.FileCBB | BitBoard.FileFBB | BitBoard.FileHBB) & BitBoard.SquareBB[pawnSq]))
{
result += ValueS.QueenValueEg - ValueS.PawnValueEg;
}
return(strongSide == pos.side_to_move() ? result : -result);
}
public static Bitboard sliding_attack(Square[] deltas, Square sq, Bitboard occupied)
{
Bitboard attack = 0;
for (int i = 0; i < 4; ++i)
{
for (Square s = sq + deltas[i];
Types.is_ok_square(s) && BitBoard.square_distance(s, s - deltas[i]) == 1;
s += deltas[i])
{
attack |= SquareBB[s];
if ((occupied & SquareBB[s]) != 0)
{
break;
}
}
}
return(attack);
}
/// K and two or more pawns vs K. There is just a single rule here: If all pawns
/// are on the same rook file and are blocked by the defending king, it's a draw.
public ScaleFactor KPsK(Position pos)
{
Debug.Assert(pos.non_pawn_material(strongSide) == ValueS.VALUE_ZERO);
Debug.Assert(pos.count(strongSide, PieceTypeS.PAWN) >= 2);
Debug.Assert(verify_material(pos, weakSide, ValueS.VALUE_ZERO, 0));
Square ksq = pos.king_square(weakSide);
Bitboard pawns = pos.pieces_color_piecetype(strongSide, PieceTypeS.PAWN);
Square psq = pos.list(strongSide, PieceTypeS.PAWN)[0];
// If all pawns are ahead of the king, on a single rook file and
// the king is within one file of the pawns, it's a draw.
if (0 == (pawns & ~BitBoard.in_front_bb(weakSide, Types.rank_of(ksq))) &&
!((pawns & ~BitBoard.FileABB) != 0 && (pawns & ~BitBoard.FileHBB) != 0) &&
BitBoard.file_distance(ksq, psq) <= 1)
{
return(ScaleFactorS.SCALE_FACTOR_DRAW);
}
return(ScaleFactorS.SCALE_FACTOR_NONE);
}
public static int generate_moves(Position pos, ExtMove[] mlist, int mPos, Color us, Bitboard target, CheckInfo ci, PieceType Pt, bool Checks)
{
Debug.Assert(Pt != PieceTypeS.KING && Pt != PieceTypeS.PAWN);
Square[] pieceList = pos.list(us, Pt);
int pl = 0;
for (Square from = pieceList[pl]; from != SquareS.SQ_NONE; from = pieceList[++pl])
{
if (Checks)
{
if ((Pt == PieceTypeS.BISHOP || Pt == PieceTypeS.ROOK || Pt == PieceTypeS.QUEEN) &&
0 == (BitBoard.PseudoAttacks[Pt][from] & target & ci.checkSq[Pt]))
{
continue;
}
if (ci.dcCandidates != 0 && (ci.dcCandidates & BitBoard.SquareBB[from]) != 0)
{
continue;
}
}
Bitboard b = pos.attacks_from_square_piecetype(from, Pt) & target;
if (Checks)
{
b &= ci.checkSq[Pt];
}
while (b != 0)
{
mlist[mPos++].move = Types.make_move(from, BitBoard.pop_lsb(ref b));
}
}
return(mPos);
}
/// KRPP vs KRP. There is just a single rule: if the stronger side has no passed
/// pawns and the defending king is actively placed, the position is drawish.
public ScaleFactor KRPPKRP(Position pos)
{
Debug.Assert(verify_material(pos, strongSide, ValueS.RookValueMg, 2));
Debug.Assert(verify_material(pos, weakSide, ValueS.RookValueMg, 1));
Square wpsq1 = pos.list(strongSide, PieceTypeS.PAWN)[0];
Square wpsq2 = pos.list(strongSide, PieceTypeS.PAWN)[1];
Square bksq = pos.king_square(weakSide);
// Does the stronger side have a passed pawn?
if (pos.pawn_passed(strongSide, wpsq1) || pos.pawn_passed(strongSide, wpsq2))
{
return(ScaleFactorS.SCALE_FACTOR_NONE);
}
Rank r = Math.Max(Types.relative_rank_square(strongSide, wpsq1), Types.relative_rank_square(strongSide, wpsq2));
if (BitBoard.file_distance(bksq, wpsq1) <= 1 &&
BitBoard.file_distance(bksq, wpsq2) <= 1 &&
Types.relative_rank_square(strongSide, bksq) > r)
{
switch (r)
{
case RankS.RANK_2: return(10);
case RankS.RANK_3: return(10);
case RankS.RANK_4: return(15);
case RankS.RANK_5: return(20);
case RankS.RANK_6: return(40);
default: Debug.Assert(false); break;
}
}
return(ScaleFactorS.SCALE_FACTOR_NONE);
}
/// generate<EVASIONS> generates all pseudo-legal check evasions when the side
/// to move is in check. Returns a pointer to the end of the move list.
public static int generate_evasions(Position pos, ExtMove[] mlist, int mPos)
{
Debug.Assert(pos.checkers() != 0);
Color us = pos.side_to_move();
Square ksq = pos.king_square(us);
Bitboard sliderAttacks = 0;
Bitboard sliders = pos.checkers() & ~pos.pieces_piecetype(PieceTypeS.KNIGHT, PieceTypeS.PAWN);
// Find all the squares attacked by slider checkers. We will remove them from
// the king evasions in order to skip known illegal moves, which avoids any
// useless legality checks later on.
while (sliders != 0)
{
Square checksq = BitBoard.pop_lsb(ref sliders);
sliderAttacks |= BitBoard.LineBB[checksq][ksq] ^ BitBoard.SquareBB[checksq];
}
// Generate evasions for king, capture and non capture moves
Bitboard b = pos.attacks_from_square_piecetype(ksq, PieceTypeS.KING) & ~pos.pieces_color(us) & ~sliderAttacks;
while (b != 0)
{
mlist[mPos++].move = Types.make_move(ksq, BitBoard.pop_lsb(ref b));
}
if (BitBoard.more_than_one(pos.checkers()))
{
return(mPos); // Double check, only a king move can save the day
}
// Generate blocking evasions or captures of the checking piece
Square checksq2 = BitBoard.lsb(pos.checkers());
Bitboard target = BitBoard.between_bb(checksq2, ksq) | BitBoard.SquareBB[checksq2];
return(us == ColorS.WHITE ? generate_all(pos, mlist, mPos, target, ColorS.WHITE, GenTypeS.EVASIONS) :
generate_all(pos, mlist, mPos, target, ColorS.BLACK, GenTypeS.EVASIONS));
}
public static int generate_all(Position pos, ExtMove[] mlist, int mPos, Bitboard target, Color us, GenType Type, CheckInfo ci = null)
{
bool Checks = Type == GenTypeS.QUIET_CHECKS;
mPos = generate_pawn_moves(pos, mlist, mPos, target, ci, us, Type);
mPos = generate_moves(pos, mlist, mPos, us, target, ci, PieceTypeS.KNIGHT, Checks);
mPos = generate_moves(pos, mlist, mPos, us, target, ci, PieceTypeS.BISHOP, Checks);
mPos = generate_moves(pos, mlist, mPos, us, target, ci, PieceTypeS.ROOK, Checks);
mPos = generate_moves(pos, mlist, mPos, us, target, ci, PieceTypeS.QUEEN, Checks);
if (Type != GenTypeS.QUIET_CHECKS && Type != GenTypeS.EVASIONS)
{
Square ksq = pos.king_square(us);
Bitboard b = pos.attacks_from_square_piecetype(ksq, PieceTypeS.KING) & target;
while (b != 0)
{
mlist[mPos++].move = Types.make_move(ksq, BitBoard.pop_lsb(ref b));
}
}
if (Type != GenTypeS.CAPTURES && Type != GenTypeS.EVASIONS && pos.can_castle_color(us) != 0)
{
if (pos.is_chess960() != 0)
{
mPos = generate_castling(pos, mlist, mPos, us, ci, (new MakeCastlingS(us, CastlingSideS.KING_SIDE)).right, Checks, true);
mPos = generate_castling(pos, mlist, mPos, us, ci, (new MakeCastlingS(us, CastlingSideS.QUEEN_SIDE)).right, Checks, true);
}
else
{
mPos = generate_castling(pos, mlist, mPos, us, ci, (new MakeCastlingS(us, CastlingSideS.KING_SIDE)).right, Checks, false);
mPos = generate_castling(pos, mlist, mPos, us, ci, (new MakeCastlingS(us, CastlingSideS.QUEEN_SIDE)).right, Checks, false);
}
}
return(mPos);
}
/// Mate with KBN vs K. This is similar to KX vs K, but we have to drive the
/// defending king towards a corner square of the right color.
public Value KBNK(Position pos)
{
Debug.Assert(verify_material(pos, strongSide, ValueS.KnightValueMg + ValueS.BishopValueMg, 0));
Debug.Assert(verify_material(pos, weakSide, ValueS.VALUE_ZERO, 0));
Square winnerKSq = pos.king_square(strongSide);
Square loserKSq = pos.king_square(weakSide);
Square bishopSq = pos.list(strongSide, PieceTypeS.BISHOP)[0];
// kbnk_mate_table() tries to drive toward corners A1 or H8. If we have a
// bishop that cannot reach the above squares, we flip the kings in order
// to drive the enemy toward corners A8 or H1.
if (Types.opposite_colors(bishopSq, SquareS.SQ_A1))
{
winnerKSq = Types.notSquare(winnerKSq);
loserKSq = Types.notSquare(loserKSq);
}
Value result = ValueS.VALUE_KNOWN_WIN
+ PushClose[BitBoard.square_distance(winnerKSq, loserKSq)]
+ PushToCorners[loserKSq];
return(strongSide == pos.side_to_move() ? result : -result);
}
/// move_to_san() takes a position and a legal Move as input and returns its
/// short algebraic notation representation.
public static string move_to_san(Position pos, Move m)
{
if (m == MoveS.MOVE_NONE)
{
return("(none)");
}
if (m == MoveS.MOVE_NULL)
{
return("(null)");
}
Debug.Assert((new MoveList(pos, GenTypeS.LEGAL).contains(m)));
Bitboard others, b;
string san = "";
Color us = pos.side_to_move();
Square from = Types.from_sq(m);
Square to = Types.to_sq(m);
Piece pc = pos.piece_on(from);
PieceType pt = Types.type_of_piece(pc);
if (Types.type_of_move(m) == MoveTypeS.CASTLING)
{
san = to > from ? "O-O" : "O-O-O";
}
else
{
if (pt != PieceTypeS.PAWN)
{
san = "" + PieceToChar[ColorS.WHITE][pt]; // Upper case
// A disambiguation occurs if we have more then one piece of type 'pt'
// that can reach 'to' with a legal move.
others = b = (pos.attacks_from_piece_square(pc, to) & pos.pieces_color_piecetype(us, pt)) ^ BitBoard.SquareBB[from];
while (b != 0)
{
Square s = BitBoard.pop_lsb(ref b);
if (!pos.legal(Types.make_move(s, to), pos.pinned_pieces(us)))
{
others ^= BitBoard.SquareBB[s];
}
}
if (0 == others)
{ /* Disambiguation is not needed */
}
else if (0 == (others & BitBoard.file_bb_square(from)))
{
san += Types.file_to_char(Types.file_of(from));
}
else if (0 == (others & BitBoard.rank_bb_square(from)))
{
san += Types.rank_to_char(Types.rank_of(from));
}
else
{
san += Types.square_to_string(from);
}
}
else if (pos.capture(m))
{
san = "" + Types.file_to_char(Types.file_of(from));
}
if (pos.capture(m))
{
san += 'x';
}
san += Types.square_to_string(to);
if (Types.type_of_move(m) == MoveTypeS.PROMOTION)
{
san += "=" + PieceToChar[ColorS.WHITE][Types.promotion_type(m)];
}
}
if (pos.gives_check(m, new CheckInfo(pos)))
{
StateInfo st = new StateInfo();
pos.do_move(m, st);
san += (new MoveList(pos, GenTypeS.LEGAL)).size() > 0 ? "+" : "#";
pos.undo_move(m);
}
return(san);
}
