const int BishopCheckBonus = 1;
const int KnightCheckBonus = 1;
- // Scan for queen contact mates?
- const bool QueenContactMates = true;
-
- // Bonus for having a mate threat
- const int MateThreatBonus = 3;
-
// InitKingDanger[] contains bonuses based on the position of the defending
// king.
const int InitKingDanger[64] = {
}
// Interpolate between the middle game and the endgame score
- Color stm = pos.side_to_move();
-
- Value v = Sign[stm] * scale_by_game_phase(ei.value, phase, factor);
-
- return (ei.mateThreat[stm] == MOVE_NONE ? v : 8 * QueenValueMidgame - v);
+ return Sign[pos.side_to_move()] * scale_by_game_phase(ei.value, phase, factor);
}
} // namespace
const Color Them = (Us == WHITE ? BLACK : WHITE);
- Bitboard undefended, attackedByOthers, escapeSquares, occ, b, b1, b2, safe;
- Square from, to;
+ Bitboard undefended, b, b1, b2, safe;
bool sente;
int attackUnits, shelter = 0;
const Square ksq = pos.king_square(Us);
// King safety. This is quite complicated, and is almost certainly far
// from optimally tuned.
if ( pos.piece_count(Them, QUEEN) >= 1
- && ei.kingAttackersCount[Them] >= 2
- && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
+ && ei.kingAttackersCount[Them] >= 2
+ && pos.non_pawn_material(Them) >= QueenValueMidgame + RookValueMidgame
&& ei.kingAdjacentZoneAttacksCount[Them])
{
// Is it the attackers turn to move?
+ InitKingDanger[relative_square(Us, ksq)]
- shelter / 32;
- // Analyse safe queen contact checks
+ // Analyse enemy's safe queen contact checks. First find undefended
+ // squares around the king attacked by enemy queen...
b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
if (b)
{
- attackedByOthers = ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
- | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK);
-
- b &= attackedByOthers;
-
- // Squares attacked by the queen and supported by another enemy piece and
- // not defended by other pieces but our king.
+ // ...then remove squares not supported by another enemy piece
+ b &= ( ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
+ | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK));
if (b)
- {
- // The bitboard b now contains the squares available for safe queen
- // contact checks.
attackUnits += QueenContactCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
-
- // Is there a mate threat?
- if (QueenContactMates && !pos.is_check())
- {
- escapeSquares = pos.attacks_from<KING>(ksq) & ~pos.pieces_of_color(Us) & ~attackedByOthers;
- occ = pos.occupied_squares();
- while (b)
- {
- to = pop_1st_bit(&b);
-
- // Do we have escape squares from queen contact check attack ?
- if (!(escapeSquares & ~queen_attacks_bb(to, occ & ClearMaskBB[ksq])))
- {
- // We have a mate, unless the queen is pinned or there
- // is an X-ray attack through the queen.
- for (int i = 0; i < pos.piece_count(Them, QUEEN); i++)
- {
- from = pos.piece_list(Them, QUEEN, i);
- if ( bit_is_set(pos.attacks_from<QUEEN>(from), to)
- && !bit_is_set(pos.pinned_pieces(Them), from)
- && !(rook_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(ROOK, QUEEN, Us))
- && !(bishop_attacks_bb(to, occ & ClearMaskBB[from]) & pos.pieces(BISHOP, QUEEN, Us)))
-
- // Set the mate threat move
- ei.mateThreat[Them] = make_move(from, to);
- }
- }
- }
- }
- }
}
- // Analyse enemy's safe distance checks
+ // Analyse enemy's safe distance checks for sliders and knights
safe = ~(pos.pieces_of_color(Them) | ei.attacked_by(Us));
b1 = pos.attacks_from<ROOK>(ksq) & safe;
b2 = pos.attacks_from<BISHOP>(ksq) & safe;
+ // Enemy queen safe checks
+ b = (b1 | b2) & ei.attacked_by(Them, QUEEN);
+ if (b)
+ attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b);
+
// Enemy rooks safe checks
b = b1 & ei.attacked_by(Them, ROOK);
if (b)
if (b)
attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b);
- // Enemy queens safe checks
- b = (b1 | b2) & ei.attacked_by(Them, QUEEN);
- if (b)
- attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b);
-
// Enemy knights safe checks
b = pos.attacks_from<KNIGHT>(ksq) & ei.attacked_by(Them, KNIGHT) & safe;
if (b)
attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b);
- // Analyse discovered checks (only for non-pawns right now, consider
- // adding pawns later).
+ // Analyse enemy's discovered checks (only for non-pawns right now,
+ // consider adding pawns later).
b = pos.discovered_check_candidates(Them) & ~pos.pieces(PAWN);
if (b)
attackUnits += DiscoveredCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
- // Has a mate threat been found? We don't do anything here if the
- // side with the mating move is the side to move, because in that
- // case the mating side will get a huge bonus at the end of the main
- // evaluation function instead.
- if (ei.mateThreat[Them] != MOVE_NONE)
- attackUnits += MateThreatBonus;
-
- // Ensure that attackUnits is between 0 and 99, in order to avoid array
- // out of bounds errors.
+ // To index KingDangerTable[] attackUnits must be in [0, 99] range
attackUnits = Min(99, Max(0, attackUnits));
// Finally, extract the king danger score from the KingDangerTable[]