V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) // 8
};
- // ThreatBonus[][] contains bonus according to which piece type
- // attacks which one.
- #define Z S(0, 0)
-
+ // ThreatBonus[attacking][attacked] contains bonus according to which
+ // piece type attacks which one.
const Score ThreatBonus[8][8] = {
- { Z, Z, Z, Z, Z, Z, Z, Z }, // not used
- { Z, S(18,37), Z, S(37,47), S(55,97), S(55,97), Z, Z }, // KNIGHT attacks
- { Z, S(18,37), S(37,47), Z, S(55,97), S(55,97), Z, Z }, // BISHOP attacks
- { Z, S( 9,27), S(27,47), S(27,47), Z, S(37,47), Z, Z }, // ROOK attacks
- { Z, S(27,37), S(27,37), S(27,37), S(27,37), Z, Z, Z }, // QUEEN attacks
- { Z, Z, Z, Z, Z, Z, Z, Z }, // not used
- { Z, Z, Z, Z, Z, Z, Z, Z }, // not used
- { Z, Z, Z, Z, Z, Z, Z, Z } // not used
+ {},
+ { S(0, 0), S(18,37), S( 0, 0), S(37,47), S(55,97), S(55,97) }, // KNIGHT
+ { S(0, 0), S(18,37), S(37,47), S( 0, 0), S(55,97), S(55,97) }, // BISHOP
+ { S(0, 0), S( 9,27), S(27,47), S(27,47), S( 0, 0), S(37,47) }, // ROOK
+ { S(0, 0), S(27,37), S(27,37), S(27,37), S(27,37), S( 0, 0) }, // QUEEN
+ {}, {}, {}
};
// ThreatedByPawnPenalty[] contains a penalty according to which piece
// type is attacked by an enemy pawn.
const Score ThreatedByPawnPenalty[8] = {
- Z, Z, S(56, 70), S(56, 70), S(76, 99), S(86, 118), Z, Z
+ S(0, 0), S(0, 0), S(56, 70), S(56, 70), S(76, 99), S(86, 118)
};
- #undef Z
#undef S
// Bonus for unstoppable passed pawns
/// the strength of the enemy attack are added up into an integer, which
/// is used as an index to KingDangerTable[].
- // Attack weights for each piece type and table indexed on piece type
- const int QueenAttackWeight = 5;
- const int RookAttackWeight = 3;
- const int BishopAttackWeight = 2;
- const int KnightAttackWeight = 2;
-
- const int AttackWeight[] = { 0, 0, KnightAttackWeight, BishopAttackWeight, RookAttackWeight, QueenAttackWeight };
+ // KingAttackWeights[] contains king attack weights by piece type
+ const int KingAttackWeights[8] = { 0, 0, 2, 2, 3, 5 };
// Bonuses for enemy's safe checks
const int QueenContactCheckBonus = 3;
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
if (b & ei.kingZone[Us])
{
ei.kingAttackersCount[Us]++;
- ei.kingAttackersWeight[Us] += AttackWeight[Piece];
+ ei.kingAttackersWeight[Us] += KingAttackWeights[Piece];
Bitboard bb = (b & ei.attackedBy[Them][KING]);
if (bb)
ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
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, count, shelter = 0;
+ int attackUnits, shelter = 0;
const Square ksq = pos.king_square(Us);
// King shelter
// 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?
- sente = (Them == pos.side_to_move());
-
- // Find the attacked squares around the king which has no defenders
- // apart from the king itself
- undefended = ei.attacked_by(Them) & ei.attacked_by(Us, KING);
- undefended &= ~( ei.attacked_by(Us, PAWN) | ei.attacked_by(Us, KNIGHT)
- | ei.attacked_by(Us, BISHOP) | ei.attacked_by(Us, ROOK)
- | ei.attacked_by(Us, QUEEN));
-
- // Initialize the 'attackUnits' variable, which is used later on as an
- // index to the KingDangerTable[] array. The initial value is based on
- // the number and types of the enemy's attacking pieces, the number of
- // attacked and undefended squares around our king, the square of the
- // king, and the quality of the pawn shelter.
- attackUnits = Min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
- + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended))
- + InitKingDanger[relative_square(Us, ksq)]
- - (shelter >> 5);
-
- // Analyse safe queen contact checks
- 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);
+ // Is it the attackers turn to move?
+ sente = (Them == pos.side_to_move());
+
+ // Find the attacked squares around the king which has no defenders
+ // apart from the king itself
+ undefended = ei.attacked_by(Them) & ei.attacked_by(Us, KING);
+ undefended &= ~( ei.attacked_by(Us, PAWN) | ei.attacked_by(Us, KNIGHT)
+ | ei.attacked_by(Us, BISHOP) | ei.attacked_by(Us, ROOK)
+ | ei.attacked_by(Us, QUEEN));
+
+ // Initialize the 'attackUnits' variable, which is used later on as an
+ // index to the KingDangerTable[] array. The initial value is based on
+ // the number and types of the enemy's attacking pieces, the number of
+ // attacked and undefended squares around our king, the square of the
+ // king, and the quality of the pawn shelter.
+ attackUnits = Min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
+ + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended))
+ + InitKingDanger[relative_square(Us, ksq)]
+ - shelter / 32;
+
+ // 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)
+ {
+ // ...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)
+ attackUnits += QueenContactCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
+ }
+
+ // Analyse enemy's safe distance checks for sliders and knights
+ safe = ~(pos.pieces_of_color(Them) | ei.attacked_by(Us));
- b &= attackedByOthers;
+ b1 = pos.attacks_from<ROOK>(ksq) & safe;
+ b2 = pos.attacks_from<BISHOP>(ksq) & safe;
- // Squares attacked by the queen and supported by another enemy piece and
- // not defended by other pieces but our king.
+ // Enemy queen safe checks
+ b = (b1 | b2) & ei.attacked_by(Them, QUEEN);
if (b)
- {
- // The bitboard b now contains the squares available for safe queen
- // contact checks.
- count = count_1s_max_15<HasPopCnt>(b);
- attackUnits += QueenContactCheckBonus * count * (sente ? 2 : 1);
+ attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b);
- // 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);
- }
- }
- }
- }
- }
- }
+ // Enemy rooks safe checks
+ b = b1 & ei.attacked_by(Them, ROOK);
+ if (b)
+ attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b);
+
+ // Enemy bishops safe checks
+ b = b2 & ei.attacked_by(Them, BISHOP);
+ if (b)
+ attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b);
- // Analyse enemy's safe distance checks
- 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 rooks safe checks
- b = b1 & ei.attacked_by(Them, ROOK);
- if (b)
- attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b);
-
- // Enemy bishops safe checks
- b = b2 & ei.attacked_by(Them, BISHOP);
- 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).
- 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.
- attackUnits = Min(99, Max(0, attackUnits));
-
- // Finally, extract the king danger score from the KingDangerTable[] array.
- // Subtract the score from evaluation, and set ei.futilityMargin[].
- // The reason for storing the king danger score to futility margin
- // is that the king danger scores can sometimes be very big, and that
- // capturing a single attacking piece can therefore result in a score
- // change far bigger than the value of the captured piece.
- ei.value -= Sign[Us] * KingDangerTable[Us][attackUnits];
- ei.futilityMargin[Us] = mg_value(KingDangerTable[Us][attackUnits]);
+ // 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 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);
+
+ // 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[]
+ // array and subtract the score from evaluation. Set also ei.kingDanger[]
+ // value that will be used for pruning because this value can sometimes
+ // be very big, and so capturing a single attacking piece can therefore
+ // result in a score change far bigger than the value of the captured piece.
+ ei.value -= Sign[Us] * KingDangerTable[Us][attackUnits];
+ ei.kingDanger[Us] = mg_value(KingDangerTable[Us][attackUnits]);
}
}
projects / stockfish / blobdiff