// kingRing[color] is the zone around the king which is considered
// by the king safety evaluation. This consists of the squares directly
- // adjacent to the king, and the three (or two, for a king on an edge file)
+ // adjacent to the king, and (only for a king on its first rank) the
// squares two ranks in front of the king. For instance, if black's king
// is on g8, kingRing[BLACK] is a bitboard containing the squares f8, h8,
// f7, g7, h7, f6, g6 and h6.
S(-20,-12), S( 1, -8), S( 2, 10), S( 9, 10)
};
- // KingProtector[PieceType-2] * "distance to own king" determines a bonus for each piece.
- const Score KingProtector[] = {S(-3, -5), S(-4, -3), S(-3, 0), S(-1, 1) };
+ // KingProtector[PieceType-2] contains a bonus according to distance from king
+ const Score KingProtector[] = { S(-3, -5), S(-4, -3), S(-3, 0), S(-1, 1) };
// Assorted bonuses and penalties used by evaluation
const Score MinorBehindPawn = S( 16, 0);
ei.attackedBy[Us][ALL_PIECES] = b | ei.attackedBy[Us][PAWN];
// Init our king safety tables only if we are going to use them
- if (pos.non_pawn_material(Them) >= QueenValueMg)
+ if (pos.non_pawn_material(Them) >= RookValueMg + KnightValueMg)
{
- ei.kingRing[Us] = b | shift<Up>(b);
+ ei.kingRing[Us] = b;
+ if (relative_rank(Us, pos.square<KING>(Us)) == RANK_1)
+ ei.kingRing[Us] |= shift<Up>(b);
+
ei.kingAttackersCount[Them] = popcount(b & ei.pe->pawn_attacks(Them));
ei.kingAdjacentZoneAttacksCount[Them] = ei.kingAttackersWeight[Them] = 0;
}
int mob = popcount(b & ei.mobilityArea[Us]);
- mobility[Us] += MobilityBonus[Pt-2][mob];
+ mobility[Us] += MobilityBonus[Pt - 2][mob];
- score += KingProtector[Pt-2] * distance(s, pos.square<KING>(Us));
+ // Bonus for this piece as a king protector
+ score += KingProtector[Pt - 2] * distance(s, pos.square<KING>(Us));
if (Pt == BISHOP || Pt == KNIGHT)
{
Score score = ei.pe->king_safety<Us>(pos, ksq);
// Main king safety evaluation
- if (ei.kingAttackersCount[Them])
+ if (ei.kingAttackersCount[Them] > (1 - pos.count<QUEEN>(Them)))
{
// Find the attacked squares which are defended only by our king...
undefended = ei.attackedBy[Them][ALL_PIECES]
+ 201 * popcount(undefended)
+ 143 * (popcount(b) + !!pos.pinned_pieces(Us))
- 848 * !pos.count<QUEEN>(Them)
- - 28 * mg_value(score) / 25 - 5;
+ - 9 * mg_value(score) / 8
+ + 40;
// Analyse the safe enemy's checks which are possible on next move
safe = ~pos.pieces(Them);
// Transform the kingDanger units into a Score, and substract it from the evaluation
if (kingDanger > 0)
- score -= make_score(kingDanger * kingDanger / 4096, 0);
+ score -= make_score(kingDanger * kingDanger / 4096, kingDanger / 16);
}
// King tropism: firstly, find squares that opponent attacks in our king flank
<< " Imbalance | " << Term(IMBALANCE)
<< " Pawns | " << Term(PAWN)
<< " Knights | " << Term(KNIGHT)
- << " Bishop | " << Term(BISHOP)
+ << " Bishops | " << Term(BISHOP)
<< " Rooks | " << Term(ROOK)
<< " Queens | " << Term(QUEEN)
<< " Mobility | " << Term(MOBILITY)