S(0, 0), S(0, 0), S(56, 70), S(56, 70), S(76, 99), S(86, 118)
};
+ // Hanging[side to move] contains a bonus for each enemy hanging piece
+ const Score Hanging[2] = { S(23, 20) , S(35, 45) };
+
#undef S
const Score Tempo = make_score(24, 11);
if (undefendedMinors)
score += UndefendedMinor;
- // Enemy pieces not defended by a pawn and under our attack
+ // Enemies not defended by a pawn and under our attack
weakEnemies = pos.pieces(Them)
& ~ei.attackedBy[Them][PAWN]
& ei.attackedBy[Us][ALL_PIECES];
// Add a bonus according if the attacking pieces are minor or major
if (weakEnemies)
{
- b = weakEnemies & (ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]);
+ b = weakEnemies & (ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]);
if (b)
score += Threat[0][type_of(pos.piece_on(lsb(b)))];
b = weakEnemies & (ei.attackedBy[Us][ROOK] | ei.attackedBy[Us][QUEEN]);
if (b)
score += Threat[1][type_of(pos.piece_on(lsb(b)))];
+
+ b = weakEnemies & ~ei.attackedBy[Them][ALL_PIECES];
+ if (b)
+ score += more_than_one(b) ? Hanging[Us != pos.side_to_move()] * popcount<Max15>(b)
+ : Hanging[Us == pos.side_to_move()];
}
if (Trace)
sf = ScaleFactor(50 * sf / SCALE_FACTOR_NORMAL);
}
+ // Stealmate detection
+ Color stm = pos.side_to_move();
+ if ( (ei.attackedBy[stm][ALL_PIECES] == ei.attackedBy[stm][KING])
+ && (!(ei.attackedBy[stm][KING] & ~ei.attackedBy[~stm][ALL_PIECES])))
+ sf = SCALE_FACTOR_DRAW;
+
// Interpolate between a middlegame and a (scaled by 'sf') endgame score
Value v = mg_value(score) * int(ei.mi->game_phase())
+ eg_value(score) * int(PHASE_MIDGAME - ei.mi->game_phase()) * sf / SCALE_FACTOR_NORMAL;
- v /= PHASE_MIDGAME;
+ v /= int(PHASE_MIDGAME);
// In case of tracing add all single evaluation contributions for both white and black
if (Trace)