#define V(v) Value(v)
#define S(mg, eg) make_score(mg, eg)
- // MobilityBonus[PieceType][attacked] contains bonuses for middle and end game,
+ // MobilityBonus[PieceType-2][attacked] contains bonuses for middle and end game,
// indexed by piece type and number of attacked squares in the mobility area.
- const Score MobilityBonus[][32] = {
- {}, {},
+ const Score MobilityBonus[4][32] = {
{ S(-75,-76), S(-57,-54), S( -9,-28), S( -2,-10), S( 6, 5), S( 14, 12), // Knights
S( 22, 26), S( 29, 29), S( 36, 29) },
{ S(-48,-59), S(-20,-23), S( 16, -3), S( 26, 13), S( 38, 24), S( 51, 42), // Bishops
S( 9, 10), S( 2, 10), S( 1, -8), S(-20,-12),
S(-20,-12), S( 1, -8), S( 2, 10), S( 9, 10)
};
+
+ // Protector[PieceType-2][distance] contains a protecting bonus for our king,
+ // indexed by piece type and distance between the piece and the king.
+ const Score Protector[4][8] = {
+ { S(0, 0), S( 7, 9), S( 7, 1), S( 1, 5), S(-10,-4), S( -1,-4), S( -7,-3), S(-16,-10) }, // Knight
+ { S(0, 0), S(11, 8), S(-7,-1), S(-1,-2), S( -1,-7), S(-11,-3), S( -9,-1), S(-16, -1) }, // Bishop
+ { S(0, 0), S(10, 0), S(-2, 2), S(-5, 4), S( -6, 2), S(-14,-3), S( -2,-9), S(-12, -7) }, // Rook
+ { S(0, 0), S( 3,-5), S( 2,-5), S(-4, 0), S( -9,-6), S(-4, 7), S(-13,-7), S(-10, -7) } // Queen
+ };
// Assorted bonuses and penalties used by evaluation
const Score MinorBehindPawn = S(16, 0);
int mob = popcount(b & ei.mobilityArea[Us]);
- mobility[Us] += MobilityBonus[Pt][mob];
+ mobility[Us] += MobilityBonus[Pt-2][mob];
+
+ // Bonus for this piece as a king protector
+ score += Protector[Pt-2][distance(s, pos.square<KING>(Us))];
if (Pt == BISHOP || Pt == KNIGHT)
{
// evaluate_king() assigns bonuses and penalties to a king of a given color
+ const Bitboard QueenSide = FileABB | FileBBB | FileCBB | FileDBB;
const Bitboard CenterFiles = FileCBB | FileDBB | FileEBB | FileFBB;
+ const Bitboard KingSide = FileEBB | FileFBB | FileGBB | FileHBB;
const Bitboard KingFlank[FILE_NB] = {
- CenterFiles >> 2, CenterFiles >> 2, CenterFiles >> 2, CenterFiles, CenterFiles,
- CenterFiles << 2, CenterFiles << 2, CenterFiles << 2
+ QueenSide, QueenSide, QueenSide, CenterFiles, CenterFiles, KingSide, KingSide, KingSide
};
template<Color Us, bool DoTrace>
const Bitboard TRank2BB = (Us == WHITE ? Rank2BB : Rank7BB);
const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
- Bitboard b, weak, defended, safeThreats;
+ Bitboard b, weak, defended, stronglyProtected, safeThreats;
Score score = SCORE_ZERO;
// Non-pawn enemies attacked by a pawn
score += ThreatBySafePawn[type_of(pos.piece_on(pop_lsb(&safeThreats)))];
}
- // Non-pawn enemies defended by a pawn
- defended = (pos.pieces(Them) ^ pos.pieces(Them, PAWN)) & ei.attackedBy[Them][PAWN];
+ // Squares strongly protected by the opponent, either because they attack the
+ // square with a pawn, or because they attack the square twice and we don't.
+ stronglyProtected = ei.attackedBy[Them][PAWN]
+ | (ei.attackedBy2[Them] & ~ei.attackedBy2[Us]);
+
+ // Non-pawn enemies, strongly protected
+ defended = (pos.pieces(Them) ^ pos.pieces(Them, PAWN))
+ & stronglyProtected;
- // Enemies not defended by a pawn and under our attack
+ // Enemies not strongly protected and under our attack
weak = pos.pieces(Them)
- & ~ei.attackedBy[Them][PAWN]
+ & ~stronglyProtected
& ei.attackedBy[Us][ALL_PIECES];
// Add a bonus according to the kind of attacking pieces
mbonus += rr + r * 2, ebonus += rr + r * 2;
} // rr != 0
- // Scale down bonus for candidate passers which need more than one pawn
- // push to become passed.
+ // Scale down bonus for candidate passers which need more than one
+ // pawn push to become passed.
if (!pos.pawn_passed(Us, s + pawn_push(Us)))
mbonus /= 2, ebonus /= 2;
if (DoTrace)
Trace::add(PASSED, Us, score);
- // Add the scores to the middlegame and endgame eval
return score;
}
int kingDistance = distance<File>(pos.square<KING>(WHITE), pos.square<KING>(BLACK))
- distance<Rank>(pos.square<KING>(WHITE), pos.square<KING>(BLACK));
int pawns = pos.count<PAWN>(WHITE) + pos.count<PAWN>(BLACK);
+ bool bothFlanks = (pos.pieces(PAWN) & QueenSide) && (pos.pieces(PAWN) & KingSide);
// Compute the initiative bonus for the attacking side
- int initiative = 8 * (asymmetry + kingDistance - 15) + 12 * pawns;
+ int initiative = 8 * (asymmetry + kingDistance - 17) + 12 * pawns + 16 * bothFlanks;
// Now apply the bonus: note that we find the attacking side by extracting
// the sign of the endgame value, and that we carefully cap the bonus so
- // that the endgame score will never be divided by more than two.
- int value = ((eg > 0) - (eg < 0)) * std::max(initiative, -abs(eg / 2));
+ // that the endgame score will never change sign after the bonus.
+ int value = ((eg > 0) - (eg < 0)) * std::max(initiative, -abs(eg));
return make_score(0, value);
}