// attacked by a given color and piece type (can be also ALL_PIECES).
Bitboard attackedBy[COLOR_NB][PIECE_TYPE_NB];
+ // attackedBy2[color] are the squares attacked by 2 pieces of a given color,
+ // possibly via x-ray or by one pawn and one piece. Diagonal x-ray through
+ // pawn or squares attacked by 2 pawns are not explicitly added.
+ Bitboard attackedBy2[COLOR_NB];
+
// 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)
const Score BishopPawns = S( 8, 12);
const Score RookOnPawn = S( 8, 24);
const Score TrappedRook = S(92, 0);
- const Score Checked = S(20, 20);
+ const Score SafeCheck = S(20, 20);
+ const Score OtherCheck = S(10, 10);
const Score ThreatByHangingPawn = S(71, 61);
const Score LooseEnemies = S( 0, 25);
+ const Score WeakQueen = S(35, 0);
const Score Hanging = S(48, 27);
const Score ThreatByPawnPush = S(38, 22);
const Score Unstoppable = S( 0, 20);
// Penalties for enemy's safe checks
const int QueenContactCheck = 89;
- const int QueenCheck = 52;
- const int RookCheck = 45;
- const int BishopCheck = 5;
- const int KnightCheck = 17;
+ const int QueenCheck = 62;
+ const int RookCheck = 57;
+ const int BishopCheck = 48;
+ const int KnightCheck = 78;
// eval_init() initializes king and attack bitboards for a given color
const Square Down = (Us == WHITE ? DELTA_S : DELTA_N);
ei.pinnedPieces[Us] = pos.pinned_pieces(Us);
- Bitboard b = ei.attackedBy[Them][KING] = pos.attacks_from<KING>(pos.square<KING>(Them));
+ Bitboard b = ei.attackedBy[Them][KING];
ei.attackedBy[Them][ALL_PIECES] |= b;
ei.attackedBy[Us][ALL_PIECES] |= ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);
+ ei.attackedBy2[Us] = ei.attackedBy[Us][PAWN] & ei.attackedBy[Us][KING];
// Init king safety tables only if we are going to use them
if (pos.non_pawn_material(Us) >= QueenValueMg)
{
ei.kingRing[Them] = b | shift_bb<Down>(b);
b &= ei.attackedBy[Us][PAWN];
- ei.kingAttackersCount[Us] = b ? popcount(b) : 0;
+ ei.kingAttackersCount[Us] = popcount(b);
ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
}
else
if (ei.pinnedPieces[Us] & s)
b &= LineBB[pos.square<KING>(Us)][s];
+ ei.attackedBy2[Us] |= ei.attackedBy[Us][ALL_PIECES] & b;
ei.attackedBy[Us][ALL_PIECES] |= ei.attackedBy[Us][Pt] |= b;
if (b & ei.kingRing[Them])
{
ei.kingAttackersCount[Us]++;
ei.kingAttackersWeight[Us] += KingAttackWeights[Pt];
- bb = b & ei.attackedBy[Them][KING];
- if (bb)
- ei.kingAdjacentZoneAttacksCount[Us] += popcount(bb);
+ ei.kingAdjacentZoneAttacksCount[Us] += popcount(b & ei.attackedBy[Them][KING]);
}
if (Pt == QUEEN)
{
// Bonus for aligning with enemy pawns on the same rank/file
if (relative_rank(Us, s) >= RANK_5)
- {
- Bitboard alignedPawns = pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s];
- if (alignedPawns)
- score += RookOnPawn * popcount(alignedPawns);
- }
+ score += RookOnPawn * popcount(pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s]);
// Bonus when on an open or semi-open file
if (ei.pi->semiopen_file(Us, file_of(s)))
score -= (TrappedRook - make_score(mob * 22, 0)) * (1 + !pos.can_castle(Us));
}
}
+
+ if (Pt == QUEEN)
+ {
+ // Penalty if any relative pin or discovered attack against the queen
+ if (pos.slider_blockers(pos.pieces(), pos.pieces(Them, ROOK, BISHOP), s))
+ score -= WeakQueen;
+ }
}
if (DoTrace)
template<Color Us, bool DoTrace>
Score evaluate_king(const Position& pos, const EvalInfo& ei) {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Square Up = (Us == WHITE ? DELTA_N : DELTA_S);
- Bitboard undefended, b, b1, b2, safe;
+ Bitboard undefended, b, b1, b2, safe, other;
int attackUnits;
const Square ksq = pos.square<KING>(Us);
if (ei.kingAttackersCount[Them])
{
// Find the attacked squares which are defended only by the king...
- undefended = ei.attackedBy[Them][ALL_PIECES]
- & ei.attackedBy[Us][KING]
- & ~( ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
- | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
- | ei.attackedBy[Us][QUEEN]);
+ undefended = ei.attackedBy[Them][ALL_PIECES]
+ & ei.attackedBy[Us][KING]
+ & ~ei.attackedBy2[Us];
// ... and those which are not defended at all in the larger king ring
b = ei.attackedBy[Them][ALL_PIECES] & ~ei.attackedBy[Us][ALL_PIECES]
// the pawn shelter (current 'score' value).
attackUnits = std::min(72, ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them])
+ 9 * ei.kingAdjacentZoneAttacksCount[Them]
- + 27 * popcount(undefended)
- + 11 * (popcount(b) + !!ei.pinnedPieces[Us])
+ + 21 * popcount(undefended)
+ + 12 * (popcount(b) + !!ei.pinnedPieces[Us])
- 64 * !pos.count<QUEEN>(Them)
- mg_value(score) / 8;
// Analyse the enemy's safe queen contact checks. Firstly, find the
// undefended squares around the king reachable by the enemy queen...
b = undefended & ei.attackedBy[Them][QUEEN] & ~pos.pieces(Them);
- if (b)
- {
- // ...and then remove squares not supported by another enemy piece
- b &= ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
- | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][ROOK]
- | ei.attackedBy[Them][KING];
- if (b)
- attackUnits += QueenContactCheck * popcount(b);
- }
+ // ...and keep squares supported by another enemy piece
+ attackUnits += QueenContactCheck * popcount(b & ei.attackedBy2[Them]);
- // Analyse the enemy's safe distance checks for sliders and knights
- safe = ~(ei.attackedBy[Us][ALL_PIECES] | pos.pieces(Them));
+ // Analyse the safe enemy's checks which are possible on next move...
+ safe = ~(ei.attackedBy[Us][ALL_PIECES] | pos.pieces(Them));
- b1 = pos.attacks_from<ROOK >(ksq) & safe;
- b2 = pos.attacks_from<BISHOP>(ksq) & safe;
+ // ... and some other potential checks, only requiring the square to be
+ // safe from pawn-attacks, and not being occupied by a blocked pawn.
+ other = ~( ei.attackedBy[Us][PAWN]
+ | (pos.pieces(Them, PAWN) & shift_bb<Up>(pos.pieces(PAWN))));
+
+ b1 = pos.attacks_from<ROOK >(ksq);
+ b2 = pos.attacks_from<BISHOP>(ksq);
// Enemy queen safe checks
- if ((b1 | b2) & ei.attackedBy[Them][QUEEN])
- attackUnits += QueenCheck, score -= Checked;
+ if ((b1 | b2) & ei.attackedBy[Them][QUEEN] & safe)
+ attackUnits += QueenCheck, score -= SafeCheck;
+
+ // For other pieces, also consider the square safe if attacked twice,
+ // and only defended by a queen.
+ safe |= ei.attackedBy2[Them]
+ & ~(ei.attackedBy2[Us] | pos.pieces(Them))
+ & ei.attackedBy[Us][QUEEN];
+
+ // Enemy rooks safe and other checks
+ if (b1 & ei.attackedBy[Them][ROOK] & safe)
+ attackUnits += RookCheck, score -= SafeCheck;
- // Enemy rooks safe checks
- if (b1 & ei.attackedBy[Them][ROOK])
- attackUnits += RookCheck, score -= Checked;
+ else if (b1 & ei.attackedBy[Them][ROOK] & other)
+ score -= OtherCheck;
- // Enemy bishops safe checks
- if (b2 & ei.attackedBy[Them][BISHOP])
- attackUnits += BishopCheck, score -= Checked;
+ // Enemy bishops safe and other checks
+ if (b2 & ei.attackedBy[Them][BISHOP] & safe)
+ attackUnits += BishopCheck, score -= SafeCheck;
- // Enemy knights safe checks
- if (pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe)
- attackUnits += KnightCheck, score -= Checked;
+ else if (b2 & ei.attackedBy[Them][BISHOP] & other)
+ score -= OtherCheck;
+
+ // Enemy knights safe and other checks
+ b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT];
+ if (b & safe)
+ attackUnits += KnightCheck, score -= SafeCheck;
+
+ else if (b & other)
+ score -= OtherCheck;
// Finally, extract the king danger score from the KingDanger[]
// array and subtract the score from the evaluation.
// evaluate_threats() assigns bonuses according to the types of the attacking
// and the attacked pieces.
+ const Bitboard WhiteCamp = Rank4BB | Rank5BB | Rank6BB | Rank7BB | Rank8BB;
+ const Bitboard BlackCamp = Rank5BB | Rank4BB | Rank3BB | Rank2BB | Rank1BB;
+ const Bitboard QueenSide = FileABB | FileBBB | FileCBB | FileDBB;
+ const Bitboard CenterFiles = FileCBB | FileDBB | FileEBB | FileFBB;
+ const Bitboard KingSide = FileEBB | FileFBB | FileGBB | FileHBB;
+
+ const Bitboard KingFlank[COLOR_NB][FILE_NB] = {
+ { QueenSide & WhiteCamp, QueenSide & WhiteCamp, QueenSide & WhiteCamp, CenterFiles & WhiteCamp,
+ CenterFiles & WhiteCamp, KingSide & WhiteCamp, KingSide & WhiteCamp, KingSide & WhiteCamp },
+ { QueenSide & BlackCamp, QueenSide & BlackCamp, QueenSide & BlackCamp, CenterFiles & BlackCamp,
+ CenterFiles & BlackCamp, KingSide & BlackCamp, KingSide & BlackCamp, KingSide & BlackCamp },
+ };
+
template<Color Us, bool DoTrace>
Score evaluate_threats(const Position& pos, const EvalInfo& ei) {
while (b)
score += Threat[Rook ][type_of(pos.piece_on(pop_lsb(&b)))];
- b = weak & ~ei.attackedBy[Them][ALL_PIECES];
- if (b)
- score += Hanging * popcount(b);
+ score += Hanging * popcount(weak & ~ei.attackedBy[Them][ALL_PIECES]);
b = weak & ei.attackedBy[Us][KING];
if (b)
& pos.pieces(Them)
& ~ei.attackedBy[Us][PAWN];
- if (b)
- score += ThreatByPawnPush * popcount(b);
+ score += ThreatByPawnPush * popcount(b);
+
+ // King tropism: firstly, find squares that we attack in the enemy king flank
+ b = ei.attackedBy[Us][ALL_PIECES] & KingFlank[Us][file_of(pos.square<KING>(Them))];
+
+ // Secondly, add to the bitboard the squares which we attack twice in that flank
+ // but which are not protected by a enemy pawn. Note the trick to shift away the
+ // previous attack bits to the empty part of the bitboard.
+ b = (b & ei.attackedBy2[Us] & ~ei.attackedBy[Them][PAWN])
+ | (Us == WHITE ? b >> 4 : b << 4);
+
+ // Count all these squares with a single popcount
+ score += make_score(7 * popcount(b), 0);
if (DoTrace)
Trace::add(THREAT, Us, score);
Square s = pop_lsb(&b);
assert(pos.pawn_passed(Us, s));
+ assert(!(pos.pieces(PAWN) & forward_bb(Us, s)));
int r = relative_rank(Us, s) - RANK_2;
int rr = r * (r - 1);
// ...count safe + (behind & safe) with a single popcount
int bonus = popcount((Us == WHITE ? safe << 32 : safe >> 32) | (behind & safe));
- int weight = pos.count<KNIGHT>(Us) + pos.count<BISHOP>(Us)
- + pos.count<KNIGHT>(Them) + pos.count<BISHOP>(Them);
+ bonus = std::min(16, bonus);
+ int weight = pos.count<ALL_PIECES>(Us);
- return make_score(bonus * weight * weight * 2 / 11, 0);
+ return make_score(bonus * weight * weight / 22, 0);
}
// Endgame with opposite-colored bishops, but also other pieces. Still
// a bit drawish, but not as drawish as with only the two bishops.
else
- sf = ScaleFactor(46 * sf / SCALE_FACTOR_NORMAL);
+ sf = ScaleFactor(46);
}
// Endings where weaker side can place his king in front of the opponent's
// pawns are drawish.
// Initialize attack and king safety bitboards
ei.attackedBy[WHITE][ALL_PIECES] = ei.attackedBy[BLACK][ALL_PIECES] = 0;
+ ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.square<KING>(WHITE));
+ ei.attackedBy[BLACK][KING] = pos.attacks_from<KING>(pos.square<KING>(BLACK));
eval_init<WHITE>(pos, ei);
eval_init<BLACK>(pos, ei);
projects / stockfish / blobdiff