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#include <algorithm> |
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#include <cassert> |
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#include "bitboard.h" |
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#include "pawns.h" |
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#include "position.h" |
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#include "thread.h" |
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namespace Stockfish { |
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namespace { |
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#define V Value |
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#define S(mg, eg) make_score(mg, eg) |
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constexpr Score Backward = S( 6, 19); |
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constexpr Score Doubled = S(11, 51); |
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constexpr Score DoubledEarly = S(17, 7); |
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constexpr Score Isolated = S( 1, 20); |
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constexpr Score WeakLever = S( 2, 57); |
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constexpr Score WeakUnopposed = S(15, 18); |
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constexpr Score BlockedPawn[2] = { S(-19, -8), S(-7, 3) }; |
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constexpr Score BlockedStorm[RANK_NB] = { |
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S(0, 0), S(0, 0), S(64, 75), S(-3, 14), S(-12, 19), S(-7, 4), S(-10, 5) |
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}; |
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constexpr int Connected[RANK_NB] = { 0, 3, 7, 7, 15, 54, 86 }; |
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constexpr Value ShelterStrength[int(FILE_NB) / 2][RANK_NB] = { |
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{ V(-2), V(85), V(95), V(53), V(39), V(23), V(25) }, |
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{ V(-55), V(64), V(32), V(-55), V(-30), V(-11), V(-61) }, |
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{ V(-11), V(75), V(19), V(-6), V(26), V(9), V(-47) }, |
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{ V(-41), V(-11), V(-27), V(-58), V(-42), V(-66), V(-163) } |
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}; |
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constexpr Value UnblockedStorm[int(FILE_NB) / 2][RANK_NB] = { |
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{ V(94), V(-280), V(-170), V(90), V(59), V(47), V(53) }, |
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{ V(43), V(-17), V(128), V(39), V(26), V(-17), V(15) }, |
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{ V(-9), V(62), V(170), V(34), V(-5), V(-20), V(-11) }, |
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{ V(-27), V(-19), V(106), V(10), V(2), V(-13), V(-24) } |
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}; |
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constexpr Score KingOnFile[2][2] = {{ S(-18,11), S(-6,-3) }, |
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{ S( 0, 0), S( 5,-4) }}; |
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#undef S |
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#undef V |
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template<Color Us> |
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Score evaluate(const Position& pos, Pawns::Entry* e) { |
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constexpr Color Them = ~Us; |
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constexpr Direction Up = pawn_push(Us); |
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constexpr Direction Down = -Up; |
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Bitboard neighbours, stoppers, support, phalanx, opposed; |
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Bitboard lever, leverPush, blocked; |
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Square s; |
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bool backward, passed, doubled; |
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Score score = SCORE_ZERO; |
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Bitboard b = pos.pieces(Us, PAWN); |
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Bitboard ourPawns = pos.pieces( Us, PAWN); |
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Bitboard theirPawns = pos.pieces(Them, PAWN); |
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Bitboard doubleAttackThem = pawn_double_attacks_bb<Them>(theirPawns); |
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e->passedPawns[Us] = 0; |
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e->kingSquares[Us] = SQ_NONE; |
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e->pawnAttacks[Us] = e->pawnAttacksSpan[Us] = pawn_attacks_bb<Us>(ourPawns); |
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e->blockedCount += popcount(shift<Up>(ourPawns) & (theirPawns | doubleAttackThem)); |
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while (b) |
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{ |
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s = pop_lsb(b); |
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assert(pos.piece_on(s) == make_piece(Us, PAWN)); |
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Rank r = relative_rank(Us, s); |
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opposed = theirPawns & forward_file_bb(Us, s); |
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blocked = theirPawns & (s + Up); |
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stoppers = theirPawns & passed_pawn_span(Us, s); |
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lever = theirPawns & pawn_attacks_bb(Us, s); |
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leverPush = theirPawns & pawn_attacks_bb(Us, s + Up); |
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doubled = ourPawns & (s - Up); |
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neighbours = ourPawns & adjacent_files_bb(s); |
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phalanx = neighbours & rank_bb(s); |
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support = neighbours & rank_bb(s - Up); |
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if (doubled) |
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{ |
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if (!(ourPawns & shift<Down>(theirPawns | pawn_attacks_bb<Them>(theirPawns)))) |
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score -= DoubledEarly; |
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} |
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backward = !(neighbours & forward_ranks_bb(Them, s + Up)) |
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&& (leverPush | blocked); |
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if (!backward && !blocked) |
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e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s); |
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passed = !(stoppers ^ lever) |
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|| ( !(stoppers ^ leverPush) |
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&& popcount(phalanx) >= popcount(leverPush)) |
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|| ( stoppers == blocked && r >= RANK_5 |
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&& (shift<Up>(support) & ~(theirPawns | doubleAttackThem))); |
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passed &= !(forward_file_bb(Us, s) & ourPawns); |
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if (passed) |
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e->passedPawns[Us] |= s; |
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if (support | phalanx) |
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{ |
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int v = Connected[r] * (2 + bool(phalanx) - bool(opposed)) |
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+ 22 * popcount(support); |
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score += make_score(v, v * (r - 2) / 4); |
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} |
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else if (!neighbours) |
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{ |
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if ( opposed |
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&& (ourPawns & forward_file_bb(Them, s)) |
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&& !(theirPawns & adjacent_files_bb(s))) |
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score -= Doubled; |
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else |
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score -= Isolated |
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+ WeakUnopposed * !opposed; |
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} |
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else if (backward) |
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score -= Backward |
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+ WeakUnopposed * !opposed * bool(~(FileABB | FileHBB) & s); |
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if (!support) |
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score -= Doubled * doubled |
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+ WeakLever * more_than_one(lever); |
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if (blocked && r >= RANK_5) |
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score += BlockedPawn[r - RANK_5]; |
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} |
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return score; |
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} |
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} |
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namespace Pawns { |
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Entry* probe(const Position& pos) { |
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Key key = pos.pawn_key(); |
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Entry* e = pos.this_thread()->pawnsTable[key]; |
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if (e->key == key) |
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return e; |
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e->key = key; |
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e->blockedCount = 0; |
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e->scores[WHITE] = evaluate<WHITE>(pos, e); |
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e->scores[BLACK] = evaluate<BLACK>(pos, e); |
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return e; |
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} |
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template<Color Us> |
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Score Entry::evaluate_shelter(const Position& pos, Square ksq) const { |
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constexpr Color Them = ~Us; |
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Bitboard b = pos.pieces(PAWN) & ~forward_ranks_bb(Them, ksq); |
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Bitboard ourPawns = b & pos.pieces(Us) & ~pawnAttacks[Them]; |
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Bitboard theirPawns = b & pos.pieces(Them); |
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Score bonus = make_score(5, 5); |
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File center = std::clamp(file_of(ksq), FILE_B, FILE_G); |
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for (File f = File(center - 1); f <= File(center + 1); ++f) |
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{ |
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b = ourPawns & file_bb(f); |
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int ourRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : 0; |
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b = theirPawns & file_bb(f); |
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int theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : 0; |
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int d = edge_distance(f); |
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bonus += make_score(ShelterStrength[d][ourRank], 0); |
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if (ourRank && (ourRank == theirRank - 1)) |
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bonus -= BlockedStorm[theirRank]; |
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else |
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bonus -= make_score(UnblockedStorm[d][theirRank], 0); |
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} |
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bonus -= KingOnFile[pos.is_on_semiopen_file(Us, ksq)][pos.is_on_semiopen_file(Them, ksq)]; |
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return bonus; |
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} |
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template<Color Us> |
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Score Entry::do_king_safety(const Position& pos) { |
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Square ksq = pos.square<KING>(Us); |
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kingSquares[Us] = ksq; |
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castlingRights[Us] = pos.castling_rights(Us); |
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auto compare = [](Score a, Score b) { return mg_value(a) < mg_value(b); }; |
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Score shelter = evaluate_shelter<Us>(pos, ksq); |
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if (pos.can_castle(Us & KING_SIDE)) |
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shelter = std::max(shelter, evaluate_shelter<Us>(pos, relative_square(Us, SQ_G1)), compare); |
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if (pos.can_castle(Us & QUEEN_SIDE)) |
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shelter = std::max(shelter, evaluate_shelter<Us>(pos, relative_square(Us, SQ_C1)), compare); |
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Bitboard pawns = pos.pieces(Us, PAWN); |
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int minPawnDist = 6; |
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if (pawns & attacks_bb<KING>(ksq)) |
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minPawnDist = 1; |
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else while (pawns) |
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minPawnDist = std::min(minPawnDist, distance(ksq, pop_lsb(pawns))); |
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return shelter - make_score(0, 16 * minPawnDist); |
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} |
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template Score Entry::do_king_safety<WHITE>(const Position& pos); |
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template Score Entry::do_king_safety<BLACK>(const Position& pos); |
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} |
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} |
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