X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fpawns.cpp;h=f2e0c4c30fe4301b8c1e3fd64adea98f74154321;hb=304deb5e833baf47c147e93377f5c7ef582ab822;hp=950994ef898b4843a869cd22898dbf933ada88e8;hpb=a492a9dd079d95faf136a744ff6d47a3d109ad68;p=stockfish diff --git a/src/pawns.cpp b/src/pawns.cpp index 950994ef..f2e0c4c3 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -26,6 +26,7 @@ namespace { + #define V Value #define S(mg, eg) make_score(mg, eg) // Doubled pawn penalty by opposed flag and file @@ -63,24 +64,34 @@ namespace { const Score PawnStructureWeight = S(233, 201); - #undef S + // Weakness of our pawn shelter in front of the king indexed by [king pawn][rank] + const Value ShelterWeakness[2][8] = + { { V(141), V(0), V(38), V(102), V(128), V(141), V(141) }, + { V( 61), V(0), V(16), V( 44), V( 56), V( 61), V( 61) } }; - inline Score apply_weight(Score v, Score w) { - return make_score((int(mg_value(v)) * mg_value(w)) / 0x100, - (int(eg_value(v)) * eg_value(w)) / 0x100); - } + // Danger of enemy pawns moving toward our king indexed by [pawn blocked][rank] + const Value StormDanger[2][8] = + { { V(26), V(0), V(128), V(51), V(26) }, + { V(13), V(0), V( 64), V(25), V(13) } }; + + // Max bonus for king safety. Corresponds to start position with all the pawns + // in front of the king and no enemy pawn on the horizont. + const Value MaxSafetyBonus = V(263); + + #undef S + #undef V } -/// PawnInfoTable::pawn_info() takes a position object as input, computes -/// a PawnInfo object, and returns a pointer to it. The result is also stored -/// in an hash table, so we don't have to recompute everything when the same -/// pawn structure occurs again. +/// PawnTable::probe() takes a position object as input, computes a PawnEntry +/// object, and returns a pointer to it. The result is also stored in a hash +/// table, so we don't have to recompute everything when the same pawn structure +/// occurs again. -PawnInfo* PawnInfoTable::pawn_info(const Position& pos) const { +PawnEntry* PawnTable::probe(const Position& pos) const { Key key = pos.pawn_key(); - PawnInfo* pi = probe(key); + PawnEntry* pi = Base::probe(key); // If pi->key matches the position's pawn hash key, it means that we // have analysed this pawn structure before, and we can simply return @@ -88,19 +99,16 @@ PawnInfo* PawnInfoTable::pawn_info(const Position& pos) const { if (pi->key == key) return pi; - // Initialize PawnInfo entry pi->key = key; pi->passedPawns[WHITE] = pi->passedPawns[BLACK] = 0; pi->kingSquares[WHITE] = pi->kingSquares[BLACK] = SQ_NONE; pi->halfOpenFiles[WHITE] = pi->halfOpenFiles[BLACK] = 0xFF; - // Calculate pawn attacks Bitboard wPawns = pos.pieces(PAWN, WHITE); Bitboard bPawns = pos.pieces(PAWN, BLACK); - pi->pawnAttacks[WHITE] = ((wPawns << 9) & ~FileABB) | ((wPawns << 7) & ~FileHBB); - pi->pawnAttacks[BLACK] = ((bPawns >> 7) & ~FileABB) | ((bPawns >> 9) & ~FileHBB); + pi->pawnAttacks[WHITE] = ((wPawns & ~FileHBB) << 9) | ((wPawns & ~FileABB) << 7); + pi->pawnAttacks[BLACK] = ((bPawns & ~FileHBB) >> 7) | ((bPawns & ~FileABB) >> 9); - // Evaluate pawns for both colors and weight the result pi->value = evaluate_pawns(pos, wPawns, bPawns, pi) - evaluate_pawns(pos, bPawns, wPawns, pi); @@ -110,11 +118,11 @@ PawnInfo* PawnInfoTable::pawn_info(const Position& pos) const { } -/// PawnInfoTable::evaluate_pawns() evaluates each pawn of the given color +/// PawnTable::evaluate_pawns() evaluates each pawn of the given color template -Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, - Bitboard theirPawns, PawnInfo* pi) { +Score PawnTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, + Bitboard theirPawns, PawnEntry* pi) { const Color Them = (Us == WHITE ? BLACK : WHITE); @@ -142,11 +150,11 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, // Flag the pawn as passed, isolated, doubled or member of a pawn // chain (but not the backward one). - passed = !(theirPawns & passed_pawn_mask(Us, s)); + chain = ourPawns & adjacent_files_bb(f) & b; + isolated = !(ourPawns & adjacent_files_bb(f)); doubled = ourPawns & squares_in_front_of(Us, s); opposed = theirPawns & squares_in_front_of(Us, s); - isolated = !(ourPawns & adjacent_files_bb(f)); - chain = ourPawns & adjacent_files_bb(f) & b; + passed = !(theirPawns & passed_pawn_mask(Us, s)); // Test for backward pawn backward = false; @@ -206,35 +214,68 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, if (candidate) value += CandidateBonus[relative_rank(Us, s)]; } + return value; } -/// PawnInfo::updateShelter() calculates and caches king shelter. It is called -/// only when king square changes, about 20% of total king_shelter() calls. +/// PawnEntry::shelter_storm() calculates shelter and storm penalties for the file +/// the king is on, as well as the two adjacent files. + template -Score PawnInfo::updateShelter(const Position& pos, Square ksq) { +Value PawnEntry::shelter_storm(const Position& pos, Square ksq) { + + const Color Them = (Us == WHITE ? BLACK : WHITE); - const int Shift = (Us == WHITE ? 8 : -8); + Value safety = MaxSafetyBonus; + Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, ksq) | rank_bb(ksq)); + Bitboard ourPawns = b & pos.pieces(Us) & ~rank_bb(ksq); + Bitboard theirPawns = b & pos.pieces(Them); + Rank rkUs, rkThem; + File kf = file_of(ksq); - Bitboard pawns; - int r, shelter = 0; + kf = (kf == FILE_A) ? kf++ : (kf == FILE_H) ? kf-- : kf; - if (relative_rank(Us, ksq) <= RANK_4) + for (int f = kf - 1; f <= kf + 1; f++) { - pawns = pos.pieces(PAWN, Us) & this_and_adjacent_files_bb(file_of(ksq)); - r = ksq & (7 << 3); - for (int i = 0; i < 3; i++) - { - r += Shift; - shelter += BitCount8Bit[(pawns >> r) & 0xFF] << (6 - i); - } + // Shelter penalty is higher for the pawn in front of the king + b = ourPawns & FileBB[f]; + rkUs = b ? rank_of(Us == WHITE ? first_1(b) : ~last_1(b)) : RANK_1; + safety -= ShelterWeakness[f != kf][rkUs]; + + // Storm danger is smaller if enemy pawn is blocked + b = theirPawns & FileBB[f]; + rkThem = b ? rank_of(Us == WHITE ? first_1(b) : ~last_1(b)) : RANK_1; + safety -= StormDanger[rkThem == rkUs + 1][rkThem]; } + + return safety; +} + + +/// PawnEntry::update_safety() calculates and caches a bonus for king safety. It is +/// called only when king square changes, about 20% of total king_safety() calls. + +template +Score PawnEntry::update_safety(const Position& pos, Square ksq) { + kingSquares[Us] = ksq; - kingShelters[Us] = make_score(shelter, 0); - return kingShelters[Us]; + + if (relative_rank(Us, ksq) > RANK_4) + return kingSafety[Us] = SCORE_ZERO; + + Value bonus = shelter_storm(pos, ksq); + + // If we can castle use the bonus after the castle if is bigger + if (pos.can_castle(Us == WHITE ? WHITE_OO : BLACK_OO)) + bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_G1))); + + if (pos.can_castle(Us == WHITE ? WHITE_OOO : BLACK_OOO)) + bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_C1))); + + return kingSafety[Us] = make_score(bonus, 0); } // Explicit template instantiation -template Score PawnInfo::updateShelter(const Position& pos, Square ksq); -template Score PawnInfo::updateShelter(const Position& pos, Square ksq); +template Score PawnEntry::update_safety(const Position& pos, Square ksq); +template Score PawnEntry::update_safety(const Position& pos, Square ksq);