X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=b4b8d9eea80b343a3647ab41f7e0d3ced5f4135d;hp=997aa2148815142da303cab5acb499bd78d0d6e9;hb=55df3fa2d7631ed67e46f9433aa7f3a71c18e5e7;hpb=2f1935078da225c90f7887ed8c345cc7baebcfcc diff --git a/src/pawns.cpp b/src/pawns.cpp index 997aa214..b4b8d9ee 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -1,7 +1,7 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -26,89 +26,104 @@ namespace { + #define V Value #define S(mg, eg) make_score(mg, eg) // Doubled pawn penalty by opposed flag and file - const Score DoubledPawnPenalty[2][8] = { + const Score DoubledPawnPenalty[2][FILE_NB] = { { S(13, 43), S(20, 48), S(23, 48), S(23, 48), S(23, 48), S(23, 48), S(20, 48), S(13, 43) }, { S(13, 43), S(20, 48), S(23, 48), S(23, 48), S(23, 48), S(23, 48), S(20, 48), S(13, 43) }}; // Isolated pawn penalty by opposed flag and file - const Score IsolatedPawnPenalty[2][8] = { + const Score IsolatedPawnPenalty[2][FILE_NB] = { { S(37, 45), S(54, 52), S(60, 52), S(60, 52), S(60, 52), S(60, 52), S(54, 52), S(37, 45) }, { S(25, 30), S(36, 35), S(40, 35), S(40, 35), S(40, 35), S(40, 35), S(36, 35), S(25, 30) }}; // Backward pawn penalty by opposed flag and file - const Score BackwardPawnPenalty[2][8] = { + const Score BackwardPawnPenalty[2][FILE_NB] = { { S(30, 42), S(43, 46), S(49, 46), S(49, 46), S(49, 46), S(49, 46), S(43, 46), S(30, 42) }, { S(20, 28), S(29, 31), S(33, 31), S(33, 31), S(33, 31), S(33, 31), S(29, 31), S(20, 28) }}; // Pawn chain membership bonus by file - const Score ChainBonus[8] = { + const Score ChainBonus[FILE_NB] = { S(11,-1), S(13,-1), S(13,-1), S(14,-1), S(14,-1), S(13,-1), S(13,-1), S(11,-1) }; // Candidate passed pawn bonus by rank - const Score CandidateBonus[8] = { + const Score CandidateBonus[RANK_NB] = { S( 0, 0), S( 6, 13), S(6,13), S(14,29), S(34,68), S(83,166), S(0, 0), S( 0, 0) }; + const Score PawnStructureWeight = S(233, 201); + + // Weakness of our pawn shelter in front of the king indexed by [king pawn][rank] + const Value ShelterWeakness[2][RANK_NB] = + { { 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) } }; + + // Danger of enemy pawns moving toward our king indexed by [pawn blocked][rank] + const Value StormDanger[2][RANK_NB] = + { { 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::get_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::get_pawn_info(const Position& pos) const { +PawnEntry* PawnTable::probe(const Position& pos) { - assert(pos.is_ok()); + Key key = pos.pawn_key(); + PawnEntry* e = entries[key]; - Key key = pos.get_pawn_key(); - PawnInfo* pi = find(key); - - // If pi->key matches the position's pawn hash key, it means that we + // If e->key matches the position's pawn hash key, it means that we // have analysed this pawn structure before, and we can simply return // the information we found the last time instead of recomputing it. - 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); - - // Evaluate pawns for both colors - pi->value = evaluate_pawns(pos, wPawns, bPawns, pi) - - evaluate_pawns(pos, bPawns, wPawns, pi); - return pi; + if (e->key == key) + return e; + + e->key = key; + e->passedPawns[WHITE] = e->passedPawns[BLACK] = 0; + e->kingSquares[WHITE] = e->kingSquares[BLACK] = SQ_NONE; + e->halfOpenFiles[WHITE] = e->halfOpenFiles[BLACK] = 0xFF; + + Bitboard wPawns = pos.pieces(WHITE, PAWN); + Bitboard bPawns = pos.pieces(BLACK, PAWN); + e->pawnAttacks[WHITE] = ((wPawns & ~FileHBB) << 9) | ((wPawns & ~FileABB) << 7); + e->pawnAttacks[BLACK] = ((bPawns & ~FileHBB) >> 7) | ((bPawns & ~FileABB) >> 9); + + e->value = evaluate_pawns(pos, wPawns, bPawns, e) + - evaluate_pawns(pos, bPawns, wPawns, e); + + e->value = apply_weight(e->value, PawnStructureWeight); + + return e; } -/// 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) const { +Score PawnTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, + Bitboard theirPawns, PawnEntry* e) { - const BitCountType Max15 = CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15; const Color Them = (Us == WHITE ? BLACK : WHITE); Bitboard b; @@ -117,43 +132,43 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, Rank r; bool passed, isolated, doubled, opposed, chain, backward, candidate; Score value = SCORE_ZERO; - const Square* ptr = pos.piece_list_begin(Us, PAWN); + const Square* pl = pos.piece_list(Us, PAWN); // Loop through all pawns of the current color and score each pawn - while ((s = *ptr++) != SQ_NONE) + while ((s = *pl++) != SQ_NONE) { assert(pos.piece_on(s) == make_piece(Us, PAWN)); - f = square_file(s); - r = square_rank(s); + f = file_of(s); + r = rank_of(s); // This file cannot be half open - pi->halfOpenFiles[Us] &= ~(1 << f); + e->halfOpenFiles[Us] &= ~(1 << f); // Our rank plus previous one. Used for chain detection b = rank_bb(r) | rank_bb(Us == WHITE ? r - Rank(1) : r + Rank(1)); // Flag the pawn as passed, isolated, doubled or member of a pawn // chain (but not the backward one). + chain = ourPawns & adjacent_files_bb(f) & b; + isolated = !(ourPawns & adjacent_files_bb(f)); + doubled = ourPawns & forward_bb(Us, s); + opposed = theirPawns & forward_bb(Us, s); passed = !(theirPawns & passed_pawn_mask(Us, s)); - doubled = ourPawns & squares_in_front_of(Us, s); - opposed = theirPawns & squares_in_front_of(Us, s); - isolated = !(ourPawns & neighboring_files_bb(f)); - chain = ourPawns & neighboring_files_bb(f) & b; // Test for backward pawn backward = false; // If the pawn is passed, isolated, or member of a pawn chain it cannot - // be backward. If there are friendly pawns behind on neighboring files + // be backward. If there are friendly pawns behind on adjacent files // or if can capture an enemy pawn it cannot be backward either. if ( !(passed | isolated | chain) && !(ourPawns & attack_span_mask(Them, s)) && !(pos.attacks_from(s, Us) & theirPawns)) { // We now know that there are no friendly pawns beside or behind this - // pawn on neighboring files. We now check whether the pawn is - // backward by looking in the forward direction on the neighboring + // pawn on adjacent files. We now check whether the pawn is + // backward by looking in the forward direction on the adjacent // files, and seeing whether we meet a friendly or an enemy pawn first. b = pos.attacks_from(s, Us); @@ -171,17 +186,17 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, // A not passed pawn is a candidate to become passed if it is free to // advance and if the number of friendly pawns beside or behind this - // pawn on neighboring files is higher or equal than the number of - // enemy pawns in the forward direction on the neighboring files. + // pawn on adjacent files is higher or equal than the number of + // enemy pawns in the forward direction on the adjacent files. candidate = !(opposed | passed | backward | isolated) - && (b = attack_span_mask(Them, s + pawn_push(Us)) & ourPawns) != EmptyBoardBB - && count_1s(b) >= count_1s(attack_span_mask(Us, s) & theirPawns); + && (b = attack_span_mask(Them, s + pawn_push(Us)) & ourPawns) != 0 + && popcount(b) >= popcount(attack_span_mask(Us, s) & theirPawns); // Passed pawns will be properly scored in evaluation because we need // full attack info to evaluate passed pawns. Only the frontmost passed // pawn on each file is considered a true passed pawn. if (passed && !doubled) - set_bit(&(pi->passedPawns[Us]), s); + e->passedPawns[Us] |= s; // Score this pawn if (isolated) @@ -199,35 +214,74 @@ 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 int Shift = (Us == WHITE ? 8 : -8); + const Color Them = (Us == WHITE ? BLACK : WHITE); + + 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_neighboring_files_bb(ksq); - r = ksq & (7 << 3); - for (int i = 0; i < 3; i++) - { - r += Shift; - shelter += BitCount8Bit[(pawns >> r) & 0xFF] * (64 >> i); - } + // Shelter penalty is higher for the pawn in front of the king + b = ourPawns & FileBB[f]; + rkUs = b ? rank_of(Us == WHITE ? lsb(b) : ~msb(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 ? lsb(b) : ~msb(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]; + castleRights[Us] = pos.can_castle(Us); + minKPdistance[Us] = 0; + + Bitboard pawns = pos.pieces(Us, PAWN); + if (pawns) + while (!(DistanceRingsBB[ksq][minKPdistance[Us]++] & pawns)) {} + + if (relative_rank(Us, ksq) > RANK_4) + return kingSafety[Us] = make_score(0, -16 * minKPdistance[Us]); + + Value bonus = shelter_storm(pos, ksq); + + // If we can castle use the bonus after the castle if is bigger + if (pos.can_castle(make_castle_right(Us, KING_SIDE))) + bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_G1))); + + if (pos.can_castle(make_castle_right(Us, QUEEN_SIDE))) + bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_C1))); + + return kingSafety[Us] = make_score(bonus, -16 * minKPdistance[Us]); } // 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);