X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fpawns.cpp;h=868d0c8ef0fb9781279d7e98d41ab5025da4b0fa;hb=HEAD;hp=29a987519182ed709d1b7889be21335866d1d2a5;hpb=3192b09fe0258ec7654aa2c13bbc17b8417e6964;p=stockfish diff --git a/src/pawns.cpp b/src/pawns.cpp deleted file mode 100644 index 29a98751..00000000 --- a/src/pawns.cpp +++ /dev/null @@ -1,311 +0,0 @@ -/* - Stockfish, a UCI chess playing engine derived from Glaurung 2.1 - Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad - Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, 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 - the Free Software Foundation, either version 3 of the License, or - (at your option) any later version. - - Stockfish is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - GNU General Public License for more details. - - You should have received a copy of the GNU General Public License - along with this program. If not, see . -*/ - -#include -#include - -#include "bitboard.h" -#include "pawns.h" -#include "position.h" -#include "thread.h" - -namespace { - - #define V Value - #define S(mg, eg) make_score(mg, eg) - - // Isolated pawn penalty - const Score Isolated = S(13, 18); - - // Backward pawn penalty - const Score Backward = S(24, 12); - - // Connected pawn bonus by opposed, phalanx, #support and rank - Score Connected[2][2][3][RANK_NB]; - - // Doubled pawn penalty - const Score Doubled = S(18, 38); - - // Weakness of our pawn shelter in front of the king by [isKingFile][distance from edge][rank]. - // RANK_1 = 0 is used for files where we have no pawns or our pawn is behind our king. - const Value ShelterWeakness[][int(FILE_NB) / 2][RANK_NB] = { - { { V( 98), V(20), V(11), V(42), V( 83), V( 84), V(101) }, // Not On King file - { V(103), V( 8), V(33), V(86), V( 87), V(105), V(113) }, - { V(100), V( 2), V(65), V(95), V( 59), V( 89), V(115) }, - { V( 72), V( 6), V(52), V(74), V( 83), V( 84), V(112) } }, - { { V(105), V(19), V( 3), V(27), V( 85), V( 93), V( 84) }, // On King file - { V(121), V( 7), V(33), V(95), V(112), V( 86), V( 72) }, - { V(121), V(26), V(65), V(90), V( 65), V( 76), V(117) }, - { V( 79), V( 0), V(45), V(65), V( 94), V( 92), V(105) } } - }; - - // Danger of enemy pawns moving toward our king by [type][distance from edge][rank]. - // For the unopposed and unblocked cases, RANK_1 = 0 is used when opponent has - // no pawn on the given file, or their pawn is behind our king. - const Value StormDanger[][4][RANK_NB] = { - { { V( 0), V(-290), V(-274), V(57), V(41) }, // BlockedByKing - { V( 0), V( 60), V( 144), V(39), V(13) }, - { V( 0), V( 65), V( 141), V(41), V(34) }, - { V( 0), V( 53), V( 127), V(56), V(14) } }, - { { V( 4), V( 73), V( 132), V(46), V(31) }, // Unopposed - { V( 1), V( 64), V( 143), V(26), V(13) }, - { V( 1), V( 47), V( 110), V(44), V(24) }, - { V( 0), V( 72), V( 127), V(50), V(31) } }, - { { V( 0), V( 0), V( 79), V(23), V( 1) }, // BlockedByPawn - { V( 0), V( 0), V( 148), V(27), V( 2) }, - { V( 0), V( 0), V( 161), V(16), V( 1) }, - { V( 0), V( 0), V( 171), V(22), V(15) } }, - { { V(22), V( 45), V( 104), V(62), V( 6) }, // Unblocked - { V(31), V( 30), V( 99), V(39), V(19) }, - { V(23), V( 29), V( 96), V(41), V(15) }, - { V(21), V( 23), V( 116), V(41), V(15) } } - }; - - // Max bonus for king safety. Corresponds to start position with all the pawns - // in front of the king and no enemy pawn on the horizon. - const Value MaxSafetyBonus = V(258); - - #undef S - #undef V - - template - Score evaluate(const Position& pos, Pawns::Entry* e) { - - const Color Them = (Us == WHITE ? BLACK : WHITE); - const Direction Up = (Us == WHITE ? NORTH : SOUTH); - - Bitboard b, neighbours, stoppers, doubled, supported, phalanx; - Bitboard lever, leverPush; - Square s; - bool opposed, backward; - Score score = SCORE_ZERO; - const Square* pl = pos.squares(Us); - - Bitboard ourPawns = pos.pieces( Us, PAWN); - Bitboard theirPawns = pos.pieces(Them, PAWN); - - e->passedPawns[Us] = e->pawnAttacksSpan[Us] = e->weakUnopposed[Us] = 0; - e->semiopenFiles[Us] = 0xFF; - e->kingSquares[Us] = SQ_NONE; - e->pawnAttacks[Us] = pawn_attacks_bb(ourPawns); - e->pawnsOnSquares[Us][BLACK] = popcount(ourPawns & DarkSquares); - e->pawnsOnSquares[Us][WHITE] = pos.count(Us) - e->pawnsOnSquares[Us][BLACK]; - - // Loop through all pawns of the current color and score each pawn - while ((s = *pl++) != SQ_NONE) - { - assert(pos.piece_on(s) == make_piece(Us, PAWN)); - - File f = file_of(s); - - e->semiopenFiles[Us] &= ~(1 << f); - e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s); - - // Flag the pawn - opposed = theirPawns & forward_file_bb(Us, s); - stoppers = theirPawns & passed_pawn_mask(Us, s); - lever = theirPawns & PawnAttacks[Us][s]; - leverPush = theirPawns & PawnAttacks[Us][s + Up]; - doubled = ourPawns & (s - Up); - neighbours = ourPawns & adjacent_files_bb(f); - phalanx = neighbours & rank_bb(s); - supported = neighbours & rank_bb(s - Up); - - // A pawn is backward when it is behind all pawns of the same color on the - // adjacent files and cannot be safely advanced. - if (!neighbours || lever || relative_rank(Us, s) >= RANK_5) - backward = false; - else - { - // Find the backmost rank with neighbours or stoppers - b = rank_bb(backmost_sq(Us, neighbours | stoppers)); - - // The pawn is backward when it cannot safely progress to that rank: - // either there is a stopper in the way on this rank, or there is a - // stopper on adjacent file which controls the way to that rank. - backward = (b | shift(b & adjacent_files_bb(f))) & stoppers; - - assert(!(backward && (forward_ranks_bb(Them, s + Up) & neighbours))); - } - - // Passed pawns will be properly scored in evaluation because we need - // full attack info to evaluate them. Include also not passed pawns - // which could become passed after one or two pawn pushes when are - // not attacked more times than defended. - if ( !(stoppers ^ lever ^ leverPush) - && !(ourPawns & forward_file_bb(Us, s)) - && popcount(supported) >= popcount(lever) - && popcount(phalanx) >= popcount(leverPush)) - e->passedPawns[Us] |= s; - - else if ( stoppers == SquareBB[s + Up] - && relative_rank(Us, s) >= RANK_5) - { - b = shift(supported) & ~theirPawns; - while (b) - if (!more_than_one(theirPawns & PawnAttacks[Us][pop_lsb(&b)])) - e->passedPawns[Us] |= s; - } - - // Score this pawn - if (supported | phalanx) - score += Connected[opposed][bool(phalanx)][popcount(supported)][relative_rank(Us, s)]; - - else if (!neighbours) - score -= Isolated, e->weakUnopposed[Us] += !opposed; - - else if (backward) - score -= Backward, e->weakUnopposed[Us] += !opposed; - - if (doubled && !supported) - score -= Doubled; - } - - return score; - } - -} // namespace - -namespace Pawns { - -/// Pawns::init() initializes some tables needed by evaluation. Instead of using -/// hard-coded tables, when makes sense, we prefer to calculate them with a formula -/// to reduce independent parameters and to allow easier tuning and better insight. - -void init() { - - static const int Seed[RANK_NB] = { 0, 13, 24, 18, 76, 100, 175, 330 }; - - for (int opposed = 0; opposed <= 1; ++opposed) - for (int phalanx = 0; phalanx <= 1; ++phalanx) - for (int support = 0; support <= 2; ++support) - for (Rank r = RANK_2; r < RANK_8; ++r) - { - int v = 17 * support; - v += (Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0)) >> opposed; - - Connected[opposed][phalanx][support][r] = make_score(v, v * (r - 2) / 4); - } -} - - -/// Pawns::probe() looks up the current position's pawns configuration in -/// the pawns hash table. It returns a pointer to the Entry if the position -/// is found. Otherwise a new Entry is computed and stored there, so we don't -/// have to recompute all when the same pawns configuration occurs again. - -Entry* probe(const Position& pos) { - - Key key = pos.pawn_key(); - Entry* e = pos.this_thread()->pawnsTable[key]; - - if (e->key == key) - return e; - - e->key = key; - e->scores[WHITE] = evaluate(pos, e); - e->scores[BLACK] = evaluate(pos, e); - e->openFiles = popcount(e->semiopenFiles[WHITE] & e->semiopenFiles[BLACK]); - e->asymmetry = popcount( (e->passedPawns[WHITE] | e->passedPawns[BLACK]) - | (e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK])); - - return e; -} - - -/// Entry::shelter_storm() calculates shelter and storm penalties for the file -/// the king is on, as well as the two closest files. - -template -Value Entry::shelter_storm(const Position& pos, Square ksq) { - - constexpr Color Them = (Us == WHITE ? BLACK : WHITE); - constexpr Bitboard ShelterMask = - Us == WHITE ? make_bitboard(SQ_A2, SQ_B3, SQ_C2, SQ_F2, SQ_G3, SQ_H2) - : make_bitboard(SQ_A7, SQ_B6, SQ_C7, SQ_F7, SQ_G6, SQ_H7); - constexpr Bitboard StormMask = - Us == WHITE ? make_bitboard(SQ_A3, SQ_C3, SQ_F3, SQ_H3) - : make_bitboard(SQ_A6, SQ_C6, SQ_F6, SQ_H6); - - enum { BlockedByKing, Unopposed, BlockedByPawn, Unblocked }; - - File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq))); - Bitboard b = pos.pieces(PAWN) - & (forward_ranks_bb(Us, ksq) | rank_bb(ksq)) - & (adjacent_files_bb(center) | file_bb(center)); - Bitboard ourPawns = b & pos.pieces(Us); - Bitboard theirPawns = b & pos.pieces(Them); - Value safety = MaxSafetyBonus; - - for (File f = File(center - 1); f <= File(center + 1); ++f) - { - b = ourPawns & file_bb(f); - Rank rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1; - - b = theirPawns & file_bb(f); - Rank rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1; - - int d = std::min(f, ~f); - safety -= ShelterWeakness[f == file_of(ksq)][d][rkUs] - + StormDanger - [f == file_of(ksq) && rkThem == relative_rank(Us, ksq) + 1 ? BlockedByKing : - rkUs == RANK_1 ? Unopposed : - rkThem == rkUs + 1 ? BlockedByPawn : Unblocked] - [d][rkThem]; - } - - if (popcount((ourPawns & ShelterMask) | (theirPawns & StormMask)) == 5) - safety += Value(300); - - return safety; -} - - -/// Entry::do_king_safety() calculates a bonus for king safety. It is called only -/// when king square changes, which is about 20% of total king_safety() calls. - -template -Score Entry::do_king_safety(const Position& pos, Square ksq) { - - kingSquares[Us] = ksq; - castlingRights[Us] = pos.can_castle(Us); - int minKingPawnDistance = 0; - - Bitboard pawns = pos.pieces(Us, PAWN); - if (pawns) - while (!(DistanceRingBB[ksq][minKingPawnDistance++] & pawns)) {} - - Value bonus = shelter_storm(pos, ksq); - - // If we can castle use the bonus after the castling if it is bigger - if (pos.can_castle(MakeCastling::right)) - bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_G1))); - - if (pos.can_castle(MakeCastling::right)) - bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_C1))); - - return make_score(bonus, -16 * minKingPawnDistance); -} - -// Explicit template instantiation -template Score Entry::do_king_safety(const Position& pos, Square ksq); -template Score Entry::do_king_safety(const Position& pos, Square ksq); - -} // namespace Pawns