X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=eeabcbae84df6e81ed22a5bbff8c5c1b684cb1fd;hp=c652b371172560d5996ffee229f82a1b47338494;hb=cc2b3ece5c5d8d1183f8526fbb0ee4e1ea7a69fe;hpb=0a6532a39d2e2cfd92ba0a2c4fa8c6ad6c29b581 diff --git a/src/pawns.cpp b/src/pawns.cpp index c652b371..eeabcbae 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 @@ -65,6 +65,19 @@ namespace { #undef S + const File ShelterFile[8] = { FILE_B, FILE_B, FILE_C, FILE_D, FILE_E, FILE_F, FILE_G, FILE_G }; + + inline Value score_non_center_file(const Value v) { + return Value(v * 7 / 16); + } + + typedef Value V; + // Arrays are indexed by rank. Zeroth value is for when no pawn on that file. + const Value PawnShelter[8] = { V(141), V(0), V( 38), V(102), V(128), V(141), V(141), V(141) }; + const Value PawnStorm[8] = { V( 26), V(0), V(128), V( 51), V( 26), V( 0), V( 0), V( 0) }; + // We compute shelter as a penalty for the given color, but shelter is used as a bonus, so we invert it using this as the basis. + const Value PawnShelterBasis = PawnShelter[0] + score_non_center_file(PawnShelter[0]) * 2; + 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); @@ -116,7 +129,6 @@ template Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, Bitboard theirPawns, PawnInfo* pi) { - const BitCountType Max15 = Is64Bit ? CNT64_MAX15 : CNT32_MAX15; const Color Them = (Us == WHITE ? BLACK : WHITE); Bitboard b; @@ -146,22 +158,22 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, 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; + isolated = !(ourPawns & adjacent_files_bb(f)); + chain = ourPawns & adjacent_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); @@ -179,17 +191,17 @@ 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) != 0 - && count_1s(b) >= count_1s(attack_span_mask(Us, s) & theirPawns); + && 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); + pi->passedPawns[Us] |= s; // Score this pawn if (isolated) @@ -210,27 +222,53 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, return value; } +template +int computePawnShelter(const Position &pos, Square ksq) { + const Color Them = (Us == WHITE ? BLACK : WHITE); + const File kingFile = ShelterFile[file_of(ksq)]; + const Bitboard ourPawns = pos.pieces(PAWN, Us) & in_front_bb(Us, ksq); + const Bitboard theirPawns = pos.pieces(PAWN, Them) & (RankBB[rank_of(ksq)] | in_front_bb(Us, ksq)); + + int shelter = 0; + + // Compute king shelter and storm values for the file the king is on, as well as the two adjacent files. + for (int fileOffset = -1; fileOffset <= 1; fileOffset++) { + // Shelter takes full penalty for center file, otherwise it's half penalty + Bitboard shelterFile = ourPawns & FileBB[kingFile + fileOffset]; + Rank shelterClosest = shelterFile ? relative_rank(shelterFile) + : RANK_1; + + shelter += fileOffset == 0 ? PawnShelter[shelterClosest] + : score_non_center_file(PawnShelter[shelterClosest]); + + // Storm takes full penalty, unless there is an enemy pawn blocking us + Bitboard stormFile = theirPawns & FileBB[kingFile + fileOffset]; + Rank stormClosest = stormFile ? relative_rank(stormFile) + : RANK_1; + + shelter += shelterClosest + 1 == stormClosest ? PawnStorm[stormClosest] / 2 + : PawnStorm[stormClosest]; + } + + return shelter; +} /// PawnInfo::updateShelter() calculates and caches king shelter. It is called /// only when king square changes, about 20% of total king_shelter() calls. template Score PawnInfo::updateShelter(const Position& pos, Square ksq) { - - const int Shift = (Us == WHITE ? 8 : -8); - - Bitboard pawns; - int r, shelter = 0; + int shelter = 0; if (relative_rank(Us, ksq) <= RANK_4) { - pawns = pos.pieces(PAWN, Us) & this_and_neighboring_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 = computePawnShelter(pos, ksq); + if (pos.can_castle(Us == WHITE ? WHITE_OO : BLACK_OO)) + shelter = std::min(shelter, computePawnShelter(pos, relative_square(Us, SQ_G1))); + if (pos.can_castle(Us == WHITE ? WHITE_OOO : BLACK_OOO)) + shelter = std::min(shelter, computePawnShelter(pos, relative_square(Us, SQ_C1))); + shelter = PawnShelterBasis - shelter; } + kingSquares[Us] = ksq; kingShelters[Us] = make_score(shelter, 0); return kingShelters[Us];