X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fpawns.cpp;h=eeabcbae84df6e81ed22a5bbff8c5c1b684cb1fd;hb=374c9e6b63d0e233371ae38cc054d885f2117884;hp=3ad88fb206aa011ece4fb6dca4c75acf17edb758;hpb=8447248705bc6cf91fc8cdbb519c31925862ea74;p=stockfish diff --git a/src/pawns.cpp b/src/pawns.cpp index 3ad88fb2..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); @@ -72,16 +85,14 @@ namespace { } -/// PawnInfoTable::get_pawn_info() takes a position object as input, computes +/// 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. -PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const { +PawnInfo* PawnInfoTable::pawn_info(const Position& pos) const { - assert(pos.is_ok()); - - Key key = pos.get_pawn_key(); + Key key = pos.pawn_key(); PawnInfo* pi = probe(key); // If pi->key matches the position's pawn hash key, it means that we @@ -118,7 +129,6 @@ template Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, Bitboard theirPawns, PawnInfo* pi) { - const BitCountType Max15 = CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15; const Color Them = (Us == WHITE ? BLACK : WHITE); Bitboard b; @@ -127,15 +137,15 @@ 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); @@ -148,22 +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); @@ -181,17 +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) != 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); + pi->passedPawns[Us] |= s; // Score this pawn if (isolated) @@ -212,27 +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(ksq); - r = ksq & (7 << 3); - for (int i = 0; i < 3; i++) - { - r += Shift; - shelter += BitCount8Bit[(pawns >> r) & 0xFF] * (64 >> 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];