X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=eeabcbae84df6e81ed22a5bbff8c5c1b684cb1fd;hp=0846344223137f93a2372c737b6a553609e8c5a4;hb=46a50cbf38bdfa5e48358585f4c98668507700ae;hpb=0ddf84870ad9f7fb4309e992e1e5eae968577958 diff --git a/src/pawns.cpp b/src/pawns.cpp index 08463442..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 @@ -17,27 +17,15 @@ along with this program. If not, see . */ - -//// -//// Includes -//// - #include -#include +#include "bitboard.h" #include "bitcount.h" #include "pawns.h" #include "position.h" - -//// -//// Local definitions -//// - namespace { - /// Constants and variables - #define S(mg, eg) make_score(mg, eg) // Doubled pawn penalty by opposed flag and file @@ -73,26 +61,39 @@ namespace { S(34,68), S(83,166), S(0, 0), S( 0, 0) }; + const Score PawnStructureWeight = S(233, 201); + #undef S -} + const File ShelterFile[8] = { FILE_B, FILE_B, FILE_C, FILE_D, FILE_E, FILE_F, FILE_G, FILE_G }; -//// -//// Functions -//// + 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; -/// PawnInfoTable::get_pawn_info() takes a position object as input, computes + 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); + } +} + + +/// 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 a hash table, so we don't have to recompute everything when the same +/// 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 { - - assert(pos.is_ok()); +PawnInfo* PawnInfoTable::pawn_info(const Position& pos) const { - Key key = pos.get_pawn_key(); - PawnInfo* pi = find(key); + Key key = pos.pawn_key(); + PawnInfo* pi = 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 @@ -100,11 +101,11 @@ PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const { if (pi->key == key) return pi; - // Clear the PawnInfo object, and set the key - memset(pi, 0, sizeof(PawnInfo)); - pi->halfOpenFiles[WHITE] = pi->halfOpenFiles[BLACK] = 0xFF; - pi->kingSquares[WHITE] = pi->kingSquares[BLACK] = SQ_NONE; + // 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); @@ -112,9 +113,12 @@ PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const { pi->pawnAttacks[WHITE] = ((wPawns << 9) & ~FileABB) | ((wPawns << 7) & ~FileHBB); pi->pawnAttacks[BLACK] = ((bPawns >> 7) & ~FileABB) | ((bPawns >> 9) & ~FileHBB); - // Evaluate pawns for both colors + // Evaluate pawns for both colors and weight the result pi->value = evaluate_pawns(pos, wPawns, bPawns, pi) - evaluate_pawns(pos, bPawns, wPawns, pi); + + pi->value = apply_weight(pi->value, PawnStructureWeight); + return pi; } @@ -123,53 +127,53 @@ PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const { template Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, - Bitboard theirPawns, PawnInfo* pi) const { + Bitboard theirPawns, PawnInfo* pi) { + + const Color Them = (Us == WHITE ? BLACK : WHITE); + Bitboard b; Square s; File f; Rank r; bool passed, isolated, doubled, opposed, chain, backward, candidate; Score value = SCORE_ZERO; - const BitCountType Max15 = CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15; - 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) == piece_of_color_and_type(Us, PAWN)); + 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); - // Our rank plus previous one. Used for chain detection. + // Our rank plus previous one. Used for chain detection b = rank_bb(r) | rank_bb(Us == WHITE ? r - Rank(1) : r + Rank(1)); - // Passed, isolated, doubled or member of a pawn - // chain (but not the backward one) ? + // 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)); 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 can capture an enemy pawn or if - // there are friendly pawns behind on neighboring files it cannot - // be backward either. + // If the pawn is passed, isolated, or member of a pawn chain it cannot + // 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(opposite_color(Us), s)) + && !(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); @@ -178,23 +182,26 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, while (!(b & (ourPawns | theirPawns))) Us == WHITE ? b <<= 8 : b >>= 8; - // The friendly pawn needs to be at least two ranks closer than the enemy - // pawn in order to help the potentially backward pawn advance. + // The friendly pawn needs to be at least two ranks closer than the + // enemy pawn in order to help the potentially backward pawn advance. backward = (b | (Us == WHITE ? b << 8 : b >> 8)) & theirPawns; } - assert(passed | opposed | (attack_span_mask(Us, s) & theirPawns)); + assert(opposed | passed | (attack_span_mask(Us, s) & theirPawns)); - // Test for candidate passed pawn - candidate = !(opposed | passed) - && (b = attack_span_mask(opposite_color(Us), s + pawn_push(Us)) & ourPawns) != EmptyBoardBB - && count_1s(b) >= count_1s(attack_span_mask(Us, s) & theirPawns); + // 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 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 + && popcount(b) >= popcount(attack_span_mask(Us, s) & theirPawns); - // Mark the pawn as passed. Pawn 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. + // 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) @@ -214,3 +221,59 @@ 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) { + int shelter = 0; + + if (relative_rank(Us, ksq) <= RANK_4) + { + 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]; +} + +// Explicit template instantiation +template Score PawnInfo::updateShelter(const Position& pos, Square ksq); +template Score PawnInfo::updateShelter(const Position& pos, Square ksq);