X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=65bb3dbaa38d1dcc9224639f6d0c5bf4ae860313;hp=58f93713bf80080ab526668d5d9fd93e16415957;hb=97f5d19bdc0439f297ad11dd59997aba9342ce93;hpb=4c58db0dab8e80cf8e57beef6ed9d3a8e2c56795 diff --git a/src/pawns.cpp b/src/pawns.cpp index 58f93713..65bb3dba 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) 2008-2009 Marco Costalba + Copyright (C) 2008-2010 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 @@ -70,6 +70,13 @@ namespace { S(34,68), S(83,166), S(0, 0), S( 0, 0) }; + // UnpairedPawnsTable[] gives a score according to the number + // of panws that do not have an enemy pawn in front of them. + const int UnpairedPawnsTable[16] = { 32, 48, 64, 80, 96, 112, 128, 128, 128 }; + + // PawnsQtyTable[] gives a score according to the number of panws + const int PawnsQtyTable[16] = { 16, 16, 16, 16, 16, 16, 16, 16, 16 }; + // Pawn storm tables for positions with opposite castling const int QStormTable[64] = { 0, 0, 0, 0, 0, 0, 0, 0, @@ -183,10 +190,11 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, Square s; File f; Rank r; - bool passed, isolated, doubled, chain, backward, candidate; + bool passed, isolated, doubled, opposed, chain, backward, candidate; int bonus; Score value = make_score(0, 0); const Square* ptr = pos.piece_list_begin(Us, PAWN); + int unpairedPawnsNum = pos.piece_count(Us, PAWN); // Initialize pawn storm scores by giving bonuses for open files for (f = FILE_A; f <= FILE_H; f++) @@ -206,9 +214,14 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN)); // Passed, isolated or doubled pawn? - passed = Position::pawn_is_passed(theirPawns, Us, s); - isolated = Position::pawn_is_isolated(ourPawns, s); - doubled = Position::pawn_is_doubled(ourPawns, Us, s); + passed = !(theirPawns & passed_pawn_mask(Us, s)); + isolated = !(ourPawns & neighboring_files_bb(s)); + doubled = ourPawns & squares_behind(Us, s); + opposed = theirPawns & squares_in_front_of(Us, s); + + // Decrease number of unpaired pawns + if (opposed) + unpairedPawnsNum--; // We calculate kingside and queenside pawn storm // scores for both colors. These are used when evaluating @@ -226,21 +239,16 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, Bitboard b = outpost_mask(Us, s) & theirPawns & (FileFBB | FileGBB | FileHBB); while (b) { + // Give a bonus according to the distance of the nearest enemy pawn Square s2 = pop_1st_bit(&b); + int v = StormLeverBonus[f] - 2 * square_distance(s, s2); + + // If enemy pawn has no pawn beside itself is particularly vulnerable. + // Big bonus, especially against a weakness on the rook file if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2))) - { - // The enemy pawn has no pawn beside itself, which makes it - // particularly vulnerable. Big bonus, especially against a - // weakness on the rook file. - if (square_file(s2) == FILE_H) - bonus += 4*StormLeverBonus[f] - 8*square_distance(s, s2); - else - bonus += 2*StormLeverBonus[f] - 4*square_distance(s, s2); - } else - // There is at least one enemy pawn beside the enemy pawn we look - // at, which means that the pawn has somewhat better chances of - // defending itself by advancing. Smaller bonus. - bonus += StormLeverBonus[f] - 2*square_distance(s, s2); + v *= (square_file(s2) == FILE_H ? 4 : 2); + + bonus += v; } } pi->ksStormValue[Us] += bonus; @@ -252,21 +260,16 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, Bitboard b = outpost_mask(Us, s) & theirPawns & (FileABB | FileBBB | FileCBB); while (b) { + // Give a bonus according to the distance of the nearest enemy pawn Square s2 = pop_1st_bit(&b); + int v = StormLeverBonus[f] - 4 * square_distance(s, s2); + + // If enemy pawn has no pawn beside itself is particularly vulnerable. + // Big bonus, especially against a weakness on the rook file if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2))) - { - // The enemy pawn has no pawn beside itself, which makes it - // particularly vulnerable. Big bonus, especially against a - // weakness on the rook file. - if (square_file(s2) == FILE_A) - bonus += 4*StormLeverBonus[f] - 16*square_distance(s, s2); - else - bonus += 2*StormLeverBonus[f] - 8*square_distance(s, s2); - } else - // There is at least one enemy pawn beside the enemy pawn we look - // at, which means that the pawn has somewhat better chances of - // defending itself by advancing. Smaller bonus. - bonus += StormLeverBonus[f] - 4*square_distance(s, s2); + v *= (square_file(s2) == FILE_A ? 4 : 2); + + bonus += v; } } pi->qsStormValue[Us] += bonus; @@ -309,7 +312,7 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, // Test for candidate passed pawn candidate = !passed - && !(theirPawns & file_bb(f)) + && !opposed && ( count_1s_max_15(neighboring_files_bb(f) & (behind_bb(Us, r) | rank_bb(r)) & ourPawns) - count_1s_max_15(neighboring_files_bb(f) & in_front_bb(Us, r) & theirPawns) >= 0); @@ -346,6 +349,9 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, value += CandidateBonus[relative_rank(Us, s)]; } + // Calculate a scale factor to be used to evaluate if position is drawish + pi->factor[Us] = UnpairedPawnsTable[unpairedPawnsNum] * PawnsQtyTable[pos.piece_count(Us, PAWN)] / 16; + return value; }