X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=b5c377efcd1e30221a514ea050e8787ba8b5a692;hp=23884204a6f96c223b421ba4cd3f692104ef8f55;hb=c295599e4ad481f677b14cb0be14174b61ebff81;hpb=0b49ec98225041533f02c60c70f71322cbba38cd diff --git a/src/pawns.cpp b/src/pawns.cpp index 23884204..b5c377ef 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -94,8 +94,8 @@ namespace { }; // Pawn storm open file bonuses by file - const int16_t KStormOpenFileBonus[8] = { 31, 31, 18, 0, 0, 0, 0, 0 }; - const int16_t QStormOpenFileBonus[8] = { 0, 0, 0, 0, 0, 26, 42, 26 }; + const int16_t QStormOpenFileBonus[8] = { 31, 31, 18, 0, 0, 0, 0, 0 }; + const int16_t KStormOpenFileBonus[8] = { 0, 0, 0, 0, 0, 26, 42, 26 }; // Pawn storm lever bonuses by file const int StormLeverBonus[8] = { -8, -8, -13, 0, 0, -13, -8, -8 }; @@ -143,12 +143,12 @@ void PawnInfo::clear() { /// in a 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) { +PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const { assert(pos.is_ok()); Key key = pos.get_pawn_key(); - int index = int(key & (size - 1)); + unsigned index = unsigned(key & (size - 1)); PawnInfo* pi = entries + index; // If pi->key matches the position's pawn hash key, it means that we @@ -178,13 +178,13 @@ PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) { template Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, - Bitboard theirPawns, PawnInfo* pi) { + Bitboard theirPawns, PawnInfo* pi) const { Bitboard b; - Square s, s2; + Square s; File f; - Rank r, r2; + Rank r; + int bonus; bool passed, isolated, doubled, opposed, chain, backward, candidate; - int bonus, v; Score value = make_score(0, 0); const Square* ptr = pos.piece_list_begin(Us, PAWN); @@ -205,61 +205,16 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN)); - // We calculate kingside and queenside pawn storm scores for - // both colors. These are used when evaluating middle game - // positions with opposite side castling. - // - // Each pawn is given a base score given by a piece square table - // (KStormTable[] or QStormTable[]). Pawns which seem to have good - // chances of creating an open file by exchanging itself against - // an enemy pawn on an adjacent file gets an additional bonus. - - // Kingside pawn storms - bonus = KStormTable[relative_square(Us, s)]; - if (f >= FILE_F) - { - b = outpost_mask(Us, s) & theirPawns & (FileFBB | FileGBB | FileHBB); - while (b) - { - // Give a bonus according to the distance of the nearest enemy pawn - s2 = pop_1st_bit(&b); - r2 = square_rank(s2); - v = StormLeverBonus[f] - 2 * rank_distance(r, r2); - - // 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))) - v *= (square_file(s2) == FILE_H ? 4 : 2); - - bonus += v; - } - } - pi->ksStormValue[Us] += bonus; + // Calculate kingside and queenside pawn storm scores for both colors to be + // used when evaluating middle game positions with opposite side castling. + bonus = (f >= FILE_F ? evaluate_pawn_storm(s, r, f, theirPawns) : 0); + pi->ksStormValue[Us] += KStormTable[relative_square(Us, s)] + bonus; - // Queenside pawn storms - bonus = QStormTable[relative_square(Us, s)]; - if (f <= FILE_C) - { - b = outpost_mask(Us, s) & theirPawns & (FileABB | FileBBB | FileCBB); - while (b) - { - // Give a bonus according to the distance of the nearest enemy pawn - s2 = pop_1st_bit(&b); - r2 = square_rank(s2); - v = StormLeverBonus[f] - 4 * rank_distance(r, r2); - - // 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))) - v *= (square_file(s2) == FILE_A ? 4 : 2); - - bonus += v; - } - } - pi->qsStormValue[Us] += bonus; + bonus = (f <= FILE_C ? evaluate_pawn_storm(s, r, f, theirPawns) : 0); + pi->qsStormValue[Us] += QStormTable[relative_square(Us, s)] + bonus; - // Our rank and previous one. Used for chain detection. - b = rank_bb(r) | rank_bb(r + (Us == WHITE ? -1 : 1)); + // Our rank plus previous one. Used for chain detection. + b = rank_bb(r) | rank_bb(Us == WHITE ? r - 1 : r + 1); // Passed, isolated, doubled or member of a pawn // chain (but not the backward one) ? @@ -271,15 +226,15 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, // 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 ( (passed | isolated | chain) - || (ourPawns & outpost_mask(opposite_color(Us), s)) - || (pos.attacks_from(s, Us) & theirPawns)) - backward = false; - else + if ( !(passed | isolated | chain) + && !(ourPawns & attack_span_mask(opposite_color(Us), 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 @@ -297,12 +252,12 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, backward = (b | (Us == WHITE ? b << 8 : b >> 8)) & theirPawns; } + assert(passed | opposed | (attack_span_mask(Us, s) & theirPawns)); + // Test for candidate passed pawn - candidate = !passed - && !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); + candidate = !(opposed | passed) + && (b = attack_span_mask(opposite_color(Us), s + pawn_push(Us)) & ourPawns) != EmptyBoardBB + && count_1s_max_15(b) >= count_1s_max_15(attack_span_mask(Us, s) & theirPawns); // In order to prevent doubled passed pawns from receiving a too big // bonus, only the frontmost passed pawn on each file is considered as @@ -319,7 +274,7 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, if (isolated) { value -= IsolatedPawnPenalty[f]; - if (!(theirPawns & file_bb(f))) + if (!opposed) value -= IsolatedPawnPenalty[f] / 2; } if (doubled) @@ -328,7 +283,7 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, if (backward) { value -= BackwardPawnPenalty[f]; - if (!(theirPawns & file_bb(f))) + if (!opposed) value -= BackwardPawnPenalty[f] / 2; } if (chain) @@ -342,6 +297,39 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, } +/// PawnInfoTable::evaluate_pawn_storm() evaluates each pawn which seems +/// to have good chances of creating an open file by exchanging itself +/// against an enemy pawn on an adjacent file. + +template +int PawnInfoTable::evaluate_pawn_storm(Square s, Rank r, File f, Bitboard theirPawns) const { + + const Bitboard StormFilesBB = (Side == KingSide ? FileFBB | FileGBB | FileHBB + : FileABB | FileBBB | FileCBB); + const int K = (Side == KingSide ? 2 : 4); + const File RookFile = (Side == KingSide ? FILE_H : FILE_A); + + Bitboard b = attack_span_mask(Us, s) & theirPawns & StormFilesBB; + int bonus = 0; + + while (b) + { + // Give a bonus according to the distance of the nearest enemy pawn + Square s2 = pop_1st_bit(&b); + Rank r2 = square_rank(s2); + int v = StormLeverBonus[f] - K * rank_distance(r, r2); + + // 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))) + v *= (square_file(s2) == RookFile ? 4 : 2); + + bonus += v; + } + return bonus; +} + + /// PawnInfo::updateShelter calculates and caches king shelter. It is called /// only when king square changes, about 20% of total get_king_shelter() calls. int PawnInfo::updateShelter(const Position& pos, Color c, Square ksq) {