From: Marco Costalba Date: Fri, 14 May 2010 08:42:53 +0000 (+0200) Subject: Introduce evaluate_pawn_storm() to unify redundant code X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=ea5af9b8c0822ded58d587a89c9b43f163552c1d Introduce evaluate_pawn_storm() to unify redundant code No functional change. Signed-off-by: Marco Costalba --- diff --git a/src/pawns.cpp b/src/pawns.cpp index 23884204..0ccfe809 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -143,7 +143,7 @@ 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()); @@ -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); @@ -205,60 +205,15 @@ 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. + // Our rank plus previous one. Used for chain detection. b = rank_bb(r) | rank_bb(r + (Us == WHITE ? -1 : 1)); // Passed, isolated, doubled or member of a pawn @@ -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 = outpost_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) { diff --git a/src/pawns.h b/src/pawns.h index 2dc86684..f9ffba0c 100644 --- a/src/pawns.h +++ b/src/pawns.h @@ -78,14 +78,19 @@ private: class PawnInfoTable { + enum SideType { KingSide, QueenSide }; + public: PawnInfoTable(unsigned numOfEntries); ~PawnInfoTable(); - PawnInfo* get_pawn_info(const Position& pos); + PawnInfo* get_pawn_info(const Position& pos) const; private: template - Score evaluate_pawns(const Position& pos, Bitboard ourPawns, Bitboard theirPawns, PawnInfo* pi); + Score evaluate_pawns(const Position& pos, Bitboard ourPawns, Bitboard theirPawns, PawnInfo* pi) const; + + template + int evaluate_pawn_storm(Square s, Rank r, File f, Bitboard theirPawns) const; unsigned size; PawnInfo* entries;