X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fpawns.cpp;h=868d0c8ef0fb9781279d7e98d41ab5025da4b0fa;hb=HEAD;hp=23d00bdecd5eb6206f11e20a31b768342481f02d;hpb=190d2ea4bc433a0c047ede87f5d9cc241de2b1e2;p=stockfish diff --git a/src/pawns.cpp b/src/pawns.cpp deleted file mode 100644 index 23d00bde..00000000 --- a/src/pawns.cpp +++ /dev/null @@ -1,291 +0,0 @@ -/* - Stockfish, a UCI chess playing engine derived from Glaurung 2.1 - Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad - Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, 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 - the Free Software Foundation, either version 3 of the License, or - (at your option) any later version. - - Stockfish is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - GNU General Public License for more details. - - You should have received a copy of the GNU General Public License - along with this program. If not, see . -*/ - -#include -#include - -#include "bitboard.h" -#include "pawns.h" -#include "position.h" -#include "thread.h" - -namespace { - - #define V Value - #define S(mg, eg) make_score(mg, eg) - - // Isolated pawn penalty by opposed flag - const Score Isolated[2] = { S(45, 40), S(30, 27) }; - - // Backward pawn penalty by opposed flag - const Score Backward[2] = { S(56, 33), S(41, 19) }; - - // Unsupported pawn penalty for pawns which are neither isolated or backward, - // by number of pawns it supports [less than 2 / exactly 2]. - const Score Unsupported[2] = { S(17, 8), S(21, 12) }; - - // Connected pawn bonus by opposed, phalanx, twice supported and rank - Score Connected[2][2][2][RANK_NB]; - - // Doubled pawn penalty - const Score Doubled = S(18,38); - - // Lever bonus by rank - const Score Lever[RANK_NB] = { - S( 0, 0), S( 0, 0), S(0, 0), S(0, 0), - S(17, 16), S(33, 32), S(0, 0), S(0, 0) }; - - // Weakness of our pawn shelter in front of the king by [distance from edge][rank] - const Value ShelterWeakness[][RANK_NB] = { - { V( 97), V(21), V(26), V(51), V(87), V( 89), V( 99) }, - { V(120), V( 0), V(28), V(76), V(88), V(103), V(104) }, - { V(101), V( 7), V(54), V(78), V(77), V( 92), V(101) }, - { V( 80), V(11), V(44), V(68), V(87), V( 90), V(119) } }; - - // Danger of enemy pawns moving toward our king by [type][distance from edge][rank] - const Value StormDanger[][4][RANK_NB] = { - { { V( 0), V( 67), V( 134), V(38), V(32) }, - { V( 0), V( 57), V( 139), V(37), V(22) }, - { V( 0), V( 43), V( 115), V(43), V(27) }, - { V( 0), V( 68), V( 124), V(57), V(32) } }, - { { V(20), V( 43), V( 100), V(56), V(20) }, - { V(23), V( 20), V( 98), V(40), V(15) }, - { V(23), V( 39), V( 103), V(36), V(18) }, - { V(28), V( 19), V( 108), V(42), V(26) } }, - { { V( 0), V( 0), V( 75), V(14), V( 2) }, - { V( 0), V( 0), V( 150), V(30), V( 4) }, - { V( 0), V( 0), V( 160), V(22), V( 5) }, - { V( 0), V( 0), V( 166), V(24), V(13) } }, - { { V( 0), V(-283), V(-281), V(57), V(31) }, - { V( 0), V( 58), V( 141), V(39), V(18) }, - { V( 0), V( 65), V( 142), V(48), V(32) }, - { V( 0), V( 60), V( 126), V(51), V(19) } } }; - - // Max bonus for king safety. Corresponds to start position with all the pawns - // in front of the king and no enemy pawn on the horizon. - const Value MaxSafetyBonus = V(258); - - #undef S - #undef V - - template - Score evaluate(const Position& pos, Pawns::Entry* e) { - - const Color Them = (Us == WHITE ? BLACK : WHITE); - const Square Up = (Us == WHITE ? DELTA_N : DELTA_S); - const Square Right = (Us == WHITE ? DELTA_NE : DELTA_SW); - const Square Left = (Us == WHITE ? DELTA_NW : DELTA_SE); - - Bitboard b, neighbours, stoppers, doubled, supported, phalanx; - Square s; - bool opposed, lever, connected, backward; - Score score = SCORE_ZERO; - const Square* pl = pos.squares(Us); - const Bitboard* pawnAttacksBB = StepAttacksBB[make_piece(Us, PAWN)]; - - Bitboard ourPawns = pos.pieces(Us , PAWN); - Bitboard theirPawns = pos.pieces(Them, PAWN); - - e->passedPawns[Us] = e->pawnAttacksSpan[Us] = 0; - e->kingSquares[Us] = SQ_NONE; - e->semiopenFiles[Us] = 0xFF; - e->pawnAttacks[Us] = shift_bb(ourPawns) | shift_bb(ourPawns); - e->pawnsOnSquares[Us][BLACK] = popcount(ourPawns & DarkSquares); - e->pawnsOnSquares[Us][WHITE] = pos.count(Us) - e->pawnsOnSquares[Us][BLACK]; - - // Loop through all pawns of the current color and score each pawn - while ((s = *pl++) != SQ_NONE) - { - assert(pos.piece_on(s) == make_piece(Us, PAWN)); - - File f = file_of(s); - - e->semiopenFiles[Us] &= ~(1 << f); - e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s); - - // Flag the pawn - opposed = theirPawns & forward_bb(Us, s); - stoppers = theirPawns & passed_pawn_mask(Us, s); - lever = theirPawns & pawnAttacksBB[s]; - doubled = ourPawns & (s + Up); - neighbours = ourPawns & adjacent_files_bb(f); - phalanx = neighbours & rank_bb(s); - supported = neighbours & rank_bb(s - Up); - connected = supported | phalanx; - - // A pawn is backward when it is behind all pawns of the same color on the - // adjacent files and cannot be safely advanced. - if (!neighbours || lever || relative_rank(Us, s) >= RANK_5) - backward = false; - else - { - // Find the backmost rank with neighbours or stoppers - b = rank_bb(backmost_sq(Us, neighbours | stoppers)); - - // The pawn is backward when it cannot safely progress to that rank: - // either there is a stopper in the way on this rank, or there is a - // stopper on adjacent file which controls the way to that rank. - backward = (b | shift_bb(b & adjacent_files_bb(f))) & stoppers; - - assert(!backward || !(pawn_attack_span(Them, s + Up) & neighbours)); - } - - // Passed pawns will be properly scored in evaluation because we need - // full attack info to evaluate them. - if (!stoppers && !(ourPawns & forward_bb(Us, s))) - e->passedPawns[Us] |= s; - - // Score this pawn - if (!neighbours) - score -= Isolated[opposed]; - - else if (backward) - score -= Backward[opposed]; - - else if (!supported) - score -= Unsupported[more_than_one(neighbours & pawnAttacksBB[s])]; - - if (connected) - score += Connected[opposed][!!phalanx][more_than_one(supported)][relative_rank(Us, s)]; - - if (doubled) - score -= Doubled; - - if (lever) - score += Lever[relative_rank(Us, s)]; - } - - b = e->semiopenFiles[Us] ^ 0xFF; - e->pawnSpan[Us] = b ? int(msb(b) - lsb(b)) : 0; - - return score; - } - -} // namespace - -namespace Pawns { - -/// Pawns::init() initializes some tables needed by evaluation. Instead of using -/// hard-coded tables, when makes sense, we prefer to calculate them with a formula -/// to reduce independent parameters and to allow easier tuning and better insight. - -void init() -{ - static const int Seed[RANK_NB] = { 0, 8, 19, 13, 71, 94, 169, 324 }; - - for (int opposed = 0; opposed <= 1; ++opposed) - for (int phalanx = 0; phalanx <= 1; ++phalanx) - for (int apex = 0; apex <= 1; ++apex) - for (Rank r = RANK_2; r < RANK_8; ++r) - { - int v = (Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0)) >> opposed; - v += (apex ? v / 2 : 0); - Connected[opposed][phalanx][apex][r] = make_score(v, v * 5 / 8); - } -} - - -/// Pawns::probe() looks up the current position's pawns configuration in -/// the pawns hash table. It returns a pointer to the Entry if the position -/// is found. Otherwise a new Entry is computed and stored there, so we don't -/// have to recompute all when the same pawns configuration occurs again. - -Entry* probe(const Position& pos) { - - Key key = pos.pawn_key(); - Entry* e = pos.this_thread()->pawnsTable[key]; - - if (e->key == key) - return e; - - e->key = key; - e->score = evaluate(pos, e) - evaluate(pos, e); - e->asymmetry = popcount(e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK]); - return e; -} - - -/// Entry::shelter_storm() calculates shelter and storm penalties for the file -/// the king is on, as well as the two adjacent files. - -template -Value Entry::shelter_storm(const Position& pos, Square ksq) { - - const Color Them = (Us == WHITE ? BLACK : WHITE); - - enum { NoFriendlyPawn, Unblocked, BlockedByPawn, BlockedByKing }; - - Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, rank_of(ksq)) | rank_bb(ksq)); - Bitboard ourPawns = b & pos.pieces(Us); - Bitboard theirPawns = b & pos.pieces(Them); - Value safety = MaxSafetyBonus; - File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq))); - - for (File f = center - File(1); f <= center + File(1); ++f) - { - b = ourPawns & file_bb(f); - Rank rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1; - - b = theirPawns & file_bb(f); - Rank rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1; - - safety -= ShelterWeakness[std::min(f, FILE_H - f)][rkUs] - + StormDanger - [f == file_of(ksq) && rkThem == relative_rank(Us, ksq) + 1 ? BlockedByKing : - rkUs == RANK_1 ? NoFriendlyPawn : - rkThem == rkUs + 1 ? BlockedByPawn : Unblocked] - [std::min(f, FILE_H - f)][rkThem]; - } - - return safety; -} - - -/// Entry::do_king_safety() calculates a bonus for king safety. It is called only -/// when king square changes, which is about 20% of total king_safety() calls. - -template -Score Entry::do_king_safety(const Position& pos, Square ksq) { - - kingSquares[Us] = ksq; - castlingRights[Us] = pos.can_castle(Us); - int minKingPawnDistance = 0; - - Bitboard pawns = pos.pieces(Us, PAWN); - if (pawns) - while (!(DistanceRingBB[ksq][minKingPawnDistance++] & pawns)) {} - - Value bonus = shelter_storm(pos, ksq); - - // If we can castle use the bonus after the castling if it is bigger - if (pos.can_castle(MakeCastling::right)) - bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_G1))); - - if (pos.can_castle(MakeCastling::right)) - bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_C1))); - - return make_score(bonus, -16 * minKingPawnDistance); -} - -// Explicit template instantiation -template Score Entry::do_king_safety(const Position& pos, Square ksq); -template Score Entry::do_king_safety(const Position& pos, Square ksq); - -} // namespace Pawns