X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=ed83fde72e5980d2a0cd8ff20f2df7f724b5675f;hp=a2063a8f8323cd9ad420e81d8cfe60cd93099ff6;hb=HEAD;hpb=5c58f6712667076babe9ebaac1689436721c42be diff --git a/src/pawns.cpp b/src/pawns.cpp deleted file mode 100644 index a2063a8f..00000000 --- a/src/pawns.cpp +++ /dev/null @@ -1,261 +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) 2015-2020 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) - - // Pawn penalties - constexpr Score Backward = S( 9, 24); - constexpr Score BlockedStorm = S(82, 82); - constexpr Score Doubled = S(11, 56); - constexpr Score Isolated = S( 5, 15); - constexpr Score WeakLever = S( 0, 56); - constexpr Score WeakUnopposed = S(13, 27); - - // Connected pawn bonus - constexpr int Connected[RANK_NB] = { 0, 7, 8, 12, 29, 48, 86 }; - - // Strength of pawn shelter for our king by [distance from edge][rank]. - // RANK_1 = 0 is used for files where we have no pawn, or pawn is behind our king. - constexpr Value ShelterStrength[int(FILE_NB) / 2][RANK_NB] = { - { V( -6), V( 81), V( 93), V( 58), V( 39), V( 18), V( 25) }, - { V(-43), V( 61), V( 35), V(-49), V(-29), V(-11), V( -63) }, - { V(-10), V( 75), V( 23), V( -2), V( 32), V( 3), V( -45) }, - { V(-39), V(-13), V(-29), V(-52), V(-48), V(-67), V(-166) } - }; - - // Danger of enemy pawns moving toward our king by [distance from edge][rank]. - // RANK_1 = 0 is used for files where the enemy has no pawn, or their pawn - // is behind our king. Note that UnblockedStorm[0][1-2] accommodate opponent pawn - // on edge, likely blocked by our king. - constexpr Value UnblockedStorm[int(FILE_NB) / 2][RANK_NB] = { - { V( 85), V(-289), V(-166), V(97), V(50), V( 45), V( 50) }, - { V( 46), V( -25), V( 122), V(45), V(37), V(-10), V( 20) }, - { V( -6), V( 51), V( 168), V(34), V(-2), V(-22), V(-14) }, - { V(-15), V( -11), V( 101), V( 4), V(11), V(-15), V(-29) } - }; - - #undef S - #undef V - - template - Score evaluate(const Position& pos, Pawns::Entry* e) { - - constexpr Color Them = ~Us; - constexpr Direction Up = pawn_push(Us); - - Bitboard neighbours, stoppers, support, phalanx, opposed; - Bitboard lever, leverPush, blocked; - Square s; - bool backward, passed, doubled; - Score score = SCORE_ZERO; - const Square* pl = pos.squares(Us); - - Bitboard ourPawns = pos.pieces( Us, PAWN); - Bitboard theirPawns = pos.pieces(Them, PAWN); - - Bitboard doubleAttackThem = pawn_double_attacks_bb(theirPawns); - - e->passedPawns[Us] = 0; - e->kingSquares[Us] = SQ_NONE; - e->pawnAttacks[Us] = e->pawnAttacksSpan[Us] = pawn_attacks_bb(ourPawns); - e->blockedCount[Us] = 0; - - // 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)); - - Rank r = relative_rank(Us, s); - - // Flag the pawn - opposed = theirPawns & forward_file_bb(Us, s); - blocked = theirPawns & (s + Up); - stoppers = theirPawns & passed_pawn_span(Us, s); - lever = theirPawns & PawnAttacks[Us][s]; - leverPush = theirPawns & PawnAttacks[Us][s + Up]; - doubled = ourPawns & (s - Up); - neighbours = ourPawns & adjacent_files_bb(s); - phalanx = neighbours & rank_bb(s); - support = neighbours & rank_bb(s - Up); - - e->blockedCount[Us] += bool(blocked); - - // A pawn is backward when it is behind all pawns of the same color on - // the adjacent files and cannot safely advance. - backward = !(neighbours & forward_ranks_bb(Them, s + Up)) - && (leverPush | blocked); - - // Compute additional span if pawn is not backward nor blocked - if (!backward && !blocked) - e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s); - - // A pawn is passed if one of the three following conditions is true: - // (a) there is no stoppers except some levers - // (b) the only stoppers are the leverPush, but we outnumber them - // (c) there is only one front stopper which can be levered. - // (Refined in Evaluation::passed) - passed = !(stoppers ^ lever) - || ( !(stoppers ^ leverPush) - && popcount(phalanx) >= popcount(leverPush)) - || ( stoppers == blocked && r >= RANK_5 - && (shift(support) & ~(theirPawns | doubleAttackThem))); - - passed &= !(forward_file_bb(Us, s) & ourPawns); - - // Passed pawns will be properly scored later in evaluation when we have - // full attack info. - if (passed) - e->passedPawns[Us] |= s; - - // Score this pawn - if (support | phalanx) - { - int v = Connected[r] * (4 + 2 * bool(phalanx) - 2 * bool(opposed) - bool(blocked)) / 2 - + 21 * popcount(support); - - score += make_score(v, v * (r - 2) / 4); - } - - else if (!neighbours) - score -= Isolated - + WeakUnopposed * !opposed; - - else if (backward) - score -= Backward - + WeakUnopposed * !opposed; - - if (!support) - score -= Doubled * doubled - + WeakLever * more_than_one(lever); - } - - return score; - } - -} // namespace - -namespace Pawns { - -/// 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->scores[WHITE] = evaluate(pos, e); - e->scores[BLACK] = evaluate(pos, e); - - return e; -} - - -/// Entry::evaluate_shelter() calculates the shelter bonus and the storm -/// penalty for a king, looking at the king file and the two closest files. - -template -Score Entry::evaluate_shelter(const Position& pos, Square ksq) { - - constexpr Color Them = ~Us; - - Bitboard b = pos.pieces(PAWN) & ~forward_ranks_bb(Them, ksq); - Bitboard ourPawns = b & pos.pieces(Us); - Bitboard theirPawns = b & pos.pieces(Them); - - Score bonus = make_score(5, 5); - - File center = Utility::clamp(file_of(ksq), FILE_B, FILE_G); - for (File f = File(center - 1); f <= File(center + 1); ++f) - { - b = ourPawns & file_bb(f); - int ourRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : 0; - - b = theirPawns & file_bb(f); - int theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : 0; - - File d = File(edge_distance(f)); - bonus += make_score(ShelterStrength[d][ourRank], 0); - - if (ourRank && (ourRank == theirRank - 1)) - bonus -= BlockedStorm * int(theirRank == RANK_3); - else - bonus -= make_score(UnblockedStorm[d][theirRank], 0); - } - - return bonus; -} - - -/// 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 = pos.square(Us); - kingSquares[Us] = ksq; - castlingRights[Us] = pos.castling_rights(Us); - auto compare = [](Score a, Score b) { return mg_value(a) < mg_value(b); }; - - Score shelter = evaluate_shelter(pos, ksq); - - // If we can castle use the bonus after castling if it is bigger - - if (pos.can_castle(Us & KING_SIDE)) - shelter = std::max(shelter, evaluate_shelter(pos, relative_square(Us, SQ_G1)), compare); - - if (pos.can_castle(Us & QUEEN_SIDE)) - shelter = std::max(shelter, evaluate_shelter(pos, relative_square(Us, SQ_C1)), compare); - - // In endgame we like to bring our king near our closest pawn - Bitboard pawns = pos.pieces(Us, PAWN); - int minPawnDist = pawns ? 8 : 0; - - if (pawns & PseudoAttacks[KING][ksq]) - minPawnDist = 1; - else while (pawns) - minPawnDist = std::min(minPawnDist, distance(ksq, pop_lsb(&pawns))); - - return shelter - make_score(0, 16 * minPawnDist); -} - -// Explicit template instantiation -template Score Entry::do_king_safety(const Position& pos); -template Score Entry::do_king_safety(const Position& pos); - -} // namespace Pawns