X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=89911e50b69bd848d59bf9ae01c2549112f72f60;hp=5c7a55be74cccabb5951bf0d764db20f77060f67;hb=5f12069cbfc882fdf989d04618ad9c33e603c419;hpb=14aebe2b7ce1fa3ba7570168115ac3b0077ea97a diff --git a/src/pawns.cpp b/src/pawns.cpp index 5c7a55be..89911e50 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) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2014 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 @@ -49,8 +49,8 @@ namespace { { S(20, 28), S(29, 31), S(33, 31), S(33, 31), S(33, 31), S(33, 31), S(29, 31), S(20, 28) } }; - // Pawn chain membership bonus by file and rank (initialized by formula) - Score ChainMember[FILE_NB][RANK_NB]; + // Connected pawn bonus by file and rank (initialized by formula) + Score Connected[FILE_NB][RANK_NB]; // Candidate passed pawn bonus by rank const Score CandidatePassed[RANK_NB] = { @@ -58,7 +58,7 @@ namespace { S(34,68), S(83,166), S(0, 0), S( 0, 0) }; // Bonus for file distance of the two outermost pawns - const Score PawnsFileSpan = S(0, 10); + const Score PawnsFileSpan = S(0, 15); // Weakness of our pawn shelter in front of the king indexed by [rank] const Value ShelterWeakness[RANK_NB] = @@ -89,7 +89,7 @@ namespace { Bitboard b; Square s; File f; - bool passed, isolated, doubled, opposed, chain, backward, candidate; + bool passed, isolated, doubled, opposed, connected, backward, candidate; Score value = SCORE_ZERO; const Square* pl = pos.list(Us); @@ -113,22 +113,22 @@ namespace { // This file cannot be semi-open e->semiopenFiles[Us] &= ~(1 << f); - // Our rank plus previous one. Used for chain detection + // Our rank plus previous one b = rank_bb(s) | rank_bb(s - pawn_push(Us)); - // Flag the pawn as passed, isolated, doubled or member of a pawn - // chain (but not the backward one). - chain = ourPawns & adjacent_files_bb(f) & b; - isolated = !(ourPawns & adjacent_files_bb(f)); - doubled = ourPawns & forward_bb(Us, s); - opposed = theirPawns & forward_bb(Us, s); - passed = !(theirPawns & passed_pawn_mask(Us, s)); + // Flag the pawn as passed, isolated, doubled or + // connected (but not the backward one). + connected = ourPawns & adjacent_files_bb(f) & b; + isolated = !(ourPawns & adjacent_files_bb(f)); + doubled = ourPawns & forward_bb(Us, s); + opposed = theirPawns & forward_bb(Us, s); + passed = !(theirPawns & passed_pawn_mask(Us, s)); // Test for backward pawn. - // If the pawn is passed, isolated, or member of a pawn chain it cannot - // be backward. If there are friendly pawns behind on adjacent files + // If the pawn is passed, isolated, or connected it cannot be + // backward. If there are friendly pawns behind on adjacent files // or if it can capture an enemy pawn it cannot be backward either. - if ( (passed | isolated | chain) + if ( (passed | isolated | connected) || (ourPawns & pawn_attack_span(Them, s)) || (pos.attacks_from(s, Us) & theirPawns)) backward = false; @@ -172,8 +172,8 @@ namespace { if (backward) value -= Backward[opposed][f]; - if (chain) - value += ChainMember[f][relative_rank(Us, s)]; + if (connected) + value += Connected[f][relative_rank(Us, s)]; if (candidate) { @@ -203,14 +203,14 @@ namespace Pawns { void init() { - const int chainByFile[8] = { 1, 3, 3, 4, 4, 3, 3, 1 }; + const int bonusesByFile[8] = { 1, 3, 3, 4, 4, 3, 3, 1 }; int bonus; for (Rank r = RANK_1; r < RANK_8; ++r) for (File f = FILE_A; f <= FILE_H; ++f) { - bonus = r * (r-1) * (r-2) + chainByFile[f] * (r/2 + 1); - ChainMember[f][r] = make_score(bonus, bonus); + bonus = r * (r-1) * (r-2) + bonusesByFile[f] * (r/2 + 1); + Connected[f][r] = make_score(bonus, bonus); } } @@ -240,6 +240,7 @@ template Value Entry::shelter_storm(const Position& pos, Square ksq) { const Color Them = (Us == WHITE ? BLACK : WHITE); + static const Bitboard MiddleEdges = (FileABB | FileHBB) & (Rank2BB | Rank3BB); Value safety = MaxSafetyBonus; Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, rank_of(ksq)) | rank_bb(ksq)); @@ -252,11 +253,17 @@ Value Entry::shelter_storm(const Position& pos, Square ksq) { { b = ourPawns & file_bb(f); rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1; - safety -= ShelterWeakness[rkUs]; b = theirPawns & file_bb(f); rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1; - safety -= StormDanger[rkUs == RANK_1 ? 0 : rkThem == rkUs + 1 ? 2 : 1][rkThem]; + + if ( (MiddleEdges & make_square(f, rkThem)) + && file_of(ksq) == f + && relative_rank(Us, ksq) == rkThem - 1) + safety += Value(200); + else + safety -= ShelterWeakness[rkUs] + + StormDanger[rkUs == RANK_1 ? 0 : rkThem == rkUs + 1 ? 2 : 1][rkThem]; } return safety; @@ -271,7 +278,7 @@ template Score Entry::update_safety(const Position& pos, Square ksq) { kingSquares[Us] = ksq; - castlingFlags[Us] = pos.can_castle(Us); + castlingRights[Us] = pos.can_castle(Us); minKPdistance[Us] = 0; Bitboard pawns = pos.pieces(Us, PAWN); @@ -284,10 +291,10 @@ Score Entry::update_safety(const Position& pos, Square ksq) { Value bonus = shelter_storm(pos, ksq); // If we can castle use the bonus after the castling if it is bigger - if (pos.can_castle(make_castling_flag(Us, KING_SIDE))) + if (pos.can_castle(MakeCastling::right)) bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_G1))); - if (pos.can_castle(make_castling_flag(Us, QUEEN_SIDE))) + if (pos.can_castle(MakeCastling::right)) bonus = std::max(bonus, shelter_storm(pos, relative_square(Us, SQ_C1))); return kingSafety[Us] = make_score(bonus, -16 * minKPdistance[Us]);