X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=89911e50b69bd848d59bf9ae01c2549112f72f60;hp=b74f0659b24a371a92a6184ce5c73a50ea57ae7c;hb=5f12069cbfc882fdf989d04618ad9c33e603c419;hpb=97015afce834a68be4a955768caab7152834d7d8 diff --git a/src/pawns.cpp b/src/pawns.cpp index b74f0659..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 @@ -30,44 +30,35 @@ namespace { #define V Value #define S(mg, eg) make_score(mg, eg) - // Doubled pawn penalty by opposed flag and file - const Score Doubled[2][FILE_NB] = { - { S(13, 43), S(20, 48), S(23, 48), S(23, 48), - S(23, 48), S(23, 48), S(20, 48), S(13, 43) }, - { S(13, 43), S(20, 48), S(23, 48), S(23, 48), - S(23, 48), S(23, 48), S(20, 48), S(13, 43) }}; + // Doubled pawn penalty by file + const Score Doubled[FILE_NB] = { + S(13, 43), S(20, 48), S(23, 48), S(23, 48), + S(23, 48), S(23, 48), S(20, 48), S(13, 43) }; // Isolated pawn penalty by opposed flag and file const Score Isolated[2][FILE_NB] = { { S(37, 45), S(54, 52), S(60, 52), S(60, 52), S(60, 52), S(60, 52), S(54, 52), S(37, 45) }, { S(25, 30), S(36, 35), S(40, 35), S(40, 35), - S(40, 35), S(40, 35), S(36, 35), S(25, 30) }}; + S(40, 35), S(40, 35), S(36, 35), S(25, 30) } }; // Backward pawn penalty by opposed flag and file const Score Backward[2][FILE_NB] = { { S(30, 42), S(43, 46), S(49, 46), S(49, 46), S(49, 46), S(49, 46), S(43, 46), S(30, 42) }, { 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 - const Score ChainMember[FILE_NB][RANK_NB] = { - { S(0, 0), S(14, 0), S(16, 4), S(18, 9), S(56, 56), S(104, 208), S(236, 472) }, - { S(0, 0), S(16, 0), S(18, 5), S(20, 10), S(60, 60), S(108, 216), S(240, 480) }, - { S(0, 0), S(16, 0), S(18, 5), S(20, 10), S(60, 60), S(108, 216), S(240, 480) }, - { S(0, 0), S(17, 0), S(19, 6), S(22, 11), S(66, 66), S(118, 236), S(254, 508) }, - { S(0, 0), S(17, 0), S(19, 6), S(22, 11), S(66, 66), S(118, 236), S(254, 508) }, - { S(0, 0), S(16, 0), S(18, 5), S(20, 10), S(60, 60), S(108, 216), S(240, 480) }, - { S(0, 0), S(16, 0), S(18, 5), S(20, 10), S(60, 60), S(108, 216), S(240, 480) }, - { S(0, 0), S(14, 0), S(16, 4), S(18, 9), S(56, 56), S(104, 208), S(236, 472) } - }; + S(33, 31), S(33, 31), S(29, 31), S(20, 28) } }; + + // 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] = { S( 0, 0), S( 6, 13), S(6,13), S(14,29), - S(34,68), S(83,166), S(0, 0), S( 0, 0) - }; + 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, 15); // Weakness of our pawn shelter in front of the king indexed by [rank] const Value ShelterWeakness[RANK_NB] = @@ -78,10 +69,10 @@ namespace { const Value StormDanger[3][RANK_NB] = { { V( 0), V(64), V(128), V(51), V(26) }, { V(26), V(32), V( 96), V(38), V(20) }, - { V( 0), V( 0), V( 64), V(25), V(13) }}; + { V( 0), V( 0), V( 64), V(25), V(13) } }; // Max bonus for king safety. Corresponds to start position with all the pawns - // in front of the king and no enemy pawn on the horizont. + // in front of the king and no enemy pawn on the horizon. const Value MaxSafetyBonus = V(263); #undef S @@ -98,8 +89,7 @@ namespace { Bitboard b; Square s; File f; - Rank r; - 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); @@ -119,27 +109,26 @@ namespace { assert(pos.piece_on(s) == make_piece(Us, PAWN)); f = file_of(s); - r = relative_rank(Us, s); // 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 - // or if can capture an enemy pawn it cannot be backward either. - if ( (passed | isolated | chain) + // 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 | connected) || (ourPawns & pawn_attack_span(Them, s)) || (pos.attacks_from(s, Us) & theirPawns)) backward = false; @@ -159,9 +148,9 @@ namespace { assert(opposed | passed | (pawn_attack_span(Us, s) & theirPawns)); - // A not passed pawn is a candidate to become passed if it is free to + // A not-passed pawn is a candidate to become passed, if it is free to // advance and if the number of friendly pawns beside or behind this - // pawn on adjacent files is higher or equal than the number of + // pawn on adjacent files is higher than or equal to the number of // enemy pawns in the forward direction on the adjacent files. candidate = !(opposed | passed | backward | isolated) && (b = pawn_attack_span(Them, s + pawn_push(Us)) & ourPawns) != 0 @@ -178,23 +167,31 @@ namespace { value -= Isolated[opposed][f]; if (doubled) - value -= Doubled[opposed][f]; + value -= Doubled[f]; if (backward) value -= Backward[opposed][f]; - if (chain) - value += opposed ? ChainMember[f][r] / 2 : ChainMember[f][r]; + if (connected) + value += Connected[f][relative_rank(Us, s)]; if (candidate) { - value += CandidatePassed[r]; + value += CandidatePassed[relative_rank(Us, s)]; if (!doubled) e->candidatePawns[Us] |= s; } } + // In endgame it's better to have pawns on both wings. So give a bonus according + // to file distance between left and right outermost pawns. + if (pos.count(Us) > 1) + { + b = e->semiopenFiles[Us] ^ 0xFF; + value += PawnsFileSpan * int(msb(b) - lsb(b)); + } + return value; } @@ -202,6 +199,22 @@ namespace { namespace Pawns { +/// init() initializes some tables by formula instead of hard-coding their values + +void init() { + + 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) + bonusesByFile[f] * (r/2 + 1); + Connected[f][r] = make_score(bonus, bonus); + } +} + + /// probe() takes a position object as input, computes a Entry object, and returns /// a pointer to it. The result is also stored in a hash table, so we don't have /// to recompute everything when the same pawn structure occurs again. @@ -227,6 +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)); @@ -235,29 +249,36 @@ Value Entry::shelter_storm(const Position& pos, Square ksq) { Rank rkUs, rkThem; File kf = std::max(FILE_B, std::min(FILE_G, file_of(ksq))); - for (int f = kf - 1; f <= kf + 1; ++f) + for (File f = kf - File(1); f <= kf + File(1); ++f) { - b = ourPawns & FileBB[f]; + b = ourPawns & file_bb(f); rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1; - safety -= ShelterWeakness[rkUs]; - b = theirPawns & FileBB[f]; + 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; } -/// Entry::update_safety() calculates and caches a bonus for king safety. It is -/// called only when king square changes, about 20% of total king_safety() calls. +/// Entry::update_safety() calculates and caches 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::update_safety(const Position& pos, Square ksq) { kingSquares[Us] = ksq; - castleRights[Us] = pos.can_castle(Us); + castlingRights[Us] = pos.can_castle(Us); minKPdistance[Us] = 0; Bitboard pawns = pos.pieces(Us, PAWN); @@ -269,11 +290,11 @@ Score Entry::update_safety(const Position& pos, Square ksq) { Value bonus = shelter_storm(pos, ksq); - // If we can castle use the bonus after the castle if is bigger - if (pos.can_castle(make_castle_right(Us, KING_SIDE))) + // 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(make_castle_right(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]);