X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=b5c377efcd1e30221a514ea050e8787ba8b5a692;hp=19a37ee3d8b935f05f5ab62077c510e74c26d645;hb=c295599e4ad481f677b14cb0be14174b61ebff81;hpb=bb751d6c890f5c50c642366d601740366cfae8d0 diff --git a/src/pawns.cpp b/src/pawns.cpp index 19a37ee3..b5c377ef 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -1,17 +1,18 @@ /* - Glaurung, a UCI chess playing engine. - Copyright (C) 2004-2008 Tord Romstad + Stockfish, a UCI chess playing engine derived from Glaurung 2.1 + Copyright (C) 2004-2008 Tord Romstad (Glaurung author) + Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad - Glaurung is free software: you can redistribute it and/or modify + 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. - - Glaurung is distributed in the hope that it will be useful, + + 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 . */ @@ -22,8 +23,11 @@ //// #include +#include +#include "bitcount.h" #include "pawns.h" +#include "position.h" //// @@ -34,101 +38,69 @@ namespace { /// Constants and variables - // Doubled pawn penalty by file, middle game. - const Value DoubledPawnMidgamePenalty[8] = { - Value(20), Value(30), Value(34), Value(34), - Value(34), Value(34), Value(30), Value(20) - }; - - // Doubled pawn penalty by file, endgame. - const Value DoubledPawnEndgamePenalty[8] = { - Value(35), Value(40), Value(40), Value(40), - Value(40), Value(40), Value(40), Value(35) - }; - - // Isolated pawn penalty by file, middle game. - const Value IsolatedPawnMidgamePenalty[8] = { - Value(20), Value(30), Value(34), Value(34), - Value(34), Value(34), Value(30), Value(20) - }; - - // Isolated pawn penalty by file, endgame. - const Value IsolatedPawnEndgamePenalty[8] = { - Value(35), Value(40), Value(40), Value(40), - Value(40), Value(40), Value(40), Value(35) - }; + #define S(mg, eg) make_score(mg, eg) - // Backward pawn penalty by file, middle game. - const Value BackwardPawnMidgamePenalty[8] = { - Value(16), Value(24), Value(27), Value(27), - Value(27), Value(27), Value(24), Value(16) + // Doubled pawn penalty by file + const Score DoubledPawnPenalty[8] = { + S(13, 43), S(20, 48), S(23, 48), S(23, 48), + S(23, 48), S(23, 48), S(20, 48), S(13, 43) }; - // Backward pawn penalty by file, endgame. - const Value BackwardPawnEndgamePenalty[8] = { - Value(28), Value(32), Value(32), Value(32), - Value(32), Value(32), Value(32), Value(28) + // Isolated pawn penalty by file + const Score IsolatedPawnPenalty[8] = { + S(25, 30), S(36, 35), S(40, 35), S(40, 35), + S(40, 35), S(40, 35), S(36, 35), S(25, 30) }; - // Pawn chain membership bonus by file, middle game. - const Value ChainMidgameBonus[8] = { - Value(14), Value(16), Value(17), Value(18), - Value(18), Value(17), Value(16), Value(14) + // Backward pawn penalty by file + const Score BackwardPawnPenalty[8] = { + 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, endgame. - const Value ChainEndgameBonus[8] = { - Value(16), Value(16), Value(16), Value(16), - Value(16), Value(16), Value(16), Value(16) + // Pawn chain membership bonus by file + const Score ChainBonus[8] = { + S(11,-1), S(13,-1), S(13,-1), S(14,-1), + S(14,-1), S(13,-1), S(13,-1), S(11,-1) }; - // Candidate passed pawn bonus by rank, middle game. - const Value CandidateMidgameBonus[8] = { - Value(0), Value(12), Value(12), Value(20), - Value(40), Value(90), Value(0), Value(0) + // Candidate passed pawn bonus by rank + const Score CandidateBonus[8] = { + S( 0, 0), S( 6, 13), S(6,13), S(14,29), + S(34,68), S(83,166), S(0, 0), S( 0, 0) }; - // Candidate passed pawn bonus by rank, endgame. - const Value CandidateEndgameBonus[8] = { - Value(0), Value(24), Value(24), Value(40), - Value(80), Value(180), Value(0), Value(0) - }; - - // Evaluate pawn storms? - const bool EvaluatePawnStorms = true; - - // Pawn storm tables for positions with opposite castling: + // Pawn storm tables for positions with opposite castling const int QStormTable[64] = { - 0, 0, 0, 0, 0, 0, 0, 0, - -22, -22, -22, -13, -4, 0, 0, 0, - -4, -9, -9, -9, -4, 0, 0, 0, - 9, 18, 22, 18, 9, 0, 0, 0, - 22, 31, 31, 22, 0, 0, 0, 0, - 31, 40, 40, 31, 0, 0, 0, 0, - 31, 40, 40, 31, 0, 0, 0, 0, - 0, 0, 0, 0, 0, 0, 0, 0 + 0, 0, 0, 0, 0, 0, 0, 0, + -22,-22,-22,-14,-6, 0, 0, 0, + -6,-10,-10,-10,-6, 0, 0, 0, + 4, 12, 16, 12, 4, 0, 0, 0, + 16, 23, 23, 16, 0, 0, 0, 0, + 23, 31, 31, 23, 0, 0, 0, 0, + 23, 31, 31, 23, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0 }; - + const int KStormTable[64] = { - 0, 0, 0, 0, 0, 0, 0, 0, - 0, 0, 0, -4, -13, -22, -27, -27, - 0, 0, 0, -4, -9, -13, -18, -18, - 0, 0, 0, 0, 9, 9, 9, 9, - 0, 0, 0, 0, 9, 18, 27, 27, - 0, 0, 0, 0, 9, 27, 40, 36, - 0, 0, 0, 0, 0, 31, 40, 31, - 0, 0, 0, 0, 0, 0, 0, 0 + 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0,-10,-19,-28,-33,-33, + 0, 0, 0,-10,-15,-19,-24,-24, + 0, 0, 0, 0, 1, 1, 1, 1, + 0, 0, 0, 0, 1, 10, 19, 19, + 0, 0, 0, 0, 1, 19, 31, 27, + 0, 0, 0, 0, 0, 22, 31, 22, + 0, 0, 0, 0, 0, 0, 0, 0 }; - // Pawn storm open file bonuses by file: - const int KStormOpenFileBonus[8] = { - 45, 45, 30, 0, 0, 0, 0, 0 - }; + // Pawn storm open file bonuses by file + const int16_t QStormOpenFileBonus[8] = { 31, 31, 18, 0, 0, 0, 0, 0 }; + const int16_t KStormOpenFileBonus[8] = { 0, 0, 0, 0, 0, 26, 42, 26 }; - const int QStormOpenFileBonus[8] = { - 0, 0, 0, 0, 0, 30, 45, 30 - }; + // Pawn storm lever bonuses by file + const int StormLeverBonus[8] = { -8, -8, -13, 0, 0, -13, -8, -8 }; + #undef S } @@ -136,250 +108,242 @@ namespace { //// Functions //// -/// Constructor +/// PawnInfoTable c'tor and d'tor instantiated one each thread + +PawnInfoTable::PawnInfoTable(unsigned numOfEntries) : size(numOfEntries) { -PawnInfoTable::PawnInfoTable(unsigned numOfEntries) { - size = numOfEntries; entries = new PawnInfo[size]; - if(entries == NULL) { - std::cerr << "Failed to allocate " << (numOfEntries * sizeof(PawnInfo)) - << " bytes for pawn hash table." << std::endl; - exit(EXIT_FAILURE); + if (!entries) + { + std::cerr << "Failed to allocate " << (numOfEntries * sizeof(PawnInfo)) + << " bytes for pawn hash table." << std::endl; + Application::exit_with_failure(); } - this->clear(); } -/// Destructor - PawnInfoTable::~PawnInfoTable() { + delete [] entries; } -/// PawnInfoTable::clear() clears the pawn hash table by setting all -/// entries to 0. +/// PawnInfo::clear() resets to zero the PawnInfo entry. Note that +/// kingSquares[] is initialized to SQ_NONE instead. -void PawnInfoTable::clear() { - memset(entries, 0, size * sizeof(PawnInfo)); +void PawnInfo::clear() { + + memset(this, 0, sizeof(PawnInfo)); + kingSquares[WHITE] = kingSquares[BLACK] = SQ_NONE; } /// PawnInfoTable::get_pawn_info() takes a position object as input, computes -/// a PawnInfo 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. +/// a PawnInfo 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. + +PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const { -PawnInfo *PawnInfoTable::get_pawn_info(const Position &pos) { assert(pos.is_ok()); Key key = pos.get_pawn_key(); - int index = int(key & (size - 1)); - PawnInfo *pi = entries + index; + unsigned index = unsigned(key & (size - 1)); + PawnInfo* pi = entries + index; - // If pi->key matches the position's pawn hash key, it means that we - // have analysed this pawn structure before, and we can simply return the - // information we found the last time instead of recomputing it: - if(pi->key == key) - return pi; + // If pi->key matches the position's pawn hash key, it means that we + // have analysed this pawn structure before, and we can simply return + // the information we found the last time instead of recomputing it. + if (pi->key == key) + return pi; - // Clear the PawnInfo object, and set the key: + // Clear the PawnInfo object, and set the key pi->clear(); pi->key = key; - Value mgValue[2] = {Value(0), Value(0)}; - Value egValue[2] = {Value(0), Value(0)}; - - // Loop through the pawns for both colors: - for(Color us = WHITE; us <= BLACK; us++) { - Color them = opposite_color(us); - Bitboard ourPawns = pos.pawns(us); - Bitboard theirPawns = pos.pawns(them); - Bitboard pawns = ourPawns; - - // Initialize pawn storm scores by giving bonuses for open files: - if(EvaluatePawnStorms) - for(File f = FILE_A; f <= FILE_H; f++) - if(pos.file_is_half_open(us, f)) { - pi->ksStormValue[us] += KStormOpenFileBonus[f]; - pi->qsStormValue[us] += QStormOpenFileBonus[f]; - } - - // Loop through all pawns of the current color and score each pawn: - while(pawns) { - Square s = pop_1st_bit(&pawns); - File f = square_file(s); - Rank r = square_rank(s); - bool passed, doubled, isolated, backward, chain, candidate; - int bonus; - - assert(pos.piece_on(s) == pawn_of_color(us)); - - // The file containing the pawn is not half open: - pi->halfOpenFiles[us] &= ~(1 << f); - - // Passed, isolated or doubled pawn? - passed = pos.pawn_is_passed(us, s); - isolated = pos.pawn_is_isolated(us, s); - doubled = pos.pawn_is_doubled(us, s); - - if(EvaluatePawnStorms) { - // 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[]). This score is increased if - // there are enemy pawns on adjacent files in front of the pawn. - // This is because we want to be able to open files against the - // enemy king, and to avoid blocking the pawn structure (e.g. white - // pawns on h6, g5, black pawns on h7, g6, f7). - - // Kingside pawn storms: - bonus = KStormTable[relative_square(us, s)]; - if(bonus > 0 && outpost_mask(us, s) & theirPawns) { - switch(f) { - - case FILE_F: - bonus += bonus / 4; - break; - - case FILE_G: - bonus += bonus / 2 + bonus / 4; - break; - - case FILE_H: - bonus += bonus / 2; - break; - - default: - break; - } - } - pi->ksStormValue[us] += bonus; - - // Queenside pawn storms: - bonus = QStormTable[relative_square(us, s)]; - if(bonus > 0 && passed_pawn_mask(us, s) & theirPawns) { - switch(f) { - - case FILE_A: - bonus += bonus / 2; - break; - - case FILE_B: - bonus += bonus / 2 + bonus / 4; - break; - - case FILE_C: - bonus += bonus / 2; - break; - - default: - break; - } - } - pi->qsStormValue[us] += bonus; + // Calculate pawn attacks + Bitboard whitePawns = pos.pieces(PAWN, WHITE); + Bitboard blackPawns = pos.pieces(PAWN, BLACK); + pi->pawnAttacks[WHITE] = ((whitePawns << 9) & ~FileABB) | ((whitePawns << 7) & ~FileHBB); + pi->pawnAttacks[BLACK] = ((blackPawns >> 7) & ~FileABB) | ((blackPawns >> 9) & ~FileHBB); + + // Evaluate pawns for both colors + pi->value = evaluate_pawns(pos, whitePawns, blackPawns, pi) + - evaluate_pawns(pos, blackPawns, whitePawns, pi); + return pi; +} + + +/// PawnInfoTable::evaluate_pawns() evaluates each pawn of the given color + +template +Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, + Bitboard theirPawns, PawnInfo* pi) const { + Bitboard b; + Square s; + File f; + Rank r; + int bonus; + bool passed, isolated, doubled, opposed, chain, backward, candidate; + Score value = make_score(0, 0); + const Square* ptr = pos.piece_list_begin(Us, PAWN); + + // Initialize pawn storm scores by giving bonuses for open files + for (f = FILE_A; f <= FILE_H; f++) + if (!(ourPawns & file_bb(f))) + { + pi->ksStormValue[Us] += KStormOpenFileBonus[f]; + pi->qsStormValue[Us] += QStormOpenFileBonus[f]; + pi->halfOpenFiles[Us] |= (1 << f); } - - // Member of a pawn chain? We could speed up the test a little by - // introducing an array of masks indexed by color and square for doing - // the test, but because everything is hashed, it probably won't make - // any noticable difference. - chain = (us == WHITE)? - (ourPawns & neighboring_files_bb(f) & (rank_bb(r) | rank_bb(r-1))) : - (ourPawns & neighboring_files_bb(f) & (rank_bb(r) | rank_bb(r+1))); - - - // Test for backward pawn. - - // If the pawn is isolated, passed, or member of a pawn chain, it cannot - // be backward: - if(passed || isolated || chain) - backward = false; - // If the pawn can capture an enemy pawn, it's not backward: - else if(pos.pawn_attacks(us, s) & theirPawns) - backward = false; - // Check for friendly pawns behind on neighboring files: - else if(ourPawns & in_front_bb(them, r) & neighboring_files_bb(f)) - backward = false; - else { - // We now know that there is no friendly pawns beside or behind this - // pawn on neighboring files. We now check whether the pawn is - // backward by looking in the forward direction on the neighboring - // files, and seeing whether we meet a friendly or an enemy pawn first. - Bitboard b; - if(us == WHITE) { - for(b=pos.pawn_attacks(us, s); !(b&(ourPawns|theirPawns)); b<<=8); - backward = (b | (b << 8)) & theirPawns; - } - else { - for(b=pos.pawn_attacks(us, s); !(b&(ourPawns|theirPawns)); b>>=8); - backward = (b | (b >> 8)) & theirPawns; - } + + // Loop through all pawns of the current color and score each pawn + while ((s = *ptr++) != SQ_NONE) + { + f = square_file(s); + r = square_rank(s); + + assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN)); + + // 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; + + bonus = (f <= FILE_C ? evaluate_pawn_storm(s, r, f, theirPawns) : 0); + pi->qsStormValue[Us] += QStormTable[relative_square(Us, s)] + bonus; + + // Our rank plus previous one. Used for chain detection. + b = rank_bb(r) | rank_bb(Us == WHITE ? r - 1 : r + 1); + + // Passed, isolated, doubled or member of a pawn + // chain (but not the backward one) ? + passed = !(theirPawns & passed_pawn_mask(Us, s)); + doubled = ourPawns & squares_behind(Us, s); + opposed = theirPawns & squares_in_front_of(Us, s); + isolated = !(ourPawns & neighboring_files_bb(f)); + chain = ourPawns & neighboring_files_bb(f) & b; + + // Test for backward pawn + // + backward = false; + + // If the pawn is passed, isolated, or member of a pawn chain + // it cannot be backward. If can capture an enemy pawn or if + // there are friendly pawns behind on neighboring files it cannot + // be backward either. + if ( !(passed | isolated | chain) + && !(ourPawns & attack_span_mask(opposite_color(Us), s)) + && !(pos.attacks_from(s, Us) & theirPawns)) + { + // We now know that there are no friendly pawns beside or behind this + // pawn on neighboring files. We now check whether the pawn is + // backward by looking in the forward direction on the neighboring + // files, and seeing whether we meet a friendly or an enemy pawn first. + b = pos.attacks_from(s, Us); + + // Note that we are sure to find something because pawn is not passed + // nor isolated, so loop is potentially infinite, but it isn't. + while (!(b & (ourPawns | theirPawns))) + Us == WHITE ? b <<= 8 : b >>= 8; + + // The friendly pawn needs to be at least two ranks closer than the enemy + // pawn in order to help the potentially backward pawn advance. + backward = (b | (Us == WHITE ? b << 8 : b >> 8)) & theirPawns; } - // Test for candidate passed pawn. - candidate = - (!passed && pos.file_is_half_open(them, f) && - count_1s_max_15(neighboring_files_bb(f) - & (in_front_bb(them, r) | rank_bb(r)) - & ourPawns) - - count_1s_max_15(neighboring_files_bb(f) & in_front_bb(us, r) - & theirPawns) - >= 0); + assert(passed | opposed | (attack_span_mask(Us, s) & theirPawns)); + + // Test for candidate passed pawn + candidate = !(opposed | passed) + && (b = attack_span_mask(opposite_color(Us), s + pawn_push(Us)) & ourPawns) != EmptyBoardBB + && count_1s_max_15(b) >= count_1s_max_15(attack_span_mask(Us, s) & theirPawns); // In order to prevent doubled passed pawns from receiving a too big // bonus, only the frontmost passed pawn on each file is considered as // a true passed pawn. - if(passed && (ourPawns & squares_in_front_of(us, s))) { - // candidate = true; - passed = false; - } - - // Score this pawn: - Value mv = Value(0), ev = Value(0); - if(isolated) { - mv -= IsolatedPawnMidgamePenalty[f]; - ev -= IsolatedPawnEndgamePenalty[f]; - if(pos.file_is_half_open(them, f)) { - mv -= IsolatedPawnMidgamePenalty[f] / 2; - ev -= IsolatedPawnEndgamePenalty[f] / 2; - } - } - if(doubled) { - mv -= DoubledPawnMidgamePenalty[f]; - ev -= DoubledPawnEndgamePenalty[f]; + if (passed && (ourPawns & squares_in_front_of(Us, s))) + passed = false; + + // Mark the pawn as passed. Pawn will be properly scored in evaluation + // because we need full attack info to evaluate passed pawns. + if (passed) + set_bit(&(pi->passedPawns), s); + + // Score this pawn + if (isolated) + { + value -= IsolatedPawnPenalty[f]; + if (!opposed) + value -= IsolatedPawnPenalty[f] / 2; } - if(backward) { - mv -= BackwardPawnMidgamePenalty[f]; - ev -= BackwardPawnEndgamePenalty[f]; - if(pos.file_is_half_open(them, f)) { - mv -= BackwardPawnMidgamePenalty[f] / 2; - ev -= BackwardPawnEndgamePenalty[f] / 2; - } - } - if(chain) { - mv += ChainMidgameBonus[f]; - ev += ChainEndgameBonus[f]; - } - if(candidate) { - mv += CandidateMidgameBonus[pawn_rank(us, s)]; - ev += CandidateEndgameBonus[pawn_rank(us, s)]; + if (doubled) + value -= DoubledPawnPenalty[f]; + + if (backward) + { + value -= BackwardPawnPenalty[f]; + if (!opposed) + value -= BackwardPawnPenalty[f] / 2; } + if (chain) + value += ChainBonus[f]; - mgValue[us] += mv; - egValue[us] += ev; - - // If the pawn is passed, set the square of the pawn in the passedPawns - // bitboard: - if(passed) - set_bit(&(pi->passedPawns), s); - } + if (candidate) + value += CandidateBonus[relative_rank(Us, s)]; } - pi->mgValue = int16_t(mgValue[WHITE] - mgValue[BLACK]); - pi->egValue = int16_t(egValue[WHITE] - egValue[BLACK]); + return value; +} + - return pi; +/// 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 = attack_span_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) { + + Bitboard pawns = pos.pieces(PAWN, c) & this_and_neighboring_files_bb(ksq); + unsigned shelter = 0; + unsigned r = ksq & (7 << 3); + + for (int i = 1, k = (c ? -8 : 8); i < 4; i++) + { + r += k; + shelter += BitCount8Bit[(pawns >> r) & 0xFF] * (128 >> i); + } + kingSquares[c] = ksq; + kingShelters[c] = shelter; + return shelter; }