X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=997aa2148815142da303cab5acb499bd78d0d6e9;hp=6fdd5c130ea57b372d574ee0cd2b6b744d3c412d;hb=2f1935078da225c90f7887ed8c345cc7baebcfcc;hpb=787d3585548ed7dac06597780a7d0adb64482d41 diff --git a/src/pawns.cpp b/src/pawns.cpp index 6fdd5c13..997aa214 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -1,387 +1,233 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008 Marco Costalba + Copyright (C) 2008-2010 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 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 . */ - -//// -//// Includes -//// - #include -#include +#include "bitboard.h" +#include "bitcount.h" #include "pawns.h" - - -//// -//// Local definitions -//// +#include "position.h" 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) + #define S(mg, eg) make_score(mg, eg) + + // Doubled pawn penalty by opposed flag and file + const Score DoubledPawnPenalty[2][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) }, + { 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 IsolatedPawnPenalty[2][8] = { + { 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) }}; + + // Backward pawn penalty by opposed flag and file + const Score BackwardPawnPenalty[2][8] = { + { 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 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) }; - // 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) + // 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) }; - // 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) - }; - - // 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) - }; - - // 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) - }; - - // 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) - }; + #undef S +} - // 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) - }; - // 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) - }; +/// 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 an hash table, so we don't have to recompute everything when the same +/// pawn structure occurs again. - // 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) - }; +PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const { - // Evaluate pawn storms? - const bool EvaluatePawnStorms = true; - - // 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 - }; - - 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 - }; + assert(pos.is_ok()); - // Pawn storm open file bonuses by file: - const int KStormOpenFileBonus[8] = { - 45, 45, 30, 0, 0, 0, 0, 0 - }; + Key key = pos.get_pawn_key(); + PawnInfo* pi = find(key); - const int QStormOpenFileBonus[8] = { - 0, 0, 0, 0, 0, 30, 45, 30 - }; + // 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; + // Initialize PawnInfo entry + pi->key = key; + pi->passedPawns[WHITE] = pi->passedPawns[BLACK] = 0; + pi->kingSquares[WHITE] = pi->kingSquares[BLACK] = SQ_NONE; + pi->halfOpenFiles[WHITE] = pi->halfOpenFiles[BLACK] = 0xFF; + + // Calculate pawn attacks + Bitboard wPawns = pos.pieces(PAWN, WHITE); + Bitboard bPawns = pos.pieces(PAWN, BLACK); + pi->pawnAttacks[WHITE] = ((wPawns << 9) & ~FileABB) | ((wPawns << 7) & ~FileHBB); + pi->pawnAttacks[BLACK] = ((bPawns >> 7) & ~FileABB) | ((bPawns >> 9) & ~FileHBB); + + // Evaluate pawns for both colors + pi->value = evaluate_pawns(pos, wPawns, bPawns, pi) + - evaluate_pawns(pos, bPawns, wPawns, pi); + return pi; } -//// -//// Functions -//// +/// 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 { + + const BitCountType Max15 = CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15; + const Color Them = (Us == WHITE ? BLACK : WHITE); + + Bitboard b; + Square s; + File f; + Rank r; + bool passed, isolated, doubled, opposed, chain, backward, candidate; + Score value = SCORE_ZERO; + const Square* ptr = pos.piece_list_begin(Us, PAWN); + + // Loop through all pawns of the current color and score each pawn + while ((s = *ptr++) != SQ_NONE) + { + assert(pos.piece_on(s) == make_piece(Us, PAWN)); + + f = square_file(s); + r = square_rank(s); + + // This file cannot be half open + pi->halfOpenFiles[Us] &= ~(1 << f); + + // Our rank plus previous one. Used for chain detection + b = rank_bb(r) | rank_bb(Us == WHITE ? r - Rank(1) : r + Rank(1)); + + // Flag the pawn as passed, isolated, doubled or member of a pawn + // chain (but not the backward one). + passed = !(theirPawns & passed_pawn_mask(Us, s)); + doubled = ourPawns & squares_in_front_of(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 there are friendly pawns behind on neighboring files + // or if can capture an enemy pawn it cannot be backward either. + if ( !(passed | isolated | chain) + && !(ourPawns & attack_span_mask(Them, 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; + } -/// Constructor + assert(opposed | passed | (attack_span_mask(Us, s) & theirPawns)); -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); - } - this->clear(); -} + // 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 neighboring files is higher or equal than the number of + // enemy pawns in the forward direction on the neighboring files. + candidate = !(opposed | passed | backward | isolated) + && (b = attack_span_mask(Them, s + pawn_push(Us)) & ourPawns) != EmptyBoardBB + && count_1s(b) >= count_1s(attack_span_mask(Us, s) & theirPawns); + // Passed pawns will be properly scored in evaluation because we need + // full attack info to evaluate passed pawns. Only the frontmost passed + // pawn on each file is considered a true passed pawn. + if (passed && !doubled) + set_bit(&(pi->passedPawns[Us]), s); -/// Destructor + // Score this pawn + if (isolated) + value -= IsolatedPawnPenalty[opposed][f]; -PawnInfoTable::~PawnInfoTable() { - delete [] entries; -} + if (doubled) + value -= DoubledPawnPenalty[opposed][f]; + if (backward) + value -= BackwardPawnPenalty[opposed][f]; -/// PawnInfoTable::clear() clears the pawn hash table by setting all -/// entries to 0. + if (chain) + value += ChainBonus[f]; -void PawnInfoTable::clear() { - memset(entries, 0, size * sizeof(PawnInfo)); + if (candidate) + value += CandidateBonus[relative_rank(Us, s)]; + } + return value; } -/// 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. - -PawnInfo *PawnInfoTable::get_pawn_info(const Position &pos) { - assert(pos.is_ok()); +/// PawnInfo::updateShelter() calculates and caches king shelter. It is called +/// only when king square changes, about 20% of total king_shelter() calls. +template +Score PawnInfo::updateShelter(const Position& pos, Square ksq) { - Key key = pos.get_pawn_key(); - int index = int(key & (size - 1)); - PawnInfo *pi = entries + index; + const int Shift = (Us == WHITE ? 8 : -8); - // 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; + Bitboard pawns; + int r, shelter = 0; - // 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; - } - - // 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; - } + if (relative_rank(Us, ksq) <= RANK_4) + { + pawns = pos.pieces(PAWN, Us) & this_and_neighboring_files_bb(ksq); + r = ksq & (7 << 3); + for (int i = 0; i < 3; i++) + { + r += Shift; + shelter += BitCount8Bit[(pawns >> r) & 0xFF] * (64 >> i); } - - // 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); - - // 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(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[relative_rank(us, s)]; - ev += CandidateEndgameBonus[relative_rank(us, s)]; - } - - 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); - } } - - pi->mgValue = int16_t(mgValue[WHITE] - mgValue[BLACK]); - pi->egValue = int16_t(egValue[WHITE] - egValue[BLACK]); - - return pi; + kingSquares[Us] = ksq; + kingShelters[Us] = make_score(shelter, 0); + return kingShelters[Us]; } + +// Explicit template instantiation +template Score PawnInfo::updateShelter(const Position& pos, Square ksq); +template Score PawnInfo::updateShelter(const Position& pos, Square ksq);