X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=8f4232d7580a49e7008706abf55e14cbb360e4ac;hp=a09fe68337d8aa7ab3bbbd5f93dc86023e901fc1;hb=2ed3358fafdd7189637b9db4d20d7fb725b7a122;hpb=ab29d8df678adb97e2bc40b04f13e4f17577ada0 diff --git a/src/pawns.cpp b/src/pawns.cpp index a09fe683..8f4232d7 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -1,18 +1,18 @@ /* 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 . */ @@ -25,7 +25,9 @@ #include #include +#include "bitcount.h" #include "pawns.h" +#include "position.h" //// @@ -36,100 +38,67 @@ 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) - }; + #define S(mg, eg) make_score(mg, eg) - // 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) + // 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, middle game. - const Value BackwardPawnMidgamePenalty[8] = { - Value(16), Value(24), Value(27), Value(27), - Value(27), Value(27), Value(24), Value(16) + // 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) }; - // 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) + // 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, middle game. - const Value ChainMidgameBonus[8] = { - Value(14), Value(16), Value(17), Value(18), - Value(18), Value(17), Value(16), Value(14) + // 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) }; - // 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 + 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, 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, 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, + -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 KStormOpenFileBonus[8] = { 31, 31, 18, 0, 0, 0, 0, 0 }; + const int16_t QStormOpenFileBonus[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 }; } @@ -144,13 +113,12 @@ PawnInfoTable::PawnInfoTable(unsigned numOfEntries) { size = numOfEntries; entries = new PawnInfo[size]; - if (entries == NULL) + if (!entries) { std::cerr << "Failed to allocate " << (numOfEntries * sizeof(PawnInfo)) << " bytes for pawn hash table." << std::endl; - exit(EXIT_FAILURE); + Application::exit_with_failure(); } - clear(); } @@ -161,30 +129,32 @@ PawnInfoTable::~PawnInfoTable() { } -/// 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 +/// 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) { +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; + 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 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; @@ -192,200 +162,197 @@ PawnInfo *PawnInfoTable::get_pawn_info(const Position &pos) { pi->clear(); pi->key = key; - Value mgValue[2] = {Value(0), Value(0)}; - Value egValue[2] = {Value(0), Value(0)}; + // 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); - // 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) - { - bool passed, doubled, isolated, backward, chain, candidate; - Square s = pop_1st_bit(&pawns); - File f = square_file(s); - Rank r = square_rank(s); - - 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 and queenside pawn storms - int KBonus = KStormTable[relative_square(us, s)]; - int QBonus = QStormTable[relative_square(us, s)]; - bool outPost = (KBonus > 0 && (outpost_mask(us, s) & theirPawns)); - bool passed = (QBonus > 0 && (passed_pawn_mask(us, s) & theirPawns)); - - switch (f) { - - case FILE_A: - QBonus += passed * QBonus / 2; - break; - - case FILE_B: - QBonus += passed * (QBonus / 2 + QBonus / 4); - break; - - case FILE_C: - QBonus += passed * QBonus / 2; - break; - - case FILE_F: - KBonus += outPost * KBonus / 4; - break; - - case FILE_G: - KBonus += outPost * (KBonus / 2 + KBonus / 4); - break; - - case FILE_H: - KBonus += outPost * KBonus / 2; - break; - - default: - break; - } - pi->ksStormValue[us] += KBonus; - pi->qsStormValue[us] += QBonus; - } - - // Member of a pawn chain (but not the backward one)? 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 = ourPawns - & neighboring_files_bb(f) - & (rank_bb(r) | rank_bb(r - (us == WHITE ? 1 : -1))); - - // Test for backward pawn - // - // 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 - || (pos.pawn_attacks(us, s) & theirPawns) - || (ourPawns & behind_bb(us, r) & neighboring_files_bb(f))) - backward = false; - else - { - // 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. - 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; - } - } - - // Test for candidate passed pawn - candidate = !passed - && pos.file_is_half_open(them, f) - && ( count_1s_max_15(neighboring_files_bb(f) & (behind_bb(us, 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); - } // while(pawns) - } // for(colors) - - pi->mgValue = int16_t(mgValue[WHITE] - mgValue[BLACK]); - pi->egValue = int16_t(egValue[WHITE] - egValue[BLACK]); + // 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) { + Square s; + File f; + Rank r; + bool passed, isolated, doubled, chain, backward, candidate; + int bonus; + 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); + } + + // 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)); + + // Passed, isolated or doubled pawn? + passed = Position::pawn_is_passed(theirPawns, Us, s); + isolated = Position::pawn_is_isolated(ourPawns, s); + doubled = Position::pawn_is_doubled(ourPawns, Us, s); + + // 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[]). Pawns which seem to have good + // chances of creating an open file by exchanging itself against an + // enemy pawn on an adjacent file gets an additional bonus. + + // Kingside pawn storms + bonus = KStormTable[relative_square(Us, s)]; + if (f >= FILE_F) + { + Bitboard b = outpost_mask(Us, s) & theirPawns & (FileFBB | FileGBB | FileHBB); + while (b) + { + // Give a bonus according to the distance of the nearest enemy pawn + Square s2 = pop_1st_bit(&b); + int v = StormLeverBonus[f] - 2 * square_distance(s, s2); + + // 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) == FILE_H ? 4 : 2); + + bonus += v; + } + } + pi->ksStormValue[Us] += bonus; + + // Queenside pawn storms + bonus = QStormTable[relative_square(Us, s)]; + if (f <= FILE_C) + { + Bitboard b = outpost_mask(Us, s) & theirPawns & (FileABB | FileBBB | FileCBB); + while (b) + { + // Give a bonus according to the distance of the nearest enemy pawn + Square s2 = pop_1st_bit(&b); + int v = StormLeverBonus[f] - 4 * square_distance(s, s2); + + // 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) == FILE_A ? 4 : 2); + + bonus += v; + } + } + pi->qsStormValue[Us] += bonus; + + // Member of a pawn chain (but not the backward one)? 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 = ourPawns + & neighboring_files_bb(f) + & (rank_bb(r) | rank_bb(r - (Us == WHITE ? 1 : -1))); + + // Test for backward pawn + // + // 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 & behind_bb(Us, r) & neighboring_files_bb(f)) + || (pos.attacks_from(s, Us) & theirPawns)) + backward = false; + else + { + // 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. + Bitboard 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 + && !(theirPawns & file_bb(f)) + && ( count_1s_max_15(neighboring_files_bb(f) & (behind_bb(Us, 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))) + passed = false; + + // Score this pawn + if (passed) + set_bit(&(pi->passedPawns), s); + + if (isolated) + { + value -= IsolatedPawnPenalty[f]; + if (!(theirPawns & file_bb(f))) + value -= IsolatedPawnPenalty[f] / 2; + } + if (doubled) + value -= DoubledPawnPenalty[f]; + + if (backward) + { + value -= BackwardPawnPenalty[f]; + if (!(theirPawns & file_bb(f))) + value -= BackwardPawnPenalty[f] / 2; + } + if (chain) + value += ChainBonus[f]; + + if (candidate) + value += CandidateBonus[relative_rank(Us, s)]; + } + + return value; +} + + +/// 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) { + + unsigned shelter = 0; + Bitboard pawns = pos.pieces(PAWN, c) & this_and_neighboring_files_bb(ksq); + 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; +}