X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=0449222e016406f5e2e63804e8f695e5771cf28c;hp=c09a953b62e3a7612d53f03069266a2a00493d6d;hb=0c1f119069bf915b85126159d4865c4bcc532239;hpb=073eed590edf992ed3aeb6c754cb0b3b394fe79d diff --git a/src/position.cpp b/src/position.cpp index c09a953b..0449222e 100644 --- a/src/position.cpp +++ b/src/position.cpp @@ -2,7 +2,7 @@ Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad - Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad + Copyright (C) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, 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 @@ -32,6 +32,7 @@ #include "thread.h" #include "tt.h" #include "uci.h" +#include "syzygy/tbprobe.h" using std::string; @@ -44,14 +45,17 @@ namespace Zobrist { Key psq[PIECE_NB][SQUARE_NB]; Key enpassant[FILE_NB]; Key castling[CASTLING_RIGHT_NB]; - Key side; + Key side, noPawns; } namespace { const string PieceToChar(" PNBRQK pnbrqk"); -// min_attacker() is a helper function used by see() to locate the least +const Piece Pieces[] = { W_PAWN, W_KNIGHT, W_BISHOP, W_ROOK, W_QUEEN, W_KING, + B_PAWN, B_KNIGHT, B_BISHOP, B_ROOK, B_QUEEN, B_KING }; + +// min_attacker() is a helper function used by see_ge() to locate the least // valuable attacker for the side to move, remove the attacker we just found // from the bitboards and scan for new X-ray attacks behind it. @@ -61,7 +65,7 @@ PieceType min_attacker(const Bitboard* bb, Square to, Bitboard stmAttackers, Bitboard b = stmAttackers & bb[Pt]; if (!b) - return min_attacker(bb, to, stmAttackers, occupied, attackers); + return min_attacker(bb, to, stmAttackers, occupied, attackers); occupied ^= b & ~(b - 1); @@ -98,11 +102,25 @@ std::ostream& operator<<(std::ostream& os, const Position& pos) { } os << "\nFen: " << pos.fen() << "\nKey: " << std::hex << std::uppercase - << std::setfill('0') << std::setw(16) << pos.key() << std::dec << "\nCheckers: "; + << std::setfill('0') << std::setw(16) << pos.key() + << std::setfill(' ') << std::dec << "\nCheckers: "; for (Bitboard b = pos.checkers(); b; ) os << UCI::square(pop_lsb(&b)) << " "; + if ( int(Tablebases::MaxCardinality) >= popcount(pos.pieces()) + && !pos.can_castle(ANY_CASTLING)) + { + StateInfo st; + Position p; + p.set(pos.fen(), pos.is_chess960(), &st, pos.this_thread()); + Tablebases::ProbeState s1, s2; + Tablebases::WDLScore wdl = Tablebases::probe_wdl(p, &s1); + int dtz = Tablebases::probe_dtz(p, &s2); + os << "\nTablebases WDL: " << std::setw(4) << wdl << " (" << s1 << ")" + << "\nTablebases DTZ: " << std::setw(4) << dtz << " (" << s2 << ")"; + } + return os; } @@ -133,6 +151,7 @@ void Position::init() { } Zobrist::side = rng.rand(); + Zobrist::noPawns = rng.rand(); } @@ -164,8 +183,9 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th 4) En passant target square (in algebraic notation). If there's no en passant target square, this is "-". If a pawn has just made a 2-square move, this - is the position "behind" the pawn. This is recorded regardless of whether - there is a pawn in position to make an en passant capture. + is the position "behind" the pawn. This is recorded only if there is a pawn + in position to make an en passant capture, and if there really is a pawn + that might have advanced two squares. 5) Halfmove clock. This is the number of halfmoves since the last pawn advance or capture. This is used to determine if a draw can be claimed under the @@ -242,7 +262,8 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th { st->epSquare = make_square(File(col - 'a'), Rank(row - '1')); - if (!(attackers_to(st->epSquare) & pieces(sideToMove, PAWN))) + if ( !(attackers_to(st->epSquare) & pieces(sideToMove, PAWN)) + || !(pieces(~sideToMove, PAWN) & (st->epSquare + pawn_push(~sideToMove)))) st->epSquare = SQ_NONE; } else @@ -317,7 +338,8 @@ void Position::set_check_info(StateInfo* si) const { void Position::set_state(StateInfo* si) const { - si->key = si->pawnKey = si->materialKey = 0; + si->key = si->materialKey = 0; + si->pawnKey = Zobrist::noPawns; si->nonPawnMaterial[WHITE] = si->nonPawnMaterial[BLACK] = VALUE_ZERO; si->psq = SCORE_ZERO; si->checkersBB = attackers_to(square(sideToMove)) & pieces(~sideToMove); @@ -357,6 +379,28 @@ void Position::set_state(StateInfo* si) const { } +/// Position::set() is an overload to initialize the position object with +/// the given endgame code string like "KBPKN". It is mainly a helper to +/// get the material key out of an endgame code. Position is not playable, +/// indeed is even not guaranteed to be legal. + +Position& Position::set(const string& code, Color c, StateInfo* si) { + + assert(code.length() > 0 && code.length() < 8); + assert(code[0] == 'K'); + + string sides[] = { code.substr(code.find('K', 1)), // Weak + code.substr(0, code.find('K', 1)) }; // Strong + + std::transform(sides[c].begin(), sides[c].end(), sides[c].begin(), tolower); + + string fenStr = sides[0] + char(8 - sides[0].length() + '0') + "/8/8/8/8/8/8/" + + sides[1] + char(8 - sides[1].length() + '0') + " w - - 0 10"; + + return set(fenStr, false, si, nullptr); +} + + /// Position::fen() returns a FEN representation of the position. In case of /// Chess960 the Shredder-FEN notation is used. This is mainly a debugging function. @@ -554,7 +598,7 @@ bool Position::pseudo_legal(const Move m) const { && empty(to - pawn_push(us)))) return false; } - else if (!(attacks_from(pc, from) & to)) + else if (!(attacks_from(type_of(pc), from) & to)) return false; // Evasions generator already takes care to avoid some kind of illegal moves @@ -607,7 +651,7 @@ bool Position::gives_check(Move m) const { return false; case PROMOTION: - return attacks_bb(Piece(promotion_type(m)), to, pieces() ^ from) & square(~sideToMove); + return attacks_bb(promotion_type(m), to, pieces() ^ from) & square(~sideToMove); // En passant capture with check? We have already handled the case // of direct checks and ordinary discovered check, so the only case we @@ -786,7 +830,7 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { // Update pawn hash key and prefetch access to pawnsTable st->pawnKey ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to]; - prefetch(thisThread->pawnsTable[st->pawnKey]); + prefetch2(thisThread->pawnsTable[st->pawnKey]); // Reset rule 50 draw counter st->rule50 = 0; @@ -1038,18 +1082,29 @@ bool Position::see_ge(Move m, Value v) const { /// Position::is_draw() tests whether the position is drawn by 50-move rule /// or by repetition. It does not detect stalemates. -bool Position::is_draw() const { +bool Position::is_draw(int ply) const { if (st->rule50 > 99 && (!checkers() || MoveList(*this).size())) return true; - StateInfo* stp = st; - for (int i = 2, e = std::min(st->rule50, st->pliesFromNull); i <= e; i += 2) + int end = std::min(st->rule50, st->pliesFromNull); + + if (end < 4) + return false; + + StateInfo* stp = st->previous->previous; + int cnt = 0; + + for (int i = 4; i <= end; i += 2) { stp = stp->previous->previous; - if (stp->key == st->key) - return true; // Draw at first repetition + // At root position ply is 1, so return a draw score if a position + // repeats once earlier but after or at the root, or repeats twice + // strictly before the root. + if ( stp->key == st->key + && ++cnt + (ply - i > 0) == 2) + return true; } return false;