X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=1a8c7e00d6a0bc24af2e44c395a70fb9eb6c1d4b;hp=4045a25d96f454182b9de283b593d0b0d48c53c1;hb=d3608c4e79a29110f4c4a369d7207c6dd8e01f34;hpb=483c98a69e8c6836c655d92a150d70fbe780341f diff --git a/src/position.cpp b/src/position.cpp index 4045a25d..1a8c7e00 100644 --- a/src/position.cpp +++ b/src/position.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) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2013 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 @@ -19,6 +19,7 @@ #include #include +#include #include #include #include @@ -278,11 +279,11 @@ void Position::set(const string& fenStr, bool isChess960, Thread* th) { } // 5-6. Halfmove clock and fullmove number - ss >> std::skipws >> st->rule50 >> startPosPly; + ss >> std::skipws >> st->rule50 >> gamePly; // Convert from fullmove starting from 1 to ply starting from 0, // handle also common incorrect FEN with fullmove = 0. - startPosPly = std::max(2 * (startPosPly - 1), 0) + int(sideToMove == BLACK); + gamePly = std::max(2 * (gamePly - 1), 0) + int(sideToMove == BLACK); st->key = compute_key(); st->pawnKey = compute_pawn_key(); @@ -373,7 +374,7 @@ const string Position::fen() const { ss << '-'; ss << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ") - << st->rule50 << " " << 1 + (startPosPly - int(sideToMove == BLACK)) / 2; + << st->rule50 << " " << 1 + (gamePly - int(sideToMove == BLACK)) / 2; return ss.str(); } @@ -400,14 +401,15 @@ const string Position::pretty(Move move) const { if (piece_on(sq) != NO_PIECE) brd[513 - 68*rank_of(sq) + 4*file_of(sq)] = PieceToChar[piece_on(sq)]; - ss << brd << "\nFen: " << fen() << "\nKey: " << st->key << "\nCheckers: "; + ss << brd << "\nFen: " << fen() << "\nKey: " << std::hex << std::uppercase + << std::setfill('0') << std::setw(16) << st->key << "\nCheckers: "; for (Bitboard b = checkers(); b; ) ss << square_to_string(pop_lsb(&b)) << " "; ss << "\nLegal moves: "; - for (MoveList ml(*this); !ml.end(); ++ml) - ss << move_to_san(*const_cast(this), ml.move()) << " "; + for (MoveList it(*this); *it; ++it) + ss << move_to_san(*const_cast(this), *it) << " "; return ss.str(); } @@ -735,8 +737,9 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI // Update side to move k ^= Zobrist::side; - // Increment the 50 moves rule draw counter. Resetting it to zero in the - // case of a capture or a pawn move is taken care of later. + // Increment ply counters.In particular rule50 will be later reset it to zero + // in case of a capture or a pawn move. + gamePly++; st->rule50++; st->pliesFromNull++; @@ -802,7 +805,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI // Update piece list, move the last piece at index[capsq] position and // shrink the list. // - // WARNING: This is a not revresible operation. When we will reinsert the + // WARNING: This is a not reversible operation. When we will reinsert the // captured piece in undo_move() we will put it at the end of the list and // not in its original place, it means index[] and pieceList[] are not // guaranteed to be invariant to a do_move() + undo_move() sequence. @@ -1054,6 +1057,7 @@ void Position::undo_move(Move m) { // Finally point our state pointer back to the previous state st = st->previous; + gamePly--; assert(pos_is_ok()); } @@ -1125,10 +1129,10 @@ void Position::undo_null_move() { /// Position::see() is a static exchange evaluator: It tries to estimate the -/// material gain or loss resulting from a move. There are three versions of -/// this function: One which takes a destination square as input, one takes a -/// move, and one which takes a 'from' and a 'to' square. The function does -/// not yet understand promotions captures. +/// material gain or loss resulting from a move. Parameter 'asymmThreshold' takes +/// tempi into account. If the side who initiated the capturing sequence does the +/// last capture, he loses a tempo and if the result is below 'asymmThreshold' +/// the capturing sequence is considered bad. int Position::see_sign(Move m) const { @@ -1143,7 +1147,7 @@ int Position::see_sign(Move m) const { return see(m); } -int Position::see(Move m) const { +int Position::see(Move m, int asymmThreshold) const { Square from, to; Bitboard occupied, attackers, stmAttackers; @@ -1220,6 +1224,15 @@ int Position::see(Move m) const { } while (stmAttackers); + // If we are doing asymmetric SEE evaluation and the same side does the first + // and the last capture, he loses a tempo and gain must be at least worth + // 'asymmThreshold', otherwise we replace the score with a very low value, + // before negamaxing. + if (asymmThreshold) + for (int i = 0; i < slIndex; i += 2) + if (swapList[i] < asymmThreshold) + swapList[i] = - QueenValueMg * 16; + // Having built the swap list, we negamax through it to find the best // achievable score from the point of view of the side to move. while (--slIndex) @@ -1363,42 +1376,38 @@ Value Position::compute_non_pawn_material(Color c) const { /// Position::is_draw() tests whether the position is drawn by material, /// repetition, or the 50 moves rule. It does not detect stalemates, this /// must be done by the search. -template bool Position::is_draw() const { + // Draw by material? if ( !pieces(PAWN) && (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMg)) return true; + // Draw by the 50 moves rule? if (st->rule50 > 99 && (!checkers() || MoveList(*this).size())) return true; - if (CheckRepetition) + // Draw by repetition? + int i = 4, e = std::min(st->rule50, st->pliesFromNull); + + if (i <= e) { - int i = 4, e = std::min(st->rule50, st->pliesFromNull), cnt; + StateInfo* stp = st->previous->previous; - if (i <= e) - { - StateInfo* stp = st->previous->previous; + do { + stp = stp->previous->previous; - for (cnt = 0; i <= e; i += 2) - { - stp = stp->previous->previous; + if (stp->key == st->key) + return true; - if (stp->key == st->key && (!CheckThreeFold || ++cnt >= 2)) - return true; - } - } + i += 2; + + } while (i <= e); } return false; } -// Explicit template instantiations -template bool Position::is_draw() const; -template bool Position::is_draw() const; -template bool Position::is_draw() const; - /// Position::flip() flips position with the white and black sides reversed. This /// is only useful for debugging especially for finding evaluation symmetry bugs. @@ -1413,7 +1422,7 @@ void Position::flip() { thisThread = pos.this_thread(); nodes = pos.nodes_searched(); chess960 = pos.is_chess960(); - startPosPly = pos.startpos_ply_counter(); + gamePly = pos.game_ply(); for (Square s = SQ_A1; s <= SQ_H8; s++) if (!pos.is_empty(s))