X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=93c42291b658d6d90ec9236d2a8642c3073c6037;hp=591d48fbb41b3254bf8cef4c6a63edcebe91c94a;hb=3e40bd0648ab69c04e37da50fd3f3d4beb072df2;hpb=d3f99aea6b6a7653c2d60ac94e600b1b2f5800e1 diff --git a/src/position.cpp b/src/position.cpp index 591d48fb..93c42291 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 Marco Costalba + Copyright (C) 2008-2009 Marco Costalba Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -35,13 +35,13 @@ #include "san.h" #include "ucioption.h" +using std::string; + //// //// Variables //// -extern SearchStack EmptySearchStack; - int Position::castleRightsMask[64]; Key Position::zobrist[2][8][64]; @@ -65,7 +65,7 @@ Position::Position(const Position& pos) { copy(pos); } -Position::Position(const std::string& fen) { +Position::Position(const string& fen) { from_fen(fen); } @@ -74,9 +74,9 @@ Position::Position(const std::string& fen) { /// string. This function is not very robust - make sure that input FENs are /// correct (this is assumed to be the responsibility of the GUI). -void Position::from_fen(const std::string& fen) { +void Position::from_fen(const string& fen) { - static const std::string pieceLetters = "KQRBNPkqrbnp"; + static const string pieceLetters = "KQRBNPkqrbnp"; static const Piece pieces[] = { WK, WQ, WR, WB, WN, WP, BK, BQ, BR, BB, BN, BP }; clear(); @@ -100,7 +100,7 @@ void Position::from_fen(const std::string& fen) { continue; } size_t idx = pieceLetters.find(fen[i]); - if (idx == std::string::npos) + if (idx == string::npos) { std::cout << "Error in FEN at character " << i << std::endl; return; @@ -213,18 +213,18 @@ void Position::from_fen(const std::string& fen) { st->materialKey = compute_material_key(); st->mgValue = compute_value(); st->egValue = compute_value(); - npMaterial[WHITE] = compute_non_pawn_material(WHITE); - npMaterial[BLACK] = compute_non_pawn_material(BLACK); + st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); + st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); } /// Position::to_fen() converts the position object to a FEN string. This is /// probably only useful for debugging. -const std::string Position::to_fen() const { +const string Position::to_fen() const { - static const std::string pieceLetters = " PNBRQK pnbrqk"; - std::string fen; + static const string pieceLetters = " PNBRQK pnbrqk"; + string fen; int skip; for (Rank rank = RANK_8; rank >= RANK_1; rank--) @@ -274,7 +274,7 @@ const std::string Position::to_fen() const { void Position::print(Move m) const { - static const std::string pieceLetters = " PNBRQK PNBRQK ."; + static const string pieceLetters = " PNBRQK PNBRQK ."; // Check for reentrancy, as example when called from inside // MovePicker that is used also here in move_to_san() @@ -286,7 +286,7 @@ void Position::print(Move m) const { std::cout << std::endl; if (m != MOVE_NONE) { - std::string col = (color_of_piece_on(move_from(m)) == BLACK ? ".." : ""); + string col = (color_of_piece_on(move_from(m)) == BLACK ? ".." : ""); std::cout << "Move is: " << col << move_to_san(*this, m) << std::endl; } for (Rank rank = RANK_8; rank >= RANK_1; rank--) @@ -377,9 +377,7 @@ Bitboard Position::discovered_check_candidates(Color c) const { } /// Position::attacks_to() computes a bitboard containing all pieces which -/// attacks a given square. There are two versions of this function: One -/// which finds attackers of both colors, and one which only finds the -/// attackers for one side. +/// attacks a given square. Bitboard Position::attacks_to(Square s) const { @@ -460,7 +458,9 @@ void Position::find_checkers() { bool Position::pl_move_is_legal(Move m) const { - return pl_move_is_legal(m, pinned_pieces(side_to_move())); + // If we're in check, all pseudo-legal moves are legal, because our + // check evasion generator only generates true legal moves. + return is_check() || pl_move_is_legal(m, pinned_pieces(side_to_move())); } bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { @@ -468,11 +468,7 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { assert(is_ok()); assert(move_is_ok(m)); assert(pinned == pinned_pieces(side_to_move())); - - // If we're in check, all pseudo-legal moves are legal, because our - // check evasion generator only generates true legal moves. - if (is_check()) - return true; + assert(!is_check()); // Castling moves are checked for legality during move generation. if (move_is_castle(m)) @@ -599,19 +595,17 @@ bool Position::move_is_check(Move m, Bitboard dcCandidates) const { case BISHOP: return (dcCandidates && bit_is_set(dcCandidates, from)) - || ( direction_between_squares(ksq, to) != DIR_NONE - && bit_is_set(piece_attacks(ksq), to)); + || (direction_is_diagonal(ksq, to) && bit_is_set(piece_attacks(ksq), to)); case ROOK: return (dcCandidates && bit_is_set(dcCandidates, from)) - || ( direction_between_squares(ksq, to) != DIR_NONE - && bit_is_set(piece_attacks(ksq), to)); + || (direction_is_straight(ksq, to) && bit_is_set(piece_attacks(ksq), to)); case QUEEN: // Discovered checks are impossible! assert(!bit_is_set(dcCandidates, from)); - return ( direction_between_squares(ksq, to) != DIR_NONE - && bit_is_set(piece_attacks(ksq), to)); + return ( (direction_is_straight(ksq, to) && bit_is_set(piece_attacks(ksq), to)) + || (direction_is_diagonal(ksq, to) && bit_is_set(piece_attacks(ksq), to))); case KING: // Discovered check? @@ -651,20 +645,6 @@ bool Position::move_is_check(Move m, Bitboard dcCandidates) const { } -/// Position::move_is_capture() tests whether a move from the current -/// position is a capture. Move must not be MOVE_NONE. - -bool Position::move_is_capture(Move m) const { - - assert(m != MOVE_NONE); - - return ( !square_is_empty(move_to(m)) - && (color_of_piece_on(move_to(m)) != color_of_piece_on(move_from(m))) - ) - || move_is_ep(m); -} - - /// Position::update_checkers() udpates chekers info given the move. It is called /// in do_move() and is faster then find_checkers(). @@ -676,6 +656,7 @@ inline void Position::update_checkers(Bitboard* pCheckersBB, Square ksq, Square const bool Rook = (Piece == QUEEN || Piece == ROOK); const bool Slider = Bishop || Rook; + // Direct checks if ( ( (Bishop && bit_is_set(BishopPseudoAttacks[ksq], to)) || (Rook && bit_is_set(RookPseudoAttacks[ksq], to))) && bit_is_set(piece_attacks(ksq), to)) // slow, try to early skip @@ -686,6 +667,7 @@ inline void Position::update_checkers(Bitboard* pCheckersBB, Square ksq, Square && bit_is_set(piece_attacks(ksq), to)) set_bit(pCheckersBB, to); + // Discovery checks if (Piece != QUEEN && bit_is_set(dcCandidates, from)) { if (Piece != ROOK) @@ -719,6 +701,7 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) { int castleRights, rule50; Square epSquare; Value mgValue, egValue; + Value npMaterial[2]; }; memcpy(&newSt, st, sizeof(ReducedStateInfo)); @@ -755,15 +738,14 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) { st->capture = type_of_piece_on(to); if (st->capture) - do_capture_move(m, st->capture, them, to); + do_capture_move(st->capture, them, to); // Move the piece - clear_bit(&(byColorBB[us]), from); - clear_bit(&(byTypeBB[piece]), from); - clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares - set_bit(&(byColorBB[us]), to); - set_bit(&(byTypeBB[piece]), to); - set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares + Bitboard move_bb = make_move_bb(from, to); + do_move_bb(&(byColorBB[us]), move_bb); + do_move_bb(&(byTypeBB[piece]), move_bb); + do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares + board[to] = board[from]; board[from] = EMPTY; @@ -848,13 +830,14 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) { /// Position::do_capture_move() is a private method used to update captured /// piece info. It is called from the main Position::do_move function. -void Position::do_capture_move(Move m, PieceType capture, Color them, Square to) { +void Position::do_capture_move(PieceType capture, Color them, Square to) { assert(capture != KING); // Remove captured piece clear_bit(&(byColorBB[them]), to); clear_bit(&(byTypeBB[capture]), to); + clear_bit(&(byTypeBB[0]), to); // Update hash key st->key ^= zobrist[them][capture][to]; @@ -867,11 +850,9 @@ void Position::do_capture_move(Move m, PieceType capture, Color them, Square to) st->mgValue -= pst(them, capture, to); st->egValue -= pst(them, capture, to); - assert(!move_promotion(m) || capture != PAWN); - // Update material if (capture != PAWN) - npMaterial[them] -= piece_value_midgame(capture); + st->npMaterial[them] -= piece_value_midgame(capture); // Update material hash key st->materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]]; @@ -1010,7 +991,7 @@ void Position::do_promotion_move(Move m) { st->capture = type_of_piece_on(to); if (st->capture) - do_capture_move(m, st->capture, them, to); + do_capture_move(st->capture, them, to); // Remove pawn clear_bit(&(byColorBB[us]), from); @@ -1053,7 +1034,7 @@ void Position::do_promotion_move(Move m) { st->egValue += pst(us, promotion, to); // Update material - npMaterial[us] += piece_value_midgame(promotion); + st->npMaterial[us] += piece_value_midgame(promotion); // Clear the en passant square if (st->epSquare != SQ_NONE) @@ -1189,17 +1170,13 @@ void Position::undo_move(Move m) { assert(color_of_piece_on(to) == us); // Put the piece back at the source square + Bitboard move_bb = make_move_bb(to, from); piece = type_of_piece_on(to); - set_bit(&(byColorBB[us]), from); - set_bit(&(byTypeBB[piece]), from); - set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares + do_move_bb(&(byColorBB[us]), move_bb); + do_move_bb(&(byTypeBB[piece]), move_bb); + do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares board[from] = piece_of_color_and_type(us, piece); - // Clear the destination square - clear_bit(&(byColorBB[us]), to); - clear_bit(&(byTypeBB[piece]), to); - clear_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares - // If the moving piece was a king, update the king square if (piece == KING) kingSquare[us] = from; @@ -1212,16 +1189,12 @@ void Position::undo_move(Move m) { { assert(st->capture != KING); - // Replace the captured piece + // Restore the captured piece set_bit(&(byColorBB[them]), to); set_bit(&(byTypeBB[st->capture]), to); set_bit(&(byTypeBB[0]), to); board[to] = piece_of_color_and_type(them, st->capture); - // Update material - if (st->capture != PAWN) - npMaterial[them] += piece_value_midgame(st->capture); - // Update piece list pieceList[them][st->capture][pieceCount[them][st->capture]] = to; index[to] = pieceCount[them][st->capture]; @@ -1343,9 +1316,6 @@ void Position::undo_promotion_move(Move m) { set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares board[from] = piece_of_color_and_type(us, PAWN); - // Update material - npMaterial[us] -= piece_value_midgame(promotion); - // Update piece list pieceList[us][PAWN][pieceCount[us][PAWN]] = from; index[from] = pieceCount[us][PAWN]; @@ -1367,11 +1337,6 @@ void Position::undo_promotion_move(Move m) { set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares board[to] = piece_of_color_and_type(them, st->capture); - // Update material. Because the move is a promotion move, we know - // that the captured piece cannot be a pawn. - assert(st->capture != PAWN); - npMaterial[them] += piece_value_midgame(st->capture); - // Update piece list pieceList[them][st->capture][pieceCount[them][st->capture]] = to; index[to] = pieceCount[them][st->capture]; @@ -1424,13 +1389,13 @@ void Position::undo_ep_move(Move m) { set_bit(&(byTypeBB[0]), from); board[from] = piece_of_color_and_type(us, PAWN); - // Update piece list: + // Update piece list pieceList[us][PAWN][index[to]] = from; index[from] = index[to]; pieceList[them][PAWN][pieceCount[them][PAWN]] = capsq; index[capsq] = pieceCount[them][PAWN]; - // Update piece count: + // Update piece count pieceCount[them][PAWN]++; } @@ -1444,12 +1409,13 @@ void Position::do_null_move(StateInfo& backupSt) { assert(!is_check()); // Back up the information necessary to undo the null move to the supplied - // StateInfo object. In the case of a null move, the only thing we need to - // remember is the last move made and the en passant square. + // StateInfo object. // Note that differently from normal case here backupSt is actually used as // a backup storage not as a new state to be used. - backupSt.lastMove = st->lastMove; backupSt.epSquare = st->epSquare; + backupSt.key = st->key; + backupSt.mgValue = st->mgValue; + backupSt.egValue = st->egValue; backupSt.previous = st->previous; st->previous = &backupSt; @@ -1482,21 +1448,16 @@ void Position::undo_null_move() { assert(!is_check()); // Restore information from the our backup StateInfo object - st->lastMove = st->previous->lastMove; st->epSquare = st->previous->epSquare; + st->key = st->previous->key; + st->mgValue = st->previous->mgValue; + st->egValue = st->previous->egValue; st->previous = st->previous->previous; - if (st->epSquare != SQ_NONE) - st->key ^= zobEp[st->epSquare]; - // Update the necessary information sideToMove = opposite_color(sideToMove); st->rule50--; gamePly--; - st->key ^= zobSideToMove; - - st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; - st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; assert(is_ok()); } @@ -1531,7 +1492,7 @@ int Position::see(Square from, Square to) const { 0, 0 }; - Bitboard attackers, occ, b; + Bitboard attackers, stmAttackers, occ, b; assert(square_is_ok(from) || from == SQ_NONE); assert(square_is_ok(to)); @@ -1555,7 +1516,6 @@ int Position::see(Square from, Square to) const { Square capQq = (side_to_move() == WHITE)? (to - DELTA_N) : (to - DELTA_S); capture = piece_on(capQq); - assert(type_of_piece_on(capQq) == PAWN); // Remove the captured pawn @@ -1590,7 +1550,8 @@ int Position::see(Square from, Square to) const { } // If the opponent has no attackers we are finished - if ((attackers & pieces_of_color(them)) == EmptyBoardBB) + stmAttackers = attackers & pieces_of_color(them); + if (!stmAttackers) return seeValues[capture]; attackers &= occ; // Remove the moving piece @@ -1612,13 +1573,13 @@ int Position::see(Square from, Square to) const { // Locate the least valuable attacker for the side to move. The loop // below looks like it is potentially infinite, but it isn't. We know // that the side to move still has at least one attacker left. - for (pt = PAWN; !(attackers & pieces_of_color_and_type(c, pt)); pt++) + for (pt = PAWN; !(stmAttackers & pieces_of_type(pt)); pt++) assert(pt < KING); // Remove the attacker we just found from the 'attackers' bitboard, // and scan for new X-ray attacks behind the attacker. - b = attackers & pieces_of_color_and_type(c, pt); - occ ^= (b & -b); + b = stmAttackers & pieces_of_type(pt); + occ ^= (b & (~b + 1)); attackers |= (rook_attacks_bb(to, occ) & rooks_and_queens()) | (bishop_attacks_bb(to, occ) & bishops_and_queens()); @@ -1633,15 +1594,16 @@ int Position::see(Square from, Square to) const { // before beginning the next iteration lastCapturingPieceValue = seeValues[pt]; c = opposite_color(c); + stmAttackers = attackers & pieces_of_color(c); // Stop after a king capture - if (pt == KING && (attackers & pieces_of_color(c))) + if (pt == KING && stmAttackers) { assert(n < 32); swapList[n++] = 100; break; } - } while (attackers & pieces_of_color(c)); + } while (stmAttackers); // 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 @@ -1869,21 +1831,6 @@ Value Position::compute_non_pawn_material(Color c) const { } -/// Position::is_mate() returns true or false depending on whether the -/// side to move is checkmated. Note that this function is currently very -/// slow, and shouldn't be used frequently inside the search. - -bool Position::is_mate() const { - - if (is_check()) - { - MovePicker mp = MovePicker(*this, false, MOVE_NONE, EmptySearchStack, Depth(0)); - return mp.get_next_move() == MOVE_NONE; - } - return false; -} - - /// 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. @@ -1908,21 +1855,25 @@ bool Position::is_draw() const { } +/// Position::is_mate() returns true or false depending on whether the +/// side to move is checkmated. + +bool Position::is_mate() const { + + MoveStack moves[256]; + + return is_check() && !generate_evasions(*this, moves, pinned_pieces(sideToMove)); +} + + /// Position::has_mate_threat() tests whether a given color has a mate in one -/// from the current position. This function is quite slow, but it doesn't -/// matter, because it is currently only called from PV nodes, which are rare. +/// from the current position. bool Position::has_mate_threat(Color c) { StateInfo st1, st2; Color stm = side_to_move(); - // The following lines are useless and silly, but prevents gcc from - // emitting a stupid warning stating that u1.lastMove and u1.epSquare might - // be used uninitialized. - st1.lastMove = st->lastMove; - st1.epSquare = st->epSquare; - if (is_check()) return false; @@ -1933,18 +1884,26 @@ bool Position::has_mate_threat(Color c) { MoveStack mlist[120]; int count; bool result = false; + Bitboard dc = discovered_check_candidates(sideToMove); + Bitboard pinned = pinned_pieces(sideToMove); - // Generate legal moves - count = generate_legal_moves(*this, mlist); + // Generate pseudo-legal non-capture and capture check moves + count = generate_non_capture_checks(*this, mlist, dc); + count += generate_captures(*this, mlist + count); // Loop through the moves, and see if one of them is mate for (int i = 0; i < count; i++) { - do_move(mlist[i].move, st2); + Move move = mlist[i].move; + + if (!pl_move_is_legal(move, pinned)) + continue; + + do_move(move, st2); if (is_mate()) result = true; - undo_move(mlist[i].move); + undo_move(move); } // Undo null move, if necessary @@ -1960,26 +1919,26 @@ bool Position::has_mate_threat(Color c) { void Position::init_zobrist() { - for(Piece p = WP; p <= BK; p++) - for(Square s = SQ_A1; s <= SQ_H8; s++) - zobrist[color_of_piece(p)][type_of_piece(p)][s] = genrand_int64(); + for (int i = 0; i < 2; i++) + for (int j = 0; j < 8; j++) + for (int k = 0; k < 64; k++) + zobrist[i][j][k] = Key(genrand_int64()); - zobEp[0] = 0ULL; - for(int i = 1; i < 64; i++) - zobEp[i] = genrand_int64(); + for (int i = 0; i < 64; i++) + zobEp[i] = Key(genrand_int64()); - for(int i = 15; i >= 0; i--) - zobCastle[(i&8) | (i&1) | ((i&2) << 1) | ((i&4) >> 1)] = genrand_int64(); + for (int i = 0; i < 16; i++) + zobCastle[i] = genrand_int64(); zobSideToMove = genrand_int64(); for (int i = 0; i < 2; i++) for (int j = 0; j < 8; j++) for (int k = 0; k < 16; k++) - zobMaterial[i][j][k] = (k > 0)? genrand_int64() : 0LL; + zobMaterial[i][j][k] = (k > 0)? Key(genrand_int64()) : Key(0LL); for (int i = 0; i < 16; i++) - zobMaterial[0][KING][i] = zobMaterial[1][KING][i] = 0ULL; + zobMaterial[0][KING][i] = zobMaterial[1][KING][i] = Key(0ULL); } @@ -2065,8 +2024,8 @@ void Position::flipped_copy(const Position &pos) { st->egValue = compute_value(); // Material - npMaterial[WHITE] = compute_non_pawn_material(WHITE); - npMaterial[BLACK] = compute_non_pawn_material(BLACK); + st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); + st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); assert(is_ok()); } @@ -2202,10 +2161,10 @@ bool Position::is_ok(int* failedStep) const { if (failedStep) (*failedStep)++; if (debugNonPawnMaterial) { - if (npMaterial[WHITE] != compute_non_pawn_material(WHITE)) + if (st->npMaterial[WHITE] != compute_non_pawn_material(WHITE)) return false; - if (npMaterial[BLACK] != compute_non_pawn_material(BLACK)) + if (st->npMaterial[BLACK] != compute_non_pawn_material(BLACK)) return false; }