X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=c09a953b62e3a7612d53f03069266a2a00493d6d;hp=573b5df59a7885071a73855d9a0ff49739f0227b;hb=073eed590edf992ed3aeb6c754cb0b3b394fe79d;hpb=6c040c821a50475840607ef5f11c270ee21d61da diff --git a/src/position.cpp b/src/position.cpp index 573b5df5..c09a953b 100644 --- a/src/position.cpp +++ b/src/position.cpp @@ -2,6 +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 Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -19,47 +20,43 @@ #include #include -#include // For std::memset, std::memcmp +#include // For offsetof() +#include // For std::memset, std::memcmp #include #include -#include "bitcount.h" +#include "bitboard.h" #include "misc.h" #include "movegen.h" #include "position.h" -#include "psqtab.h" #include "thread.h" #include "tt.h" #include "uci.h" using std::string; -Value PieceValue[PHASE_NB][PIECE_NB] = { -{ VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg }, -{ VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg } }; +namespace PSQT { + extern Score psq[PIECE_NB][SQUARE_NB]; +} namespace Zobrist { - Key psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB]; + Key psq[PIECE_NB][SQUARE_NB]; Key enpassant[FILE_NB]; Key castling[CASTLING_RIGHT_NB]; Key side; - Key exclusion; } -Key Position::exclusion_key() const { return st->key ^ Zobrist::exclusion; } - namespace { const string PieceToChar(" PNBRQK pnbrqk"); -Score psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB]; // min_attacker() is a helper function used by see() 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. template -PieceType min_attacker(const Bitboard* bb, const Square& to, const Bitboard& stmAttackers, +PieceType min_attacker(const Bitboard* bb, Square to, Bitboard stmAttackers, Bitboard& occupied, Bitboard& attackers) { Bitboard b = stmAttackers & bb[Pt]; @@ -79,32 +76,13 @@ PieceType min_attacker(const Bitboard* bb, const Square& to, const Bitboard& stm } template<> -PieceType min_attacker(const Bitboard*, const Square&, const Bitboard&, Bitboard&, Bitboard&) { +PieceType min_attacker(const Bitboard*, Square, Bitboard, Bitboard&, Bitboard&) { return KING; // No need to update bitboards: it is the last cycle } } // namespace -/// CheckInfo c'tor - -CheckInfo::CheckInfo(const Position& pos) { - - Color them = ~pos.side_to_move(); - ksq = pos.king_square(them); - - pinned = pos.pinned_pieces(pos.side_to_move()); - dcCandidates = pos.discovered_check_candidates(); - - checkSq[PAWN] = pos.attacks_from(ksq, them); - checkSq[KNIGHT] = pos.attacks_from(ksq); - checkSq[BISHOP] = pos.attacks_from(ksq); - checkSq[ROOK] = pos.attacks_from(ksq); - checkSq[QUEEN] = checkSq[BISHOP] | checkSq[ROOK]; - checkSq[KING] = 0; -} - - /// operator<<(Position) returns an ASCII representation of the position std::ostream& operator<<(std::ostream& os, const Position& pos) { @@ -120,7 +98,7 @@ 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.st->key << std::dec << "\nCheckers: "; + << std::setfill('0') << std::setw(16) << pos.key() << std::dec << "\nCheckers: "; for (Bitboard b = pos.checkers(); b; ) os << UCI::square(pop_lsb(&b)) << " "; @@ -130,19 +108,15 @@ std::ostream& operator<<(std::ostream& os, const Position& pos) { /// Position::init() initializes at startup the various arrays used to compute -/// hash keys and the piece square tables. The latter is a two-step operation: -/// Firstly, the white halves of the tables are copied from PSQT[] tables. -/// Secondly, the black halves of the tables are initialized by flipping and -/// changing the sign of the white scores. +/// hash keys. void Position::init() { PRNG rng(1070372); - for (Color c = WHITE; c <= BLACK; ++c) - for (PieceType pt = PAWN; pt <= KING; ++pt) - for (Square s = SQ_A1; s <= SQ_H8; ++s) - Zobrist::psq[c][pt][s] = rng.rand(); + for (Piece pc : Pieces) + for (Square s = SQ_A1; s <= SQ_H8; ++s) + Zobrist::psq[pc][s] = rng.rand(); for (File f = FILE_A; f <= FILE_H; ++f) Zobrist::enpassant[f] = rng.rand(); @@ -159,52 +133,6 @@ void Position::init() { } Zobrist::side = rng.rand(); - Zobrist::exclusion = rng.rand(); - - for (PieceType pt = PAWN; pt <= KING; ++pt) - { - PieceValue[MG][make_piece(BLACK, pt)] = PieceValue[MG][pt]; - PieceValue[EG][make_piece(BLACK, pt)] = PieceValue[EG][pt]; - - Score v = make_score(PieceValue[MG][pt], PieceValue[EG][pt]); - - for (Square s = SQ_A1; s <= SQ_H8; ++s) - { - psq[WHITE][pt][ s] = (v + PSQT[pt][s]); - psq[BLACK][pt][~s] = -(v + PSQT[pt][s]); - } - } -} - - -/// Position::operator=() creates a copy of 'pos' but detaching the state pointer -/// from the source to be self-consistent and not depending on any external data. - -Position& Position::operator=(const Position& pos) { - - std::memcpy(this, &pos, sizeof(Position)); - std::memcpy(&startState, st, sizeof(StateInfo)); - st = &startState; - nodes = 0; - - assert(pos_is_ok()); - - return *this; -} - - -/// Position::clear() erases the position object to a pristine state, with an -/// empty board, white to move, and no castling rights. - -void Position::clear() { - - std::memset(this, 0, sizeof(Position)); - startState.epSquare = SQ_NONE; - st = &startState; - - for (int i = 0; i < PIECE_TYPE_NB; ++i) - for (int j = 0; j < 16; ++j) - pieceList[WHITE][i][j] = pieceList[BLACK][i][j] = SQ_NONE; } @@ -212,7 +140,7 @@ void Position::clear() { /// 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::set(const string& fenStr, bool isChess960, Thread* th) { +Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Thread* th) { /* A FEN string defines a particular position using only the ASCII character set. @@ -252,7 +180,11 @@ void Position::set(const string& fenStr, bool isChess960, Thread* th) { Square sq = SQ_A8; std::istringstream ss(fenStr); - clear(); + std::memset(this, 0, sizeof(Position)); + std::memset(si, 0, sizeof(StateInfo)); + std::fill_n(&pieceList[0][0], sizeof(pieceList) / sizeof(Square), SQ_NONE); + st = si; + ss >> std::noskipws; // 1. Piece placement @@ -266,7 +198,7 @@ void Position::set(const string& fenStr, bool isChess960, Thread* th) { else if ((idx = PieceToChar.find(token)) != string::npos) { - put_piece(color_of(Piece(idx)), type_of(Piece(idx)), sq); + put_piece(Piece(idx), sq); ++sq; } } @@ -285,14 +217,15 @@ void Position::set(const string& fenStr, bool isChess960, Thread* th) { { Square rsq; Color c = islower(token) ? BLACK : WHITE; + Piece rook = make_piece(c, ROOK); token = char(toupper(token)); if (token == 'K') - for (rsq = relative_square(c, SQ_H1); type_of(piece_on(rsq)) != ROOK; --rsq) {} + for (rsq = relative_square(c, SQ_H1); piece_on(rsq) != rook; --rsq) {} else if (token == 'Q') - for (rsq = relative_square(c, SQ_A1); type_of(piece_on(rsq)) != ROOK; ++rsq) {} + for (rsq = relative_square(c, SQ_A1); piece_on(rsq) != rook; ++rsq) {} else if (token >= 'A' && token <= 'H') rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1)); @@ -312,6 +245,8 @@ void Position::set(const string& fenStr, bool isChess960, Thread* th) { if (!(attackers_to(st->epSquare) & pieces(sideToMove, PAWN))) st->epSquare = SQ_NONE; } + else + st->epSquare = SQ_NONE; // 5-6. Halfmove clock and fullmove number ss >> std::skipws >> st->rule50 >> gamePly; @@ -325,6 +260,8 @@ void Position::set(const string& fenStr, bool isChess960, Thread* th) { set_state(st); assert(pos_is_ok()); + + return *this; } @@ -333,7 +270,7 @@ void Position::set(const string& fenStr, bool isChess960, Thread* th) { void Position::set_castling_right(Color c, Square rfrom) { - Square kfrom = king_square(c); + Square kfrom = square(c); CastlingSide cs = kfrom < rfrom ? KING_SIDE : QUEEN_SIDE; CastlingRight cr = (c | cs); @@ -355,6 +292,24 @@ void Position::set_castling_right(Color c, Square rfrom) { } +/// Position::set_check_info() sets king attacks to detect if a move gives check + +void Position::set_check_info(StateInfo* si) const { + + si->blockersForKing[WHITE] = slider_blockers(pieces(BLACK), square(WHITE), si->pinnersForKing[WHITE]); + si->blockersForKing[BLACK] = slider_blockers(pieces(WHITE), square(BLACK), si->pinnersForKing[BLACK]); + + Square ksq = square(~sideToMove); + + si->checkSquares[PAWN] = attacks_from(ksq, ~sideToMove); + si->checkSquares[KNIGHT] = attacks_from(ksq); + si->checkSquares[BISHOP] = attacks_from(ksq); + si->checkSquares[ROOK] = attacks_from(ksq); + si->checkSquares[QUEEN] = si->checkSquares[BISHOP] | si->checkSquares[ROOK]; + si->checkSquares[KING] = 0; +} + + /// Position::set_state() computes the hash keys of the position, and other /// data that once computed is updated incrementally as moves are made. /// The function is only used when a new position is set up, and to verify @@ -365,15 +320,16 @@ void Position::set_state(StateInfo* si) const { si->key = si->pawnKey = si->materialKey = 0; si->nonPawnMaterial[WHITE] = si->nonPawnMaterial[BLACK] = VALUE_ZERO; si->psq = SCORE_ZERO; + si->checkersBB = attackers_to(square(sideToMove)) & pieces(~sideToMove); - si->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove); + set_check_info(si); for (Bitboard b = pieces(); b; ) { Square s = pop_lsb(&b); Piece pc = piece_on(s); - si->key ^= Zobrist::psq[color_of(pc)][type_of(pc)][s]; - si->psq += psq[color_of(pc)][type_of(pc)][s]; + si->key ^= Zobrist::psq[pc][s]; + si->psq += PSQT::psq[pc][s]; } if (si->epSquare != SQ_NONE) @@ -387,17 +343,17 @@ void Position::set_state(StateInfo* si) const { for (Bitboard b = pieces(PAWN); b; ) { Square s = pop_lsb(&b); - si->pawnKey ^= Zobrist::psq[color_of(piece_on(s))][PAWN][s]; + si->pawnKey ^= Zobrist::psq[piece_on(s)][s]; } - for (Color c = WHITE; c <= BLACK; ++c) - for (PieceType pt = PAWN; pt <= KING; ++pt) - for (int cnt = 0; cnt < pieceCount[c][pt]; ++cnt) - si->materialKey ^= Zobrist::psq[c][pt][cnt]; + for (Piece pc : Pieces) + { + if (type_of(pc) != PAWN && type_of(pc) != KING) + si->nonPawnMaterial[color_of(pc)] += pieceCount[pc] * PieceValue[MG][pc]; - for (Color c = WHITE; c <= BLACK; ++c) - for (PieceType pt = KNIGHT; pt <= QUEEN; ++pt) - si->nonPawnMaterial[c] += pieceCount[c][pt] * PieceValue[MG][pt]; + for (int cnt = 0; cnt < pieceCount[pc]; ++cnt) + si->materialKey ^= Zobrist::psq[pc][cnt]; + } } @@ -464,28 +420,33 @@ Phase Position::game_phase() const { } -/// Position::check_blockers() returns a bitboard of all the pieces with color -/// 'c' that are blocking check on the king with color 'kingColor'. A piece -/// blocks a check if removing that piece from the board would result in a -/// position where the king is in check. A check blocking piece can be either a -/// pinned or a discovered check piece, according if its color 'c' is the same -/// or the opposite of 'kingColor'. +/// Position::slider_blockers() returns a bitboard of all the pieces (both colors) +/// that are blocking attacks on the square 's' from 'sliders'. A piece blocks a +/// slider if removing that piece from the board would result in a position where +/// square 's' is attacked. For example, a king-attack blocking piece can be either +/// a pinned or a discovered check piece, according if its color is the opposite +/// or the same of the color of the slider. -Bitboard Position::check_blockers(Color c, Color kingColor) const { +Bitboard Position::slider_blockers(Bitboard sliders, Square s, Bitboard& pinners) const { - Bitboard b, pinners, result = 0; - Square ksq = king_square(kingColor); + Bitboard result = 0; + pinners = 0; - // Pinners are sliders that give check when a pinned piece is removed - pinners = ( (pieces( ROOK, QUEEN) & PseudoAttacks[ROOK ][ksq]) - | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq])) & pieces(~kingColor); + // Snipers are sliders that attack 's' when a piece is removed + Bitboard snipers = ( (PseudoAttacks[ROOK ][s] & pieces(QUEEN, ROOK)) + | (PseudoAttacks[BISHOP][s] & pieces(QUEEN, BISHOP))) & sliders; - while (pinners) + while (snipers) { - b = between_bb(ksq, pop_lsb(&pinners)) & pieces(); - - if (!more_than_one(b)) - result |= b & pieces(c); + Square sniperSq = pop_lsb(&snipers); + Bitboard b = between_bb(s, sniperSq) & pieces(); + + if (!more_than_one(b)) + { + result |= b; + if (b & pieces(color_of(piece_on(s)))) + pinners |= sniperSq; + } } return result; } @@ -507,23 +468,22 @@ Bitboard Position::attackers_to(Square s, Bitboard occupied) const { /// Position::legal() tests whether a pseudo-legal move is legal -bool Position::legal(Move m, Bitboard pinned) const { +bool Position::legal(Move m) const { assert(is_ok(m)); - assert(pinned == pinned_pieces(sideToMove)); Color us = sideToMove; Square from = from_sq(m); assert(color_of(moved_piece(m)) == us); - assert(piece_on(king_square(us)) == make_piece(us, KING)); + assert(piece_on(square(us)) == make_piece(us, KING)); // En passant captures are a tricky special case. Because they are rather // uncommon, we do it simply by testing whether the king is attacked after // the move is made. if (type_of(m) == ENPASSANT) { - Square ksq = king_square(us); + Square ksq = square(us); Square to = to_sq(m); Square capsq = to - pawn_push(us); Bitboard occupied = (pieces() ^ from ^ capsq) | to; @@ -545,9 +505,8 @@ bool Position::legal(Move m, Bitboard pinned) const { // A non-king move is legal if and only if it is not pinned or it // is moving along the ray towards or away from the king. - return !pinned - || !(pinned & from) - || aligned(from, to_sq(m), king_square(us)); + return !(pinned_pieces(us) & from) + || aligned(from, to_sq(m), square(us)); } @@ -610,7 +569,7 @@ bool Position::pseudo_legal(const Move m) const { return false; // Our move must be a blocking evasion or a capture of the checking piece - if (!((between_bb(lsb(checkers()), king_square(us)) | checkers()) & to)) + if (!((between_bb(lsb(checkers()), square(us)) | checkers()) & to)) return false; } // In case of king moves under check we have to remove king so as to catch @@ -625,23 +584,21 @@ bool Position::pseudo_legal(const Move m) const { /// Position::gives_check() tests whether a pseudo-legal move gives a check -bool Position::gives_check(Move m, const CheckInfo& ci) const { +bool Position::gives_check(Move m) const { assert(is_ok(m)); - assert(ci.dcCandidates == discovered_check_candidates()); assert(color_of(moved_piece(m)) == sideToMove); Square from = from_sq(m); Square to = to_sq(m); // Is there a direct check? - if (ci.checkSq[type_of(piece_on(from))] & to) + if (st->checkSquares[type_of(piece_on(from))] & to) return true; // Is there a discovered check? - if ( ci.dcCandidates - && (ci.dcCandidates & from) - && !aligned(from, to, ci.ksq)) + if ( (discovered_check_candidates() & from) + && !aligned(from, to, square(~sideToMove))) return true; switch (type_of(m)) @@ -650,7 +607,7 @@ bool Position::gives_check(Move m, const CheckInfo& ci) const { return false; case PROMOTION: - return attacks_bb(Piece(promotion_type(m)), to, pieces() ^ from) & ci.ksq; + return attacks_bb(Piece(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 @@ -661,8 +618,8 @@ bool Position::gives_check(Move m, const CheckInfo& ci) const { Square capsq = make_square(file_of(to), rank_of(from)); Bitboard b = (pieces() ^ from ^ capsq) | to; - return (attacks_bb< ROOK>(ci.ksq, b) & pieces(sideToMove, QUEEN, ROOK)) - | (attacks_bb(ci.ksq, b) & pieces(sideToMove, QUEEN, BISHOP)); + return (attacks_bb< ROOK>(square(~sideToMove), b) & pieces(sideToMove, QUEEN, ROOK)) + | (attacks_bb(square(~sideToMove), b) & pieces(sideToMove, QUEEN, BISHOP)); } case CASTLING: { @@ -671,8 +628,8 @@ bool Position::gives_check(Move m, const CheckInfo& ci) const { Square kto = relative_square(sideToMove, rfrom > kfrom ? SQ_G1 : SQ_C1); Square rto = relative_square(sideToMove, rfrom > kfrom ? SQ_F1 : SQ_D1); - return (PseudoAttacks[ROOK][rto] & ci.ksq) - && (attacks_bb(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & ci.ksq); + return (PseudoAttacks[ROOK][rto] & square(~sideToMove)) + && (attacks_bb(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & square(~sideToMove)); } default: assert(false); @@ -710,23 +667,24 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { Color them = ~us; Square from = from_sq(m); Square to = to_sq(m); - PieceType pt = type_of(piece_on(from)); - PieceType captured = type_of(m) == ENPASSANT ? PAWN : type_of(piece_on(to)); + Piece pc = piece_on(from); + Piece captured = type_of(m) == ENPASSANT ? make_piece(them, PAWN) : piece_on(to); - assert(color_of(piece_on(from)) == us); - assert(piece_on(to) == NO_PIECE || color_of(piece_on(to)) == (type_of(m) != CASTLING ? them : us)); - assert(captured != KING); + assert(color_of(pc) == us); + assert(captured == NO_PIECE || color_of(captured) == (type_of(m) != CASTLING ? them : us)); + assert(type_of(captured) != KING); if (type_of(m) == CASTLING) { - assert(pt == KING); + assert(pc == make_piece(us, KING)); + assert(captured == make_piece(us, ROOK)); Square rfrom, rto; do_castling(us, from, to, rfrom, rto); - captured = NO_PIECE_TYPE; - st->psq += psq[us][ROOK][rto] - psq[us][ROOK][rfrom]; - k ^= Zobrist::psq[us][ROOK][rfrom] ^ Zobrist::psq[us][ROOK][rto]; + st->psq += PSQT::psq[captured][rto] - PSQT::psq[captured][rfrom]; + k ^= Zobrist::psq[captured][rfrom] ^ Zobrist::psq[captured][rto]; + captured = NO_PIECE; } if (captured) @@ -735,13 +693,13 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { // If the captured piece is a pawn, update pawn hash key, otherwise // update non-pawn material. - if (captured == PAWN) + if (type_of(captured) == PAWN) { if (type_of(m) == ENPASSANT) { capsq -= pawn_push(us); - assert(pt == PAWN); + assert(pc == make_piece(us, PAWN)); assert(to == st->epSquare); assert(relative_rank(us, to) == RANK_6); assert(piece_on(to) == NO_PIECE); @@ -750,28 +708,28 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { board[capsq] = NO_PIECE; // Not done by remove_piece() } - st->pawnKey ^= Zobrist::psq[them][PAWN][capsq]; + st->pawnKey ^= Zobrist::psq[captured][capsq]; } else st->nonPawnMaterial[them] -= PieceValue[MG][captured]; // Update board and piece lists - remove_piece(them, captured, capsq); + remove_piece(captured, capsq); // Update material hash key and prefetch access to materialTable - k ^= Zobrist::psq[them][captured][capsq]; - st->materialKey ^= Zobrist::psq[them][captured][pieceCount[them][captured]]; + k ^= Zobrist::psq[captured][capsq]; + st->materialKey ^= Zobrist::psq[captured][pieceCount[captured]]; prefetch(thisThread->materialTable[st->materialKey]); // Update incremental scores - st->psq -= psq[them][captured][capsq]; + st->psq -= PSQT::psq[captured][capsq]; // Reset rule 50 counter st->rule50 = 0; } // Update hash key - k ^= Zobrist::psq[us][pt][from] ^ Zobrist::psq[us][pt][to]; + k ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to]; // Reset en passant square if (st->epSquare != SQ_NONE) @@ -790,10 +748,10 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { // Move the piece. The tricky Chess960 castling is handled earlier if (type_of(m) != CASTLING) - move_piece(us, pt, from, to); + move_piece(pc, from, to); // If the moving piece is a pawn do some special extra work - if (pt == PAWN) + if (type_of(pc) == PAWN) { // Set en-passant square if the moved pawn can be captured if ( (int(to) ^ int(from)) == 16 @@ -805,29 +763,29 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { else if (type_of(m) == PROMOTION) { - PieceType promotion = promotion_type(m); + Piece promotion = make_piece(us, promotion_type(m)); assert(relative_rank(us, to) == RANK_8); - assert(promotion >= KNIGHT && promotion <= QUEEN); + assert(type_of(promotion) >= KNIGHT && type_of(promotion) <= QUEEN); - remove_piece(us, PAWN, to); - put_piece(us, promotion, to); + remove_piece(pc, to); + put_piece(promotion, to); // Update hash keys - k ^= Zobrist::psq[us][PAWN][to] ^ Zobrist::psq[us][promotion][to]; - st->pawnKey ^= Zobrist::psq[us][PAWN][to]; - st->materialKey ^= Zobrist::psq[us][promotion][pieceCount[us][promotion]-1] - ^ Zobrist::psq[us][PAWN][pieceCount[us][PAWN]]; + k ^= Zobrist::psq[pc][to] ^ Zobrist::psq[promotion][to]; + st->pawnKey ^= Zobrist::psq[pc][to]; + st->materialKey ^= Zobrist::psq[promotion][pieceCount[promotion]-1] + ^ Zobrist::psq[pc][pieceCount[pc]]; // Update incremental score - st->psq += psq[us][promotion][to] - psq[us][PAWN][to]; + st->psq += PSQT::psq[promotion][to] - PSQT::psq[pc][to]; // Update material st->nonPawnMaterial[us] += PieceValue[MG][promotion]; } // Update pawn hash key and prefetch access to pawnsTable - st->pawnKey ^= Zobrist::psq[us][PAWN][from] ^ Zobrist::psq[us][PAWN][to]; + st->pawnKey ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to]; prefetch(thisThread->pawnsTable[st->pawnKey]); // Reset rule 50 draw counter @@ -835,19 +793,22 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { } // Update incremental scores - st->psq += psq[us][pt][to] - psq[us][pt][from]; + st->psq += PSQT::psq[pc][to] - PSQT::psq[pc][from]; // Set capture piece - st->capturedType = captured; + st->capturedPiece = captured; // Update the key with the final value st->key = k; // Calculate checkers bitboard (if move gives check) - st->checkersBB = givesCheck ? attackers_to(king_square(them)) & pieces(us) : 0; + st->checkersBB = givesCheck ? attackers_to(square(them)) & pieces(us) : 0; sideToMove = ~sideToMove; + // Update king attacks used for fast check detection + set_check_info(st); + assert(pos_is_ok()); } @@ -864,20 +825,20 @@ void Position::undo_move(Move m) { Color us = sideToMove; Square from = from_sq(m); Square to = to_sq(m); - PieceType pt = type_of(piece_on(to)); + Piece pc = piece_on(to); assert(empty(from) || type_of(m) == CASTLING); - assert(st->capturedType != KING); + assert(type_of(st->capturedPiece) != KING); if (type_of(m) == PROMOTION) { assert(relative_rank(us, to) == RANK_8); - assert(pt == promotion_type(m)); - assert(pt >= KNIGHT && pt <= QUEEN); + assert(type_of(pc) == promotion_type(m)); + assert(type_of(pc) >= KNIGHT && type_of(pc) <= QUEEN); - remove_piece(us, pt, to); - put_piece(us, PAWN, to); - pt = PAWN; + remove_piece(pc, to); + pc = make_piece(us, PAWN); + put_piece(pc, to); } if (type_of(m) == CASTLING) @@ -887,9 +848,9 @@ void Position::undo_move(Move m) { } else { - move_piece(us, pt, to, from); // Put the piece back at the source square + move_piece(pc, to, from); // Put the piece back at the source square - if (st->capturedType) + if (st->capturedPiece) { Square capsq = to; @@ -897,14 +858,14 @@ void Position::undo_move(Move m) { { capsq -= pawn_push(us); - assert(pt == PAWN); + assert(type_of(pc) == PAWN); assert(to == st->previous->epSquare); assert(relative_rank(us, to) == RANK_6); assert(piece_on(capsq) == NO_PIECE); - assert(st->capturedType == PAWN); + assert(st->capturedPiece == make_piece(~us, PAWN)); } - put_piece(~us, st->capturedType, capsq); // Restore the captured piece + put_piece(st->capturedPiece, capsq); // Restore the captured piece } } @@ -917,7 +878,7 @@ void Position::undo_move(Move m) { /// Position::do_castling() is a helper used to do/undo a castling move. This -/// is a bit tricky, especially in Chess960. +/// is a bit tricky in Chess960 where from/to squares can overlap. template void Position::do_castling(Color us, Square from, Square& to, Square& rfrom, Square& rto) { @@ -927,11 +888,11 @@ void Position::do_castling(Color us, Square from, Square& to, Square& rfrom, Squ to = relative_square(us, kingSide ? SQ_G1 : SQ_C1); // Remove both pieces first since squares could overlap in Chess960 - remove_piece(us, KING, Do ? from : to); - remove_piece(us, ROOK, Do ? rfrom : rto); + remove_piece(make_piece(us, KING), Do ? from : to); + remove_piece(make_piece(us, ROOK), Do ? rfrom : rto); board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do it for us - put_piece(us, KING, Do ? to : from); - put_piece(us, ROOK, Do ? rto : rfrom); + put_piece(make_piece(us, KING), Do ? to : from); + put_piece(make_piece(us, ROOK), Do ? rto : rfrom); } @@ -961,6 +922,8 @@ void Position::do_null_move(StateInfo& newSt) { sideToMove = ~sideToMove; + set_check_info(st); + assert(pos_is_ok()); } @@ -979,103 +942,96 @@ void Position::undo_null_move() { Key Position::key_after(Move m) const { - Color us = sideToMove; Square from = from_sq(m); Square to = to_sq(m); - PieceType pt = type_of(piece_on(from)); - PieceType captured = type_of(piece_on(to)); + Piece pc = piece_on(from); + Piece captured = piece_on(to); Key k = st->key ^ Zobrist::side; if (captured) - k ^= Zobrist::psq[~us][captured][to]; + k ^= Zobrist::psq[captured][to]; - return k ^ Zobrist::psq[us][pt][to] ^ Zobrist::psq[us][pt][from]; + return k ^ Zobrist::psq[pc][to] ^ Zobrist::psq[pc][from]; } -/// Position::see() is a static exchange evaluator: It tries to estimate the -/// material gain or loss resulting from a move. +/// Position::see_ge (Static Exchange Evaluation Greater or Equal) tests if the +/// SEE value of move is greater or equal to the given value. We'll use an +/// algorithm similar to alpha-beta pruning with a null window. -Value Position::see_sign(Move m) const { +bool Position::see_ge(Move m, Value v) const { assert(is_ok(m)); - // Early return if SEE cannot be negative because captured piece value - // is not less then capturing one. Note that king moves always return - // here because king midgame value is set to 0. - if (PieceValue[MG][moved_piece(m)] <= PieceValue[MG][piece_on(to_sq(m))]) - return VALUE_KNOWN_WIN; - - return see(m); -} + // Castling moves are implemented as king capturing the rook so cannot be + // handled correctly. Simply assume the SEE value is VALUE_ZERO that is always + // correct unless in the rare case the rook ends up under attack. + if (type_of(m) == CASTLING) + return VALUE_ZERO >= v; -Value Position::see(Move m) const { + Square from = from_sq(m), to = to_sq(m); + PieceType nextVictim = type_of(piece_on(from)); + Color stm = ~color_of(piece_on(from)); // First consider opponent's move + Value balance; // Values of the pieces taken by us minus opponent's ones + Bitboard occupied, stmAttackers; - Square from, to; - Bitboard occupied, attackers, stmAttackers; - Value swapList[32]; - int slIndex = 1; - PieceType captured; - Color stm; + if (type_of(m) == ENPASSANT) + { + occupied = SquareBB[to - pawn_push(~stm)]; // Remove the captured pawn + balance = PieceValue[MG][PAWN]; + } + else + { + balance = PieceValue[MG][piece_on(to)]; + occupied = 0; + } - assert(is_ok(m)); + if (balance < v) + return false; - from = from_sq(m); - to = to_sq(m); - swapList[0] = PieceValue[MG][piece_on(to)]; - stm = color_of(piece_on(from)); - occupied = pieces() ^ from; + if (nextVictim == KING) + return true; - // Castling moves are implemented as king capturing the rook so cannot - // be handled correctly. Simply return VALUE_ZERO that is always correct - // unless in the rare case the rook ends up under attack. - if (type_of(m) == CASTLING) - return VALUE_ZERO; + balance -= PieceValue[MG][nextVictim]; - if (type_of(m) == ENPASSANT) - { - occupied ^= to - pawn_push(stm); // Remove the captured pawn - swapList[0] = PieceValue[MG][PAWN]; - } + if (balance >= v) + return true; - // Find all attackers to the destination square, with the moving piece - // removed, but possibly an X-ray attacker added behind it. - attackers = attackers_to(to, occupied) & occupied; + bool relativeStm = true; // True if the opponent is to move + occupied ^= pieces() ^ from ^ to; - // If the opponent has no attackers we are finished - stm = ~stm; - stmAttackers = attackers & pieces(stm); - if (!stmAttackers) - return swapList[0]; + // Find all attackers to the destination square, with the moving piece removed, + // but possibly an X-ray attacker added behind it. + Bitboard attackers = attackers_to(to, occupied) & occupied; - // The destination square is defended, which makes things rather more - // difficult to compute. We proceed by building up a "swap list" containing - // the material gain or loss at each stop in a sequence of captures to the - // destination square, where the sides alternately capture, and always - // capture with the least valuable piece. After each capture, we look for - // new X-ray attacks from behind the capturing piece. - captured = type_of(piece_on(from)); + while (true) + { + stmAttackers = attackers & pieces(stm); - do { - assert(slIndex < 32); + // Don't allow pinned pieces to attack pieces except the king as long all + // pinners are on their original square. + if (!(st->pinnersForKing[stm] & ~occupied)) + stmAttackers &= ~st->blockersForKing[stm]; - // Add the new entry to the swap list - swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[MG][captured]; + if (!stmAttackers) + return relativeStm; // Locate and remove the next least valuable attacker - captured = min_attacker(byTypeBB, to, stmAttackers, occupied, attackers); - stm = ~stm; - stmAttackers = attackers & pieces(stm); - ++slIndex; + nextVictim = min_attacker(byTypeBB, to, stmAttackers, occupied, attackers); + + if (nextVictim == KING) + return relativeStm == bool(attackers & pieces(~stm)); - } while (stmAttackers && (captured != KING || (--slIndex, false))); // Stop before a king capture + balance += relativeStm ? PieceValue[MG][nextVictim] + : -PieceValue[MG][nextVictim]; - // 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) - swapList[slIndex - 1] = std::min(-swapList[slIndex], swapList[slIndex - 1]); + relativeStm = !relativeStm; - return swapList[0]; + if (relativeStm == (balance >= v)) + return relativeStm; + + stm = ~stm; + } } @@ -1129,7 +1085,7 @@ void Position::flip() { std::getline(ss, token); // Half and full moves f += token; - set(f, is_chess960(), this_thread()); + set(f, is_chess960(), st, this_thread()); assert(pos_is_ok()); } @@ -1151,8 +1107,8 @@ bool Position::pos_is_ok(int* failedStep) const { if (step == Default) if ( (sideToMove != WHITE && sideToMove != BLACK) - || piece_on(king_square(WHITE)) != W_KING - || piece_on(king_square(BLACK)) != B_KING + || piece_on(square(WHITE)) != W_KING + || piece_on(square(BLACK)) != B_KING || ( ep_square() != SQ_NONE && relative_rank(sideToMove, ep_square()) != RANK_6)) return false; @@ -1160,7 +1116,7 @@ bool Position::pos_is_ok(int* failedStep) const { if (step == King) if ( std::count(board, board + SQUARE_NB, W_KING) != 1 || std::count(board, board + SQUARE_NB, B_KING) != 1 - || attackers_to(king_square(~sideToMove)) & pieces(sideToMove)) + || attackers_to(square(~sideToMove)) & pieces(sideToMove)) return false; if (step == Bitboards) @@ -1184,17 +1140,15 @@ bool Position::pos_is_ok(int* failedStep) const { } if (step == Lists) - for (Color c = WHITE; c <= BLACK; ++c) - for (PieceType pt = PAWN; pt <= KING; ++pt) - { - if (pieceCount[c][pt] != popcount(pieces(c, pt))) - return false; + for (Piece pc : Pieces) + { + if (pieceCount[pc] != popcount(pieces(color_of(pc), type_of(pc)))) + return false; - for (int i = 0; i < pieceCount[c][pt]; ++i) - if ( board[pieceList[c][pt][i]] != make_piece(c, pt) - || index[pieceList[c][pt][i]] != i) - return false; - } + for (int i = 0; i < pieceCount[pc]; ++i) + if (board[pieceList[pc][i]] != pc || index[pieceList[pc][i]] != i) + return false; + } if (step == Castling) for (Color c = WHITE; c <= BLACK; ++c) @@ -1205,7 +1159,7 @@ bool Position::pos_is_ok(int* failedStep) const { if ( piece_on(castlingRookSquare[c | s]) != make_piece(c, ROOK) || castlingRightsMask[castlingRookSquare[c | s]] != (c | s) - ||(castlingRightsMask[king_square(c)] & (c | s)) != (c | s)) + ||(castlingRightsMask[square(c)] & (c | s)) != (c | s)) return false; } }