X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=fd3f8035f30251c18211e633b835fc8fb49fc410;hp=3a0f8b1c90f8bba670b942488b87966092cefd69;hb=27f2ce8f6e8462bd9be4b201dd95fc2df17aafe6;hpb=c2fc80e5d16339266b5bf6687fa843ff65de3b3e diff --git a/src/position.cpp b/src/position.cpp index 3a0f8b1c..fd3f8035 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 @@ -17,14 +17,16 @@ along with this program. If not, see . */ +#include #include #include +#include #include #include -#include #include "bitcount.h" #include "movegen.h" +#include "notation.h" #include "position.h" #include "psqtab.h" #include "rkiss.h" @@ -35,43 +37,59 @@ using std::string; using std::cout; using std::endl; -Key Position::zobrist[2][8][64]; -Key Position::zobEp[8]; -Key Position::zobCastle[16]; -Key Position::zobSideToMove; -Key Position::zobExclusion; - -Score Position::pieceSquareTable[16][64]; - -// Material values arrays, indexed by Piece -const Value PieceValueMidgame[17] = { - VALUE_ZERO, - PawnValueMidgame, KnightValueMidgame, BishopValueMidgame, - RookValueMidgame, QueenValueMidgame, - VALUE_ZERO, VALUE_ZERO, VALUE_ZERO, - PawnValueMidgame, KnightValueMidgame, BishopValueMidgame, - RookValueMidgame, QueenValueMidgame -}; - -const Value PieceValueEndgame[17] = { - VALUE_ZERO, - PawnValueEndgame, KnightValueEndgame, BishopValueEndgame, - RookValueEndgame, QueenValueEndgame, - VALUE_ZERO, VALUE_ZERO, VALUE_ZERO, - PawnValueEndgame, KnightValueEndgame, BishopValueEndgame, - RookValueEndgame, QueenValueEndgame -}; +static const string PieceToChar(" PNBRQK pnbrqk"); + +CACHE_LINE_ALIGNMENT +Score psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB]; +Value PieceValue[PHASE_NB][PIECE_NB] = { +{ VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg }, +{ VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg } }; + +namespace Zobrist { + + Key psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB]; + Key enpassant[FILE_NB]; + Key castle[CASTLE_RIGHT_NB]; + Key side; + Key exclusion; +} + +Key Position::exclusion_key() const { return st->key ^ Zobrist::exclusion;} namespace { - // Bonus for having the side to move (modified by Joona Kiiski) - const Score Tempo = make_score(48, 22); +// min_attacker() is an 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 FORCE_INLINE +PieceType min_attacker(const Bitboard* bb, const Square& to, const Bitboard& stmAttackers, + Bitboard& occupied, Bitboard& attackers) { + + Bitboard b = stmAttackers & bb[Pt]; + if (!b) + return min_attacker(bb, to, stmAttackers, occupied, attackers); - // To convert a Piece to and from a FEN char - const string PieceToChar(" PNBRQK pnbrqk ."); + occupied ^= b & ~(b - 1); + + if (Pt == PAWN || Pt == BISHOP || Pt == QUEEN) + attackers |= attacks_bb(to, occupied) & (bb[BISHOP] | bb[QUEEN]); + + if (Pt == ROOK || Pt == QUEEN) + attackers |= attacks_bb(to, occupied) & (bb[ROOK] | bb[QUEEN]); + + attackers &= occupied; // After X-ray that may add already processed pieces + return (PieceType)Pt; +} + +template<> FORCE_INLINE +PieceType min_attacker(const Bitboard*, const Square&, const Bitboard&, Bitboard&, Bitboard&) { + return KING; // No need to update bitboards, it is the last cycle } +} // namespace + /// CheckInfo c'tor @@ -92,27 +110,75 @@ CheckInfo::CheckInfo(const Position& pos) { } -/// Position::copy() creates a copy of 'pos'. We want the new born Position +/// 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: +/// First, the white halves of the tables are copied from PSQT[] tables. Second, +/// the black halves of the tables are initialized by flipping and changing the +/// sign of the white scores. + +void Position::init() { + + RKISS rk; + + 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] = rk.rand(); + + for (File f = FILE_A; f <= FILE_H; f++) + Zobrist::enpassant[f] = rk.rand(); + + for (int cr = CASTLES_NONE; cr <= ALL_CASTLES; cr++) + { + Bitboard b = cr; + while (b) + { + Key k = Zobrist::castle[1ULL << pop_lsb(&b)]; + Zobrist::castle[cr] ^= k ? k : rk.rand(); + } + } + + Zobrist::side = rk.rand(); + Zobrist::exclusion = rk.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'. We want the new born Position /// object do not depend on any external data so we detach state pointer from /// the source one. -void Position::copy(const Position& pos, Thread* th) { +Position& Position::operator=(const Position& pos) { - memcpy(this, &pos, sizeof(Position)); + std::memcpy(this, &pos, sizeof(Position)); startState = *st; st = &startState; - thisThread = th; nodes = 0; assert(pos_is_ok()); + + return *this; } -/// Position::from_fen() initializes the position object with the given 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). +/// Position::set() initializes the position object with the given 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 string& fenStr, bool isChess960, Thread* th) { +void Position::set(const string& fenStr, bool isChess960, Thread* th) { /* A FEN string defines a particular position using only the ASCII character set. @@ -150,38 +216,38 @@ void Position::from_fen(const string& fenStr, bool isChess960, Thread* th) { char col, row, token; size_t p; Square sq = SQ_A8; - std::istringstream fen(fenStr); + std::istringstream ss(fenStr); clear(); - fen >> std::noskipws; + ss >> std::noskipws; // 1. Piece placement - while ((fen >> token) && !isspace(token)) + while ((ss >> token) && !isspace(token)) { if (isdigit(token)) sq += Square(token - '0'); // Advance the given number of files else if (token == '/') - sq = make_square(FILE_A, rank_of(sq) - Rank(2)); + sq -= Square(16); else if ((p = PieceToChar.find(token)) != string::npos) { - put_piece(Piece(p), sq); + put_piece(sq, color_of(Piece(p)), type_of(Piece(p))); sq++; } } // 2. Active color - fen >> token; + ss >> token; sideToMove = (token == 'w' ? WHITE : BLACK); - fen >> token; + ss >> token; // 3. Castling availability. Compatible with 3 standards: Normal FEN standard, // Shredder-FEN that uses the letters of the columns on which the rooks began // the game instead of KQkq and also X-FEN standard that, in case of Chess960, // if an inner rook is associated with the castling right, the castling tag is // replaced by the file letter of the involved rook, as for the Shredder-FEN. - while ((fen >> token) && !isspace(token)) + while ((ss >> token) && !isspace(token)) { Square rsq; Color c = islower(token) ? BLACK : WHITE; @@ -195,7 +261,7 @@ void Position::from_fen(const string& fenStr, bool isChess960, Thread* th) { for (rsq = relative_square(c, SQ_A1); type_of(piece_on(rsq)) != ROOK; rsq++) {} else if (token >= 'A' && token <= 'H') - rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1)); + rsq = File(token - 'A') | relative_rank(c, RANK_1); else continue; @@ -204,26 +270,26 @@ void Position::from_fen(const string& fenStr, bool isChess960, Thread* th) { } // 4. En passant square. Ignore if no pawn capture is possible - if ( ((fen >> col) && (col >= 'a' && col <= 'h')) - && ((fen >> row) && (row == '3' || row == '6'))) + if ( ((ss >> col) && (col >= 'a' && col <= 'h')) + && ((ss >> row) && (row == '3' || row == '6'))) { - st->epSquare = make_square(File(col - 'a'), Rank(row - '1')); + st->epSquare = File(col - 'a') | Rank(row - '1'); - if (!(attackers_to(st->epSquare) & pieces(PAWN, sideToMove))) + if (!(attackers_to(st->epSquare) & pieces(sideToMove, PAWN))) st->epSquare = SQ_NONE; } // 5-6. Halfmove clock and fullmove number - fen >> 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(); st->materialKey = compute_material_key(); - st->psqScore = compute_psq_score(); + st->psq = compute_psq_score(); st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove); @@ -240,158 +306,148 @@ void Position::from_fen(const string& fenStr, bool isChess960, Thread* th) { void Position::set_castle_right(Color c, Square rfrom) { Square kfrom = king_square(c); - bool kingSide = kfrom < rfrom; - int cr = (kingSide ? WHITE_OO : WHITE_OOO) << c; + CastlingSide cs = kfrom < rfrom ? KING_SIDE : QUEEN_SIDE; + CastleRight cr = make_castle_right(c, cs); st->castleRights |= cr; castleRightsMask[kfrom] |= cr; castleRightsMask[rfrom] |= cr; - castleRookSquare[cr] = rfrom; + castleRookSquare[c][cs] = rfrom; - Square kto = relative_square(c, kingSide ? SQ_G1 : SQ_C1); - Square rto = relative_square(c, kingSide ? SQ_F1 : SQ_D1); + Square kto = relative_square(c, cs == KING_SIDE ? SQ_G1 : SQ_C1); + Square rto = relative_square(c, cs == KING_SIDE ? SQ_F1 : SQ_D1); for (Square s = std::min(rfrom, rto); s <= std::max(rfrom, rto); s++) if (s != kfrom && s != rfrom) - castlePath[cr] |= s; + castlePath[c][cs] |= s; for (Square s = std::min(kfrom, kto); s <= std::max(kfrom, kto); s++) if (s != kfrom && s != rfrom) - castlePath[cr] |= s; + castlePath[c][cs] |= s; } -/// Position::to_fen() returns a FEN representation of the position. In case +/// Position::fen() returns a FEN representation of the position. In case /// of Chess960 the Shredder-FEN notation is used. Mainly a debugging function. -const string Position::to_fen() const { +const string Position::fen() const { - std::ostringstream fen; - Square sq; - int emptyCnt; + std::ostringstream ss; for (Rank rank = RANK_8; rank >= RANK_1; rank--) { - emptyCnt = 0; - for (File file = FILE_A; file <= FILE_H; file++) { - sq = make_square(file, rank); + Square sq = file | rank; - if (square_empty(sq)) - emptyCnt++; - else + if (is_empty(sq)) { - if (emptyCnt > 0) - { - fen << emptyCnt; - emptyCnt = 0; - } - fen << PieceToChar[piece_on(sq)]; + int emptyCnt = 1; + + for ( ; file < FILE_H && is_empty(sq++); file++) + emptyCnt++; + + ss << emptyCnt; } + else + ss << PieceToChar[piece_on(sq)]; } - if (emptyCnt > 0) - fen << emptyCnt; - if (rank > RANK_1) - fen << '/'; + ss << '/'; } - fen << (sideToMove == WHITE ? " w " : " b "); + ss << (sideToMove == WHITE ? " w " : " b "); if (can_castle(WHITE_OO)) - fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE_OO))))) : 'K'); + ss << (chess960 ? file_to_char(file_of(castle_rook_square(WHITE, KING_SIDE)), false) : 'K'); if (can_castle(WHITE_OOO)) - fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE_OOO))))) : 'Q'); + ss << (chess960 ? file_to_char(file_of(castle_rook_square(WHITE, QUEEN_SIDE)), false) : 'Q'); if (can_castle(BLACK_OO)) - fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OO))) : 'k'); + ss << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, KING_SIDE)), true) : 'k'); if (can_castle(BLACK_OOO)) - fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OOO))) : 'q'); + ss << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, QUEEN_SIDE)), true) : 'q'); if (st->castleRights == CASTLES_NONE) - fen << '-'; + ss << '-'; - fen << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ") - << st->rule50 << " " << 1 + (startPosPly - int(sideToMove == BLACK)) / 2; + ss << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ") + << st->rule50 << " " << 1 + (gamePly - int(sideToMove == BLACK)) / 2; - return fen.str(); + return ss.str(); } -/// Position::print() prints an ASCII representation of the position to -/// the standard output. If a move is given then also the san is printed. +/// Position::pretty() returns an ASCII representation of the position to be +/// printed to the standard output together with the move's san notation. -void Position::print(Move move) const { +const string Position::pretty(Move move) const { - const char* dottedLine = "\n+---+---+---+---+---+---+---+---+\n"; + const string dottedLine = "\n+---+---+---+---+---+---+---+---+"; + const string twoRows = dottedLine + "\n| | . | | . | | . | | . |" + + dottedLine + "\n| . | | . | | . | | . | |"; - if (move) + string brd = twoRows + twoRows + twoRows + twoRows + dottedLine; + + for (Bitboard b = pieces(); b; ) { - Position p(*this, thisThread); - cout << "\nMove is: " << (sideToMove == BLACK ? ".." : "") << move_to_san(p, move); + Square s = pop_lsb(&b); + brd[513 - 68 * rank_of(s) + 4 * file_of(s)] = PieceToChar[piece_on(s)]; } - for (Rank rank = RANK_8; rank >= RANK_1; rank--) - { - cout << dottedLine << '|'; - for (File file = FILE_A; file <= FILE_H; file++) - { - Square sq = make_square(file, rank); - Piece piece = piece_on(sq); - char c = (color_of(piece) == BLACK ? '=' : ' '); + std::ostringstream ss; - if (piece == NO_PIECE && !opposite_colors(sq, SQ_A1)) - piece++; // Index the dot + if (move) + ss << "\nMove: " << (sideToMove == BLACK ? ".." : "") + << move_to_san(*const_cast(this), move); - cout << c << PieceToChar[piece] << c << '|'; - } - } - cout << dottedLine << "Fen is: " << to_fen() << "\nKey is: " << st->key << endl; + 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 it(*this); *it; ++it) + ss << move_to_san(*const_cast(this), *it) << " "; + + return ss.str(); } -/// Position:hidden_checkers<>() returns a bitboard of all pinned (against the -/// king) pieces for the given color. Or, when template parameter FindPinned is -/// false, the function return the pieces of the given color candidate for a -/// discovery check against the enemy king. -template -Bitboard Position::hidden_checkers() const { +/// Position:hidden_checkers() returns a bitboard of all pinned / discovery check +/// pieces, according to the call parameters. Pinned pieces protect our king, +/// discovery check pieces attack the enemy king. + +Bitboard Position::hidden_checkers(Square ksq, Color c) const { - // Pinned pieces protect our king, dicovery checks attack the enemy king - Bitboard b, result = 0; - Bitboard pinners = pieces(FindPinned ? ~sideToMove : sideToMove); - Square ksq = king_square(FindPinned ? sideToMove : ~sideToMove); + Bitboard b, pinners, result = 0; - // Pinners are sliders, that give check when candidate pinned is removed - pinners &= (pieces(ROOK, QUEEN) & PseudoAttacks[ROOK][ksq]) - | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq]); + // Pinners are sliders that give check when pinned piece is removed + pinners = ( (pieces( ROOK, QUEEN) & PseudoAttacks[ROOK ][ksq]) + | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq])) & pieces(c); while (pinners) { - b = squares_between(ksq, pop_1st_bit(&pinners)) & pieces(); + b = between_bb(ksq, pop_lsb(&pinners)) & pieces(); - if (b && single_bit(b) && (b & pieces(sideToMove))) - result |= b; + if (!more_than_one(b)) + result |= b & pieces(sideToMove); } return result; } -// Explicit template instantiations -template Bitboard Position::hidden_checkers() const; -template Bitboard Position::hidden_checkers() const; - /// Position::attackers_to() computes a bitboard of all pieces which attack a /// given square. Slider attacks use occ bitboard as occupancy. Bitboard Position::attackers_to(Square s, Bitboard occ) const { - return (attacks_from(s, BLACK) & pieces(PAWN, WHITE)) - | (attacks_from(s, WHITE) & pieces(PAWN, BLACK)) + return (attacks_from(s, BLACK) & pieces(WHITE, PAWN)) + | (attacks_from(s, WHITE) & pieces(BLACK, PAWN)) | (attacks_from(s) & pieces(KNIGHT)) | (attacks_bb(s, occ) & pieces(ROOK, QUEEN)) | (attacks_bb(s, occ) & pieces(BISHOP, QUEEN)) @@ -416,37 +472,6 @@ Bitboard Position::attacks_from(Piece p, Square s, Bitboard occ) { } -/// Position::move_attacks_square() tests whether a move from the current -/// position attacks a given square. - -bool Position::move_attacks_square(Move m, Square s) const { - - assert(is_ok(m)); - assert(is_ok(s)); - - Bitboard occ, xray; - Square from = from_sq(m); - Square to = to_sq(m); - Piece piece = piece_moved(m); - - assert(!square_empty(from)); - - // Update occupancy as if the piece is moving - occ = pieces() ^ from ^ to; - - // The piece moved in 'to' attacks the square 's' ? - if (attacks_from(piece, to, occ) & s) - return true; - - // Scan for possible X-ray attackers behind the moved piece - xray = (attacks_bb(s, occ) & pieces(ROOK, QUEEN, color_of(piece))) - |(attacks_bb(s, occ) & pieces(BISHOP, QUEEN, color_of(piece))); - - // Verify attackers are triggered by our move and not already existing - return xray && (xray ^ (xray & attacks_from(s))); -} - - /// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { @@ -463,7 +488,7 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { // 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 (is_enpassant(m)) + if (type_of(m) == ENPASSANT) { Color them = ~us; Square to = to_sq(m); @@ -476,15 +501,15 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { assert(piece_on(capsq) == make_piece(them, PAWN)); assert(piece_on(to) == NO_PIECE); - return !(attacks_bb(ksq, b) & pieces(ROOK, QUEEN, them)) - && !(attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, them)); + return !(attacks_bb< ROOK>(ksq, b) & pieces(them, QUEEN, ROOK)) + && !(attacks_bb(ksq, b) & pieces(them, QUEEN, BISHOP)); } // If the moving piece is a king, check whether the destination // square is attacked by the opponent. Castling moves are checked // for legality during move generation. if (type_of(piece_on(from)) == KING) - return is_castle(m) || !(attackers_to(to_sq(m)) & pieces(~us)); + return type_of(m) == CASTLE || !(attackers_to(to_sq(m)) & pieces(~us)); // 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. @@ -494,20 +519,6 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { } -/// Position::move_is_legal() takes a random move and tests whether the move -/// is legal. This version is not very fast and should be used only in non -/// time-critical paths. - -bool Position::move_is_legal(const Move m) const { - - for (MoveList ml(*this); !ml.end(); ++ml) - if (ml.move() == m) - return true; - - return false; -} - - /// Position::is_pseudo_legal() takes a random move and tests whether the move /// is pseudo legal. It is used to validate moves from TT that can be corrupted /// due to SMP concurrent access or hash position key aliasing. @@ -515,14 +526,13 @@ bool Position::move_is_legal(const Move m) const { bool Position::is_pseudo_legal(const Move m) const { Color us = sideToMove; - Color them = ~sideToMove; Square from = from_sq(m); Square to = to_sq(m); Piece pc = piece_moved(m); // Use a slower but simpler function for uncommon cases - if (is_special(m)) - return move_is_legal(m); + if (type_of(m) != NORMAL) + return MoveList(*this).contains(m); // Is not a promotion, so promotion piece must be empty if (promotion_type(m) - 2 != NO_PIECE_TYPE) @@ -534,7 +544,7 @@ bool Position::is_pseudo_legal(const Move m) const { return false; // The destination square cannot be occupied by a friendly piece - if (color_of(piece_on(to)) == us) + if (pieces(us) & to) return false; // Handle the special case of a pawn move @@ -560,7 +570,7 @@ bool Position::is_pseudo_legal(const Move m) const { case DELTA_SE: // Capture. The destination square must be occupied by an enemy // piece (en passant captures was handled earlier). - if (color_of(piece_on(to)) != them) + if (piece_on(to) == NO_PIECE || color_of(piece_on(to)) != ~us) return false; // From and to files must be one file apart, avoids a7h5 @@ -571,7 +581,7 @@ bool Position::is_pseudo_legal(const Move m) const { case DELTA_N: case DELTA_S: // Pawn push. The destination square must be empty. - if (!square_empty(to)) + if (!is_empty(to)) return false; break; @@ -579,9 +589,9 @@ bool Position::is_pseudo_legal(const Move m) const { // Double white pawn push. The destination square must be on the fourth // rank, and both the destination square and the square between the // source and destination squares must be empty. - if ( rank_of(to) != RANK_4 - || !square_empty(to) - || !square_empty(from + DELTA_N)) + if ( rank_of(to) != RANK_4 + || !is_empty(to) + || !is_empty(from + DELTA_N)) return false; break; @@ -589,9 +599,9 @@ bool Position::is_pseudo_legal(const Move m) const { // Double black pawn push. The destination square must be on the fifth // rank, and both the destination square and the square between the // source and destination squares must be empty. - if ( rank_of(to) != RANK_5 - || !square_empty(to) - || !square_empty(from + DELTA_S)) + if ( rank_of(to) != RANK_5 + || !is_empty(to) + || !is_empty(from + DELTA_S)) return false; break; @@ -605,18 +615,16 @@ bool Position::is_pseudo_legal(const Move m) const { // Evasions generator already takes care to avoid some kind of illegal moves // and pl_move_is_legal() relies on this. So we have to take care that the // same kind of moves are filtered out here. - if (in_check()) + if (checkers()) { if (type_of(pc) != KING) { - Bitboard b = checkers(); - Square checksq = pop_1st_bit(&b); - - if (b) // double check ? In this case a king move is required + // Double check? In this case a king move is required + if (more_than_one(checkers())) return false; // Our move must be a blocking evasion or a capture of the checking piece - if (!((squares_between(checksq, king_square(us)) | checkers()) & to)) + if (!((between_bb(lsb(checkers()), king_square(us)) | checkers()) & to)) return false; } // In case of king moves under check we have to remove king so to catch @@ -646,51 +654,52 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const { return true; // Discovery check ? - if (ci.dcCandidates && (ci.dcCandidates & from)) + if (unlikely(ci.dcCandidates) && (ci.dcCandidates & from)) { // For pawn and king moves we need to verify also direction - if ( (pt != PAWN && pt != KING) + if ( (pt != PAWN && pt != KING) || !squares_aligned(from, to, king_square(~sideToMove))) return true; } // Can we skip the ugly special cases ? - if (!is_special(m)) + if (type_of(m) == NORMAL) return false; Color us = sideToMove; Square ksq = king_square(~us); - // Promotion with check ? - if (is_promotion(m)) + switch (type_of(m)) + { + case PROMOTION: return attacks_from(Piece(promotion_type(m)), to, pieces() ^ from) & ksq; // En passant capture with check ? We have already handled the case // of direct checks and ordinary discovered check, the only case we // need to handle is the unusual case of a discovered check through // the captured pawn. - if (is_enpassant(m)) + case ENPASSANT: { - Square capsq = make_square(file_of(to), rank_of(from)); + Square capsq = file_of(to) | rank_of(from); Bitboard b = (pieces() ^ from ^ capsq) | to; - return (attacks_bb< ROOK>(ksq, b) & pieces( ROOK, QUEEN, us)) - | (attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, us)); + return (attacks_bb< ROOK>(ksq, b) & pieces(us, QUEEN, ROOK)) + | (attacks_bb(ksq, b) & pieces(us, QUEEN, BISHOP)); } - - // Castling with check ? - if (is_castle(m)) + case CASTLE: { Square kfrom = from; Square rfrom = to; // 'King captures the rook' notation Square kto = relative_square(us, rfrom > kfrom ? SQ_G1 : SQ_C1); Square rto = relative_square(us, rfrom > kfrom ? SQ_F1 : SQ_D1); - Bitboard b = (pieces() ^ kfrom ^ rfrom) | rto | kto; - return attacks_bb(rto, b) & ksq; + return (PseudoAttacks[ROOK][rto] & ksq) + && (attacks_bb(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & ksq); + } + default: + assert(false); + return false; } - - return false; } @@ -713,48 +722,50 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI Key k = st->key; // Copy some fields of old state to our new StateInfo object except the ones - // which are recalculated from scratch anyway, then switch our state pointer - // to point to the new, ready to be updated, state. - struct ReducedStateInfo { - Key pawnKey, materialKey; - Value npMaterial[2]; - int castleRights, rule50, pliesFromNull; - Score psq_score; - Square epSquare; - }; - - memcpy(&newSt, st, sizeof(ReducedStateInfo)); + // which are going to be recalculated from scratch anyway, then switch our state + // pointer to point to the new, ready to be updated, state. + std::memcpy(&newSt, st, StateCopySize64 * sizeof(uint64_t)); newSt.previous = st; st = &newSt; // Update side to move - k ^= zobSideToMove; + 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++; - if (is_castle(m)) - { - st->key = k; - do_castle_move(m); - return; - } - Color us = sideToMove; Color them = ~us; Square from = from_sq(m); Square to = to_sq(m); - Piece piece = piece_on(from); - PieceType pt = type_of(piece); - PieceType capture = is_enpassant(m) ? PAWN : type_of(piece_on(to)); + Piece pc = piece_on(from); + PieceType pt = type_of(pc); + PieceType capture = type_of(m) == ENPASSANT ? PAWN : type_of(piece_on(to)); - assert(color_of(piece) == us); - assert(color_of(piece_on(to)) != us); + assert(color_of(pc) == us); + assert(piece_on(to) == NO_PIECE || color_of(piece_on(to)) == them || type_of(m) == CASTLE); assert(capture != KING); + if (type_of(m) == CASTLE) + { + assert(pc == make_piece(us, KING)); + + bool kingSide = to > from; + Square rfrom = to; // Castle is encoded as "king captures friendly rook" + Square rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1); + to = relative_square(us, kingSide ? SQ_G1 : SQ_C1); + capture = NO_PIECE_TYPE; + + do_castle(from, to, rfrom, rto); + + st->psq += psq[us][ROOK][rto] - psq[us][ROOK][rfrom]; + k ^= Zobrist::psq[us][ROOK][rfrom] ^ Zobrist::psq[us][ROOK][rto]; + } + if (capture) { Square capsq = to; @@ -763,7 +774,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI // update non-pawn material. if (capture == PAWN) { - if (is_enpassant(m)) + if (type_of(m) == ENPASSANT) { capsq += pawn_push(them); @@ -776,46 +787,33 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI board[capsq] = NO_PIECE; } - st->pawnKey ^= zobrist[them][PAWN][capsq]; + st->pawnKey ^= Zobrist::psq[them][PAWN][capsq]; } else - st->npMaterial[them] -= PieceValueMidgame[capture]; - - // Remove the captured piece - byTypeBB[ALL_PIECES] ^= capsq; - byTypeBB[capture] ^= capsq; - byColorBB[them] ^= capsq; - - // 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 - // 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. - Square lastSquare = pieceList[them][capture][--pieceCount[them][capture]]; - index[lastSquare] = index[capsq]; - pieceList[them][capture][index[lastSquare]] = lastSquare; - pieceList[them][capture][pieceCount[them][capture]] = SQ_NONE; - - // Update hash keys - k ^= zobrist[them][capture][capsq]; - st->materialKey ^= zobrist[them][capture][pieceCount[them][capture]]; + st->npMaterial[them] -= PieceValue[MG][capture]; + + // Update board and piece lists + remove_piece(capsq, them, capture); + + // Update material hash key and prefetch access to materialTable + k ^= Zobrist::psq[them][capture][capsq]; + st->materialKey ^= Zobrist::psq[them][capture][pieceCount[them][capture]]; + prefetch((char*)thisThread->materialTable[st->materialKey]); // Update incremental scores - st->psqScore -= pieceSquareTable[make_piece(them, capture)][capsq]; + st->psq -= psq[them][capture][capsq]; // Reset rule 50 counter st->rule50 = 0; } // Update hash key - k ^= zobrist[us][pt][from] ^ zobrist[us][pt][to]; + k ^= Zobrist::psq[us][pt][from] ^ Zobrist::psq[us][pt][to]; // Reset en passant square if (st->epSquare != SQ_NONE) { - k ^= zobEp[file_of(st->epSquare)]; + k ^= Zobrist::enpassant[file_of(st->epSquare)]; st->epSquare = SQ_NONE; } @@ -823,86 +821,61 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI if (st->castleRights && (castleRightsMask[from] | castleRightsMask[to])) { int cr = castleRightsMask[from] | castleRightsMask[to]; - k ^= zobCastle[st->castleRights & cr]; + k ^= Zobrist::castle[st->castleRights & cr]; st->castleRights &= ~cr; } - // Prefetch TT access as soon as we know key is updated + // Prefetch TT access as soon as we know the new hash key prefetch((char*)TT.first_entry(k)); - // Move the piece - Bitboard from_to_bb = SquareBB[from] | SquareBB[to]; - byTypeBB[ALL_PIECES] ^= from_to_bb; - byTypeBB[pt] ^= from_to_bb; - byColorBB[us] ^= from_to_bb; - - board[to] = board[from]; - board[from] = NO_PIECE; - - // Update piece lists, index[from] is not updated and becomes stale. This - // works as long as index[] is accessed just by known occupied squares. - index[to] = index[from]; - pieceList[us][pt][index[to]] = to; + // Move the piece. The tricky Chess960 castle is handled earlier + if (type_of(m) != CASTLE) + move_piece(from, to, us, pt); // If the moving piece is a pawn do some special extra work if (pt == PAWN) { // Set en-passant square, only if moved pawn can be captured if ( (int(to) ^ int(from)) == 16 - && (attacks_from(from + pawn_push(us), us) & pieces(PAWN, them))) + && (attacks_from(from + pawn_push(us), us) & pieces(them, PAWN))) { st->epSquare = Square((from + to) / 2); - k ^= zobEp[file_of(st->epSquare)]; + k ^= Zobrist::enpassant[file_of(st->epSquare)]; } - if (is_promotion(m)) + if (type_of(m) == PROMOTION) { PieceType promotion = promotion_type(m); assert(relative_rank(us, to) == RANK_8); assert(promotion >= KNIGHT && promotion <= QUEEN); - // Replace the pawn with the promoted piece - byTypeBB[PAWN] ^= to; - byTypeBB[promotion] |= to; - board[to] = make_piece(us, promotion); - - // Update piece lists, move the last pawn at index[to] position - // and shrink the list. Add a new promotion piece to the list. - Square lastSquare = pieceList[us][PAWN][--pieceCount[us][PAWN]]; - index[lastSquare] = index[to]; - pieceList[us][PAWN][index[lastSquare]] = lastSquare; - pieceList[us][PAWN][pieceCount[us][PAWN]] = SQ_NONE; - index[to] = pieceCount[us][promotion]; - pieceList[us][promotion][index[to]] = to; + remove_piece(to, us, PAWN); + put_piece(to, us, promotion); // Update hash keys - k ^= zobrist[us][PAWN][to] ^ zobrist[us][promotion][to]; - st->pawnKey ^= zobrist[us][PAWN][to]; - st->materialKey ^= zobrist[us][promotion][pieceCount[us][promotion]++] - ^ zobrist[us][PAWN][pieceCount[us][PAWN]]; + 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]]; // Update incremental score - st->psqScore += pieceSquareTable[make_piece(us, promotion)][to] - - pieceSquareTable[make_piece(us, PAWN)][to]; + st->psq += psq[us][promotion][to] - psq[us][PAWN][to]; // Update material - st->npMaterial[us] += PieceValueMidgame[promotion]; + st->npMaterial[us] += PieceValue[MG][promotion]; } - // Update pawn hash key - st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; + // Update pawn hash key and prefetch access to pawnsTable + st->pawnKey ^= Zobrist::psq[us][PAWN][from] ^ Zobrist::psq[us][PAWN][to]; + prefetch((char*)thisThread->pawnsTable[st->pawnKey]); // Reset rule 50 draw counter st->rule50 = 0; } - // Prefetch pawn and material hash tables - prefetch((char*)thisThread->pawnTable.entries[st->pawnKey]); - prefetch((char*)thisThread->materialTable.entries[st->materialKey]); - // Update incremental scores - st->psqScore += psq_delta(piece, from, to); + st->psq += psq[us][pt][to] - psq[us][pt][from]; // Set capture piece st->capturedType = capture; @@ -915,7 +888,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI if (moveIsCheck) { - if (is_special(m)) + if (type_of(m) != NORMAL) st->checkersBB = attackers_to(king_square(them)) & pieces(us); else { @@ -927,17 +900,15 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI if (ci.dcCandidates && (ci.dcCandidates & from)) { if (pt != ROOK) - st->checkersBB |= attacks_from(king_square(them)) & pieces(ROOK, QUEEN, us); + st->checkersBB |= attacks_from(king_square(them)) & pieces(us, QUEEN, ROOK); if (pt != BISHOP) - st->checkersBB |= attacks_from(king_square(them)) & pieces(BISHOP, QUEEN, us); + st->checkersBB |= attacks_from(king_square(them)) & pieces(us, QUEEN, BISHOP); } } } - // Finish sideToMove = ~sideToMove; - st->psqScore += (sideToMove == WHITE ? Tempo : -Tempo); assert(pos_is_ok()); } @@ -952,25 +923,17 @@ void Position::undo_move(Move m) { sideToMove = ~sideToMove; - if (is_castle(m)) - { - do_castle_move(m); - return; - } - Color us = sideToMove; Color them = ~us; Square from = from_sq(m); Square to = to_sq(m); - Piece piece = piece_on(to); - PieceType pt = type_of(piece); + PieceType pt = type_of(piece_on(to)); PieceType capture = st->capturedType; - assert(square_empty(from)); - assert(color_of(piece) == us); + assert(is_empty(from) || type_of(m) == CASTLE); assert(capture != KING); - if (is_promotion(m)) + if (type_of(m) == PROMOTION) { PieceType promotion = promotion_type(m); @@ -978,42 +941,29 @@ void Position::undo_move(Move m) { assert(relative_rank(us, to) == RANK_8); assert(promotion >= KNIGHT && promotion <= QUEEN); - // Replace the promoted piece with the pawn - byTypeBB[promotion] ^= to; - byTypeBB[PAWN] |= to; - board[to] = make_piece(us, PAWN); - - // Update piece lists, move the last promoted piece at index[to] position - // and shrink the list. Add a new pawn to the list. - Square lastSquare = pieceList[us][promotion][--pieceCount[us][promotion]]; - index[lastSquare] = index[to]; - pieceList[us][promotion][index[lastSquare]] = lastSquare; - pieceList[us][promotion][pieceCount[us][promotion]] = SQ_NONE; - index[to] = pieceCount[us][PAWN]++; - pieceList[us][PAWN][index[to]] = to; - + remove_piece(to, us, promotion); + put_piece(to, us, PAWN); pt = PAWN; } - // Put the piece back at the source square - Bitboard from_to_bb = SquareBB[from] | SquareBB[to]; - byTypeBB[ALL_PIECES] ^= from_to_bb; - byTypeBB[pt] ^= from_to_bb; - byColorBB[us] ^= from_to_bb; - - board[from] = board[to]; - board[to] = NO_PIECE; - - // Update piece lists, index[to] is not updated and becomes stale. This - // works as long as index[] is accessed just by known occupied squares. - index[from] = index[to]; - pieceList[us][pt][index[from]] = from; + if (type_of(m) == CASTLE) + { + bool kingSide = to > from; + Square rfrom = to; // Castle is encoded as "king captures friendly rook" + Square rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1); + to = relative_square(us, kingSide ? SQ_G1 : SQ_C1); + capture = NO_PIECE_TYPE; + pt = KING; + do_castle(to, from, rto, rfrom); + } + else + move_piece(to, from, us, pt); // Put the piece back at the source square if (capture) { Square capsq = to; - if (is_enpassant(m)) + if (type_of(m) == ENPASSANT) { capsq -= pawn_push(us); @@ -1023,180 +973,74 @@ void Position::undo_move(Move m) { assert(piece_on(capsq) == NO_PIECE); } - // Restore the captured piece - byTypeBB[ALL_PIECES] |= capsq; - byTypeBB[capture] |= capsq; - byColorBB[them] |= capsq; - - board[capsq] = make_piece(them, capture); - - // Update piece list, add a new captured piece in capsq square - index[capsq] = pieceCount[them][capture]++; - pieceList[them][capture][index[capsq]] = capsq; + put_piece(capsq, them, capture); // Restore the captured piece } // Finally point our state pointer back to the previous state st = st->previous; + gamePly--; assert(pos_is_ok()); } -/// Position::do_castle_move() is a private method used to do/undo a castling -/// move. Note that castling moves are encoded as "king captures friendly rook" -/// moves, for instance white short castling in a non-Chess960 game is encoded -/// as e1h1. -template -void Position::do_castle_move(Move m) { - - assert(is_ok(m)); - assert(is_castle(m)); - - Square kto, kfrom, rfrom, rto, kAfter, rAfter; +/// Position::do_castle() is a helper used to do/undo a castling move. This +/// is a bit tricky, especially in Chess960. - Color us = sideToMove; - Square kBefore = from_sq(m); - Square rBefore = to_sq(m); +void Position::do_castle(Square kfrom, Square kto, Square rfrom, Square rto) { - // Find after-castle squares for king and rook - if (rBefore > kBefore) // O-O - { - kAfter = relative_square(us, SQ_G1); - rAfter = relative_square(us, SQ_F1); - } - else // O-O-O - { - kAfter = relative_square(us, SQ_C1); - rAfter = relative_square(us, SQ_D1); - } + // Remove both pieces first since squares could overlap in Chess960 + remove_piece(kfrom, sideToMove, KING); + remove_piece(rfrom, sideToMove, ROOK); + board[kfrom] = board[rfrom] = NO_PIECE; // Since remove_piece doesn't do it for us + put_piece(kto, sideToMove, KING); + put_piece(rto, sideToMove, ROOK); +} - kfrom = Do ? kBefore : kAfter; - rfrom = Do ? rBefore : rAfter; - - kto = Do ? kAfter : kBefore; - rto = Do ? rAfter : rBefore; - - assert(piece_on(kfrom) == make_piece(us, KING)); - assert(piece_on(rfrom) == make_piece(us, ROOK)); - - // Remove pieces from source squares - byTypeBB[ALL_PIECES] ^= kfrom; - byTypeBB[KING] ^= kfrom; - byColorBB[us] ^= kfrom; - byTypeBB[ALL_PIECES] ^= rfrom; - byTypeBB[ROOK] ^= rfrom; - byColorBB[us] ^= rfrom; - - // Put pieces on destination squares - byTypeBB[ALL_PIECES] |= kto; - byTypeBB[KING] |= kto; - byColorBB[us] |= kto; - byTypeBB[ALL_PIECES] |= rto; - byTypeBB[ROOK] |= rto; - byColorBB[us] |= rto; - - // Update board - Piece king = make_piece(us, KING); - Piece rook = make_piece(us, ROOK); - board[kfrom] = board[rfrom] = NO_PIECE; - board[kto] = king; - board[rto] = rook; - - // Update piece lists - pieceList[us][KING][index[kfrom]] = kto; - pieceList[us][ROOK][index[rfrom]] = rto; - int tmp = index[rfrom]; // In Chess960 could be kto == rfrom - index[kto] = index[kfrom]; - index[rto] = tmp; - - if (Do) - { - // Reset capture field - st->capturedType = NO_PIECE_TYPE; - // Update incremental scores - st->psqScore += psq_delta(king, kfrom, kto); - st->psqScore += psq_delta(rook, rfrom, rto); +/// Position::do(undo)_null_move() is used to do(undo) a "null move": It flips +/// the side to move without executing any move on the board. - // Update hash key - st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto]; - st->key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto]; +void Position::do_null_move(StateInfo& newSt) { - // Clear en passant square - if (st->epSquare != SQ_NONE) - { - st->key ^= zobEp[file_of(st->epSquare)]; - st->epSquare = SQ_NONE; - } + assert(!checkers()); - // Update castling rights - st->key ^= zobCastle[st->castleRights & castleRightsMask[kfrom]]; - st->castleRights &= ~castleRightsMask[kfrom]; + std::memcpy(&newSt, st, sizeof(StateInfo)); // Fully copy here - // Update checkers BB - st->checkersBB = attackers_to(king_square(~us)) & pieces(us); + newSt.previous = st; + st = &newSt; - // Finish - sideToMove = ~sideToMove; - st->psqScore += (sideToMove == WHITE ? Tempo : -Tempo); + if (st->epSquare != SQ_NONE) + { + st->key ^= Zobrist::enpassant[file_of(st->epSquare)]; + st->epSquare = SQ_NONE; } - else - // Undo: point our state pointer back to the previous state - st = st->previous; - - assert(pos_is_ok()); -} - -/// Position::do_null_move() is used to do/undo a "null move": It flips the side -/// to move and updates the hash key without executing any move on the board. -template -void Position::do_null_move(StateInfo& backupSt) { + st->key ^= Zobrist::side; + prefetch((char*)TT.first_entry(st->key)); - assert(!in_check()); - - // Back up the information necessary to undo the null move to the supplied - // StateInfo object. Note that differently from normal case here backupSt - // is actually used as a backup storage not as the new state. This reduces - // the number of fields to be copied. - StateInfo* src = Do ? st : &backupSt; - StateInfo* dst = Do ? &backupSt : st; - - dst->key = src->key; - dst->epSquare = src->epSquare; - dst->psqScore = src->psqScore; - dst->rule50 = src->rule50; - dst->pliesFromNull = src->pliesFromNull; + st->rule50++; + st->pliesFromNull = 0; sideToMove = ~sideToMove; - if (Do) - { - if (st->epSquare != SQ_NONE) - st->key ^= zobEp[file_of(st->epSquare)]; + assert(pos_is_ok()); +} - st->key ^= zobSideToMove; - prefetch((char*)TT.first_entry(st->key)); +void Position::undo_null_move() { - st->epSquare = SQ_NONE; - st->rule50++; - st->pliesFromNull = 0; - st->psqScore += (sideToMove == WHITE ? Tempo : -Tempo); - } + assert(!checkers()); - assert(pos_is_ok()); + st = st->previous; + sideToMove = ~sideToMove; } -// Explicit template instantiations -template void Position::do_null_move(StateInfo& backupSt); -template void Position::do_null_move(StateInfo& backupSt); - /// 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 { @@ -1205,56 +1049,49 @@ int Position::see_sign(Move m) const { // 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 (PieceValueMidgame[piece_on(to_sq(m))] >= PieceValueMidgame[piece_moved(m)]) + if (PieceValue[MG][piece_moved(m)] <= PieceValue[MG][piece_on(to_sq(m))]) return 1; return see(m); } -int Position::see(Move m) const { +int Position::see(Move m, int asymmThreshold) const { Square from, to; - Bitboard occ, attackers, stmAttackers, b; + Bitboard occupied, attackers, stmAttackers; int swapList[32], slIndex = 1; - PieceType capturedType, pt; + PieceType captured; Color stm; assert(is_ok(m)); - // As castle moves are implemented as capturing the rook, they have - // SEE == RookValueMidgame most of the times (unless the rook is under - // attack). - if (is_castle(m)) - return 0; - from = from_sq(m); to = to_sq(m); - capturedType = type_of(piece_on(to)); - occ = pieces(); + swapList[0] = PieceValue[MG][type_of(piece_on(to))]; + stm = color_of(piece_on(from)); + occupied = pieces() ^ from; + + // Castle moves are implemented as king capturing the rook so cannot be + // handled correctly. Simply return 0 that is always the correct value + // unless in the rare case the rook ends up under attack. + if (type_of(m) == CASTLE) + return 0; - // Handle en passant moves - if (is_enpassant(m)) + if (type_of(m) == ENPASSANT) { - Square capQq = to - pawn_push(sideToMove); - - assert(!capturedType); - assert(type_of(piece_on(capQq)) == PAWN); - - // Remove the captured pawn - occ ^= capQq; - capturedType = PAWN; + occupied ^= to - pawn_push(stm); // Remove the captured pawn + swapList[0] = PieceValue[MG][PAWN]; } // Find all attackers to the destination square, with the moving piece // removed, but possibly an X-ray attacker added behind it. - occ ^= from; - attackers = attackers_to(to, occ); + attackers = attackers_to(to, occupied) & occupied; // If the opponent has no attackers we are finished - stm = ~color_of(piece_on(from)); + stm = ~stm; stmAttackers = attackers & pieces(stm); if (!stmAttackers) - return PieceValueMidgame[capturedType]; + return swapList[0]; // The destination square is defended, which makes things rather more // difficult to compute. We proceed by building up a "swap list" containing @@ -1262,45 +1099,38 @@ int Position::see(Move m) const { // 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. - swapList[0] = PieceValueMidgame[capturedType]; - capturedType = type_of(piece_on(from)); + captured = type_of(piece_on(from)); do { - // 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; !(stmAttackers & pieces(pt)); pt++) - assert(pt < KING); - - // Remove the attacker we just found from the 'occupied' bitboard, - // and scan for new X-ray attacks behind the attacker. - b = stmAttackers & pieces(pt); - occ ^= (b & (~b + 1)); - attackers |= (attacks_bb(to, occ) & pieces(ROOK, QUEEN)) - | (attacks_bb(to, occ) & pieces(BISHOP, QUEEN)); - - attackers &= occ; // Cut out pieces we've already done + assert(slIndex < 32); // Add the new entry to the swap list - assert(slIndex < 32); - swapList[slIndex] = -swapList[slIndex - 1] + PieceValueMidgame[capturedType]; + swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[MG][captured]; slIndex++; - // Remember the value of the capturing piece, and change the side to - // move before beginning the next iteration. - capturedType = pt; + // Locate and remove the next least valuable attacker + captured = min_attacker(byTypeBB, to, stmAttackers, occupied, attackers); stm = ~stm; stmAttackers = attackers & pieces(stm); // Stop before processing a king capture - if (capturedType == KING && stmAttackers) + if (captured == KING && stmAttackers) { - assert(slIndex < 32); - swapList[slIndex++] = QueenValueMidgame*10; + swapList[slIndex++] = QueenValueMg * 16; break; } + } 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) @@ -1315,34 +1145,13 @@ int Position::see(Move m) const { void Position::clear() { - memset(this, 0, sizeof(Position)); + std::memset(this, 0, sizeof(Position)); startState.epSquare = SQ_NONE; st = &startState; - for (int i = 0; i < 8; i++) + for (int i = 0; i < PIECE_TYPE_NB; i++) for (int j = 0; j < 16; j++) - pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE; - - for (Square sq = SQ_A1; sq <= SQ_H8; sq++) - board[sq] = NO_PIECE; -} - - -/// Position::put_piece() puts a piece on the given square of the board, -/// updating the board array, pieces list, bitboards, and piece counts. - -void Position::put_piece(Piece p, Square s) { - - Color c = color_of(p); - PieceType pt = type_of(p); - - board[s] = p; - index[s] = pieceCount[c][pt]++; - pieceList[c][pt][index[s]] = s; - - byTypeBB[ALL_PIECES] |= s; - byTypeBB[pt] |= s; - byColorBB[c] |= s; + pieceList[WHITE][i][j] = pieceList[BLACK][i][j] = SQ_NONE; } @@ -1353,19 +1162,21 @@ void Position::put_piece(Piece p, Square s) { Key Position::compute_key() const { - Key result = zobCastle[st->castleRights]; + Key k = Zobrist::castle[st->castleRights]; - for (Square s = SQ_A1; s <= SQ_H8; s++) - if (!square_empty(s)) - result ^= zobrist[color_of(piece_on(s))][type_of(piece_on(s))][s]; + for (Bitboard b = pieces(); b; ) + { + Square s = pop_lsb(&b); + k ^= Zobrist::psq[color_of(piece_on(s))][type_of(piece_on(s))][s]; + } if (ep_square() != SQ_NONE) - result ^= zobEp[file_of(ep_square())]; + k ^= Zobrist::enpassant[file_of(ep_square())]; if (sideToMove == BLACK) - result ^= zobSideToMove; + k ^= Zobrist::side; - return result; + return k; } @@ -1377,16 +1188,15 @@ Key Position::compute_key() const { Key Position::compute_pawn_key() const { - Bitboard b; - Key result = 0; + Key k = 0; - for (Color c = WHITE; c <= BLACK; c++) + for (Bitboard b = pieces(PAWN); b; ) { - b = pieces(PAWN, c); - while (b) - result ^= zobrist[c][PAWN][pop_1st_bit(&b)]; + Square s = pop_lsb(&b); + k ^= Zobrist::psq[color_of(piece_on(s))][PAWN][s]; } - return result; + + return k; } @@ -1398,14 +1208,14 @@ Key Position::compute_pawn_key() const { Key Position::compute_material_key() const { - Key result = 0; + Key k = 0; for (Color c = WHITE; c <= BLACK; c++) for (PieceType pt = PAWN; pt <= QUEEN; pt++) - for (int i = 0; i < piece_count(c, pt); i++) - result ^= zobrist[c][pt][i]; + for (int cnt = 0; cnt < pieceCount[c][pt]; cnt++) + k ^= Zobrist::psq[c][pt][cnt]; - return result; + return k; } @@ -1413,21 +1223,19 @@ Key Position::compute_material_key() const { /// game and the endgame. These functions are used to initialize the incremental /// scores when a new position is set up, and to verify that the scores are correctly /// updated by do_move and undo_move when the program is running in debug mode. + Score Position::compute_psq_score() const { - Bitboard b; - Score result = SCORE_ZERO; + Score score = SCORE_ZERO; - for (Color c = WHITE; c <= BLACK; c++) - for (PieceType pt = PAWN; pt <= KING; pt++) - { - b = pieces(pt, c); - while (b) - result += pieceSquareTable[make_piece(c, pt)][pop_1st_bit(&b)]; - } + for (Bitboard b = pieces(); b; ) + { + Square s = pop_lsb(&b); + Piece pc = piece_on(s); + score += psq[color_of(pc)][type_of(pc)][s]; + } - result += (sideToMove == WHITE ? Tempo / 2 : -Tempo / 2); - return result; + return score; } @@ -1438,150 +1246,83 @@ Score Position::compute_psq_score() const { Value Position::compute_non_pawn_material(Color c) const { - Value result = VALUE_ZERO; + Value value = VALUE_ZERO; for (PieceType pt = KNIGHT; pt <= QUEEN; pt++) - result += piece_count(c, pt) * PieceValueMidgame[pt]; + value += pieceCount[c][pt] * PieceValue[MG][pt]; - return result; + return value; } /// 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) <= BishopValueMidgame)) + && (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMg)) return true; // Draw by the 50 moves rule? - if (st->rule50 > 99 && (!in_check() || MoveList(*this).size())) + if (st->rule50 > 99 && (!checkers() || MoveList(*this).size())) return true; - // Draw by repetition? - if (!SkipRepetition) - { - int i = 4, e = std::min(st->rule50, st->pliesFromNull); + int i = 4, e = std::min(st->rule50, st->pliesFromNull); - if (i <= e) - { - StateInfo* stp = st->previous->previous; + if (i <= e) + { + StateInfo* stp = st->previous->previous; - do { - stp = stp->previous->previous; + do { + stp = stp->previous->previous; - if (stp->key == st->key) - return true; + if (stp->key == st->key) + return true; // Draw after first repetition - i +=2; + i += 2; - } while (i <= e); - } + } while (i <= e); } return false; } -// Explicit template instantiations -template bool Position::is_draw() const; -template bool Position::is_draw() const; - - -/// Position::init() is a static member function which initializes at startup -/// the various arrays used to compute hash keys and the piece square tables. -/// The latter is a two-step operation: First, the white halves of the tables -/// are copied from PSQT[] tables. Second, the black halves of the tables are -/// initialized by flipping and changing the sign of the white scores. -void Position::init() { +/// Position::flip() flips position with the white and black sides reversed. This +/// is only useful for debugging especially for finding evaluation symmetry bugs. - RKISS rk; +static char toggle_case(char c) { + return char(islower(c) ? toupper(c) : tolower(c)); +} - for (Color c = WHITE; c <= BLACK; c++) - for (PieceType pt = PAWN; pt <= KING; pt++) - for (Square s = SQ_A1; s <= SQ_H8; s++) - zobrist[c][pt][s] = rk.rand(); +void Position::flip() { - for (File f = FILE_A; f <= FILE_H; f++) - zobEp[f] = rk.rand(); + string f, token; + std::stringstream ss(fen()); - for (int cr = CASTLES_NONE; cr <= ALL_CASTLES; cr++) + for (Rank rank = RANK_8; rank >= RANK_1; rank--) // Piece placement { - Bitboard b = cr; - while (b) - { - Key k = zobCastle[1ULL << pop_1st_bit(&b)]; - zobCastle[cr] ^= k ? k : rk.rand(); - } + std::getline(ss, token, rank > RANK_1 ? '/' : ' '); + f.insert(0, token + (f.empty() ? " " : "/")); } - zobSideToMove = rk.rand(); - zobExclusion = rk.rand(); - - for (Piece p = W_PAWN; p <= W_KING; p++) - { - Score ps = make_score(PieceValueMidgame[p], PieceValueEndgame[p]); - - for (Square s = SQ_A1; s <= SQ_H8; s++) - { - pieceSquareTable[p][s] = ps + PSQT[p][s]; - pieceSquareTable[p+8][~s] = -pieceSquareTable[p][s]; - } - } -} + ss >> token; // Active color + f += (token == "w" ? "B " : "W "); // Will be lowercased later + ss >> token; // Castling availability + f += token + " "; -/// Position::flip() flips position with the white and black sides reversed. This -/// is only useful for debugging especially for finding evaluation symmetry bugs. + std::transform(f.begin(), f.end(), f.begin(), toggle_case); -void Position::flip() { + ss >> token; // En passant square + f += (token == "-" ? token : token.replace(1, 1, token[1] == '3' ? "6" : "3")); - // Make a copy of current position before to start changing - const Position pos(*this, thisThread); + std::getline(ss, token); // Half and full moves + f += token; - clear(); - thisThread = pos.this_thread(); - - // Board - for (Square s = SQ_A1; s <= SQ_H8; s++) - if (!pos.square_empty(s)) - put_piece(Piece(pos.piece_on(s) ^ 8), ~s); - - // Side to move - sideToMove = ~pos.side_to_move(); - - // Castling rights - if (pos.can_castle(WHITE_OO)) - set_castle_right(BLACK, ~pos.castle_rook_square(WHITE_OO)); - if (pos.can_castle(WHITE_OOO)) - set_castle_right(BLACK, ~pos.castle_rook_square(WHITE_OOO)); - if (pos.can_castle(BLACK_OO)) - set_castle_right(WHITE, ~pos.castle_rook_square(BLACK_OO)); - if (pos.can_castle(BLACK_OOO)) - set_castle_right(WHITE, ~pos.castle_rook_square(BLACK_OOO)); - - // En passant square - if (pos.st->epSquare != SQ_NONE) - st->epSquare = ~pos.st->epSquare; - - // Checkers - st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove); - - // Hash keys - st->key = compute_key(); - st->pawnKey = compute_pawn_key(); - st->materialKey = compute_material_key(); - - // Incremental scores - st->psqScore = compute_psq_score(); - - // Material - st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); - st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); + set(f, is_chess960(), this_thread()); assert(pos_is_ok()); } @@ -1592,42 +1333,39 @@ void Position::flip() { bool Position::pos_is_ok(int* failedStep) const { + int dummy, *step = failedStep ? failedStep : &dummy; + // What features of the position should be verified? - const bool debugAll = false; - - const bool debugBitboards = debugAll || false; - const bool debugKingCount = debugAll || false; - const bool debugKingCapture = debugAll || false; - const bool debugCheckerCount = debugAll || false; - const bool debugKey = debugAll || false; - const bool debugMaterialKey = debugAll || false; - const bool debugPawnKey = debugAll || false; - const bool debugIncrementalEval = debugAll || false; - const bool debugNonPawnMaterial = debugAll || false; - const bool debugPieceCounts = debugAll || false; - const bool debugPieceList = debugAll || false; - const bool debugCastleSquares = debugAll || false; - - if (failedStep) *failedStep = 1; - - // Side to move OK? + const bool all = false; + + const bool debugBitboards = all || false; + const bool debugKingCount = all || false; + const bool debugKingCapture = all || false; + const bool debugCheckerCount = all || false; + const bool debugKey = all || false; + const bool debugMaterialKey = all || false; + const bool debugPawnKey = all || false; + const bool debugIncrementalEval = all || false; + const bool debugNonPawnMaterial = all || false; + const bool debugPieceCounts = all || false; + const bool debugPieceList = all || false; + const bool debugCastleSquares = all || false; + + *step = 1; + if (sideToMove != WHITE && sideToMove != BLACK) return false; - // Are the king squares in the position correct? - if (failedStep) (*failedStep)++; - if (piece_on(king_square(WHITE)) != W_KING) + if ((*step)++, piece_on(king_square(WHITE)) != W_KING) return false; - if (failedStep) (*failedStep)++; - if (piece_on(king_square(BLACK)) != B_KING) + if ((*step)++, piece_on(king_square(BLACK)) != B_KING) return false; - // Do both sides have exactly one king? - if (failedStep) (*failedStep)++; - if (debugKingCount) + if ((*step)++, debugKingCount) { - int kingCount[2] = {0, 0}; + int kingCount[COLOR_NB] = {}; + for (Square s = SQ_A1; s <= SQ_H8; s++) if (type_of(piece_on(s)) == KING) kingCount[color_of(piece_on(s))]++; @@ -1636,25 +1374,14 @@ bool Position::pos_is_ok(int* failedStep) const { return false; } - // Can the side to move capture the opponent's king? - if (failedStep) (*failedStep)++; - if (debugKingCapture) - { - Color us = sideToMove; - Color them = ~us; - Square ksq = king_square(them); - if (attackers_to(ksq) & pieces(us)) + if ((*step)++, debugKingCapture) + if (attackers_to(king_square(~sideToMove)) & pieces(sideToMove)) return false; - } - // Is there more than 2 checkers? - if (failedStep) (*failedStep)++; - if (debugCheckerCount && popcount(st->checkersBB) > 2) + if ((*step)++, debugCheckerCount && popcount(st->checkersBB) > 2) return false; - // Bitboards OK? - if (failedStep) (*failedStep)++; - if (debugBitboards) + if ((*step)++, debugBitboards) { // The intersection of the white and black pieces must be empty if (pieces(WHITE) & pieces(BLACK)) @@ -1672,82 +1399,55 @@ bool Position::pos_is_ok(int* failedStep) const { return false; } - // En passant square OK? - if (failedStep) (*failedStep)++; - if (ep_square() != SQ_NONE) - { - // The en passant square must be on rank 6, from the point of view of the - // side to move. - if (relative_rank(sideToMove, ep_square()) != RANK_6) - return false; - } - - // Hash key OK? - if (failedStep) (*failedStep)++; - if (debugKey && st->key != compute_key()) + if ((*step)++, ep_square() != SQ_NONE && relative_rank(sideToMove, ep_square()) != RANK_6) return false; - // Pawn hash key OK? - if (failedStep) (*failedStep)++; - if (debugPawnKey && st->pawnKey != compute_pawn_key()) + if ((*step)++, debugKey && st->key != compute_key()) return false; - // Material hash key OK? - if (failedStep) (*failedStep)++; - if (debugMaterialKey && st->materialKey != compute_material_key()) + if ((*step)++, debugPawnKey && st->pawnKey != compute_pawn_key()) return false; - // Incremental eval OK? - if (failedStep) (*failedStep)++; - if (debugIncrementalEval && st->psqScore != compute_psq_score()) + if ((*step)++, debugMaterialKey && st->materialKey != compute_material_key()) return false; - // Non-pawn material OK? - if (failedStep) (*failedStep)++; - if (debugNonPawnMaterial) - { - if (st->npMaterial[WHITE] != compute_non_pawn_material(WHITE)) - return false; + if ((*step)++, debugIncrementalEval && st->psq != compute_psq_score()) + return false; - if (st->npMaterial[BLACK] != compute_non_pawn_material(BLACK)) + if ((*step)++, debugNonPawnMaterial) + if ( st->npMaterial[WHITE] != compute_non_pawn_material(WHITE) + || st->npMaterial[BLACK] != compute_non_pawn_material(BLACK)) return false; - } - // Piece counts OK? - if (failedStep) (*failedStep)++; - if (debugPieceCounts) + if ((*step)++, debugPieceCounts) for (Color c = WHITE; c <= BLACK; c++) for (PieceType pt = PAWN; pt <= KING; pt++) - if (pieceCount[c][pt] != popcount(pieces(pt, c))) + if (pieceCount[c][pt] != popcount(pieces(c, pt))) return false; - if (failedStep) (*failedStep)++; - if (debugPieceList) + if ((*step)++, debugPieceList) for (Color c = WHITE; c <= BLACK; c++) for (PieceType pt = PAWN; pt <= KING; pt++) for (int i = 0; i < pieceCount[c][pt]; i++) - { - if (piece_on(piece_list(c, pt)[i]) != make_piece(c, pt)) - return false; - - if (index[piece_list(c, pt)[i]] != i) + if ( board[pieceList[c][pt][i]] != make_piece(c, pt) + || index[pieceList[c][pt][i]] != i) return false; - } - if (failedStep) (*failedStep)++; - if (debugCastleSquares) - for (CastleRight f = WHITE_OO; f <= BLACK_OOO; f = CastleRight(f << 1)) - { - if (!can_castle(f)) - continue; + if ((*step)++, debugCastleSquares) + for (Color c = WHITE; c <= BLACK; c++) + for (CastlingSide s = KING_SIDE; s <= QUEEN_SIDE; s = CastlingSide(s + 1)) + { + CastleRight cr = make_castle_right(c, s); - Piece rook = (f & (WHITE_OO | WHITE_OOO) ? W_ROOK : B_ROOK); + if (!can_castle(cr)) + continue; - if ( piece_on(castleRookSquare[f]) != rook - || castleRightsMask[castleRookSquare[f]] != f) - return false; - } + if ( (castleRightsMask[king_square(c)] & cr) != cr + || piece_on(castleRookSquare[c][s]) != make_piece(c, ROOK) + || castleRightsMask[castleRookSquare[c][s]] != cr) + return false; + } - if (failedStep) *failedStep = 0; + *step = 0; return true; }