/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008 Marco Costalba
+ Copyright (C) 2008-2014 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
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-
-////
-//// Includes
-////
-
+#include <algorithm>
#include <cassert>
-#include <iostream>
-#include <fstream>
+#include <cstring>
+#include <iomanip>
+#include <sstream>
-#include "mersenne.h"
+#include "bitcount.h"
#include "movegen.h"
-#include "movepick.h"
#include "position.h"
#include "psqtab.h"
-#include "san.h"
-#include "ucioption.h"
-
-
-////
-//// Variables
-////
-
-extern SearchStack EmptySearchStack;
-
-int Position::castleRightsMask[64];
-
-Key Position::zobrist[2][8][64];
-Key Position::zobEp[64];
-Key Position::zobCastle[16];
-Key Position::zobMaterial[2][8][16];
-Key Position::zobSideToMove;
+#include "rkiss.h"
+#include "thread.h"
+#include "tt.h"
+#include "uci.h"
-Value Position::MgPieceSquareTable[16][64];
-Value Position::EgPieceSquareTable[16][64];
+using std::string;
-static bool RequestPending = false;
+CACHE_LINE_ALIGNMENT
-////
-//// Functions
-////
+Value PieceValue[PHASE_NB][PIECE_NB] = {
+{ VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg },
+{ VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg } };
-/// Constructors
+namespace Zobrist {
-Position::Position(const Position& pos) {
- copy(pos);
+ Key psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB];
+ Key enpassant[FILE_NB];
+ Key castling[CASTLING_RIGHT_NB];
+ Key side;
+ Key exclusion;
}
-Position::Position(const std::string& fen) {
- from_fen(fen);
-}
+Key Position::exclusion_key() const { return st->key ^ Zobrist::exclusion;}
+namespace {
-/// 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).
+const string PieceToChar(" PNBRQK pnbrqk");
+Score psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB];
-void Position::from_fen(const std::string& fen) {
+// 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.
- static const std::string pieceLetters = "KQRBNPkqrbnp";
- static const Piece pieces[] = { WK, WQ, WR, WB, WN, WP, BK, BQ, BR, BB, BN, BP };
+template<int Pt> FORCE_INLINE
+PieceType min_attacker(const Bitboard* bb, const Square& to, const Bitboard& stmAttackers,
+ Bitboard& occupied, Bitboard& attackers) {
- clear();
+ Bitboard b = stmAttackers & bb[Pt];
+ if (!b)
+ return min_attacker<Pt+1>(bb, to, stmAttackers, occupied, attackers);
- // Board
- Rank rank = RANK_8;
- File file = FILE_A;
- size_t i = 0;
- for ( ; fen[i] != ' '; i++)
- {
- if (isdigit(fen[i]))
- {
- // Skip the given number of files
- file += (fen[i] - '1' + 1);
- continue;
- }
- else if (fen[i] == '/')
- {
- file = FILE_A;
- rank--;
- continue;
- }
- size_t idx = pieceLetters.find(fen[i]);
- if (idx == std::string::npos)
- {
- std::cout << "Error in FEN at character " << i << std::endl;
- return;
- }
- Square square = make_square(file, rank);
- put_piece(pieces[idx], square);
- file++;
- }
+ occupied ^= b & ~(b - 1);
- // Side to move
- i++;
- if (fen[i] != 'w' && fen[i] != 'b')
- {
- std::cout << "Error in FEN at character " << i << std::endl;
- return;
- }
- sideToMove = (fen[i] == 'w' ? WHITE : BLACK);
+ if (Pt == PAWN || Pt == BISHOP || Pt == QUEEN)
+ attackers |= attacks_bb<BISHOP>(to, occupied) & (bb[BISHOP] | bb[QUEEN]);
- // Castling rights:
- i++;
- if (fen[i] != ' ')
- {
- std::cout << "Error in FEN at character " << i << std::endl;
- return;
- }
+ if (Pt == ROOK || Pt == QUEEN)
+ attackers |= attacks_bb<ROOK>(to, occupied) & (bb[ROOK] | bb[QUEEN]);
- i++;
- while(strchr("KQkqabcdefghABCDEFGH-", fen[i])) {
- if(fen[i] == '-') {
- i++; break;
- }
- else if(fen[i] == 'K') allow_oo(WHITE);
- else if(fen[i] == 'Q') allow_ooo(WHITE);
- else if(fen[i] == 'k') allow_oo(BLACK);
- else if(fen[i] == 'q') allow_ooo(BLACK);
- else if(fen[i] >= 'A' && fen[i] <= 'H') {
- File rookFile, kingFile = FILE_NONE;
- for(Square square = SQ_B1; square <= SQ_G1; square++)
- if(piece_on(square) == WK)
- kingFile = square_file(square);
- if(kingFile == FILE_NONE) {
- std::cout << "Error in FEN at character " << i << std::endl;
- return;
- }
- initialKFile = kingFile;
- rookFile = File(fen[i] - 'A') + FILE_A;
- if(rookFile < initialKFile) {
- allow_ooo(WHITE);
- initialQRFile = rookFile;
- }
- else {
- allow_oo(WHITE);
- initialKRFile = rookFile;
- }
- }
- else if(fen[i] >= 'a' && fen[i] <= 'h') {
- File rookFile, kingFile = FILE_NONE;
- for(Square square = SQ_B8; square <= SQ_G8; square++)
- if(piece_on(square) == BK)
- kingFile = square_file(square);
- if(kingFile == FILE_NONE) {
- std::cout << "Error in FEN at character " << i << std::endl;
- return;
- }
- initialKFile = kingFile;
- rookFile = File(fen[i] - 'a') + FILE_A;
- if(rookFile < initialKFile) {
- allow_ooo(BLACK);
- initialQRFile = rookFile;
- }
- else {
- allow_oo(BLACK);
- initialKRFile = rookFile;
- }
- }
- else {
- std::cout << "Error in FEN at character " << i << std::endl;
- return;
- }
- i++;
- }
+ attackers &= occupied; // After X-ray that may add already processed pieces
+ return (PieceType)Pt;
+}
- // Skip blanks
- while (fen[i] == ' ')
- i++;
-
- // En passant square
- if ( i < fen.length() - 2
- && (fen[i] >= 'a' && fen[i] <= 'h')
- && (fen[i+1] == '3' || fen[i+1] == '6'))
- epSquare = square_from_string(fen.substr(i, 2));
-
- // Various initialisation
- for (Square sq = SQ_A1; sq <= SQ_H8; sq++)
- castleRightsMask[sq] = ALL_CASTLES;
-
- castleRightsMask[make_square(initialKFile, RANK_1)] ^= (WHITE_OO|WHITE_OOO);
- castleRightsMask[make_square(initialKFile, RANK_8)] ^= (BLACK_OO|BLACK_OOO);
- castleRightsMask[make_square(initialKRFile, RANK_1)] ^= WHITE_OO;
- castleRightsMask[make_square(initialKRFile, RANK_8)] ^= BLACK_OO;
- castleRightsMask[make_square(initialQRFile, RANK_1)] ^= WHITE_OOO;
- castleRightsMask[make_square(initialQRFile, RANK_8)] ^= BLACK_OOO;
-
- find_checkers();
-
- key = compute_key();
- pawnKey = compute_pawn_key();
- materialKey = compute_material_key();
- mgValue = compute_mg_value();
- egValue = compute_eg_value();
- npMaterial[WHITE] = compute_non_pawn_material(WHITE);
- npMaterial[BLACK] = compute_non_pawn_material(BLACK);
+template<> FORCE_INLINE
+PieceType min_attacker<KING>(const Bitboard*, const Square&, const Bitboard&, Bitboard&, Bitboard&) {
+ return KING; // No need to update bitboards: it is the last cycle
}
+} // namespace
-/// Position::to_fen() converts the position object to a FEN string. This is
-/// probably only useful for debugging.
-const std::string Position::to_fen() const {
+/// CheckInfo c'tor
- static const std::string pieceLetters = " PNBRQK pnbrqk";
- std::string fen;
- int skip;
+CheckInfo::CheckInfo(const Position& pos) {
- for (Rank rank = RANK_8; rank >= RANK_1; rank--)
- {
- skip = 0;
- for (File file = FILE_A; file <= FILE_H; file++)
- {
- Square sq = make_square(file, rank);
- if (!square_is_occupied(sq))
- { skip++;
- continue;
- }
- if (skip > 0)
- {
- fen += (char)skip + '0';
- skip = 0;
- }
- fen += pieceLetters[piece_on(sq)];
- }
- if (skip > 0)
- fen += (char)skip + '0';
+ Color them = ~pos.side_to_move();
+ ksq = pos.king_square(them);
- fen += (rank > RANK_1 ? '/' : ' ');
- }
- fen += (sideToMove == WHITE ? "w " : "b ");
- if (castleRights != NO_CASTLES)
- {
- if (can_castle_kingside(WHITE)) fen += 'K';
- if (can_castle_queenside(WHITE)) fen += 'Q';
- if (can_castle_kingside(BLACK)) fen += 'k';
- if (can_castle_queenside(BLACK)) fen += 'q';
- } else
- fen += '-';
-
- fen += ' ';
- if (ep_square() != SQ_NONE)
- fen += square_to_string(ep_square());
- else
- fen += '-';
+ pinned = pos.pinned_pieces(pos.side_to_move());
+ dcCandidates = pos.discovered_check_candidates();
- return fen;
+ checkSq[PAWN] = pos.attacks_from<PAWN>(ksq, them);
+ checkSq[KNIGHT] = pos.attacks_from<KNIGHT>(ksq);
+ checkSq[BISHOP] = pos.attacks_from<BISHOP>(ksq);
+ checkSq[ROOK] = pos.attacks_from<ROOK>(ksq);
+ checkSq[QUEEN] = checkSq[BISHOP] | checkSq[ROOK];
+ checkSq[KING] = 0;
}
-/// Position::print() prints an ASCII representation of the position to
-/// the standard output. If a move is given then also the san is print.
+/// 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.
-void Position::print(Move m) const {
+void Position::init() {
- static const std::string pieceLetters = " PNBRQK PNBRQK .";
+ RKISS rk;
- // Check for reentrancy, as example when called from inside
- // MovePicker that is used also here in move_to_san()
- if (RequestPending)
- return;
+ 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<Key>();
- RequestPending = true;
+ for (File f = FILE_A; f <= FILE_H; ++f)
+ Zobrist::enpassant[f] = rk.rand<Key>();
- std::cout << std::endl;
- if (m != MOVE_NONE)
+ for (int cf = NO_CASTLING; cf <= ANY_CASTLING; ++cf)
{
- std::string col = (color_of_piece_on(move_from(m)) == BLACK ? ".." : "");
- std::cout << "Move is: " << col << move_to_san(*this, m) << std::endl;
- }
- for (Rank rank = RANK_8; rank >= RANK_1; rank--)
- {
- std::cout << "+---+---+---+---+---+---+---+---+" << std::endl;
- for (File file = FILE_A; file <= FILE_H; file++)
+ Bitboard b = cf;
+ while (b)
{
- Square sq = make_square(file, rank);
- Piece piece = piece_on(sq);
- if (piece == EMPTY && square_color(sq) == WHITE)
- piece = NO_PIECE;
-
- char col = (color_of_piece_on(sq) == BLACK ? '=' : ' ');
- std::cout << '|' << col << pieceLetters[piece] << col;
+ Key k = Zobrist::castling[1ULL << pop_lsb(&b)];
+ Zobrist::castling[cf] ^= k ? k : rk.rand<Key>();
}
- std::cout << '|' << std::endl;
}
- std::cout << "+---+---+---+---+---+---+---+---+" << std::endl
- << "Fen is: " << to_fen() << std::endl
- << "Key is: " << key << std::endl;
- RequestPending = false;
-}
+ Zobrist::side = rk.rand<Key>();
+ Zobrist::exclusion = rk.rand<Key>();
+ 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];
-/// Position::copy() creates a copy of the input position.
-
-void Position::copy(const Position &pos) {
+ Score v = make_score(PieceValue[MG][pt], PieceValue[EG][pt]);
- memcpy(this, &pos, sizeof(Position));
+ 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:pinned_pieces() returns a bitboard of all pinned (against the
-/// king) pieces for the given color.
-Bitboard Position::pinned_pieces(Color c) const {
-
- Square ksq = king_square(c);
- return hidden_checks<ROOK, true>(c, ksq) | hidden_checks<BISHOP, true>(c, ksq);
-}
+/// Position::operator=() creates a copy of 'pos'. We want the new born Position
+/// object to not depend on any external data so we detach state pointer from
+/// the source one.
+Position& Position::operator=(const Position& pos) {
-/// Position:discovered_check_candidates() returns a bitboard containing all
-/// pieces for the given side which are candidates for giving a discovered
-/// check. The code is almost the same as the function for finding pinned
-/// pieces.
+ std::memcpy(this, &pos, sizeof(Position));
+ startState = *st;
+ st = &startState;
+ nodes = 0;
-Bitboard Position::discovered_check_candidates(Color c) const {
+ assert(pos_is_ok());
- Square ksq = king_square(opposite_color(c));
- return hidden_checks<ROOK, false>(c, ksq) | hidden_checks<BISHOP, false>(c, ksq);
+ return *this;
}
-/// Position:hidden_checks<>() returns a bitboard of all pinned (against the
-/// king) pieces for the given color and for the given pinner type. Or, when
-/// template parameter FindPinned is false, the pinned pieces of opposite color
-/// that are, indeed, the pieces candidate for a discovery check.
-template<PieceType Piece, bool FindPinned>
-Bitboard Position::hidden_checks(Color c, Square ksq) const {
-
- Square s;
- Bitboard sliders, result = EmptyBoardBB;
-
- if (Piece == ROOK) // Resolved at compile time
- sliders = rooks_and_queens(FindPinned ? opposite_color(c) : c) & RookPseudoAttacks[ksq];
- else
- sliders = bishops_and_queens(FindPinned ? opposite_color(c) : c) & BishopPseudoAttacks[ksq];
-
- if (sliders && (!FindPinned || (sliders & ~checkersBB)))
- {
- // King blockers are candidate pinned pieces
- Bitboard candidate_pinned = piece_attacks<Piece>(ksq) & pieces_of_color(c);
+/// Position::clear() erases the position object to a pristine state, with an
+/// empty board, white to move, and no castling rights.
- // Pinners are sliders, not checkers, that give check when
- // candidate pinned are removed.
- Bitboard pinners = (FindPinned ? sliders & ~checkersBB : sliders);
+void Position::clear() {
- if (Piece == ROOK)
- pinners &= rook_attacks_bb(ksq, occupied_squares() ^ candidate_pinned);
- else
- pinners &= bishop_attacks_bb(ksq, occupied_squares() ^ candidate_pinned);
+ std::memset(this, 0, sizeof(Position));
+ startState.epSquare = SQ_NONE;
+ st = &startState;
- // Finally for each pinner find the corresponding pinned piece (if same color of king)
- // or discovery checker (if opposite color) among the candidates.
- while (pinners)
- {
- s = pop_1st_bit(&pinners);
- result |= (squares_between(s, ksq) & candidate_pinned);
- }
- }
- return result;
+ 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;
}
-/// Position::square_is_attacked() checks whether the given side attacks the
-/// given square.
+/// 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.
-bool Position::square_is_attacked(Square s, Color c) const {
+void Position::set(const string& fenStr, bool isChess960, Thread* th) {
+/*
+ A FEN string defines a particular position using only the ASCII character set.
- return (pawn_attacks(opposite_color(c), s) & pawns(c))
- || (piece_attacks<KNIGHT>(s) & knights(c))
- || (piece_attacks<KING>(s) & kings(c))
- || (piece_attacks<ROOK>(s) & rooks_and_queens(c))
- || (piece_attacks<BISHOP>(s) & bishops_and_queens(c));
-}
+ A FEN string contains six fields separated by a space. The fields are:
+ 1) Piece placement (from white's perspective). Each rank is described, starting
+ with rank 8 and ending with rank 1. Within each rank, the contents of each
+ square are described from file A through file H. Following the Standard
+ Algebraic Notation (SAN), each piece is identified by a single letter taken
+ from the standard English names. White pieces are designated using upper-case
+ letters ("PNBRQK") whilst Black uses lowercase ("pnbrqk"). Blank squares are
+ noted using digits 1 through 8 (the number of blank squares), and "/"
+ separates ranks.
-/// Position::attacks_to() computes a bitboard containing all pieces which
-/// attacks a given square. There are two versions of this function: One
-/// which finds attackers of both colors, and one which only finds the
-/// attackers for one side.
+ 2) Active color. "w" means white moves next, "b" means black.
-Bitboard Position::attacks_to(Square s) const {
+ 3) Castling availability. If neither side can castle, this is "-". Otherwise,
+ this has one or more letters: "K" (White can castle kingside), "Q" (White
+ can castle queenside), "k" (Black can castle kingside), and/or "q" (Black
+ can castle queenside).
- return (pawn_attacks(BLACK, s) & pawns(WHITE))
- | (pawn_attacks(WHITE, s) & pawns(BLACK))
- | (piece_attacks<KNIGHT>(s) & pieces_of_type(KNIGHT))
- | (piece_attacks<ROOK>(s) & rooks_and_queens())
- | (piece_attacks<BISHOP>(s) & bishops_and_queens())
- | (piece_attacks<KING>(s) & pieces_of_type(KING));
-}
+ 4) En passant target square (in algebraic notation). If there's no en passant
+ target square, this is "-". If a pawn has just made a 2-square move, this
+ is the position "behind" the pawn. This is recorded regardless of whether
+ there is a pawn in position to make an en passant capture.
-Bitboard Position::attacks_to(Square s, Color c) const {
+ 5) Halfmove clock. This is the number of halfmoves since the last pawn advance
+ or capture. This is used to determine if a draw can be claimed under the
+ fifty-move rule.
- return attacks_to(s) & pieces_of_color(c);
-}
+ 6) Fullmove number. The number of the full move. It starts at 1, and is
+ incremented after Black's move.
+*/
+ unsigned char col, row, token;
+ size_t idx;
+ Square sq = SQ_A8;
+ std::istringstream ss(fenStr);
-/// Position::piece_attacks_square() tests whether the piece on square f
-/// attacks square t.
+ clear();
+ ss >> std::noskipws;
-bool Position::piece_attacks_square(Square f, Square t) const {
+ // 1. Piece placement
+ while ((ss >> token) && !isspace(token))
+ {
+ if (isdigit(token))
+ sq += Square(token - '0'); // Advance the given number of files
- assert(square_is_ok(f));
- assert(square_is_ok(t));
+ else if (token == '/')
+ sq -= Square(16);
- switch (piece_on(f))
- {
- case WP: return pawn_attacks_square(WHITE, f, t);
- case BP: return pawn_attacks_square(BLACK, f, t);
- case WN: case BN: return piece_attacks_square<KNIGHT>(f, t);
- case WB: case BB: return piece_attacks_square<BISHOP>(f, t);
- case WR: case BR: return piece_attacks_square<ROOK>(f, t);
- case WQ: case BQ: return piece_attacks_square<QUEEN>(f, t);
- case WK: case BK: return piece_attacks_square<KING>(f, t);
- default: break;
+ else if ((idx = PieceToChar.find(token)) != string::npos)
+ {
+ put_piece(sq, color_of(Piece(idx)), type_of(Piece(idx)));
+ ++sq;
+ }
}
- return false;
-}
+ // 2. Active color
+ ss >> token;
+ sideToMove = (token == 'w' ? WHITE : BLACK);
+ 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 ((ss >> token) && !isspace(token))
+ {
+ Square rsq;
+ Color c = islower(token) ? BLACK : WHITE;
+
+ token = char(toupper(token));
-/// Position::move_attacks_square() tests whether a move from the current
-/// position attacks a given square. Only attacks by the moving piece are
-/// considered; the function does not handle X-ray attacks.
+ if (token == 'K')
+ for (rsq = relative_square(c, SQ_H1); type_of(piece_on(rsq)) != ROOK; --rsq) {}
-bool Position::move_attacks_square(Move m, Square s) const {
+ else if (token == 'Q')
+ for (rsq = relative_square(c, SQ_A1); type_of(piece_on(rsq)) != ROOK; ++rsq) {}
- assert(move_is_ok(m));
- assert(square_is_ok(s));
+ else if (token >= 'A' && token <= 'H')
+ rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1));
- Square f = move_from(m), t = move_to(m);
+ else
+ continue;
- assert(square_is_occupied(f));
+ set_castling_right(c, rsq);
+ }
- switch (piece_on(f))
+ // 4. En passant square. Ignore if no pawn capture is possible
+ if ( ((ss >> col) && (col >= 'a' && col <= 'h'))
+ && ((ss >> row) && (row == '3' || row == '6')))
{
- case WP: return pawn_attacks_square(WHITE, t, s);
- case BP: return pawn_attacks_square(BLACK, t, s);
- case WN: case BN: return piece_attacks_square<KNIGHT>(t, s);
- case WB: case BB: return piece_attacks_square<BISHOP>(t, s);
- case WR: case BR: return piece_attacks_square<ROOK>(t, s);
- case WQ: case BQ: return piece_attacks_square<QUEEN>(t, s);
- case WK: case BK: return piece_attacks_square<KING>(t, s);
- default: break;
+ st->epSquare = make_square(File(col - 'a'), Rank(row - '1'));
+
+ if (!(attackers_to(st->epSquare) & pieces(sideToMove, PAWN)))
+ st->epSquare = SQ_NONE;
}
- return false;
-}
+ // 5-6. Halfmove clock and fullmove number
+ ss >> std::skipws >> st->rule50 >> gamePly;
-/// Position::find_checkers() computes the checkersBB bitboard, which
-/// contains a nonzero bit for each checking piece (0, 1 or 2). It
-/// currently works by calling Position::attacks_to, which is probably
-/// inefficient. Consider rewriting this function to use the last move
-/// played, like in non-bitboard versions of Glaurung.
+ // Convert from fullmove starting from 1 to ply starting from 0,
+ // handle also common incorrect FEN with fullmove = 0.
+ gamePly = std::max(2 * (gamePly - 1), 0) + (sideToMove == BLACK);
-void Position::find_checkers() {
+ chess960 = isChess960;
+ thisThread = th;
+ set_state(st);
- Color us = side_to_move();
- checkersBB = attacks_to(king_square(us), opposite_color(us));
+ assert(pos_is_ok());
}
-/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal.
-/// There are two versions of this function: One which takes only a
-/// move as input, and one which takes a move and a bitboard of pinned
-/// pieces. The latter function is faster, and should always be preferred
-/// when a pinned piece bitboard has already been computed.
+/// Position::set_castling_right() is a helper function used to set castling
+/// rights given the corresponding color and the rook starting square.
-bool Position::pl_move_is_legal(Move m) const {
+void Position::set_castling_right(Color c, Square rfrom) {
- return pl_move_is_legal(m, pinned_pieces(side_to_move()));
-}
+ Square kfrom = king_square(c);
+ CastlingSide cs = kfrom < rfrom ? KING_SIDE : QUEEN_SIDE;
+ CastlingRight cr = (c | cs);
-bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
+ st->castlingRights |= cr;
+ castlingRightsMask[kfrom] |= cr;
+ castlingRightsMask[rfrom] |= cr;
+ castlingRookSquare[cr] = rfrom;
- assert(is_ok());
- assert(move_is_ok(m));
- assert(pinned == pinned_pieces(side_to_move()));
+ Square kto = relative_square(c, cs == KING_SIDE ? SQ_G1 : SQ_C1);
+ Square rto = relative_square(c, cs == KING_SIDE ? SQ_F1 : SQ_D1);
- // If we're in check, all pseudo-legal moves are legal, because our
- // check evasion generator only generates true legal moves.
- if (is_check())
- return true;
+ for (Square s = std::min(rfrom, rto); s <= std::max(rfrom, rto); ++s)
+ if (s != kfrom && s != rfrom)
+ castlingPath[cr] |= s;
- // Castling moves are checked for legality during move generation.
- if (move_is_castle(m))
- return true;
+ for (Square s = std::min(kfrom, kto); s <= std::max(kfrom, kto); ++s)
+ if (s != kfrom && s != rfrom)
+ castlingPath[cr] |= s;
+}
- Color us = side_to_move();
- Color them = opposite_color(us);
- Square from = move_from(m);
- Square ksq = king_square(us);
- assert(color_of_piece_on(from) == us);
- assert(piece_on(ksq) == king_of_color(us));
+/// 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
+/// the correctness of the StateInfo data when running in debug mode.
- // 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 (move_is_ep(m))
- {
- Square to = move_to(m);
- Square capsq = make_square(square_file(to), square_rank(from));
- Bitboard b = occupied_squares();
+void Position::set_state(StateInfo* si) const {
- assert(to == ep_square());
- assert(piece_on(from) == pawn_of_color(us));
- assert(piece_on(capsq) == pawn_of_color(them));
- assert(piece_on(to) == EMPTY);
+ si->key = si->pawnKey = si->materialKey = 0;
+ si->npMaterial[WHITE] = si->npMaterial[BLACK] = VALUE_ZERO;
+ si->psq = SCORE_ZERO;
- clear_bit(&b, from);
- clear_bit(&b, capsq);
- set_bit(&b, to);
+ si->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove);
- return !(rook_attacks_bb(ksq, b) & rooks_and_queens(them))
- && !(bishop_attacks_bb(ksq, b) & bishops_and_queens(them));
+ 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];
}
- // If the moving piece is a king, check whether the destination
- // square is attacked by the opponent.
- if (from == ksq)
- return !(square_is_attacked(move_to(m), them));
+ if (ep_square() != SQ_NONE)
+ si->key ^= Zobrist::enpassant[file_of(ep_square())];
- // 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 ( !bit_is_set(pinned, from)
- || (direction_between_squares(from, ksq) == direction_between_squares(move_to(m), ksq)));
-}
+ if (sideToMove == BLACK)
+ si->key ^= Zobrist::side;
+ si->key ^= Zobrist::castling[st->castlingRights];
-/// Position::move_is_check() tests whether a pseudo-legal move is a check.
-/// There are two versions of this function: One which takes only a move as
-/// input, and one which takes a move and a bitboard of discovered check
-/// candidates. The latter function is faster, and should always be preferred
-/// when a discovered check candidates bitboard has already been computed.
+ for (Bitboard b = pieces(PAWN); b; )
+ {
+ Square s = pop_lsb(&b);
+ si->pawnKey ^= Zobrist::psq[color_of(piece_on(s))][PAWN][s];
+ }
-bool Position::move_is_check(Move m) const {
+ 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];
- Bitboard dc = discovered_check_candidates(side_to_move());
- return move_is_check(m, dc);
+ for (Color c = WHITE; c <= BLACK; ++c)
+ for (PieceType pt = KNIGHT; pt <= QUEEN; ++pt)
+ si->npMaterial[c] += pieceCount[c][pt] * PieceValue[MG][pt];
}
-bool Position::move_is_check(Move m, Bitboard dcCandidates) const {
- assert(is_ok());
- assert(move_is_ok(m));
- assert(dcCandidates == discovered_check_candidates(side_to_move()));
+/// Position::fen() returns a FEN representation of the position. In case of
+/// Chess960 the Shredder-FEN notation is used. This is mainly a debugging function.
- Color us = side_to_move();
- Color them = opposite_color(us);
- Square from = move_from(m);
- Square to = move_to(m);
- Square ksq = king_square(them);
+const string Position::fen() const {
- assert(color_of_piece_on(from) == us);
- assert(piece_on(ksq) == king_of_color(them));
+ int emptyCnt;
+ std::ostringstream ss;
- // Proceed according to the type of the moving piece
- switch (type_of_piece_on(from))
+ for (Rank r = RANK_8; r >= RANK_1; --r)
{
- case PAWN:
-
- if (bit_is_set(pawn_attacks(them, ksq), to)) // Normal check?
- return true;
-
- if ( bit_is_set(dcCandidates, from) // Discovered check?
- && (direction_between_squares(from, ksq) != direction_between_squares(to, ksq)))
- return true;
-
- if (move_promotion(m)) // Promotion with check?
+ for (File f = FILE_A; f <= FILE_H; ++f)
{
- Bitboard b = occupied_squares();
- clear_bit(&b, from);
+ for (emptyCnt = 0; f <= FILE_H && empty(make_square(f, r)); ++f)
+ ++emptyCnt;
- switch (move_promotion(m))
- {
- case KNIGHT:
- return bit_is_set(piece_attacks<KNIGHT>(to), ksq);
- case BISHOP:
- return bit_is_set(bishop_attacks_bb(to, b), ksq);
- case ROOK:
- return bit_is_set(rook_attacks_bb(to, b), ksq);
- case QUEEN:
- return bit_is_set(queen_attacks_bb(to, b), ksq);
- default:
- assert(false);
- }
- }
- // 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.
- else if (move_is_ep(m))
- {
- Square capsq = make_square(square_file(to), square_rank(from));
- Bitboard b = occupied_squares();
- clear_bit(&b, from);
- clear_bit(&b, capsq);
- set_bit(&b, to);
- return (rook_attacks_bb(ksq, b) & rooks_and_queens(us))
- ||(bishop_attacks_bb(ksq, b) & bishops_and_queens(us));
- }
- return false;
+ if (emptyCnt)
+ ss << emptyCnt;
- case KNIGHT:
- return bit_is_set(dcCandidates, from) // Discovered check?
- || bit_is_set(piece_attacks<KNIGHT>(ksq), to); // Normal check?
-
- case BISHOP:
- return bit_is_set(dcCandidates, from) // Discovered check?
- || bit_is_set(piece_attacks<BISHOP>(ksq), to); // Normal check?
-
- case ROOK:
- return bit_is_set(dcCandidates, from) // Discovered check?
- || bit_is_set(piece_attacks<ROOK>(ksq), to); // Normal check?
-
- case QUEEN:
- // Discovered checks are impossible!
- assert(!bit_is_set(dcCandidates, from));
- return bit_is_set(piece_attacks<QUEEN>(ksq), to); // Normal check?
-
- case KING:
- // Discovered check?
- if ( bit_is_set(dcCandidates, from)
- && (direction_between_squares(from, ksq) != direction_between_squares(to, ksq)))
- return true;
-
- // Castling with check?
- if (move_is_castle(m))
- {
- Square kfrom, kto, rfrom, rto;
- Bitboard b = occupied_squares();
- kfrom = from;
- rfrom = to;
-
- if (rfrom > kfrom)
- {
- kto = relative_square(us, SQ_G1);
- rto = relative_square(us, SQ_F1);
- } else {
- kto = relative_square(us, SQ_C1);
- rto = relative_square(us, SQ_D1);
- }
- clear_bit(&b, kfrom);
- clear_bit(&b, rfrom);
- set_bit(&b, rto);
- set_bit(&b, kto);
- return bit_is_set(rook_attacks_bb(rto, b), ksq);
+ if (f <= FILE_H)
+ ss << PieceToChar[piece_on(make_square(f, r))];
}
- return false;
- default: // NO_PIECE_TYPE
- break;
+ if (r > RANK_1)
+ ss << '/';
}
- assert(false);
- return false;
-}
+ ss << (sideToMove == WHITE ? " w " : " b ");
-/// Position::move_is_capture() tests whether a move from the current
-/// position is a capture. Move must not be MOVE_NONE.
+ if (can_castle(WHITE_OO))
+ ss << (chess960 ? 'A' + file_of(castling_rook_square(WHITE | KING_SIDE)) : 'K');
-bool Position::move_is_capture(Move m) const {
+ if (can_castle(WHITE_OOO))
+ ss << (chess960 ? 'A' + file_of(castling_rook_square(WHITE | QUEEN_SIDE)) : 'Q');
- assert(m != MOVE_NONE);
+ if (can_castle(BLACK_OO))
+ ss << (chess960 ? 'a' + file_of(castling_rook_square(BLACK | KING_SIDE)) : 'k');
- return ( !square_is_empty(move_to(m))
- && (color_of_piece_on(move_to(m)) == opposite_color(side_to_move()))
- )
- || move_is_ep(m);
-}
+ if (can_castle(BLACK_OOO))
+ ss << (chess960 ? 'a' + file_of(castling_rook_square(BLACK | QUEEN_SIDE)) : 'q');
+ if (!can_castle(WHITE) && !can_castle(BLACK))
+ ss << '-';
-/// Position::backup() is called when making a move. All information
-/// necessary to restore the position when the move is later unmade
-/// is saved to an UndoInfo object. The function Position::restore
-/// does the reverse operation: When one does a backup followed by
-/// a restore with the same UndoInfo object, the position is restored
-/// to the state before backup was called.
-
-void Position::backup(UndoInfo& u) const {
-
- u.castleRights = castleRights;
- u.epSquare = epSquare;
- u.checkersBB = checkersBB;
- u.key = key;
- u.pawnKey = pawnKey;
- u.materialKey = materialKey;
- u.rule50 = rule50;
- u.lastMove = lastMove;
- u.mgValue = mgValue;
- u.egValue = egValue;
- u.capture = NO_PIECE_TYPE;
-}
+ ss << (ep_square() == SQ_NONE ? " - " : " " + UCI::format_square(ep_square()) + " ")
+ << st->rule50 << " " << 1 + (gamePly - (sideToMove == BLACK)) / 2;
-
-/// Position::restore() is called when unmaking a move. It copies back
-/// the information backed up during a previous call to Position::backup.
-
-void Position::restore(const UndoInfo& u) {
-
- castleRights = u.castleRights;
- epSquare = u.epSquare;
- checkersBB = u.checkersBB;
- key = u.key;
- pawnKey = u.pawnKey;
- materialKey = u.materialKey;
- rule50 = u.rule50;
- lastMove = u.lastMove;
- mgValue = u.mgValue;
- egValue = u.egValue;
- // u.capture is restored in undo_move()
-}
-
-/// Position::do_move() makes a move, and backs up all information necessary
-/// to undo the move to an UndoInfo object. The move is assumed to be legal.
-/// Pseudo-legal moves should be filtered out before this function is called.
-/// There are two versions of this function, one which takes only the move and
-/// the UndoInfo as input, and one which takes a third parameter, a bitboard of
-/// discovered check candidates. The second version is faster, because knowing
-/// the discovered check candidates makes it easier to update the checkersBB
-/// member variable in the position object.
-
-void Position::do_move(Move m, UndoInfo& u) {
-
- do_move(m, u, discovered_check_candidates(side_to_move()));
+ return ss.str();
}
-void Position::do_move(Move m, UndoInfo& u, Bitboard dcCandidates) {
- assert(is_ok());
- assert(move_is_ok(m));
+/// Position::pretty() returns an ASCII representation of the position
- // Back up the necessary information to our UndoInfo object (except the
- // captured piece, which is taken care of later.
- backup(u);
+const string Position::pretty() const {
- // Save the current key to the history[] array, in order to be able to
- // detect repetition draws.
- history[gamePly] = key;
+ std::ostringstream ss;
- // Increment the 50 moves rule draw counter. Resetting it to zero in the
- // case of non-reversible moves is taken care of later.
- rule50++;
+ ss << "\n +---+---+---+---+---+---+---+---+\n";
- if (move_is_castle(m))
- do_castle_move(m);
- else if (move_promotion(m))
- do_promotion_move(m, u);
- else if (move_is_ep(m))
- do_ep_move(m);
- else
+ for (Rank r = RANK_8; r >= RANK_1; --r)
{
- Color us = side_to_move();
- Color them = opposite_color(us);
- Square from = move_from(m);
- Square to = move_to(m);
-
- assert(color_of_piece_on(from) == us);
- assert(color_of_piece_on(to) == them || piece_on(to) == EMPTY);
-
- PieceType piece = type_of_piece_on(from);
- PieceType capture = type_of_piece_on(to);
-
- if (capture)
- {
- u.capture = capture;
- do_capture_move(m, capture, them, to);
- }
-
- // Move the piece
- clear_bit(&(byColorBB[us]), from);
- clear_bit(&(byTypeBB[piece]), from);
- clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
- set_bit(&(byColorBB[us]), to);
- set_bit(&(byTypeBB[piece]), to);
- set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
- board[to] = board[from];
- board[from] = EMPTY;
-
- // Update hash key
- key ^= zobrist[us][piece][from] ^ zobrist[us][piece][to];
-
- // Update incremental scores
- mgValue -= mg_pst(us, piece, from);
- mgValue += mg_pst(us, piece, to);
- egValue -= eg_pst(us, piece, from);
- egValue += eg_pst(us, piece, to);
-
- // If the moving piece was a king, update the king square
- if (piece == KING)
- kingSquare[us] = to;
-
- // If the move was a double pawn push, set the en passant square.
- // This code is a bit ugly right now, and should be cleaned up later.
- // FIXME
- if (epSquare != SQ_NONE)
- {
- key ^= zobEp[epSquare];
- epSquare = SQ_NONE;
- }
- if (piece == PAWN)
- {
- if (abs(int(to) - int(from)) == 16)
- {
- if( ( us == WHITE
- && (pawn_attacks(WHITE, from + DELTA_N) & pawns(BLACK)))
- || ( us == BLACK
- && (pawn_attacks(BLACK, from + DELTA_S) & pawns(WHITE))))
- {
- epSquare = Square((int(from) + int(to)) / 2);
- key ^= zobEp[epSquare];
- }
- }
- // Reset rule 50 draw counter
- rule50 = 0;
-
- // Update pawn hash key
- pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
- }
- // Update piece lists
- pieceList[us][piece][index[from]] = to;
- index[to] = index[from];
-
- // Update castle rights
- key ^= zobCastle[castleRights];
- castleRights &= castleRightsMask[from];
- castleRights &= castleRightsMask[to];
- key ^= zobCastle[castleRights];
-
- // Update checkers bitboard
- checkersBB = EmptyBoardBB;
- Square ksq = king_square(them);
- switch (piece)
- {
- case PAWN:
- if (bit_is_set(pawn_attacks(them, ksq), to))
- set_bit(&checkersBB, to);
-
- if (bit_is_set(dcCandidates, from))
- checkersBB |= ( (piece_attacks<ROOK>(ksq) & rooks_and_queens(us))
- |(piece_attacks<BISHOP>(ksq) & bishops_and_queens(us)));
- break;
-
- case KNIGHT:
- if (bit_is_set(piece_attacks<KNIGHT>(ksq), to))
- set_bit(&checkersBB, to);
-
- if (bit_is_set(dcCandidates, from))
- checkersBB |= ( (piece_attacks<ROOK>(ksq) & rooks_and_queens(us))
- |(piece_attacks<BISHOP>(ksq) & bishops_and_queens(us)));
- break;
-
- case BISHOP:
- if (bit_is_set(piece_attacks<BISHOP>(ksq), to))
- set_bit(&checkersBB, to);
-
- if (bit_is_set(dcCandidates, from))
- checkersBB |= (piece_attacks<ROOK>(ksq) & rooks_and_queens(us));
- break;
-
- case ROOK:
- if (bit_is_set(piece_attacks<ROOK>(ksq), to))
- set_bit(&checkersBB, to);
-
- if (bit_is_set(dcCandidates, from))
- checkersBB |= (piece_attacks<BISHOP>(ksq) & bishops_and_queens(us));
- break;
-
- case QUEEN:
- if (bit_is_set(piece_attacks<QUEEN>(ksq), to))
- set_bit(&checkersBB, to);
- break;
-
- case KING:
- if (bit_is_set(dcCandidates, from))
- checkersBB |= ( (piece_attacks<ROOK>(ksq) & rooks_and_queens(us))
- |(piece_attacks<BISHOP>(ksq) & bishops_and_queens(us)));
- break;
-
- default:
- assert(false);
- break;
- }
+ for (File f = FILE_A; f <= FILE_H; ++f)
+ ss << " | " << PieceToChar[piece_on(make_square(f, r))];
+
+ ss << " |\n +---+---+---+---+---+---+---+---+\n";
}
- // Finish
- key ^= zobSideToMove;
- sideToMove = opposite_color(sideToMove);
- gamePly++;
+ ss << "\nFen: " << fen() << "\nKey: " << std::hex << std::uppercase
+ << std::setfill('0') << std::setw(16) << st->key << "\nCheckers: ";
- mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
- egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
+ for (Bitboard b = checkers(); b; )
+ ss << UCI::format_square(pop_lsb(&b)) << " ";
- assert(is_ok());
+ return ss.str();
}
-/// Position::do_capture_move() is a private method used to update captured
-/// piece info. It is called from the main Position::do_move function.
+/// Position::game_phase() calculates the game phase interpolating total non-pawn
+/// material between endgame and midgame limits.
-void Position::do_capture_move(Move m, PieceType capture, Color them, Square to) {
+Phase Position::game_phase() const {
- assert(capture != KING);
+ Value npm = st->npMaterial[WHITE] + st->npMaterial[BLACK];
- // Remove captured piece
- clear_bit(&(byColorBB[them]), to);
- clear_bit(&(byTypeBB[capture]), to);
+ npm = std::max(EndgameLimit, std::min(npm, MidgameLimit));
- // Update hash key
- key ^= zobrist[them][capture][to];
-
- // If the captured piece was a pawn, update pawn hash key
- if (capture == PAWN)
- pawnKey ^= zobrist[them][PAWN][to];
+ return Phase(((npm - EndgameLimit) * 128) / (MidgameLimit - EndgameLimit));
+}
- // Update incremental scores
- mgValue -= mg_pst(them, capture, to);
- egValue -= eg_pst(them, capture, to);
- assert(!move_promotion(m) || capture != PAWN);
+/// 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'.
- // Update material
- if (capture != PAWN)
- npMaterial[them] -= piece_value_midgame(capture);
+Bitboard Position::check_blockers(Color c, Color kingColor) const {
- // Update material hash key
- materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]];
+ Bitboard b, pinners, result = 0;
+ Square ksq = king_square(kingColor);
- // Update piece count
- pieceCount[them][capture]--;
+ // 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);
- // Update piece list
- pieceList[them][capture][index[to]] = pieceList[them][capture][pieceCount[them][capture]];
- index[pieceList[them][capture][index[to]]] = index[to];
+ while (pinners)
+ {
+ b = between_bb(ksq, pop_lsb(&pinners)) & pieces();
- // Reset rule 50 counter
- rule50 = 0;
+ if (!more_than_one(b))
+ result |= b & pieces(c);
+ }
+ return result;
}
-/// Position::do_castle_move() is a private method used to make a castling
-/// move. It is called from the main Position::do_move function. 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.
+/// Position::attackers_to() computes a bitboard of all pieces which attack a
+/// given square. Slider attacks use the occ bitboard to indicate occupancy.
-void Position::do_castle_move(Move m) {
+Bitboard Position::attackers_to(Square s, Bitboard occ) const {
- assert(is_ok());
- assert(move_is_ok(m));
- assert(move_is_castle(m));
+ return (attacks_from<PAWN>(s, BLACK) & pieces(WHITE, PAWN))
+ | (attacks_from<PAWN>(s, WHITE) & pieces(BLACK, PAWN))
+ | (attacks_from<KNIGHT>(s) & pieces(KNIGHT))
+ | (attacks_bb<ROOK>(s, occ) & pieces(ROOK, QUEEN))
+ | (attacks_bb<BISHOP>(s, occ) & pieces(BISHOP, QUEEN))
+ | (attacks_from<KING>(s) & pieces(KING));
+}
- Color us = side_to_move();
- Color them = opposite_color(us);
- // Find source squares for king and rook
- Square kfrom = move_from(m);
- Square rfrom = move_to(m); // HACK: See comment at beginning of function
- Square kto, rto;
+/// Position::legal() tests whether a pseudo-legal move is legal
- assert(piece_on(kfrom) == king_of_color(us));
- assert(piece_on(rfrom) == rook_of_color(us));
+bool Position::legal(Move m, Bitboard pinned) const {
- // Find destination squares for king and rook
- if (rfrom > kfrom) // O-O
- {
- kto = relative_square(us, SQ_G1);
- rto = relative_square(us, SQ_F1);
- } else { // O-O-O
- kto = relative_square(us, SQ_C1);
- rto = relative_square(us, SQ_D1);
- }
-
- // Remove pieces from source squares
- clear_bit(&(byColorBB[us]), kfrom);
- clear_bit(&(byTypeBB[KING]), kfrom);
- clear_bit(&(byTypeBB[0]), kfrom); // HACK: byTypeBB[0] == occupied squares
- clear_bit(&(byColorBB[us]), rfrom);
- clear_bit(&(byTypeBB[ROOK]), rfrom);
- clear_bit(&(byTypeBB[0]), rfrom); // HACK: byTypeBB[0] == occupied squares
-
- // Put pieces on destination squares
- set_bit(&(byColorBB[us]), kto);
- set_bit(&(byTypeBB[KING]), kto);
- set_bit(&(byTypeBB[0]), kto); // HACK: byTypeBB[0] == occupied squares
- set_bit(&(byColorBB[us]), rto);
- set_bit(&(byTypeBB[ROOK]), rto);
- set_bit(&(byTypeBB[0]), rto); // HACK: byTypeBB[0] == occupied squares
-
- // Update board array
- board[kfrom] = board[rfrom] = EMPTY;
- board[kto] = king_of_color(us);
- board[rto] = rook_of_color(us);
-
- // Update king square
- kingSquare[us] = kto;
-
- // Update piece lists
- pieceList[us][KING][index[kfrom]] = kto;
- pieceList[us][ROOK][index[rfrom]] = rto;
- int tmp = index[rfrom];
- index[kto] = index[kfrom];
- index[rto] = tmp;
+ assert(is_ok(m));
+ assert(pinned == pinned_pieces(sideToMove));
- // Update incremental scores
- mgValue -= mg_pst(us, KING, kfrom);
- mgValue += mg_pst(us, KING, kto);
- egValue -= eg_pst(us, KING, kfrom);
- egValue += eg_pst(us, KING, kto);
- mgValue -= mg_pst(us, ROOK, rfrom);
- mgValue += mg_pst(us, ROOK, rto);
- egValue -= eg_pst(us, ROOK, rfrom);
- egValue += eg_pst(us, ROOK, rto);
+ Color us = sideToMove;
+ Square from = from_sq(m);
- // Update hash key
- key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto];
- key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto];
+ assert(color_of(moved_piece(m)) == us);
+ assert(piece_on(king_square(us)) == make_piece(us, KING));
- // Clear en passant square
- if(epSquare != SQ_NONE)
+ // 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)
{
- key ^= zobEp[epSquare];
- epSquare = SQ_NONE;
- }
+ Square ksq = king_square(us);
+ Square to = to_sq(m);
+ Square capsq = to - pawn_push(us);
+ Bitboard occ = (pieces() ^ from ^ capsq) | to;
- // Update castling rights
- key ^= zobCastle[castleRights];
- castleRights &= castleRightsMask[kfrom];
- key ^= zobCastle[castleRights];
+ assert(to == ep_square());
+ assert(moved_piece(m) == make_piece(us, PAWN));
+ assert(piece_on(capsq) == make_piece(~us, PAWN));
+ assert(piece_on(to) == NO_PIECE);
- // Reset rule 50 counter
- rule50 = 0;
+ return !(attacks_bb< ROOK>(ksq, occ) & pieces(~us, QUEEN, ROOK))
+ && !(attacks_bb<BISHOP>(ksq, occ) & pieces(~us, QUEEN, BISHOP));
+ }
- // Update checkers BB
- checkersBB = attacks_to(king_square(them), us);
+ // 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 type_of(m) == CASTLING || !(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.
+ return !pinned
+ || !(pinned & from)
+ || aligned(from, to_sq(m), king_square(us));
}
-/// Position::do_promotion_move() is a private method used to make a promotion
-/// move. It is called from the main Position::do_move function. The
-/// UndoInfo object, which has been initialized in Position::do_move, is
-/// used to store the captured piece (if any).
+/// Position::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.
-void Position::do_promotion_move(Move m, UndoInfo &u) {
+bool Position::pseudo_legal(const Move m) const {
- Color us, them;
- Square from, to;
- PieceType capture, promotion;
+ Color us = sideToMove;
+ Square from = from_sq(m);
+ Square to = to_sq(m);
+ Piece pc = moved_piece(m);
- assert(is_ok());
- assert(move_is_ok(m));
- assert(move_promotion(m));
+ // Use a slower but simpler function for uncommon cases
+ if (type_of(m) != NORMAL)
+ return MoveList<LEGAL>(*this).contains(m);
- us = side_to_move();
- them = opposite_color(us);
- from = move_from(m);
- to = move_to(m);
+ // Is not a promotion, so promotion piece must be empty
+ if (promotion_type(m) - 2 != NO_PIECE_TYPE)
+ return false;
- assert(relative_rank(us, to) == RANK_8);
- assert(piece_on(from) == pawn_of_color(us));
- assert(color_of_piece_on(to) == them || square_is_empty(to));
+ // If the 'from' square is not occupied by a piece belonging to the side to
+ // move, the move is obviously not legal.
+ if (pc == NO_PIECE || color_of(pc) != us)
+ return false;
- capture = type_of_piece_on(to);
+ // The destination square cannot be occupied by a friendly piece
+ if (pieces(us) & to)
+ return false;
- if (capture)
+ // Handle the special case of a pawn move
+ if (type_of(pc) == PAWN)
{
- u.capture = capture;
- do_capture_move(m, capture, them, to);
- }
-
- // Remove pawn
- clear_bit(&(byColorBB[us]), from);
- clear_bit(&(byTypeBB[PAWN]), from);
- clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
- board[from] = EMPTY;
-
- // Insert promoted piece
- promotion = move_promotion(m);
- assert(promotion >= KNIGHT && promotion <= QUEEN);
- set_bit(&(byColorBB[us]), to);
- set_bit(&(byTypeBB[promotion]), to);
- set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
- board[to] = piece_of_color_and_type(us, promotion);
-
- // Update hash key
- key ^= zobrist[us][PAWN][from] ^ zobrist[us][promotion][to];
-
- // Update pawn hash key
- pawnKey ^= zobrist[us][PAWN][from];
-
- // Update material key
- materialKey ^= zobMaterial[us][PAWN][pieceCount[us][PAWN]];
- materialKey ^= zobMaterial[us][promotion][pieceCount[us][promotion]+1];
-
- // Update piece counts
- pieceCount[us][PAWN]--;
- pieceCount[us][promotion]++;
-
- // Update piece lists
- pieceList[us][PAWN][index[from]] = pieceList[us][PAWN][pieceCount[us][PAWN]];
- index[pieceList[us][PAWN][index[from]]] = index[from];
- pieceList[us][promotion][pieceCount[us][promotion] - 1] = to;
- index[to] = pieceCount[us][promotion] - 1;
+ // We have already handled promotion moves, so destination
+ // cannot be on the 8th/1st rank.
+ if (rank_of(to) == relative_rank(us, RANK_8))
+ return false;
- // Update incremental scores
- mgValue -= mg_pst(us, PAWN, from);
- mgValue += mg_pst(us, promotion, to);
- egValue -= eg_pst(us, PAWN, from);
- egValue += eg_pst(us, promotion, to);
+ if ( !(attacks_from<PAWN>(from, us) & pieces(~us) & to) // Not a capture
- // Update material
- npMaterial[us] += piece_value_midgame(promotion);
+ && !((from + pawn_push(us) == to) && empty(to)) // Not a single push
- // Clear the en passant square
- if (epSquare != SQ_NONE)
- {
- key ^= zobEp[epSquare];
- epSquare = SQ_NONE;
+ && !( (from + 2 * pawn_push(us) == to) // Not a double push
+ && (rank_of(from) == relative_rank(us, RANK_2))
+ && empty(to)
+ && empty(to - pawn_push(us))))
+ return false;
}
+ else if (!(attacks_from(pc, from) & to))
+ return false;
- // Update castle rights
- key ^= zobCastle[castleRights];
- castleRights &= castleRightsMask[to];
- key ^= zobCastle[castleRights];
+ // Evasions generator already takes care to avoid some kind of illegal moves
+ // and legal() relies on this. We therefore have to take care that the same
+ // kind of moves are filtered out here.
+ if (checkers())
+ {
+ if (type_of(pc) != KING)
+ {
+ // Double check? In this case a king move is required
+ if (more_than_one(checkers()))
+ return false;
- // Reset rule 50 counter
- rule50 = 0;
+ // Our move must be a blocking evasion or a capture of the checking piece
+ 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 as to catch
+ // invalid moves like b1a1 when opposite queen is on c1.
+ else if (attackers_to(to, pieces() ^ from) & pieces(~us))
+ return false;
+ }
- // Update checkers BB
- checkersBB = attacks_to(king_square(them), us);
+ return true;
}
-/// Position::do_ep_move() is a private method used to make an en passant
-/// capture. It is called from the main Position::do_move function. Because
-/// the captured piece is always a pawn, we don't need to pass an UndoInfo
-/// object in which to store the captured piece.
-
-void Position::do_ep_move(Move m) {
-
- Color us, them;
- Square from, to, capsq;
+/// Position::gives_check() tests whether a pseudo-legal move gives a check
- assert(is_ok());
- assert(move_is_ok(m));
- assert(move_is_ep(m));
+bool Position::gives_check(Move m, const CheckInfo& ci) const {
- us = side_to_move();
- them = opposite_color(us);
- from = move_from(m);
- to = move_to(m);
- capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S);
+ assert(is_ok(m));
+ assert(ci.dcCandidates == discovered_check_candidates());
+ assert(color_of(moved_piece(m)) == sideToMove);
- assert(to == epSquare);
- assert(relative_rank(us, to) == RANK_6);
- assert(piece_on(to) == EMPTY);
- assert(piece_on(from) == pawn_of_color(us));
- assert(piece_on(capsq) == pawn_of_color(them));
+ Square from = from_sq(m);
+ Square to = to_sq(m);
+ PieceType pt = type_of(piece_on(from));
- // Remove captured piece
- clear_bit(&(byColorBB[them]), capsq);
- clear_bit(&(byTypeBB[PAWN]), capsq);
- clear_bit(&(byTypeBB[0]), capsq); // HACK: byTypeBB[0] == occupied squares
- board[capsq] = EMPTY;
-
- // Remove moving piece from source square
- clear_bit(&(byColorBB[us]), from);
- clear_bit(&(byTypeBB[PAWN]), from);
- clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
+ // Is there a direct check?
+ if (ci.checkSq[pt] & to)
+ return true;
- // Put moving piece on destination square
- set_bit(&(byColorBB[us]), to);
- set_bit(&(byTypeBB[PAWN]), to);
- set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
- board[to] = board[from];
- board[from] = EMPTY;
+ // Is there a discovered check?
+ if ( unlikely(ci.dcCandidates)
+ && (ci.dcCandidates & from)
+ && !aligned(from, to, ci.ksq))
+ return true;
- // Update material hash key
- materialKey ^= zobMaterial[them][PAWN][pieceCount[them][PAWN]];
+ switch (type_of(m))
+ {
+ case NORMAL:
+ return false;
- // Update piece count
- pieceCount[them][PAWN]--;
+ case PROMOTION:
+ return attacks_bb(Piece(promotion_type(m)), to, pieces() ^ from) & ci.ksq;
- // Update piece list
- pieceList[us][PAWN][index[from]] = to;
- index[to] = index[from];
- pieceList[them][PAWN][index[capsq]] = pieceList[them][PAWN][pieceCount[them][PAWN]];
- index[pieceList[them][PAWN][index[capsq]]] = index[capsq];
+ // En passant capture with check? We have already handled the case
+ // of direct checks and ordinary discovered check, so the only case we
+ // need to handle is the unusual case of a discovered check through
+ // the captured pawn.
+ case ENPASSANT:
+ {
+ Square capsq = make_square(file_of(to), rank_of(from));
+ Bitboard b = (pieces() ^ from ^ capsq) | to;
- // Update hash key
- key ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
- key ^= zobrist[them][PAWN][capsq];
- key ^= zobEp[epSquare];
+ return (attacks_bb< ROOK>(ci.ksq, b) & pieces(sideToMove, QUEEN, ROOK))
+ | (attacks_bb<BISHOP>(ci.ksq, b) & pieces(sideToMove, QUEEN, BISHOP));
+ }
+ case CASTLING:
+ {
+ Square kfrom = from;
+ Square rfrom = to; // Castling is encoded as 'King captures the rook'
+ Square kto = relative_square(sideToMove, rfrom > kfrom ? SQ_G1 : SQ_C1);
+ Square rto = relative_square(sideToMove, rfrom > kfrom ? SQ_F1 : SQ_D1);
- // Update pawn hash key
- pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
- pawnKey ^= zobrist[them][PAWN][capsq];
+ return (PseudoAttacks[ROOK][rto] & ci.ksq)
+ && (attacks_bb<ROOK>(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & ci.ksq);
+ }
+ default:
+ assert(false);
+ return false;
+ }
+}
- // Update incremental scores
- mgValue -= mg_pst(them, PAWN, capsq);
- mgValue -= mg_pst(us, PAWN, from);
- mgValue += mg_pst(us, PAWN, to);
- egValue -= eg_pst(them, PAWN, capsq);
- egValue -= eg_pst(us, PAWN, from);
- egValue += eg_pst(us, PAWN, to);
- // Reset en passant square
- epSquare = SQ_NONE;
+/// Position::do_move() makes a move, and saves all information necessary
+/// to a StateInfo object. The move is assumed to be legal. Pseudo-legal
+/// moves should be filtered out before this function is called.
- // Reset rule 50 counter
- rule50 = 0;
+void Position::do_move(Move m, StateInfo& newSt) {
- // Update checkers BB
- checkersBB = attacks_to(king_square(them), us);
+ CheckInfo ci(*this);
+ do_move(m, newSt, ci, gives_check(m, ci));
}
+void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveIsCheck) {
-/// Position::undo_move() unmakes a move. When it returns, the position should
-/// be restored to exactly the same state as before the move was made. It is
-/// important that Position::undo_move is called with the same move and UndoInfo
-/// object as the earlier call to Position::do_move.
+ assert(is_ok(m));
+ assert(&newSt != st);
-void Position::undo_move(Move m, const UndoInfo &u) {
+ ++nodes;
+ Key k = st->key;
- assert(is_ok());
- assert(move_is_ok(m));
+ // Copy some fields of the old state to our new StateInfo object except the
+ // ones which are going to be recalculated from scratch anyway and then switch
+ // our state pointer to point to the new (ready to be updated) state.
+ std::memcpy(&newSt, st, StateCopySize64 * sizeof(uint64_t));
- gamePly--;
- sideToMove = opposite_color(sideToMove);
+ newSt.previous = st;
+ st = &newSt;
- // Restore information from our UndoInfo object (except the captured piece,
- // which is taken care of later)
- restore(u);
+ // Update side to move
+ k ^= Zobrist::side;
- if (move_is_castle(m))
- undo_castle_move(m);
- else if (move_promotion(m))
- undo_promotion_move(m, u);
- else if (move_is_ep(m))
- undo_ep_move(m);
- else
- {
- Color us, them;
- Square from, to;
- PieceType piece, capture;
-
- us = side_to_move();
- them = opposite_color(us);
- from = move_from(m);
- to = move_to(m);
+ // Increment ply counters. In particular, rule50 will be reset to zero later on
+ // in case of a capture or a pawn move.
+ ++gamePly;
+ ++st->rule50;
+ ++st->pliesFromNull;
- assert(piece_on(from) == EMPTY);
- assert(color_of_piece_on(to) == us);
+ Color us = sideToMove;
+ Color them = ~us;
+ Square from = from_sq(m);
+ Square to = to_sq(m);
+ Piece pc = piece_on(from);
+ PieceType pt = type_of(pc);
+ PieceType captured = type_of(m) == ENPASSANT ? PAWN : type_of(piece_on(to));
- // Put the piece back at the source square
- piece = type_of_piece_on(to);
- set_bit(&(byColorBB[us]), from);
- set_bit(&(byTypeBB[piece]), from);
- set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
- board[from] = piece_of_color_and_type(us, piece);
+ assert(color_of(pc) == us);
+ assert(piece_on(to) == NO_PIECE || color_of(piece_on(to)) == them || type_of(m) == CASTLING);
+ assert(captured != KING);
- // Clear the destination square
- clear_bit(&(byColorBB[us]), to);
- clear_bit(&(byTypeBB[piece]), to);
- clear_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
+ if (type_of(m) == CASTLING)
+ {
+ assert(pc == make_piece(us, KING));
- // If the moving piece was a king, update the king square
- if (piece == KING)
- kingSquare[us] = from;
+ Square rfrom, rto;
+ do_castling<true>(from, to, rfrom, rto);
- // Update piece list
- pieceList[us][piece][index[to]] = from;
- index[from] = index[to];
+ 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];
+ }
- capture = u.capture;
+ if (captured)
+ {
+ Square capsq = to;
- if (capture)
+ // If the captured piece is a pawn, update pawn hash key, otherwise
+ // update non-pawn material.
+ if (captured == PAWN)
{
- assert(capture != KING);
-
- // Replace the captured piece
- set_bit(&(byColorBB[them]), to);
- set_bit(&(byTypeBB[capture]), to);
- set_bit(&(byTypeBB[0]), to);
- board[to] = piece_of_color_and_type(them, capture);
-
- // Update material
- if (capture != PAWN)
- npMaterial[them] += piece_value_midgame(capture);
-
- // Update piece list
- pieceList[them][capture][pieceCount[them][capture]] = to;
- index[to] = pieceCount[them][capture];
+ if (type_of(m) == ENPASSANT)
+ {
+ capsq += pawn_push(them);
- // Update piece count
- pieceCount[them][capture]++;
- } else
- board[to] = EMPTY;
- }
+ assert(pt == PAWN);
+ assert(to == st->epSquare);
+ assert(relative_rank(us, to) == RANK_6);
+ assert(piece_on(to) == NO_PIECE);
+ assert(piece_on(capsq) == make_piece(them, PAWN));
- assert(is_ok());
-}
+ board[capsq] = NO_PIECE;
+ }
+ st->pawnKey ^= Zobrist::psq[them][PAWN][capsq];
+ }
+ else
+ st->npMaterial[them] -= PieceValue[MG][captured];
-/// Position::undo_castle_move() is a private method used to unmake a castling
-/// move. It is called from the main Position::undo_move function. 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.
+ // Update board and piece lists
+ remove_piece(capsq, them, captured);
-void Position::undo_castle_move(Move m) {
+ // Update material hash key and prefetch access to materialTable
+ k ^= Zobrist::psq[them][captured][capsq];
+ st->materialKey ^= Zobrist::psq[them][captured][pieceCount[them][captured]];
+ prefetch((char*)thisThread->materialTable[st->materialKey]);
- assert(move_is_ok(m));
- assert(move_is_castle(m));
+ // Update incremental scores
+ st->psq -= psq[them][captured][capsq];
- // When we have arrived here, some work has already been done by
- // Position::undo_move. In particular, the side to move has been switched,
- // so the code below is correct.
- Color us = side_to_move();
+ // Reset rule 50 counter
+ st->rule50 = 0;
+ }
- // Find source squares for king and rook
- Square kfrom = move_from(m);
- Square rfrom = move_to(m); // HACK: See comment at beginning of function
- Square kto, rto;
+ // Update hash key
+ k ^= Zobrist::psq[us][pt][from] ^ Zobrist::psq[us][pt][to];
- // Find destination squares for king and rook
- if (rfrom > kfrom) // O-O
+ // Reset en passant square
+ if (st->epSquare != SQ_NONE)
{
- kto = relative_square(us, SQ_G1);
- rto = relative_square(us, SQ_F1);
- } else { // O-O-O
- kto = relative_square(us, SQ_C1);
- rto = relative_square(us, SQ_D1);
+ k ^= Zobrist::enpassant[file_of(st->epSquare)];
+ st->epSquare = SQ_NONE;
}
- assert(piece_on(kto) == king_of_color(us));
- assert(piece_on(rto) == rook_of_color(us));
-
- // Remove pieces from destination squares
- clear_bit(&(byColorBB[us]), kto);
- clear_bit(&(byTypeBB[KING]), kto);
- clear_bit(&(byTypeBB[0]), kto); // HACK: byTypeBB[0] == occupied squares
- clear_bit(&(byColorBB[us]), rto);
- clear_bit(&(byTypeBB[ROOK]), rto);
- clear_bit(&(byTypeBB[0]), rto); // HACK: byTypeBB[0] == occupied squares
-
- // Put pieces on source squares
- set_bit(&(byColorBB[us]), kfrom);
- set_bit(&(byTypeBB[KING]), kfrom);
- set_bit(&(byTypeBB[0]), kfrom); // HACK: byTypeBB[0] == occupied squares
- set_bit(&(byColorBB[us]), rfrom);
- set_bit(&(byTypeBB[ROOK]), rfrom);
- set_bit(&(byTypeBB[0]), rfrom); // HACK: byTypeBB[0] == occupied squares
-
- // Update board
- board[rto] = board[kto] = EMPTY;
- board[rfrom] = rook_of_color(us);
- board[kfrom] = king_of_color(us);
-
- // Update king square
- kingSquare[us] = kfrom;
-
- // Update piece lists
- pieceList[us][KING][index[kto]] = kfrom;
- pieceList[us][ROOK][index[rto]] = rfrom;
- int tmp = index[rto]; // Necessary because we may have rto == kfrom in FRC.
- index[kfrom] = index[kto];
- index[rfrom] = tmp;
-}
-
-
-/// Position::undo_promotion_move() is a private method used to unmake a
-/// promotion move. It is called from the main Position::do_move
-/// function. The UndoInfo object, which has been initialized in
-/// Position::do_move, is used to put back the captured piece (if any).
-
-void Position::undo_promotion_move(Move m, const UndoInfo &u) {
-
- Color us, them;
- Square from, to;
- PieceType capture, promotion;
-
- assert(move_is_ok(m));
- assert(move_promotion(m));
-
- // When we have arrived here, some work has already been done by
- // Position::undo_move. In particular, the side to move has been switched,
- // so the code below is correct.
- us = side_to_move();
- them = opposite_color(us);
- from = move_from(m);
- to = move_to(m);
-
- assert(relative_rank(us, to) == RANK_8);
- assert(piece_on(from) == EMPTY);
-
- // Remove promoted piece
- promotion = move_promotion(m);
- assert(piece_on(to)==piece_of_color_and_type(us, promotion));
- assert(promotion >= KNIGHT && promotion <= QUEEN);
- clear_bit(&(byColorBB[us]), to);
- clear_bit(&(byTypeBB[promotion]), to);
- clear_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
-
- // Insert pawn at source square
- set_bit(&(byColorBB[us]), from);
- set_bit(&(byTypeBB[PAWN]), from);
- set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
- board[from] = pawn_of_color(us);
-
- // Update material
- npMaterial[us] -= piece_value_midgame(promotion);
-
- // Update piece list
- pieceList[us][PAWN][pieceCount[us][PAWN]] = from;
- index[from] = pieceCount[us][PAWN];
- pieceList[us][promotion][index[to]] =
- pieceList[us][promotion][pieceCount[us][promotion] - 1];
- index[pieceList[us][promotion][index[to]]] = index[to];
-
- // Update piece counts
- pieceCount[us][promotion]--;
- pieceCount[us][PAWN]++;
-
- capture = u.capture;
-
- if (capture)
+ // Update castling rights if needed
+ if (st->castlingRights && (castlingRightsMask[from] | castlingRightsMask[to]))
{
- assert(capture != KING);
-
- // Insert captured piece:
- set_bit(&(byColorBB[them]), to);
- set_bit(&(byTypeBB[capture]), to);
- set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
- board[to] = piece_of_color_and_type(them, capture);
-
- // Update material. Because the move is a promotion move, we know
- // that the captured piece cannot be a pawn.
- assert(capture != PAWN);
- npMaterial[them] += piece_value_midgame(capture);
-
- // Update piece list
- pieceList[them][capture][pieceCount[them][capture]] = to;
- index[to] = pieceCount[them][capture];
-
- // Update piece count
- pieceCount[them][capture]++;
- } else
- board[to] = EMPTY;
-}
-
-
-/// Position::undo_ep_move() is a private method used to unmake an en passant
-/// capture. It is called from the main Position::undo_move function. Because
-/// the captured piece is always a pawn, we don't need to pass an UndoInfo
-/// object from which to retrieve the captured piece.
-
-void Position::undo_ep_move(Move m) {
-
- assert(move_is_ok(m));
- assert(move_is_ep(m));
-
- // When we have arrived here, some work has already been done by
- // Position::undo_move. In particular, the side to move has been switched,
- // so the code below is correct.
- Color us = side_to_move();
- Color them = opposite_color(us);
- Square from = move_from(m);
- Square to = move_to(m);
- Square capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S);
-
- assert(to == ep_square());
- assert(relative_rank(us, to) == RANK_6);
- assert(piece_on(to) == pawn_of_color(us));
- assert(piece_on(from) == EMPTY);
- assert(piece_on(capsq) == EMPTY);
-
- // Replace captured piece
- set_bit(&(byColorBB[them]), capsq);
- set_bit(&(byTypeBB[PAWN]), capsq);
- set_bit(&(byTypeBB[0]), capsq);
- board[capsq] = pawn_of_color(them);
-
- // Remove moving piece from destination square
- clear_bit(&(byColorBB[us]), to);
- clear_bit(&(byTypeBB[PAWN]), to);
- clear_bit(&(byTypeBB[0]), to);
- board[to] = EMPTY;
-
- // Replace moving piece at source square
- set_bit(&(byColorBB[us]), from);
- set_bit(&(byTypeBB[PAWN]), from);
- set_bit(&(byTypeBB[0]), from);
- board[from] = pawn_of_color(us);
-
- // Update piece list:
- pieceList[us][PAWN][index[to]] = from;
- index[from] = index[to];
- pieceList[them][PAWN][pieceCount[them][PAWN]] = capsq;
- index[capsq] = pieceCount[them][PAWN];
-
- // Update piece count:
- pieceCount[them][PAWN]++;
-}
-
-
-/// Position::do_null_move makes() a "null move": It switches the side to move
-/// and updates the hash key without executing any move on the board.
-
-void Position::do_null_move(UndoInfo &u) {
-
- assert(is_ok());
- assert(!is_check());
-
- // Back up the information necessary to undo the null move to the supplied
- // UndoInfo object. In the case of a null move, the only thing we need to
- // remember is the last move made and the en passant square.
- u.lastMove = lastMove;
- u.epSquare = epSquare;
+ int cr = castlingRightsMask[from] | castlingRightsMask[to];
+ k ^= Zobrist::castling[st->castlingRights & cr];
+ st->castlingRights &= ~cr;
+ }
- // Save the current key to the history[] array, in order to be able to
- // detect repetition draws.
- history[gamePly] = key;
+ // Move the piece. The tricky Chess960 castling is handled earlier
+ if (type_of(m) != CASTLING)
+ move_piece(from, to, us, pt);
- // Update the necessary information
- sideToMove = opposite_color(sideToMove);
- if (epSquare != SQ_NONE)
- key ^= zobEp[epSquare];
+ // If the moving piece is a pawn do some special extra work
+ if (pt == PAWN)
+ {
+ // Set en-passant square if the moved pawn can be captured
+ if ( (int(to) ^ int(from)) == 16
+ && (attacks_from<PAWN>(from + pawn_push(us), us) & pieces(them, PAWN)))
+ {
+ st->epSquare = Square((from + to) / 2);
+ k ^= Zobrist::enpassant[file_of(st->epSquare)];
+ }
- epSquare = SQ_NONE;
- rule50++;
- gamePly++;
- key ^= zobSideToMove;
+ else if (type_of(m) == PROMOTION)
+ {
+ PieceType promotion = promotion_type(m);
- mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
- egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
+ assert(relative_rank(us, to) == RANK_8);
+ assert(promotion >= KNIGHT && promotion <= QUEEN);
- assert(is_ok());
-}
+ remove_piece(to, us, PAWN);
+ put_piece(to, us, promotion);
+ // 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]];
-/// Position::undo_null_move() unmakes a "null move".
+ // Update incremental score
+ st->psq += psq[us][promotion][to] - psq[us][PAWN][to];
-void Position::undo_null_move(const UndoInfo &u) {
+ // Update material
+ st->npMaterial[us] += PieceValue[MG][promotion];
+ }
- assert(is_ok());
- assert(!is_check());
+ // 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]);
- // Restore information from the supplied UndoInfo object:
- lastMove = u.lastMove;
- epSquare = u.epSquare;
- if (epSquare != SQ_NONE)
- key ^= zobEp[epSquare];
+ // Reset rule 50 draw counter
+ st->rule50 = 0;
+ }
- // Update the necessary information.
- sideToMove = opposite_color(sideToMove);
- rule50--;
- gamePly--;
- key ^= zobSideToMove;
+ // Update incremental scores
+ st->psq += psq[us][pt][to] - psq[us][pt][from];
- mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
- egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
+ // Set capture piece
+ st->capturedType = captured;
- assert(is_ok());
-}
+ // Update the key with the final value
+ st->key = k;
+ // Update checkers bitboard: piece must be already moved due to attacks_from()
+ st->checkersBB = 0;
-/// 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 or en passant captures.
+ if (moveIsCheck)
+ {
+ if (type_of(m) != NORMAL)
+ st->checkersBB = attackers_to(king_square(them)) & pieces(us);
+ else
+ {
+ // Direct checks
+ if (ci.checkSq[pt] & to)
+ st->checkersBB |= to;
-int Position::see(Square to) const {
+ // Discovered checks
+ if (unlikely(ci.dcCandidates) && (ci.dcCandidates & from))
+ {
+ if (pt != ROOK)
+ st->checkersBB |= attacks_from<ROOK>(king_square(them)) & pieces(us, QUEEN, ROOK);
- assert(square_is_ok(to));
- return see(SQ_NONE, to);
-}
+ if (pt != BISHOP)
+ st->checkersBB |= attacks_from<BISHOP>(king_square(them)) & pieces(us, QUEEN, BISHOP);
+ }
+ }
+ }
-int Position::see(Move m) const {
+ sideToMove = ~sideToMove;
- assert(move_is_ok(m));
- return see(move_from(m), move_to(m));
+ assert(pos_is_ok());
}
-int Position::see(Square from, Square to) const {
- // Material values
- static const int seeValues[18] = {
- 0, PawnValueMidgame, KnightValueMidgame, BishopValueMidgame,
- RookValueMidgame, QueenValueMidgame, QueenValueMidgame*10, 0,
- 0, PawnValueMidgame, KnightValueMidgame, BishopValueMidgame,
- RookValueMidgame, QueenValueMidgame, QueenValueMidgame*10, 0,
- 0, 0
- };
+/// Position::undo_move() unmakes a move. When it returns, the position should
+/// be restored to exactly the same state as before the move was made.
- Bitboard attackers, occ, b;
+void Position::undo_move(Move m) {
- assert(square_is_ok(from) || from == SQ_NONE);
- assert(square_is_ok(to));
+ assert(is_ok(m));
- // Initialize colors
- Color us = (from != SQ_NONE ? color_of_piece_on(from) : opposite_color(color_of_piece_on(to)));
- Color them = opposite_color(us);
+ sideToMove = ~sideToMove;
- // Initialize pieces
- Piece piece = piece_on(from);
- Piece capture = piece_on(to);
+ Color us = sideToMove;
+ Square from = from_sq(m);
+ Square to = to_sq(m);
+ PieceType pt = type_of(piece_on(to));
- // Find all attackers to the destination square, with the moving piece
- // removed, but possibly an X-ray attacker added behind it.
- occ = occupied_squares();
+ assert(empty(from) || type_of(m) == CASTLING);
+ assert(st->capturedType != KING);
- // Handle enpassant moves
- if (ep_square() == to && type_of_piece_on(from) == PAWN)
+ if (type_of(m) == PROMOTION)
{
- assert(capture == EMPTY);
-
- Square capQq = (side_to_move() == WHITE)? (to - DELTA_N) : (to - DELTA_S);
- capture = piece_on(capQq);
-
- assert(type_of_piece_on(capQq) == PAWN);
+ assert(pt == promotion_type(m));
+ assert(relative_rank(us, to) == RANK_8);
+ assert(promotion_type(m) >= KNIGHT && promotion_type(m) <= QUEEN);
- // Remove the captured pawn
- clear_bit(&occ, capQq);
+ remove_piece(to, us, promotion_type(m));
+ put_piece(to, us, PAWN);
+ pt = PAWN;
}
- while (true)
+ if (type_of(m) == CASTLING)
{
- clear_bit(&occ, from);
- attackers = (rook_attacks_bb(to, occ) & rooks_and_queens())
- | (bishop_attacks_bb(to, occ) & bishops_and_queens())
- | (piece_attacks<KNIGHT>(to) & knights())
- | (piece_attacks<KING>(to) & kings())
- | (pawn_attacks(WHITE, to) & pawns(BLACK))
- | (pawn_attacks(BLACK, to) & pawns(WHITE));
-
- if (from != SQ_NONE)
- break;
-
- // If we don't have any attacker we are finished
- if ((attackers & pieces_of_color(us)) == EmptyBoardBB)
- return 0;
-
- // Locate the least valuable attacker to the destination square
- // and use it to initialize from square.
- PieceType pt;
- for (pt = PAWN; !(attackers & pieces_of_color_and_type(us, pt)); pt++)
- assert(pt < KING);
-
- from = first_1(attackers & pieces_of_color_and_type(us, pt));
- piece = piece_on(from);
+ Square rfrom, rto;
+ do_castling<false>(from, to, rfrom, rto);
}
+ else
+ {
+ move_piece(to, from, us, pt); // Put the piece back at the source square
- // If the opponent has no attackers we are finished
- if ((attackers & pieces_of_color(them)) == EmptyBoardBB)
- return seeValues[capture];
-
- attackers &= occ; // Remove the moving piece
-
- // 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.
- int lastCapturingPieceValue = seeValues[piece];
- int swapList[32], n = 1;
- Color c = them;
- PieceType pt;
-
- swapList[0] = seeValues[capture];
-
- 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; !(attackers & pieces_of_color_and_type(c, pt)); pt++)
- assert(pt < KING);
-
- // Remove the attacker we just found from the 'attackers' bitboard,
- // and scan for new X-ray attacks behind the attacker.
- b = attackers & pieces_of_color_and_type(c, pt);
- occ ^= (b & -b);
- attackers |= (rook_attacks_bb(to, occ) & rooks_and_queens())
- | (bishop_attacks_bb(to, occ) & bishops_and_queens());
-
- attackers &= occ;
+ if (st->capturedType)
+ {
+ Square capsq = to;
- // Add the new entry to the swap list
- assert(n < 32);
- swapList[n] = -swapList[n - 1] + lastCapturingPieceValue;
- n++;
+ if (type_of(m) == ENPASSANT)
+ {
+ capsq -= pawn_push(us);
- // Remember the value of the capturing piece, and change the side to move
- // before beginning the next iteration
- lastCapturingPieceValue = seeValues[pt];
- c = opposite_color(c);
+ assert(pt == PAWN);
+ assert(to == st->previous->epSquare);
+ assert(relative_rank(us, to) == RANK_6);
+ assert(piece_on(capsq) == NO_PIECE);
+ }
- // Stop after a king capture
- if (pt == KING && (attackers & pieces_of_color(c)))
- {
- assert(n < 32);
- swapList[n++] = 100;
- break;
+ put_piece(capsq, ~us, st->capturedType); // Restore the captured piece
}
- } while (attackers & pieces_of_color(c));
+ }
- // 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 (--n)
- swapList[n-1] = Min(-swapList[n], swapList[n-1]);
+ // Finally point our state pointer back to the previous state
+ st = st->previous;
+ --gamePly;
- return swapList[0];
+ assert(pos_is_ok());
}
-/// Position::clear() erases the position object to a pristine state, with an
-/// empty board, white to move, and no castling rights.
+/// Position::do_castling() is a helper used to do/undo a castling move. This
+/// is a bit tricky, especially in Chess960.
+template<bool Do>
+void Position::do_castling(Square from, Square& to, Square& rfrom, Square& rto) {
-void Position::clear() {
+ bool kingSide = to > from;
+ rfrom = to; // Castling is encoded as "king captures friendly rook"
+ rto = relative_square(sideToMove, kingSide ? SQ_F1 : SQ_D1);
+ to = relative_square(sideToMove, kingSide ? SQ_G1 : SQ_C1);
- for (int i = 0; i < 64; i++)
- {
- board[i] = EMPTY;
- index[i] = 0;
- }
-
- for (int i = 0; i < 2; i++)
- byColorBB[i] = EmptyBoardBB;
-
- for (int i = 0; i < 7; i++)
- {
- byTypeBB[i] = EmptyBoardBB;
- pieceCount[0][i] = pieceCount[1][i] = 0;
- for (int j = 0; j < 8; j++)
- pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE;
- }
-
- checkersBB = EmptyBoardBB;
-
- lastMove = MOVE_NONE;
-
- sideToMove = WHITE;
- castleRights = NO_CASTLES;
- initialKFile = FILE_E;
- initialKRFile = FILE_H;
- initialQRFile = FILE_A;
- epSquare = SQ_NONE;
- rule50 = 0;
- gamePly = 0;
+ // Remove both pieces first since squares could overlap in Chess960
+ remove_piece(Do ? from : to, sideToMove, KING);
+ remove_piece(Do ? rfrom : rto, sideToMove, ROOK);
+ board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do it for us
+ put_piece(Do ? to : from, sideToMove, KING);
+ put_piece(Do ? rto : rfrom, sideToMove, ROOK);
}
-/// Position::reset_game_ply() simply sets gamePly to 0. It is used from the
-/// UCI interface code, whenever a non-reversible move is made in a
-/// 'position fen <fen> moves m1 m2 ...' command. This makes it possible
-/// for the program to handle games of arbitrary length, as long as the GUI
-/// handles draws by the 50 move rule correctly.
+/// 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.
-void Position::reset_game_ply() {
-
- gamePly = 0;
-}
+void Position::do_null_move(StateInfo& newSt) {
+ assert(!checkers());
-/// Position::put_piece() puts a piece on the given square of the board,
-/// updating the board array, bitboards, and piece counts.
+ std::memcpy(&newSt, st, sizeof(StateInfo)); // Fully copy here
-void Position::put_piece(Piece p, Square s) {
+ newSt.previous = st;
+ st = &newSt;
- Color c = color_of_piece(p);
- PieceType pt = type_of_piece(p);
+ if (st->epSquare != SQ_NONE)
+ {
+ st->key ^= Zobrist::enpassant[file_of(st->epSquare)];
+ st->epSquare = SQ_NONE;
+ }
- board[s] = p;
- index[s] = pieceCount[c][pt];
- pieceList[c][pt][index[s]] = s;
+ st->key ^= Zobrist::side;
+ prefetch((char*)TT.first_entry(st->key));
- set_bit(&(byTypeBB[pt]), s);
- set_bit(&(byColorBB[c]), s);
- set_bit(&byTypeBB[0], s); // HACK: byTypeBB[0] contains all occupied squares.
+ ++st->rule50;
+ st->pliesFromNull = 0;
- pieceCount[c][pt]++;
+ sideToMove = ~sideToMove;
- if (pt == KING)
- kingSquare[c] = s;
+ assert(pos_is_ok());
}
+void Position::undo_null_move() {
-/// Position::allow_oo() gives the given side the right to castle kingside.
-/// Used when setting castling rights during parsing of FEN strings.
-
-void Position::allow_oo(Color c) {
+ assert(!checkers());
- castleRights |= (1 + int(c));
+ st = st->previous;
+ sideToMove = ~sideToMove;
}
-/// Position::allow_ooo() gives the given side the right to castle queenside.
-/// Used when setting castling rights during parsing of FEN strings.
+/// Position::key_after() computes the new hash key after the given moven. Needed
+/// for speculative prefetch. It doesn't recognize special moves like castling,
+/// en-passant and promotions.
-void Position::allow_ooo(Color c) {
+Key Position::key_after(Move m) const {
- castleRights |= (4 + 4*int(c));
-}
+ 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));
+ Key k = st->key ^ Zobrist::side;
+ if (captured)
+ k ^= Zobrist::psq[~us][captured][to];
-/// Position::compute_key() computes the hash key of the position. The hash
-/// key is usually updated incrementally as moves are made and unmade, the
-/// compute_key() function is only used when a new position is set up, and
-/// to verify the correctness of the hash key when running in debug mode.
+ return k ^ Zobrist::psq[us][pt][to] ^ Zobrist::psq[us][pt][from];
+}
-Key Position::compute_key() const {
- Key result = Key(0ULL);
+/// Position::see() is a static exchange evaluator: It tries to estimate the
+/// material gain or loss resulting from a move.
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- if (square_is_occupied(s))
- result ^= zobrist[color_of_piece_on(s)][type_of_piece_on(s)][s];
+Value Position::see_sign(Move m) const {
- if (ep_square() != SQ_NONE)
- result ^= zobEp[ep_square()];
+ assert(is_ok(m));
- result ^= zobCastle[castleRights];
- if (side_to_move() == BLACK)
- result ^= zobSideToMove;
+ // 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 result;
+ return see(m);
}
+Value Position::see(Move m) const {
-/// Position::compute_pawn_key() computes the hash key of the position. The
-/// hash key is usually updated incrementally as moves are made and unmade,
-/// the compute_pawn_key() function is only used when a new position is set
-/// up, and to verify the correctness of the pawn hash key when running in
-/// debug mode.
-
-Key Position::compute_pawn_key() const {
-
- Key result = Key(0ULL);
- Bitboard b;
- Square s;
-
- for (Color c = WHITE; c <= BLACK; c++)
+ Square from, to;
+ Bitboard occupied, attackers, stmAttackers;
+ Value swapList[32];
+ int slIndex = 1;
+ PieceType captured;
+ Color stm;
+
+ assert(is_ok(m));
+
+ from = from_sq(m);
+ to = to_sq(m);
+ swapList[0] = PieceValue[MG][piece_on(to)];
+ stm = color_of(piece_on(from));
+ occupied = pieces() ^ from;
+
+ // Castling 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) == CASTLING)
+ return VALUE_ZERO;
+
+ if (type_of(m) == ENPASSANT)
{
- b = pawns(c);
- while(b)
- {
- s = pop_1st_bit(&b);
- result ^= zobrist[c][PAWN][s];
- }
+ occupied ^= to - pawn_push(stm); // Remove the captured pawn
+ swapList[0] = PieceValue[MG][PAWN];
}
- return result;
-}
+ // 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;
-/// Position::compute_material_key() computes the hash key of the position.
-/// The hash key is usually updated incrementally as moves are made and unmade,
-/// the compute_material_key() function is only used when a new position is set
-/// up, and to verify the correctness of the material hash key when running in
-/// debug mode.
-
-Key Position::compute_material_key() const {
-
- Key result = Key(0ULL);
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= QUEEN; pt++)
- {
- int count = piece_count(c, pt);
- for (int i = 0; i <= count; i++)
- result ^= zobMaterial[c][pt][i];
- }
- return result;
-}
+ // If the opponent has no attackers we are finished
+ stm = ~stm;
+ stmAttackers = attackers & pieces(stm);
+ if (!stmAttackers)
+ 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
+ // 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));
-/// Position::compute_mg_value() and Position::compute_eg_value() compute the
-/// incremental scores for the middle 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.
+ do {
+ assert(slIndex < 32);
-Value Position::compute_mg_value() const {
+ // Add the new entry to the swap list
+ swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[MG][captured];
- Value result = Value(0);
- Bitboard b;
- Square s;
+ // Locate and remove the next least valuable attacker
+ captured = min_attacker<PAWN>(byTypeBB, to, stmAttackers, occupied, attackers);
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= KING; pt++)
+ // Stop before processing a king capture
+ if (captured == KING)
{
- b = pieces_of_color_and_type(c, pt);
- while(b)
- {
- s = pop_1st_bit(&b);
- assert(piece_on(s) == piece_of_color_and_type(c, pt));
- result += mg_pst(c, pt, s);
- }
- }
- result += (side_to_move() == WHITE)? TempoValueMidgame / 2 : -TempoValueMidgame / 2;
- return result;
-}
-
-Value Position::compute_eg_value() const {
-
- Value result = Value(0);
- Bitboard b;
- Square s;
-
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= KING; pt++)
- {
- b = pieces_of_color_and_type(c, pt);
- while(b)
- {
- s = pop_1st_bit(&b);
- assert(piece_on(s) == piece_of_color_and_type(c, pt));
- result += eg_pst(c, pt, s);
- }
- }
- result += (side_to_move() == WHITE)? TempoValueEndgame / 2 : -TempoValueEndgame / 2;
- return result;
-}
-
-
-/// Position::compute_non_pawn_material() computes the total non-pawn middle
-/// game material score for the given side. Material scores are updated
-/// incrementally during the search, this function is only used while
-/// initializing a new Position object.
+ if (stmAttackers == attackers)
+ ++slIndex;
-Value Position::compute_non_pawn_material(Color c) const {
-
- Value result = Value(0);
- Square s;
-
- for (PieceType pt = KNIGHT; pt <= QUEEN; pt++)
- {
- Bitboard b = pieces_of_color_and_type(c, pt);
- while(b)
- {
- s = pop_1st_bit(&b);
- assert(piece_on(s) == piece_of_color_and_type(c, pt));
- result += piece_value_midgame(pt);
+ break;
}
- }
- return result;
-}
+ stm = ~stm;
+ stmAttackers = attackers & pieces(stm);
+ ++slIndex;
-/// Position::is_mate() returns true or false depending on whether the
-/// side to move is checkmated. Note that this function is currently very
-/// slow, and shouldn't be used frequently inside the search.
+ } while (stmAttackers);
-bool Position::is_mate() const {
+ // 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]);
- if (is_check())
- {
- MovePicker mp = MovePicker(*this, false, MOVE_NONE, EmptySearchStack, Depth(0));
- return mp.get_next_move() == MOVE_NONE;
- }
- return false;
+ return swapList[0];
}
-/// 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.
+/// Position::is_draw() tests whether the position is drawn by material, 50 moves
+/// rule or repetition. It does not detect stalemates.
bool Position::is_draw() const {
- // Draw by material?
- if ( !pawns()
- && (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMidgame))
+ if (st->rule50 > 99 && (!checkers() || MoveList<LEGAL>(*this).size()))
return true;
- // Draw by the 50 moves rule?
- if (rule50 > 100 || (rule50 == 100 && !is_check()))
- return true;
-
- // Draw by repetition?
- for (int i = 2; i < Min(gamePly, rule50); i += 2)
- if (history[gamePly - i] == key)
- return true;
-
- return false;
-}
-
-
-/// Position::has_mate_threat() tests whether a given color has a mate in one
-/// from the current position. This function is quite slow, but it doesn't
-/// matter, because it is currently only called from PV nodes, which are rare.
-
-bool Position::has_mate_threat(Color c) {
-
- UndoInfo u1, u2;
- Color stm = side_to_move();
-
- // The following lines are useless and silly, but prevents gcc from
- // emitting a stupid warning stating that u1.lastMove and u1.epSquare might
- // be used uninitialized.
- u1.lastMove = lastMove;
- u1.epSquare = epSquare;
-
- if (is_check())
- return false;
-
- // If the input color is not equal to the side to move, do a null move
- if (c != stm)
- do_null_move(u1);
-
- MoveStack mlist[120];
- int count;
- bool result = false;
-
- // Generate legal moves
- count = generate_legal_moves(*this, mlist);
-
- // Loop through the moves, and see if one of them is mate
- for (int i = 0; i < count; i++)
+ StateInfo* stp = st;
+ for (int i = 2, e = std::min(st->rule50, st->pliesFromNull); i <= e; i += 2)
{
- do_move(mlist[i].move, u2);
- if (is_mate())
- result = true;
+ stp = stp->previous->previous;
- undo_move(mlist[i].move, u2);
+ if (stp->key == st->key)
+ return true; // Draw at first repetition
}
- // Undo null move, if necessary
- if (c != stm)
- undo_null_move(u1);
-
- return result;
+ return false;
}
-/// Position::init_zobrist() is a static member function which initializes the
-/// various arrays used to compute hash keys.
-
-void Position::init_zobrist() {
-
- for (int i = 0; i < 2; i++)
- for (int j = 0; j < 8; j++)
- for (int k = 0; k < 64; k++)
- zobrist[i][j][k] = Key(genrand_int64());
-
- for (int i = 0; i < 64; i++)
- zobEp[i] = Key(genrand_int64());
-
- for (int i = 0; i < 16; i++)
- zobCastle[i] = genrand_int64();
-
- zobSideToMove = genrand_int64();
+/// Position::flip() flips position with the white and black sides reversed. This
+/// is only useful for debugging e.g. for finding evaluation symmetry bugs.
- for (int i = 0; i < 2; i++)
- for (int j = 0; j < 8; j++)
- for (int k = 0; k < 16; k++)
- zobMaterial[i][j][k] = (k > 0)? Key(genrand_int64()) : Key(0LL);
-
- for (int i = 0; i < 16; i++)
- zobMaterial[0][KING][i] = zobMaterial[1][KING][i] = Key(0ULL);
+static char toggle_case(char c) {
+ return char(islower(c) ? toupper(c) : tolower(c));
}
+void Position::flip() {
-/// Position::init_piece_square_tables() initializes the piece square tables.
-/// This is a two-step operation: First, the white halves of the tables are
-/// copied from the MgPST[][] and EgPST[][] arrays, with a small random number
-/// added to each entry if the "Randomness" UCI parameter is non-zero.
-/// Second, the black halves of the tables are initialized by mirroring
-/// and changing the sign of the corresponding white scores.
-
-void Position::init_piece_square_tables() {
-
- int r = get_option_value_int("Randomness"), i;
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- for (Piece p = WP; p <= WK; p++)
- {
- i = (r == 0)? 0 : (genrand_int32() % (r*2) - r);
- MgPieceSquareTable[p][s] = Value(MgPST[p][s] + i);
- EgPieceSquareTable[p][s] = Value(EgPST[p][s] + i);
- }
+ string f, token;
+ std::stringstream ss(fen());
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- for (Piece p = BP; p <= BK; p++)
- {
- MgPieceSquareTable[p][s] = -MgPieceSquareTable[p-8][flip_square(s)];
- EgPieceSquareTable[p][s] = -EgPieceSquareTable[p-8][flip_square(s)];
- }
-}
-
-
-/// Position::flipped_copy() makes a copy of the input position, but with
-/// the white and black sides reversed. This is only useful for debugging,
-/// especially for finding evaluation symmetry bugs.
-
-void Position::flipped_copy(const Position &pos) {
-
- assert(pos.is_ok());
-
- clear();
-
- // Board
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- if (!pos.square_is_empty(s))
- put_piece(Piece(int(pos.piece_on(s)) ^ 8), flip_square(s));
-
- // Side to move
- sideToMove = opposite_color(pos.side_to_move());
-
- // Castling rights
- if (pos.can_castle_kingside(WHITE)) allow_oo(BLACK);
- if (pos.can_castle_queenside(WHITE)) allow_ooo(BLACK);
- if (pos.can_castle_kingside(BLACK)) allow_oo(WHITE);
- if (pos.can_castle_queenside(BLACK)) allow_ooo(WHITE);
-
- initialKFile = pos.initialKFile;
- initialKRFile = pos.initialKRFile;
- initialQRFile = pos.initialQRFile;
-
- for (Square sq = SQ_A1; sq <= SQ_H8; sq++)
- castleRightsMask[sq] = ALL_CASTLES;
+ for (Rank r = RANK_8; r >= RANK_1; --r) // Piece placement
+ {
+ std::getline(ss, token, r > RANK_1 ? '/' : ' ');
+ f.insert(0, token + (f.empty() ? " " : "/"));
+ }
- castleRightsMask[make_square(initialKFile, RANK_1)] ^= (WHITE_OO | WHITE_OOO);
- castleRightsMask[make_square(initialKFile, RANK_8)] ^= (BLACK_OO | BLACK_OOO);
- castleRightsMask[make_square(initialKRFile, RANK_1)] ^= WHITE_OO;
- castleRightsMask[make_square(initialKRFile, RANK_8)] ^= BLACK_OO;
- castleRightsMask[make_square(initialQRFile, RANK_1)] ^= WHITE_OOO;
- castleRightsMask[make_square(initialQRFile, RANK_8)] ^= BLACK_OOO;
+ ss >> token; // Active color
+ f += (token == "w" ? "B " : "W "); // Will be lowercased later
- // En passant square
- if (pos.epSquare != SQ_NONE)
- epSquare = flip_square(pos.epSquare);
+ ss >> token; // Castling availability
+ f += token + " ";
- // Checkers
- find_checkers();
+ std::transform(f.begin(), f.end(), f.begin(), toggle_case);
- // Hash keys
- key = compute_key();
- pawnKey = compute_pawn_key();
- materialKey = compute_material_key();
+ ss >> token; // En passant square
+ f += (token == "-" ? token : token.replace(1, 1, token[1] == '3' ? "6" : "3"));
- // Incremental scores
- mgValue = compute_mg_value();
- egValue = compute_eg_value();
+ std::getline(ss, token); // Half and full moves
+ f += token;
- // Material
- npMaterial[WHITE] = compute_non_pawn_material(WHITE);
- npMaterial[BLACK] = compute_non_pawn_material(BLACK);
+ set(f, is_chess960(), this_thread());
- assert(is_ok());
+ assert(pos_is_ok());
}
-/// Position::is_ok() performs some consitency checks for the position object.
+/// Position::pos_is_ok() performs some consistency checks for the position object.
/// This is meant to be helpful when debugging.
-bool Position::is_ok(int* failedStep) const {
-
- // What features of the position should be verified?
- static const bool debugBitboards = false;
- static const bool debugKingCount = false;
- static const bool debugKingCapture = false;
- static const bool debugCheckerCount = false;
- static const bool debugKey = false;
- static const bool debugMaterialKey = false;
- static const bool debugPawnKey = false;
- static const bool debugIncrementalEval = false;
- static const bool debugNonPawnMaterial = false;
- static const bool debugPieceCounts = false;
- static const bool debugPieceList = false;
-
- if (failedStep) *failedStep = 1;
-
- // Side to move OK?
- if (!color_is_ok(side_to_move()))
- return false;
+bool Position::pos_is_ok(int* step) const {
- // Are the king squares in the position correct?
- if (failedStep) (*failedStep)++;
- if (piece_on(king_square(WHITE)) != WK)
- return false;
+ // Which parts of the position should be verified?
+ const bool all = false;
- if (failedStep) (*failedStep)++;
- if (piece_on(king_square(BLACK)) != BK)
- return false;
+ const bool testBitboards = all || false;
+ const bool testState = all || false;
+ const bool testKingCount = all || false;
+ const bool testKingCapture = all || false;
+ const bool testPieceCounts = all || false;
+ const bool testPieceList = all || false;
+ const bool testCastlingSquares = all || false;
- // Castle files OK?
- if (failedStep) (*failedStep)++;
- if (!file_is_ok(initialKRFile))
- return false;
+ if (step)
+ *step = 1;
- if (!file_is_ok(initialQRFile))
+ if ( (sideToMove != WHITE && sideToMove != BLACK)
+ || piece_on(king_square(WHITE)) != W_KING
+ || piece_on(king_square(BLACK)) != B_KING
+ || ( ep_square() != SQ_NONE
+ && relative_rank(sideToMove, ep_square()) != RANK_6))
return false;
- // Do both sides have exactly one king?
- if (failedStep) (*failedStep)++;
- if (debugKingCount)
- {
- int kingCount[2] = {0, 0};
- for (Square s = SQ_A1; s <= SQ_H8; s++)
- if (type_of_piece_on(s) == KING)
- kingCount[color_of_piece_on(s)]++;
-
- if(kingCount[0] != 1 || kingCount[1] != 1)
- return false;
- }
-
- // Can the side to move capture the opponent's king?
- if (failedStep) (*failedStep)++;
- if (debugKingCapture)
- {
- Color us = side_to_move();
- Color them = opposite_color(us);
- Square ksq = king_square(them);
- if (square_is_attacked(ksq, us))
- return false;
- }
-
- // Is there more than 2 checkers?
- if (failedStep) (*failedStep)++;
- if (debugCheckerCount && count_1s(checkersBB) > 2)
- return false;
-
- // Bitboards OK?
- if (failedStep) (*failedStep)++;
- if (debugBitboards)
+ if (step && ++*step, testBitboards)
{
// The intersection of the white and black pieces must be empty
- if ((pieces_of_color(WHITE) & pieces_of_color(BLACK)) != EmptyBoardBB)
+ if (pieces(WHITE) & pieces(BLACK))
return false;
// The union of the white and black pieces must be equal to all
// occupied squares
- if ((pieces_of_color(WHITE) | pieces_of_color(BLACK)) != occupied_squares())
+ if ((pieces(WHITE) | pieces(BLACK)) != pieces())
return false;
// Separate piece type bitboards must have empty intersections
- for (PieceType p1 = PAWN; p1 <= KING; p1++)
- for (PieceType p2 = PAWN; p2 <= KING; p2++)
- if (p1 != p2 && (pieces_of_type(p1) & pieces_of_type(p2)))
+ for (PieceType p1 = PAWN; p1 <= KING; ++p1)
+ for (PieceType p2 = PAWN; p2 <= KING; ++p2)
+ if (p1 != p2 && (pieces(p1) & pieces(p2)))
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(side_to_move(), ep_square()) != RANK_6)
- return false;
- }
-
- // Hash key OK?
- if (failedStep) (*failedStep)++;
- if (debugKey && key != compute_key())
- return false;
-
- // Pawn hash key OK?
- if (failedStep) (*failedStep)++;
- if (debugPawnKey && pawnKey != compute_pawn_key())
- return false;
-
- // Material hash key OK?
- if (failedStep) (*failedStep)++;
- if (debugMaterialKey && materialKey != compute_material_key())
- return false;
-
- // Incremental eval OK?
- if (failedStep) (*failedStep)++;
- if (debugIncrementalEval)
+ if (step && ++*step, testState)
{
- if (mgValue != compute_mg_value())
- return false;
-
- if (egValue != compute_eg_value())
+ StateInfo si;
+ set_state(&si);
+ if ( st->key != si.key
+ || st->pawnKey != si.pawnKey
+ || st->materialKey != si.materialKey
+ || st->npMaterial[WHITE] != si.npMaterial[WHITE]
+ || st->npMaterial[BLACK] != si.npMaterial[BLACK]
+ || st->psq != si.psq
+ || st->checkersBB != si.checkersBB)
return false;
}
- // Non-pawn material OK?
- if (failedStep) (*failedStep)++;
- if (debugNonPawnMaterial)
- {
- if(npMaterial[WHITE] != compute_non_pawn_material(WHITE))
+ if (step && ++*step, testKingCount)
+ if ( std::count(board, board + SQUARE_NB, W_KING) != 1
+ || std::count(board, board + SQUARE_NB, B_KING) != 1)
return false;
- if(npMaterial[BLACK] != compute_non_pawn_material(BLACK))
+ if (step && ++*step, testKingCapture)
+ if (attackers_to(king_square(~sideToMove)) & pieces(sideToMove))
return false;
- }
- // Piece counts OK?
- if (failedStep) (*failedStep)++;
- if (debugPieceCounts)
- for (Color c = WHITE; c <= BLACK; c++)
- for (PieceType pt = PAWN; pt <= KING; pt++)
- if (pieceCount[c][pt] != count_1s(pieces_of_color_and_type(c, pt)))
+ if (step && ++*step, testPieceCounts)
+ for (Color c = WHITE; c <= BLACK; ++c)
+ for (PieceType pt = PAWN; pt <= KING; ++pt)
+ if (pieceCount[c][pt] != popcount<Full>(pieces(c, pt)))
return false;
- if (failedStep) (*failedStep)++;
- if (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)) != piece_of_color_and_type(c, pt))
+ if (step && ++*step, testPieceList)
+ for (Color c = WHITE; c <= BLACK; ++c)
+ for (PieceType pt = PAWN; pt <= KING; ++pt)
+ 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;
- if (index[piece_list(c, pt, i)] != i)
- return false;
- }
- }
- if (failedStep) *failedStep = 0;
+ if (step && ++*step, testCastlingSquares)
+ for (Color c = WHITE; c <= BLACK; ++c)
+ for (CastlingSide s = KING_SIDE; s <= QUEEN_SIDE; s = CastlingSide(s + 1))
+ {
+ if (!can_castle(c | s))
+ continue;
+
+ if ( (castlingRightsMask[king_square(c)] & (c | s)) != (c | s)
+ || piece_on(castlingRookSquare[c | s]) != make_piece(c, ROOK)
+ || castlingRightsMask[castlingRookSquare[c | s]] != (c | s))
+ return false;
+ }
+
return true;
}
projects / stockfish / blobdiff