X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fposition.cpp;h=ae63f26343f5026d14dbe989cf65f3e53415546a;hb=8a7876d48d4360d14d918c1ff444b5d6eb0382de;hp=9b9ca22ac78bed0120b8a2a62f8d0f18e4de3e2a;hpb=84d6fe0f31069bc612f856ab7cd54d9aad7907ca;p=stockfish
diff --git a/src/position.cpp b/src/position.cpp
index 9b9ca22a..918d50e5 100644
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -1,7 +1,7 @@
/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2009 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
@@ -17,2010 +17,1269 @@
along with this program. If not, see .
*/
-
-////
-//// Includes
-////
-
+#include
#include
#include
-#include
-#include
+#include
+#include
#include "bitcount.h"
-#include "mersenne.h"
#include "movegen.h"
-#include "movepick.h"
#include "position.h"
#include "psqtab.h"
-#include "san.h"
+#include "rkiss.h"
+#include "thread.h"
#include "tt.h"
-#include "ucioption.h"
+#include "uci.h"
using std::string;
+CACHE_LINE_ALIGNMENT
-////
-//// Variables
-////
-
-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;
+Value PieceValue[PHASE_NB][PIECE_NB] = {
+{ VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg },
+{ VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg } };
-Value Position::MgPieceSquareTable[16][64];
-Value Position::EgPieceSquareTable[16][64];
+namespace Zobrist {
-static bool RequestPending = false;
-
-////
-//// Functions
-////
-
-/// Constructors
-
-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 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 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 string pieceLetters = "KQRBNPkqrbnp";
- static const Piece pieces[] = { WK, WQ, WR, WB, WN, WP, BK, BQ, BR, BB, BN, BP };
+template 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(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 == 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(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(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'))
- st->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();
-
- st->key = compute_key();
- st->pawnKey = compute_pawn_key();
- st->materialKey = compute_material_key();
- st->mgValue = compute_value();
- st->egValue = compute_value();
- st->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
- st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
+template<> FORCE_INLINE
+PieceType min_attacker(const Bitboard*, const Square&, const Bitboard&, Bitboard&, Bitboard&) {
+ return KING; // No need to update bitboards: it is the last cycle
}
+} // namespace
-/// Position::to_fen() converts the position object to a FEN string. This is
-/// probably only useful for debugging.
-const string Position::to_fen() const {
+/// CheckInfo c'tor
- static const string pieceLetters = " PNBRQK pnbrqk";
- 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 (st->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(ksq, them);
+ checkSq[KNIGHT] = pos.attacks_from(ksq);
+ checkSq[BISHOP] = pos.attacks_from(ksq);
+ checkSq[ROOK] = pos.attacks_from(ksq);
+ checkSq[QUEEN] = checkSq[BISHOP] | checkSq[ROOK];
+ checkSq[KING] = 0;
}
-/// 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 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();
- RequestPending = true;
+ for (File f = FILE_A; f <= FILE_H; ++f)
+ Zobrist::enpassant[f] = rk.rand();
- std::cout << std::endl;
- if (m != MOVE_NONE)
+ for (int cf = NO_CASTLING; cf <= ANY_CASTLING; ++cf)
{
- 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();
}
- std::cout << '|' << std::endl;
}
- std::cout << "+---+---+---+---+---+---+---+---+" << std::endl
- << "Fen is: " << to_fen() << std::endl
- << "Key is: " << st->key << std::endl;
-
- RequestPending = false;
-}
+ Zobrist::side = rk.rand();
+ Zobrist::exclusion = rk.rand();
-/// Position::copy() creates a copy of the input position.
+ 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];
-void Position::copy(const Position& pos) {
+ Score v = make_score(PieceValue[MG][pt], PieceValue[EG][pt]);
- memcpy(this, &pos, sizeof(Position));
- saveState(); // detach and copy state info
+ 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:hidden_checkers<>() 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 pieces of the given color
-/// candidate for a discovery check against the enemy king.
-/// Note that checkersBB bitboard must be already updated.
+/// 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.
-template
-Bitboard Position::hidden_checkers(Color c) const {
+Position& Position::operator=(const Position& pos) {
- Bitboard pinners, result = EmptyBoardBB;
+ std::memcpy(this, &pos, sizeof(Position));
+ startState = *st;
+ st = &startState;
+ nodes = 0;
- // Pinned pieces protect our king, dicovery checks attack
- // the enemy king.
- Square ksq = king_square(FindPinned ? c : opposite_color(c));
+ assert(pos_is_ok());
- // Pinners are sliders, not checkers, that give check when
- // candidate pinned is removed.
- pinners = (pieces(ROOK, QUEEN, FindPinned ? opposite_color(c) : c) & RookPseudoAttacks[ksq])
- | (pieces(BISHOP, QUEEN, FindPinned ? opposite_color(c) : c) & BishopPseudoAttacks[ksq]);
+ return *this;
+}
- if (FindPinned && pinners)
- pinners &= ~st->checkersBB;
- while (pinners)
- {
- Square s = pop_1st_bit(&pinners);
- Bitboard b = squares_between(s, ksq) & occupied_squares();
+/// Position::clear() erases the position object to a pristine state, with an
+/// empty board, white to move, and no castling rights.
- assert(b);
+void Position::clear() {
- if ( !(b & (b - 1)) // Only one bit set?
- && (b & pieces_of_color(c))) // Is an our piece?
- result |= b;
- }
- return result;
+ std::memset(this, 0, sizeof(Position));
+ startState.epSquare = SQ_NONE;
+ st = &startState;
+
+ for (int i = 0; i < PIECE_TYPE_NB; ++i)
+ for (int j = 0; j < 16; ++j)
+ pieceList[WHITE][i][j] = pieceList[BLACK][i][j] = SQ_NONE;
}
-/// Position:pinned_pieces() returns a bitboard of all pinned (against the
-/// king) pieces for the given color.
+/// 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.
-Bitboard Position::pinned_pieces(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 hidden_checkers(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:discovered_check_candidates() returns a bitboard containing all
-/// pieces for the given side which are candidates for giving a discovered
-/// check.
+ 2) Active color. "w" means white moves next, "b" means black.
-Bitboard Position::discovered_check_candidates(Color c) 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 hidden_checkers(c);
-}
+ 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.
-/// Position::attackers_to() computes a bitboard containing all pieces which
-/// attacks a given square.
+ 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.
-Bitboard Position::attackers_to(Square s) const {
+ 6) Fullmove number. The number of the full move. It starts at 1, and is
+ incremented after Black's move.
+*/
- return (pawn_attacks_from(s, BLACK) & pieces(PAWN, WHITE))
- | (pawn_attacks_from(s, WHITE) & pieces(PAWN, BLACK))
- | (piece_attacks_from(s) & pieces(KNIGHT))
- | (piece_attacks_from(s) & pieces(ROOK, QUEEN))
- | (piece_attacks_from(s) & pieces(BISHOP, QUEEN))
- | (piece_attacks_from(s) & pieces(KING));
-}
+ unsigned char col, row, token;
+ size_t idx;
+ Square sq = SQ_A8;
+ std::istringstream ss(fenStr);
-/// Position::piece_attacks_from() computes a bitboard of all attacks
-/// of a given piece put in a given square.
+ clear();
+ ss >> std::noskipws;
-Bitboard Position::piece_attacks_from(Piece p, Square s) 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(s));
+ else if (token == '/')
+ sq -= Square(16);
- switch (p)
- {
- case WP: return pawn_attacks_from(s, WHITE);
- case BP: return pawn_attacks_from(s, BLACK);
- case WN: case BN: return piece_attacks_from(s);
- case WB: case BB: return piece_attacks_from(s);
- case WR: case BR: return piece_attacks_from(s);
- case WQ: case BQ: return piece_attacks_from(s);
- case WK: case BK: return piece_attacks_from(s);
- 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;
-/// Position::move_attacks_square() tests whether a move from the current
-/// position attacks a given square.
+ token = char(toupper(token));
-bool Position::move_attacks_square(Move m, Square s) const {
+ if (token == 'K')
+ for (rsq = relative_square(c, SQ_H1); type_of(piece_on(rsq)) != ROOK; --rsq) {}
- assert(move_is_ok(m));
- assert(square_is_ok(s));
+ else if (token == 'Q')
+ for (rsq = relative_square(c, SQ_A1); type_of(piece_on(rsq)) != ROOK; ++rsq) {}
- Square f = move_from(m), t = move_to(m);
+ else if (token >= 'A' && token <= 'H')
+ rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1));
- assert(square_is_occupied(f));
+ else
+ continue;
- if (bit_is_set(piece_attacks_from(piece_on(f), t), s))
- return true;
+ set_castling_right(c, rsq);
+ }
- // Move the piece and scan for X-ray attacks behind it
- Bitboard occ = occupied_squares();
- Color us = color_of_piece_on(f);
- clear_bit(&occ, f);
- set_bit(&occ, t);
- Bitboard xray = ( (rook_attacks_bb(s, occ) & pieces(ROOK, QUEEN))
- |(bishop_attacks_bb(s, occ) & pieces(BISHOP, QUEEN))) & pieces_of_color(us);
-
- // If we have attacks we need to verify that are caused by our move
- // and are not already existent ones.
- return xray && (xray ^ (xray & piece_attacks_from(s)));
-}
+ // 4. En passant square. Ignore if no pawn capture is possible
+ if ( ((ss >> col) && (col >= 'a' && col <= 'h'))
+ && ((ss >> row) && (row == '3' || row == '6')))
+ {
+ st->epSquare = make_square(File(col - 'a'), Rank(row - '1'));
+ if (!(attackers_to(st->epSquare) & pieces(sideToMove, PAWN)))
+ st->epSquare = SQ_NONE;
+ }
+
+ // 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::attackers_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();
- st->checkersBB = attackers_to(king_square(us)) & pieces_of_color(opposite_color(us));
+ assert(pos_is_ok());
}
-/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal
+/// 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) {
- // If we're in check, all pseudo-legal moves are legal, because our
- // check evasion generator only generates true legal moves.
- return is_check() || pl_move_is_legal(m, pinned_pieces(side_to_move()));
-}
+ 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()));
- assert(!is_check());
+ Square kto = relative_square(c, cs == KING_SIDE ? SQ_G1 : SQ_C1);
+ Square rto = relative_square(c, cs == KING_SIDE ? SQ_F1 : SQ_D1);
- // Castling moves are checked for legality during move generation.
- if (move_is_castle(m))
- return true;
+ for (Square s = std::min(rfrom, rto); s <= std::max(rfrom, rto); ++s)
+ if (s != kfrom && s != rfrom)
+ castlingPath[cr] |= s;
- Color us = side_to_move();
- Square from = move_from(m);
+ for (Square s = std::min(kfrom, kto); s <= std::max(kfrom, kto); ++s)
+ if (s != kfrom && s != rfrom)
+ castlingPath[cr] |= s;
+}
- assert(color_of_piece_on(from) == us);
- assert(piece_on(king_square(us)) == piece_of_color_and_type(us, KING));
- // En passant captures are a tricky special case. Because they are
- // rather uncommon, we do it simply by testing whether the king is attacked
- // after the move is made
- if (move_is_ep(m))
- {
- Color them = opposite_color(us);
- Square to = move_to(m);
- Square capsq = make_square(square_file(to), square_rank(from));
- Bitboard b = occupied_squares();
- Square ksq = king_square(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.
- assert(to == ep_square());
- assert(piece_on(from) == piece_of_color_and_type(us, PAWN));
- assert(piece_on(capsq) == piece_of_color_and_type(them, PAWN));
- assert(piece_on(to) == EMPTY);
+void Position::set_state(StateInfo* si) const {
+
+ 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) & pieces(ROOK, QUEEN, them))
- && !(bishop_attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, 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 (type_of_piece_on(from) == KING)
- return !(attackers_to(move_to(m)) & pieces_of_color(opposite_color(us)));
+ 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 ( !pinned
- || !bit_is_set(pinned, from)
- || (direction_between_squares(from, king_square(us)) == direction_between_squares(move_to(m), king_square(us))));
-}
+ 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
+ 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) == piece_of_color_and_type(them, KING));
+ 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_from(ksq, them), to)) // Normal check?
- return true;
-
- if ( dcCandidates // Discovered check?
- && bit_is_set(dcCandidates, from)
- && (direction_between_squares(from, ksq) != direction_between_squares(to, ksq)))
- return true;
-
- if (move_is_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_piece(m))
- {
- case KNIGHT:
- return bit_is_set(piece_attacks_from(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) & pieces(ROOK, QUEEN, us))
- ||(bishop_attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, us));
- }
- return false;
+ if (emptyCnt)
+ ss << emptyCnt;
- // Test discovered check and normal check according to piece type
- case KNIGHT:
- return (dcCandidates && bit_is_set(dcCandidates, from))
- || bit_is_set(piece_attacks_from(ksq), to);
-
- case BISHOP:
- return (dcCandidates && bit_is_set(dcCandidates, from))
- || (direction_is_diagonal(ksq, to) && bit_is_set(piece_attacks_from(ksq), to));
-
- case ROOK:
- return (dcCandidates && bit_is_set(dcCandidates, from))
- || (direction_is_straight(ksq, to) && bit_is_set(piece_attacks_from(ksq), to));
-
- case QUEEN:
- // Discovered checks are impossible!
- assert(!bit_is_set(dcCandidates, from));
- return ( (direction_is_straight(ksq, to) && bit_is_set(piece_attacks_from(ksq), to))
- || (direction_is_diagonal(ksq, to) && bit_is_set(piece_attacks_from(ksq), to)));
-
- 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;
-}
-
-
-/// Position::update_checkers() udpates chekers info given the move. It is called
-/// in do_move() and is faster then find_checkers().
-
-template
-inline void Position::update_checkers(Bitboard* pCheckersBB, Square ksq, Square from,
- Square to, Bitboard dcCandidates) {
- const bool Bishop = (Piece == QUEEN || Piece == BISHOP);
- const bool Rook = (Piece == QUEEN || Piece == ROOK);
- const bool Slider = Bishop || Rook;
+ ss << (sideToMove == WHITE ? " w " : " b ");
- // Direct checks
- if ( ( (Bishop && bit_is_set(BishopPseudoAttacks[ksq], to))
- || (Rook && bit_is_set(RookPseudoAttacks[ksq], to)))
- && bit_is_set(piece_attacks_from(ksq), to)) // slow, try to early skip
- set_bit(pCheckersBB, to);
+ if (can_castle(WHITE_OO))
+ ss << (chess960 ? 'A' + file_of(castling_rook_square(WHITE | KING_SIDE)) : 'K');
- else if ( Piece != KING
- && !Slider
- && bit_is_set(Piece == PAWN ? pawn_attacks_from(ksq, opposite_color(sideToMove))
- : piece_attacks_from(ksq), to))
- set_bit(pCheckersBB, to);
+ if (can_castle(WHITE_OOO))
+ ss << (chess960 ? 'A' + file_of(castling_rook_square(WHITE | QUEEN_SIDE)) : 'Q');
- // Discovery checks
- if (Piece != QUEEN && bit_is_set(dcCandidates, from))
- {
- if (Piece != ROOK)
- (*pCheckersBB) |= (piece_attacks_from(ksq) & pieces(ROOK, QUEEN, side_to_move()));
-
- if (Piece != BISHOP)
- (*pCheckersBB) |= (piece_attacks_from(ksq) & pieces(BISHOP, QUEEN, side_to_move()));
- }
-}
+ if (can_castle(BLACK_OO))
+ ss << (chess960 ? 'a' + file_of(castling_rook_square(BLACK | KING_SIDE)) : 'k');
+ if (can_castle(BLACK_OOO))
+ ss << (chess960 ? 'a' + file_of(castling_rook_square(BLACK | QUEEN_SIDE)) : 'q');
-/// 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.
+ if (!can_castle(WHITE) && !can_castle(BLACK))
+ ss << '-';
-void Position::do_move(Move m, StateInfo& newSt) {
+ ss << (ep_square() == SQ_NONE ? " - " : " " + UCI::format_square(ep_square()) + " ")
+ << st->rule50 << " " << 1 + (gamePly - (sideToMove == BLACK)) / 2;
- do_move(m, newSt, discovered_check_candidates(side_to_move()));
+ return ss.str();
}
-void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) {
- assert(is_ok());
- assert(move_is_ok(m));
+/// Position::pretty() returns an ASCII representation of the position
- Bitboard key = st->key;
+const string Position::pretty() const {
- // Copy some fields of old state to our new StateInfo object except the
- // ones which are recalculated from scratch anyway, then switch our state
- // pointer to point to the new, ready to be updated, state.
- struct ReducedStateInfo {
- Key key, pawnKey, materialKey;
- int castleRights, rule50;
- Square kingSquare[2], epSquare;
- Value mgValue, egValue;
- Value npMaterial[2];
- };
+ std::ostringstream ss;
- memcpy(&newSt, st, sizeof(ReducedStateInfo));
- newSt.previous = st;
- st = &newSt;
+ ss << "\n +---+---+---+---+---+---+---+---+\n";
- // Save the current key to the history[] array, in order to be able to
- // detect repetition draws.
- history[gamePly] = key;
- gamePly++;
-
- // Update side to move
- key ^= zobSideToMove;
-
- // Increment the 50 moves rule draw counter. Resetting it to zero in the
- // case of non-reversible moves is taken care of later.
- st->rule50++;
-
- if (move_is_castle(m))
+ for (Rank r = RANK_8; r >= RANK_1; --r)
{
- st->key = key;
- do_castle_move(m);
- return;
- }
+ for (File f = FILE_A; f <= FILE_H; ++f)
+ ss << " | " << PieceToChar[piece_on(make_square(f, r))];
- Color us = side_to_move();
- Color them = opposite_color(us);
- Square from = move_from(m);
- Square to = move_to(m);
- bool ep = move_is_ep(m);
- bool pm = move_is_promotion(m);
+ ss << " |\n +---+---+---+---+---+---+---+---+\n";
+ }
- Piece piece = piece_on(from);
- PieceType pt = type_of_piece(piece);
+ ss << "\nFen: " << fen() << "\nKey: " << std::hex << std::uppercase
+ << std::setfill('0') << std::setw(16) << st->key << "\nCheckers: ";
- assert(color_of_piece_on(from) == us);
- assert(color_of_piece_on(to) == them || square_is_empty(to));
- assert(!(ep || pm) || piece == piece_of_color_and_type(us, PAWN));
- assert(!pm || relative_rank(us, to) == RANK_8);
+ for (Bitboard b = checkers(); b; )
+ ss << UCI::format_square(pop_lsb(&b)) << " ";
- st->capture = ep ? PAWN : type_of_piece_on(to);
+ return ss.str();
+}
- if (st->capture)
- do_capture_move(key, st->capture, them, to, ep);
- // Update hash key
- key ^= zobrist[us][pt][from] ^ zobrist[us][pt][to];
+/// Position::game_phase() calculates the game phase interpolating total non-pawn
+/// material between endgame and midgame limits.
- // Reset en passant square
- if (st->epSquare != SQ_NONE)
- {
- key ^= zobEp[st->epSquare];
- st->epSquare = SQ_NONE;
- }
+Phase Position::game_phase() const {
- // Update castle rights, try to shortcut a common case
- int cm = castleRightsMask[from] & castleRightsMask[to];
- if (cm != ALL_CASTLES && ((cm & st->castleRights) != st->castleRights))
- {
- key ^= zobCastle[st->castleRights];
- st->castleRights &= castleRightsMask[from];
- st->castleRights &= castleRightsMask[to];
- key ^= zobCastle[st->castleRights];
- }
+ Value npm = st->npMaterial[WHITE] + st->npMaterial[BLACK];
- // Prefetch TT access as soon as we know key is updated
- TT.prefetch(key);
+ npm = std::max(EndgameLimit, std::min(npm, MidgameLimit));
- // Move the piece
- Bitboard move_bb = make_move_bb(from, to);
- do_move_bb(&(byColorBB[us]), move_bb);
- do_move_bb(&(byTypeBB[pt]), move_bb);
- do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares
+ return Phase(((npm - EndgameLimit) * 128) / (MidgameLimit - EndgameLimit));
+}
- board[to] = board[from];
- board[from] = EMPTY;
- // If the moving piece was a king, update the king square
- if (pt == KING)
- st->kingSquare[us] = to;
+/// 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 piece lists, note that index[from] is not updated and
- // becomes stale. This works as long as index[] is accessed just
- // by known occupied squares.
- index[to] = index[from];
- pieceList[us][pt][index[to]] = to;
+Bitboard Position::check_blockers(Color c, Color kingColor) const {
- // If the moving piece was a pawn do some special extra work
- if (pt == PAWN)
- {
- // Reset rule 50 draw counter
- st->rule50 = 0;
+ Bitboard b, pinners, result = 0;
+ Square ksq = king_square(kingColor);
- // Update pawn hash key
- st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
+ // 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);
- // Set en passant square, only if moved pawn can be captured
- if (abs(int(to) - int(from)) == 16)
- {
- if (pawn_attacks_from(from + (us == WHITE ? DELTA_N : DELTA_S), us) & pieces(PAWN, them))
- {
- st->epSquare = Square((int(from) + int(to)) / 2);
- key ^= zobEp[st->epSquare];
- }
- }
- }
-
- // Update incremental scores
- st->mgValue += pst_delta(piece, from, to);
- st->egValue += pst_delta(piece, from, to);
-
- if (pm) // promotion ?
+ while (pinners)
{
- PieceType promotion = move_promotion_piece(m);
-
- assert(promotion >= KNIGHT && promotion <= QUEEN);
-
- // Insert promoted piece instead of pawn
- clear_bit(&(byTypeBB[PAWN]), to);
- set_bit(&(byTypeBB[promotion]), to);
- board[to] = piece_of_color_and_type(us, promotion);
-
- // Update material key
- st->materialKey ^= zobMaterial[us][PAWN][pieceCount[us][PAWN]];
- st->materialKey ^= zobMaterial[us][promotion][pieceCount[us][promotion]+1];
-
- // Update piece counts
- pieceCount[us][PAWN]--;
- pieceCount[us][promotion]++;
-
- // Update piece lists, move the last pawn at index[to] position
- // and shrink the list. Add a new promotion piece to the list.
- Square lastPawnSquare = pieceList[us][PAWN][pieceCount[us][PAWN]];
- index[lastPawnSquare] = index[to];
- pieceList[us][PAWN][index[lastPawnSquare]] = lastPawnSquare;
- index[to] = pieceCount[us][promotion] - 1;
- pieceList[us][promotion][index[to]] = to;
-
- // Partially revert hash keys update
- key ^= zobrist[us][PAWN][to] ^ zobrist[us][promotion][to];
- st->pawnKey ^= zobrist[us][PAWN][to];
-
- // Partially revert and update incremental scores
- st->mgValue -= pst(us, PAWN, to);
- st->mgValue += pst(us, promotion, to);
- st->egValue -= pst(us, PAWN, to);
- st->egValue += pst(us, promotion, to);
-
- // Update material
- st->npMaterial[us] += piece_value_midgame(promotion);
- }
+ b = between_bb(ksq, pop_lsb(&pinners)) & pieces();
- // Update the key with the final value
- st->key = key;
-
- // Update checkers bitboard, piece must be already moved
- if (ep | pm)
- st->checkersBB = attackers_to(king_square(them)) & pieces_of_color(us);
- else
- {
- st->checkersBB = EmptyBoardBB;
- Square ksq = king_square(them);
- switch (pt)
- {
- case PAWN: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break;
- case KNIGHT: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break;
- case BISHOP: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break;
- case ROOK: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break;
- case QUEEN: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break;
- case KING: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break;
- default: assert(false); break;
- }
+ if (!more_than_one(b))
+ result |= b & pieces(c);
}
-
- // Finish
- sideToMove = opposite_color(sideToMove);
-
- st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
- st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
-
- assert(is_ok());
+ return result;
}
-/// Position::do_capture_move() is a private method used to update captured
-/// piece info. It is called from the main Position::do_move function.
-
-void Position::do_capture_move(Bitboard& key, PieceType capture, Color them, Square to, bool ep) {
+/// Position::attackers_to() computes a bitboard of all pieces which attack a
+/// given square. Slider attacks use the occ bitboard to indicate occupancy.
- assert(capture != KING);
+Bitboard Position::attackers_to(Square s, Bitboard occ) const {
- Square capsq = to;
+ return (attacks_from(s, BLACK) & pieces(WHITE, PAWN))
+ | (attacks_from(s, WHITE) & pieces(BLACK, PAWN))
+ | (attacks_from(s) & pieces(KNIGHT))
+ | (attacks_bb(s, occ) & pieces(ROOK, QUEEN))
+ | (attacks_bb(s, occ) & pieces(BISHOP, QUEEN))
+ | (attacks_from(s) & pieces(KING));
+}
- if (ep) // en passant ?
- {
- capsq = (them == BLACK)? (to - DELTA_N) : (to - DELTA_S);
- assert(to == st->epSquare);
- assert(relative_rank(opposite_color(them), to) == RANK_6);
- assert(piece_on(to) == EMPTY);
- assert(piece_on(capsq) == piece_of_color_and_type(them, PAWN));
+/// Position::legal() tests whether a pseudo-legal move is legal
- board[capsq] = EMPTY;
- }
+bool Position::legal(Move m, Bitboard pinned) const {
- // Remove captured piece
- clear_bit(&(byColorBB[them]), capsq);
- clear_bit(&(byTypeBB[capture]), capsq);
- clear_bit(&(byTypeBB[0]), capsq);
+ assert(is_ok(m));
+ assert(pinned == pinned_pieces(sideToMove));
- // Update hash key
- key ^= zobrist[them][capture][capsq];
+ Color us = sideToMove;
+ Square from = from_sq(m);
- // Update incremental scores
- st->mgValue -= pst(them, capture, capsq);
- st->egValue -= pst(them, capture, capsq);
+ assert(color_of(moved_piece(m)) == us);
+ assert(piece_on(king_square(us)) == make_piece(us, KING));
- // If the captured piece was a pawn, update pawn hash key,
- // otherwise update non-pawn material.
- if (capture == PAWN)
- st->pawnKey ^= zobrist[them][PAWN][capsq];
- else
- st->npMaterial[them] -= piece_value_midgame(capture);
+ // En passant captures are a tricky special case. Because they are rather
+ // uncommon, we do it simply by testing whether the king is attacked after
+ // the move is made.
+ if (type_of(m) == ENPASSANT)
+ {
+ Square ksq = king_square(us);
+ Square to = to_sq(m);
+ Square capsq = to - pawn_push(us);
+ Bitboard occ = (pieces() ^ from ^ capsq) | to;
- // Update material hash key
- st->materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]];
+ 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);
- // Update piece count
- pieceCount[them][capture]--;
+ return !(attacks_bb< ROOK>(ksq, occ) & pieces(~us, QUEEN, ROOK))
+ && !(attacks_bb(ksq, occ) & pieces(~us, QUEEN, BISHOP));
+ }
- // Update piece list, move the last piece at index[capsq] position
- //
- // WARNING: This is a not perfectly revresible operation. When we
- // will reinsert the captured piece in undo_move() we will put it
- // at the end of the list and not in its original place, it means
- // index[] and pieceList[] are not guaranteed to be invariant to a
- // do_move() + undo_move() sequence.
- Square lastPieceSquare = pieceList[them][capture][pieceCount[them][capture]];
- index[lastPieceSquare] = index[capsq];
- pieceList[them][capture][index[lastPieceSquare]] = lastPieceSquare;
+ // 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));
- // Reset rule 50 counter
- st->rule50 = 0;
+ // 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_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::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_castle_move(Move m) {
+bool Position::pseudo_legal(const Move m) const {
- assert(move_is_ok(m));
- assert(move_is_castle(m));
+ Color us = sideToMove;
+ Square from = from_sq(m);
+ Square to = to_sq(m);
+ Piece pc = moved_piece(m);
- Color us = side_to_move();
- Color them = opposite_color(us);
+ // Use a slower but simpler function for uncommon cases
+ if (type_of(m) != NORMAL)
+ return MoveList(*this).contains(m);
- // Reset capture field
- st->capture = NO_PIECE_TYPE;
+ // Is not a promotion, so promotion piece must be empty
+ if (promotion_type(m) - 2 != NO_PIECE_TYPE)
+ return false;
- // 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;
+ // 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;
- assert(piece_on(kfrom) == piece_of_color_and_type(us, KING));
- assert(piece_on(rfrom) == piece_of_color_and_type(us, ROOK));
+ // The destination square cannot be occupied by a friendly piece
+ if (pieces(us) & to)
+ return false;
- // Find destination squares for king and rook
- if (rfrom > kfrom) // O-O
+ // Handle the special case of a pawn move
+ if (type_of(pc) == PAWN)
{
- 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);
- }
-
- // Move the pieces
- Bitboard kmove_bb = make_move_bb(kfrom, kto);
- do_move_bb(&(byColorBB[us]), kmove_bb);
- do_move_bb(&(byTypeBB[KING]), kmove_bb);
- do_move_bb(&(byTypeBB[0]), kmove_bb); // HACK: byTypeBB[0] == occupied squares
-
- Bitboard rmove_bb = make_move_bb(rfrom, rto);
- do_move_bb(&(byColorBB[us]), rmove_bb);
- do_move_bb(&(byTypeBB[ROOK]), rmove_bb);
- do_move_bb(&(byTypeBB[0]), rmove_bb); // HACK: byTypeBB[0] == occupied squares
-
- // Update board array
- Piece king = piece_of_color_and_type(us, KING);
- Piece rook = piece_of_color_and_type(us, ROOK);
- board[kfrom] = board[rfrom] = EMPTY;
- board[kto] = king;
- board[rto] = rook;
-
- // Update king square
- st->kingSquare[us] = kto;
-
- // Update piece lists
- pieceList[us][KING][index[kfrom]] = kto;
- pieceList[us][ROOK][index[rfrom]] = rto;
- int tmp = index[rfrom]; // In Chess960 could be rto == kfrom
- index[kto] = index[kfrom];
- index[rto] = tmp;
+ // 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
- st->mgValue += pst_delta(king, kfrom, kto);
- st->egValue += pst_delta(king, kfrom, kto);
- st->mgValue += pst_delta(rook, rfrom, rto);
- st->egValue += pst_delta(rook, rfrom, rto);
+ if ( !(attacks_from(from, us) & pieces(~us) & to) // Not a capture
- // Update hash key
- st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto];
- st->key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto];
+ && !((from + pawn_push(us) == to) && empty(to)) // Not a single push
- // Clear en passant square
- if (st->epSquare != SQ_NONE)
- {
- st->key ^= zobEp[st->epSquare];
- st->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 castling rights
- st->key ^= zobCastle[st->castleRights];
- st->castleRights &= castleRightsMask[kfrom];
- st->key ^= zobCastle[st->castleRights];
-
- // Reset rule 50 counter
- st->rule50 = 0;
-
- // Update checkers BB
- st->checkersBB = attackers_to(king_square(them)) & pieces_of_color(us);
-
- // Finish
- sideToMove = opposite_color(sideToMove);
+ // 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;
- st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
- st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
+ // 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;
+ }
- assert(is_ok());
+ return true;
}
-/// 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.
-
-void Position::undo_move(Move m) {
-
- assert(is_ok());
- assert(move_is_ok(m));
+/// Position::gives_check() tests whether a pseudo-legal move gives a check
- gamePly--;
- sideToMove = opposite_color(sideToMove);
+bool Position::gives_check(Move m, const CheckInfo& ci) const {
- if (move_is_castle(m))
- {
- undo_castle_move(m);
- return;
- }
+ assert(is_ok(m));
+ assert(ci.dcCandidates == discovered_check_candidates());
+ assert(color_of(moved_piece(m)) == sideToMove);
- Color us = side_to_move();
- Color them = opposite_color(us);
- Square from = move_from(m);
- Square to = move_to(m);
- bool ep = move_is_ep(m);
- bool pm = move_is_promotion(m);
+ Square from = from_sq(m);
+ Square to = to_sq(m);
+ PieceType pt = type_of(piece_on(from));
- PieceType pt = type_of_piece_on(to);
+ // Is there a direct check?
+ if (ci.checkSq[pt] & to)
+ return true;
- assert(square_is_empty(from));
- assert(color_of_piece_on(to) == us);
- assert(!pm || relative_rank(us, to) == RANK_8);
- assert(!ep || to == st->previous->epSquare);
- assert(!ep || relative_rank(us, to) == RANK_6);
- assert(!ep || piece_on(to) == piece_of_color_and_type(us, PAWN));
+ // Is there a discovered check?
+ if ( unlikely(ci.dcCandidates)
+ && (ci.dcCandidates & from)
+ && !aligned(from, to, ci.ksq))
+ return true;
- if (pm) // promotion ?
+ switch (type_of(m))
{
- PieceType promotion = move_promotion_piece(m);
- pt = PAWN;
-
- assert(promotion >= KNIGHT && promotion <= QUEEN);
- assert(piece_on(to) == piece_of_color_and_type(us, promotion));
+ case NORMAL:
+ return false;
- // Replace promoted piece with a pawn
- clear_bit(&(byTypeBB[promotion]), to);
- set_bit(&(byTypeBB[PAWN]), to);
+ case PROMOTION:
+ return attacks_bb(Piece(promotion_type(m)), to, pieces() ^ from) & ci.ksq;
- // Update piece counts
- pieceCount[us][promotion]--;
- pieceCount[us][PAWN]++;
+ // 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 piece list replacing promotion piece with a pawn
- Square lastPromotionSquare = pieceList[us][promotion][pieceCount[us][promotion]];
- index[lastPromotionSquare] = index[to];
- pieceList[us][promotion][index[lastPromotionSquare]] = lastPromotionSquare;
- index[to] = pieceCount[us][PAWN] - 1;
- pieceList[us][PAWN][index[to]] = to;
+ return (attacks_bb< ROOK>(ci.ksq, b) & pieces(sideToMove, QUEEN, ROOK))
+ | (attacks_bb(ci.ksq, b) & pieces(sideToMove, QUEEN, BISHOP));
}
-
- // Put the piece back at the source square
- Bitboard move_bb = make_move_bb(to, from);
- do_move_bb(&(byColorBB[us]), move_bb);
- do_move_bb(&(byTypeBB[pt]), move_bb);
- do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares
-
- board[from] = piece_of_color_and_type(us, pt);
- board[to] = EMPTY;
-
- // Update piece list
- index[from] = index[to];
- pieceList[us][pt][index[from]] = from;
-
- if (st->capture)
+ case CASTLING:
{
- Square capsq = to;
-
- if (ep)
- capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S);
-
- assert(st->capture != KING);
- assert(!ep || square_is_empty(capsq));
-
- // Restore the captured piece
- set_bit(&(byColorBB[them]), capsq);
- set_bit(&(byTypeBB[st->capture]), capsq);
- set_bit(&(byTypeBB[0]), capsq);
+ 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);
- board[capsq] = piece_of_color_and_type(them, st->capture);
+ return (PseudoAttacks[ROOK][rto] & ci.ksq)
+ && (attacks_bb(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & ci.ksq);
+ }
+ default:
+ assert(false);
+ return false;
+ }
+}
- // Update piece count
- pieceCount[them][st->capture]++;
- // Update piece list, add a new captured piece in capsq square
- index[capsq] = pieceCount[them][st->capture] - 1;
- pieceList[them][st->capture][index[capsq]] = capsq;
- }
+/// 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.
- // Finally point our state pointer back to the previous state
- st = st->previous;
+void Position::do_move(Move m, StateInfo& newSt) {
- assert(is_ok());
+ 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_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.
-
-void Position::undo_castle_move(Move m) {
+ assert(is_ok(m));
+ assert(&newSt != st);
- assert(move_is_ok(m));
- assert(move_is_castle(m));
+ ++nodes;
+ Key k = st->key;
- // 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();
+ // 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));
- // 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;
+ newSt.previous = st;
+ st = &newSt;
- // Find destination squares for king and rook
- if (rfrom > kfrom) // O-O
+ // Update side to move
+ k ^= Zobrist::side;
+
+ // 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;
+
+ 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));
+
+ assert(color_of(pc) == us);
+ assert(piece_on(to) == NO_PIECE || color_of(piece_on(to)) == them || type_of(m) == CASTLING);
+ assert(captured != KING);
+
+ if (type_of(m) == CASTLING)
{
- 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);
- }
+ assert(pc == make_piece(us, KING));
- assert(piece_on(kto) == piece_of_color_and_type(us, KING));
- assert(piece_on(rto) == piece_of_color_and_type(us, ROOK));
+ Square rfrom, rto;
+ do_castling(from, to, rfrom, rto);
- // Put the pieces back at the source square
- Bitboard kmove_bb = make_move_bb(kto, kfrom);
- do_move_bb(&(byColorBB[us]), kmove_bb);
- do_move_bb(&(byTypeBB[KING]), kmove_bb);
- do_move_bb(&(byTypeBB[0]), kmove_bb); // HACK: byTypeBB[0] == occupied squares
-
- Bitboard rmove_bb = make_move_bb(rto, rfrom);
- do_move_bb(&(byColorBB[us]), rmove_bb);
- do_move_bb(&(byTypeBB[ROOK]), rmove_bb);
- do_move_bb(&(byTypeBB[0]), rmove_bb); // HACK: byTypeBB[0] == occupied squares
+ 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];
+ }
- // Update board
- board[rto] = board[kto] = EMPTY;
- board[rfrom] = piece_of_color_and_type(us, ROOK);
- board[kfrom] = piece_of_color_and_type(us, KING);
+ if (captured)
+ {
+ Square capsq = to;
- // Update piece lists
- pieceList[us][KING][index[kto]] = kfrom;
- pieceList[us][ROOK][index[rto]] = rfrom;
- int tmp = index[rto]; // In Chess960 could be rto == kfrom
- index[kfrom] = index[kto];
- index[rfrom] = tmp;
+ // If the captured piece is a pawn, update pawn hash key, otherwise
+ // update non-pawn material.
+ if (captured == PAWN)
+ {
+ if (type_of(m) == ENPASSANT)
+ {
+ capsq += pawn_push(them);
- // Finally point our state pointer back to the previous state
- st = st->previous;
+ 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::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.
+ // Update board and piece lists
+ remove_piece(capsq, them, captured);
-void Position::do_null_move(StateInfo& backupSt) {
+ // 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(is_ok());
- assert(!is_check());
+ // Update incremental scores
+ st->psq -= psq[them][captured][capsq];
- // Back up the information necessary to undo the null move to the supplied
- // StateInfo object.
- // Note that differently from normal case here backupSt is actually used as
- // a backup storage not as a new state to be used.
- backupSt.key = st->key;
- backupSt.epSquare = st->epSquare;
- backupSt.mgValue = st->mgValue;
- backupSt.egValue = st->egValue;
- backupSt.previous = st->previous;
- st->previous = &backupSt;
+ // Reset rule 50 counter
+ st->rule50 = 0;
+ }
- // Save the current key to the history[] array, in order to be able to
- // detect repetition draws.
- history[gamePly] = st->key;
+ // Update hash key
+ k ^= Zobrist::psq[us][pt][from] ^ Zobrist::psq[us][pt][to];
- // Update the necessary information
+ // Reset en passant square
if (st->epSquare != SQ_NONE)
- st->key ^= zobEp[st->epSquare];
+ {
+ k ^= Zobrist::enpassant[file_of(st->epSquare)];
+ st->epSquare = SQ_NONE;
+ }
- st->key ^= zobSideToMove;
- TT.prefetch(st->key);
+ // Update castling rights if needed
+ if (st->castlingRights && (castlingRightsMask[from] | castlingRightsMask[to]))
+ {
+ int cr = castlingRightsMask[from] | castlingRightsMask[to];
+ k ^= Zobrist::castling[st->castlingRights & cr];
+ st->castlingRights &= ~cr;
+ }
- sideToMove = opposite_color(sideToMove);
- st->epSquare = SQ_NONE;
- st->rule50++;
- gamePly++;
+ // Move the piece. The tricky Chess960 castling is handled earlier
+ if (type_of(m) != CASTLING)
+ move_piece(from, to, us, pt);
- st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
- st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
-}
+ // 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(from + pawn_push(us), us) & pieces(them, PAWN)))
+ {
+ st->epSquare = Square((from + to) / 2);
+ k ^= Zobrist::enpassant[file_of(st->epSquare)];
+ }
+ else if (type_of(m) == PROMOTION)
+ {
+ PieceType promotion = promotion_type(m);
-/// Position::undo_null_move() unmakes a "null move".
+ assert(relative_rank(us, to) == RANK_8);
+ assert(promotion >= KNIGHT && promotion <= QUEEN);
-void Position::undo_null_move() {
+ remove_piece(to, us, PAWN);
+ put_piece(to, us, promotion);
- assert(is_ok());
- assert(!is_check());
-
- // Restore information from the our backup StateInfo object
- StateInfo* backupSt = st->previous;
- st->key = backupSt->key;
- st->epSquare = backupSt->epSquare;
- st->mgValue = backupSt->mgValue;
- st->egValue = backupSt->egValue;
- st->previous = backupSt->previous;
-
- // Update the necessary information
- sideToMove = opposite_color(sideToMove);
- st->rule50--;
- gamePly--;
-}
+ // 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]];
+ // Update incremental score
+ st->psq += psq[us][promotion][to] - psq[us][PAWN][to];
-/// Position::see() is a static exchange evaluator: It tries to estimate the
-/// material gain or loss resulting from a move. There are three versions of
-/// this function: One which takes a destination square as input, one takes a
-/// move, and one which takes a 'from' and a 'to' square. The function does
-/// not yet understand promotions captures.
+ // Update material
+ st->npMaterial[us] += PieceValue[MG][promotion];
+ }
-int Position::see(Square to) const {
+ // 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]);
- assert(square_is_ok(to));
- return see(SQ_NONE, to);
-}
+ // Reset rule 50 draw counter
+ st->rule50 = 0;
+ }
-int Position::see(Move m) const {
+ // Update incremental scores
+ st->psq += psq[us][pt][to] - psq[us][pt][from];
- assert(move_is_ok(m));
- return see(move_from(m), move_to(m));
-}
+ // Set capture piece
+ st->capturedType = captured;
-int Position::see_sign(Move m) const {
+ // Update the key with the final value
+ st->key = k;
- assert(move_is_ok(m));
+ // Update checkers bitboard: piece must be already moved due to attacks_from()
+ st->checkersBB = 0;
- Square from = move_from(m);
- Square to = move_to(m);
+ 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;
- // Early return if SEE cannot be negative because capturing piece value
- // is not bigger then captured one.
- if ( midgame_value_of_piece_on(from) <= midgame_value_of_piece_on(to)
- && type_of_piece_on(from) != KING)
- return 1;
+ // Discovered checks
+ if (unlikely(ci.dcCandidates) && (ci.dcCandidates & from))
+ {
+ if (pt != ROOK)
+ st->checkersBB |= attacks_from(king_square(them)) & pieces(us, QUEEN, ROOK);
- return see(from, to);
+ if (pt != BISHOP)
+ st->checkersBB |= attacks_from(king_square(them)) & pieces(us, QUEEN, BISHOP);
+ }
+ }
+ }
+
+ sideToMove = ~sideToMove;
+
+ 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, stmAttackers, 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 en passant moves
- if (st->epSquare == to && type_of_piece_on(from) == PAWN)
+ if (type_of(m) == PROMOTION)
{
- assert(capture == EMPTY);
+ assert(pt == promotion_type(m));
+ assert(relative_rank(us, to) == RANK_8);
+ assert(promotion_type(m) >= KNIGHT && promotion_type(m) <= QUEEN);
- Square capQq = (side_to_move() == WHITE)? (to - DELTA_N) : (to - DELTA_S);
- capture = piece_on(capQq);
- assert(type_of_piece_on(capQq) == PAWN);
-
- // Remove the captured pawn
- 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) & pieces(ROOK, QUEEN))
- | (bishop_attacks_bb(to, occ) & pieces(BISHOP, QUEEN))
- | (piece_attacks_from(to) & pieces(KNIGHT))
- | (piece_attacks_from(to) & pieces(KING))
- | (pawn_attacks_from(to, WHITE) & pieces(PAWN, BLACK))
- | (pawn_attacks_from(to, BLACK) & pieces(PAWN, 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.
- stmAttackers = attackers & pieces_of_color(us);
- PieceType pt;
- for (pt = PAWN; !(stmAttackers & pieces(pt)); pt++)
- assert(pt < KING);
-
- from = first_1(stmAttackers & pieces(pt));
- piece = piece_on(from);
+ Square rfrom, rto;
+ do_castling(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
- stmAttackers = attackers & pieces_of_color(them);
- if (!stmAttackers)
- 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; !(stmAttackers & pieces(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 = stmAttackers & pieces(pt);
- occ ^= (b & (~b + 1));
- attackers |= (rook_attacks_bb(to, occ) & pieces(ROOK, QUEEN))
- | (bishop_attacks_bb(to, occ) & pieces(BISHOP, QUEEN));
-
- attackers &= occ;
-
- // Add the new entry to the swap list
- assert(n < 32);
- swapList[n] = -swapList[n - 1] + lastCapturingPieceValue;
- n++;
-
- // 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);
- stmAttackers = attackers & pieces_of_color(c);
-
- // Stop after a king capture
- if (pt == KING && stmAttackers)
+ if (st->capturedType)
{
- assert(n < 32);
- swapList[n++] = QueenValueMidgame*10;
- break;
- }
- } while (stmAttackers);
-
- // Having built the swap list, we negamax through it to find the best
- // achievable score from the point of view of the side to move
- while (--n)
- swapList[n-1] = Min(-swapList[n], swapList[n-1]);
+ Square capsq = to;
- return swapList[0];
-}
+ if (type_of(m) == ENPASSANT)
+ {
+ capsq -= pawn_push(us);
+ assert(pt == PAWN);
+ assert(to == st->previous->epSquare);
+ assert(relative_rank(us, to) == RANK_6);
+ assert(piece_on(capsq) == NO_PIECE);
+ }
-/// Position::saveState() copies the content of the current state
-/// inside startState and makes st point to it. This is needed
-/// when the st pointee could become stale, as example because
-/// the caller is about to going out of scope.
+ put_piece(capsq, ~us, st->capturedType); // Restore the captured piece
+ }
+ }
-void Position::saveState() {
+ // Finally point our state pointer back to the previous state
+ st = st->previous;
+ --gamePly;
- startState = *st;
- st = &startState;
- st->previous = NULL; // as a safe guard
+ 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
+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);
- st = &startState;
- memset(st, 0, sizeof(StateInfo));
- st->epSquare = SQ_NONE;
-
- memset(byColorBB, 0, sizeof(Bitboard) * 2);
- memset(byTypeBB, 0, sizeof(Bitboard) * 8);
- memset(pieceCount, 0, sizeof(int) * 2 * 8);
- memset(index, 0, sizeof(int) * 64);
-
- for (int i = 0; i < 64; i++)
- board[i] = EMPTY;
-
- for (int i = 0; i < 7; i++)
- for (int j = 0; j < 8; j++)
- pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE;
-
- sideToMove = WHITE;
- gamePly = 0;
- initialKFile = FILE_E;
- initialKRFile = FILE_H;
- initialQRFile = FILE_A;
+ // 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 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.
-
-void Position::reset_game_ply() {
+/// 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.
- 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)
- st->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());
- st->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 {
- st->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[st->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.
+ Square from, to;
+ Bitboard occupied, attackers, stmAttackers;
+ Value swapList[32];
+ int slIndex = 1;
+ PieceType captured;
+ Color stm;
-Key Position::compute_pawn_key() const {
+ assert(is_ok(m));
- Key result = Key(0ULL);
- Bitboard b;
- Square s;
+ from = from_sq(m);
+ to = to_sq(m);
+ swapList[0] = PieceValue[MG][piece_on(to)];
+ stm = color_of(piece_on(from));
+ occupied = pieces() ^ from;
- for (Color c = WHITE; c <= BLACK; c++)
+ // 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 = pieces(PAWN, 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 {
+ // If the opponent has no attackers we are finished
+ stm = ~stm;
+ stmAttackers = attackers & pieces(stm);
+ if (!stmAttackers)
+ return swapList[0];
- 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;
-}
+ // 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));
+ do {
+ assert(slIndex < 32);
-/// Position::compute_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.
-template
-Value Position::compute_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(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(pt, c);
- while(b)
- {
- s = pop_1st_bit(&b);
- assert(piece_on(s) == piece_of_color_and_type(c, pt));
- result += pst(c, pt, s);
- }
- }
-
- const Value TempoValue = (Phase == MidGame ? TempoValueMidgame : TempoValueEndgame);
- result += (side_to_move() == WHITE)? TempoValue / 2 : -TempoValue / 2;
- return result;
-}
+ if (stmAttackers == attackers)
+ ++slIndex;
+ break;
+ }
-/// 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.
+ stm = ~stm;
+ stmAttackers = attackers & pieces(stm);
+ ++slIndex;
-Value Position::compute_non_pawn_material(Color c) const {
+ } while (stmAttackers);
- Value result = Value(0);
+ // 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]);
- for (PieceType pt = KNIGHT; pt <= QUEEN; pt++)
- {
- Bitboard b = pieces(pt, c);
- while (b)
- {
- assert(piece_on(first_1(b)) == piece_of_color_and_type(c, pt));
- pop_1st_bit(&b);
- result += piece_value_midgame(pt);
- }
- }
- return result;
+ 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 ( !pieces(PAWN)
- && (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMidgame))
+ if (st->rule50 > 99 && (!checkers() || MoveList(*this).size()))
return true;
- // Draw by the 50 moves rule?
- if (st->rule50 > 100 || (st->rule50 == 100 && !is_check()))
- return true;
+ StateInfo* stp = st;
+ for (int i = 2, e = std::min(st->rule50, st->pliesFromNull); i <= e; i += 2)
+ {
+ stp = stp->previous->previous;
- // Draw by repetition?
- for (int i = 2; i < Min(gamePly, st->rule50); i += 2)
- if (history[gamePly - i] == st->key)
- return true;
+ if (stp->key == st->key)
+ return true; // Draw at first repetition
+ }
return false;
}
-/// Position::is_mate() returns true or false depending on whether the
-/// side to move is checkmated.
-
-bool Position::is_mate() const {
-
- MoveStack moves[256];
+/// Position::flip() flips position with the white and black sides reversed. This
+/// is only useful for debugging e.g. for finding evaluation symmetry bugs.
- return is_check() && (generate_evasions(*this, moves, pinned_pieces(sideToMove)) == moves);
+static char toggle_case(char c) {
+ return char(islower(c) ? toupper(c) : tolower(c));
}
+void Position::flip() {
-/// Position::has_mate_threat() tests whether a given color has a mate in one
-/// from the current position.
-
-bool Position::has_mate_threat(Color c) {
-
- StateInfo st1, st2;
- Color stm = side_to_move();
-
- if (is_check())
- return false;
+ string f, token;
+ std::stringstream ss(fen());
- // If the input color is not equal to the side to move, do a null move
- if (c != stm)
- do_null_move(st1);
-
- MoveStack mlist[120];
- bool result = false;
- Bitboard dc = discovered_check_candidates(sideToMove);
- Bitboard pinned = pinned_pieces(sideToMove);
-
- // Generate pseudo-legal non-capture and capture check moves
- MoveStack* last = generate_non_capture_checks(*this, mlist, dc);
- last = generate_captures(*this, last);
-
- // Loop through the moves, and see if one of them is mate
- for (MoveStack* cur = mlist; cur != last; cur++)
+ for (Rank r = RANK_8; r >= RANK_1; --r) // Piece placement
{
- Move move = cur->move;
- if (!pl_move_is_legal(move, pinned))
- continue;
-
- do_move(move, st2);
- if (is_mate())
- result = true;
-
- undo_move(move);
+ std::getline(ss, token, r > RANK_1 ? '/' : ' ');
+ f.insert(0, token + (f.empty() ? " " : "/"));
}
- // Undo null move, if necessary
- if (c != stm)
- undo_null_move();
+ ss >> token; // Active color
+ f += (token == "w" ? "B " : "W "); // Will be lowercased later
- return result;
-}
-
-
-/// Position::init_zobrist() is a static member function which initializes the
-/// various arrays used to compute hash keys.
-
-void Position::init_zobrist() {
+ ss >> token; // Castling availability
+ f += token + " ";
- 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());
+ std::transform(f.begin(), f.end(), f.begin(), toggle_case);
- for (int i = 0; i < 64; i++)
- zobEp[i] = Key(genrand_int64());
+ ss >> token; // En passant square
+ f += (token == "-" ? token : token.replace(1, 1, token[1] == '3' ? "6" : "3"));
- for (int i = 0; i < 16; i++)
- zobCastle[i] = genrand_int64();
+ std::getline(ss, token); // Half and full moves
+ f += token;
- zobSideToMove = genrand_int64();
+ set(f, is_chess960(), this_thread());
- 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);
+ assert(pos_is_ok());
}
-/// 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);
- }
-
- 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;
-
- 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;
-
- // En passant square
- if (pos.st->epSquare != SQ_NONE)
- st->epSquare = flip_square(pos.st->epSquare);
-
- // Checkers
- find_checkers();
-
- // Hash keys
- st->key = compute_key();
- st->pawnKey = compute_pawn_key();
- st->materialKey = compute_material_key();
-
- // Incremental scores
- st->mgValue = compute_value();
- st->egValue = compute_value();
-
- // Material
- st->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
- st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
-
- assert(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;
-
- // Are the king squares in the position correct?
- if (failedStep) (*failedStep)++;
- if (piece_on(king_square(WHITE)) != WK)
- return false;
-
- if (failedStep) (*failedStep)++;
- if (piece_on(king_square(BLACK)) != BK)
- return false;
-
- // Castle files OK?
- if (failedStep) (*failedStep)++;
- if (!file_is_ok(initialKRFile))
- return false;
-
- if (!file_is_ok(initialQRFile))
- return false;
+bool Position::pos_is_ok(int* step) const {
- // 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)]++;
+ // Which parts of the position should be verified?
+ const bool all = false;
- if (kingCount[0] != 1 || kingCount[1] != 1)
- 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;
- // 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 (attackers_to(ksq) & pieces_of_color(us))
- return false;
- }
+ if (step)
+ *step = 1;
- // Is there more than 2 checkers?
- if (failedStep) (*failedStep)++;
- if (debugCheckerCount && count_1s(st->checkersBB) > 2)
+ 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;
- // 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++)
+ 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)
+ if (step && ++*step, testState)
{
- // 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)
+ 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;
}
- // Hash key OK?
- if (failedStep) (*failedStep)++;
- if (debugKey && st->key != compute_key())
- return false;
-
- // Pawn hash key OK?
- if (failedStep) (*failedStep)++;
- if (debugPawnKey && st->pawnKey != compute_pawn_key())
- return false;
-
- // Material hash key OK?
- if (failedStep) (*failedStep)++;
- if (debugMaterialKey && st->materialKey != compute_material_key())
- return false;
-
- // Incremental eval OK?
- if (failedStep) (*failedStep)++;
- if (debugIncrementalEval)
- {
- if (st->mgValue != compute_value())
+ 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 (st->egValue != compute_value())
+ if (step && ++*step, testKingCapture)
+ if (attackers_to(king_square(~sideToMove)) & pieces(sideToMove))
return false;
- }
- // Non-pawn material OK?
- if (failedStep) (*failedStep)++;
- if (debugNonPawnMaterial)
- {
- if (st->npMaterial[WHITE] != compute_non_pawn_material(WHITE))
- return false;
-
- if (st->npMaterial[BLACK] != compute_non_pawn_material(BLACK))
- 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(pt, c)))
+ if (step && ++*step, testPieceCounts)
+ for (Color c = WHITE; c <= BLACK; ++c)
+ for (PieceType pt = PAWN; pt <= KING; ++pt)
+ if (pieceCount[c][pt] != popcount(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)) != (pieces(pt, c)))
+ 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;
}