/// Constructors
-Position::Position(const Position &pos) {
+Position::Position(const Position& pos) {
copy(pos);
}
-Position::Position(const std::string &fen) {
+Position::Position(const std::string& fen) {
from_fen(fen);
}
/// string. This function is not very robust - make sure that input FENs are
/// correct (this is assumed to be the responsibility of the GUI).
-void Position::from_fen(const std::string &fen) {
+void Position::from_fen(const std::string& fen) {
static const std::string pieceLetters = "KQRBNPkqrbnp";
static const Piece pieces[] = { WK, WQ, WR, WB, WN, WP, BK, BQ, BR, BB, BN, BP };
i++;
while(strchr("KQkqabcdefghABCDEFGH-", fen[i])) {
- if(fen[i] == '-') {
- i++; break;
+ if (fen[i] == '-')
+ {
+ i++;
+ break;
}
else if(fen[i] == 'K') allow_oo(WHITE);
else if(fen[i] == 'Q') allow_ooo(WHITE);
}
-/// Position::square_is_attacked() checks whether the given side attacks the
-/// given square.
-
-bool Position::square_is_attacked(Square s, Color c) const {
-
- return (pawn_attacks(opposite_color(c), s) & pawns(c))
- || (piece_attacks<KNIGHT>(s) & knights(c))
- || (piece_attacks<KING>(s) & kings(c))
- || (piece_attacks<ROOK>(s) & rooks_and_queens(c))
- || (piece_attacks<BISHOP>(s) & bishops_and_queens(c));
-}
-
-
/// Position::attacks_to() computes a bitboard containing all pieces which
/// attacks a given square. There are two versions of this function: One
/// which finds attackers of both colors, and one which only finds the
| (piece_attacks<KING>(s) & pieces_of_type(KING));
}
-Bitboard Position::attacks_to(Square s, Color c) const {
-
- return attacks_to(s) & pieces_of_color(c);
-}
-
-
/// Position::piece_attacks_square() tests whether the piece on square f
/// attacks square t.
// u.capture is restored in undo_move()
}
+
+/// Position::update_checkers() is a private method to udpate chekers info
+
+template<PieceType Piece>
+inline void Position::update_checkers(Bitboard* pCheckersBB, Square ksq, Square from,
+ Square to, Bitboard dcCandidates) {
+
+ if (Piece != KING && bit_is_set(piece_attacks<Piece>(ksq), to))
+ set_bit(pCheckersBB, to);
+
+ if (Piece != QUEEN && bit_is_set(dcCandidates, from))
+ {
+ if (Piece != ROOK)
+ (*pCheckersBB) |= (piece_attacks<ROOK>(ksq) & rooks_and_queens(side_to_move()));
+
+ if (Piece != BISHOP)
+ (*pCheckersBB) |= (piece_attacks<BISHOP>(ksq) & bishops_and_queens(side_to_move()));
+ }
+}
+
+
/// Position::do_move() makes a move, and backs up all information necessary
/// to undo the move to an UndoInfo object. The move is assumed to be legal.
/// Pseudo-legal moves should be filtered out before this function is called.
if (piece == KING)
kingSquare[us] = to;
- // If the move was a double pawn push, set the en passant square.
- // This code is a bit ugly right now, and should be cleaned up later.
- // FIXME
+ // Reset en passant square
if (epSquare != SQ_NONE)
{
key ^= zobEp[epSquare];
epSquare = SQ_NONE;
}
+
+ // If the moving piece was a pawn do some special extra work
if (piece == PAWN)
{
+ // Reset rule 50 draw counter
+ rule50 = 0;
+
+ // Update pawn hash key
+ pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
+
+ // Set en passant square, only if moved pawn can be captured
if (abs(int(to) - int(from)) == 16)
{
- if( ( us == WHITE
- && (pawn_attacks(WHITE, from + DELTA_N) & pawns(BLACK)))
- || ( us == BLACK
- && (pawn_attacks(BLACK, from + DELTA_S) & pawns(WHITE))))
+ if ( (us == WHITE && (pawn_attacks(WHITE, from + DELTA_N) & pawns(BLACK)))
+ || (us == BLACK && (pawn_attacks(BLACK, from + DELTA_S) & pawns(WHITE))))
{
epSquare = Square((int(from) + int(to)) / 2);
key ^= zobEp[epSquare];
}
}
- // Reset rule 50 draw counter
- rule50 = 0;
-
- // Update pawn hash key
- pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
}
+
// Update piece lists
pieceList[us][piece][index[from]] = to;
index[to] = index[from];
castleRights &= castleRightsMask[to];
key ^= zobCastle[castleRights];
- // Update checkers bitboard
+ // Update checkers bitboard, piece must be already moved
checkersBB = EmptyBoardBB;
Square ksq = king_square(them);
switch (piece)
{
- case PAWN:
- if (bit_is_set(pawn_attacks(them, ksq), to))
- set_bit(&checkersBB, to);
-
- if (bit_is_set(dcCandidates, from))
- checkersBB |= ( (piece_attacks<ROOK>(ksq) & rooks_and_queens(us))
- |(piece_attacks<BISHOP>(ksq) & bishops_and_queens(us)));
- break;
-
- case KNIGHT:
- if (bit_is_set(piece_attacks<KNIGHT>(ksq), to))
- set_bit(&checkersBB, to);
-
- if (bit_is_set(dcCandidates, from))
- checkersBB |= ( (piece_attacks<ROOK>(ksq) & rooks_and_queens(us))
- |(piece_attacks<BISHOP>(ksq) & bishops_and_queens(us)));
- break;
-
- case BISHOP:
- if (bit_is_set(piece_attacks<BISHOP>(ksq), to))
- set_bit(&checkersBB, to);
-
- if (bit_is_set(dcCandidates, from))
- checkersBB |= (piece_attacks<ROOK>(ksq) & rooks_and_queens(us));
- break;
-
- case ROOK:
- if (bit_is_set(piece_attacks<ROOK>(ksq), to))
- set_bit(&checkersBB, to);
-
- if (bit_is_set(dcCandidates, from))
- checkersBB |= (piece_attacks<BISHOP>(ksq) & bishops_and_queens(us));
- break;
-
- case QUEEN:
- if (bit_is_set(piece_attacks<QUEEN>(ksq), to))
- set_bit(&checkersBB, to);
- break;
-
- case KING:
- if (bit_is_set(dcCandidates, from))
- checkersBB |= ( (piece_attacks<ROOK>(ksq) & rooks_and_queens(us))
- |(piece_attacks<BISHOP>(ksq) & bishops_and_queens(us)));
- break;
-
- default:
- assert(false);
- break;
+ case PAWN: update_checkers<PAWN>(&checkersBB, ksq, from, to, dcCandidates); break;
+ case KNIGHT: update_checkers<KNIGHT>(&checkersBB, ksq, from, to, dcCandidates); break;
+ case BISHOP: update_checkers<BISHOP>(&checkersBB, ksq, from, to, dcCandidates); break;
+ case ROOK: update_checkers<ROOK>(&checkersBB, ksq, from, to, dcCandidates); break;
+ case QUEEN: update_checkers<QUEEN>(&checkersBB, ksq, from, to, dcCandidates); break;
+ case KING: update_checkers<KING>(&checkersBB, ksq, from, to, dcCandidates); break;
+ default: assert(false); break;
}
}
key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto];
// Clear en passant square
- if(epSquare != SQ_NONE)
+ if (epSquare != SQ_NONE)
{
key ^= zobEp[epSquare];
epSquare = SQ_NONE;
}
-/// Position::undo_move() unmakes a move. When it returns, the position should
-/// be restored to exactly the same state as before the move was made. It is
+/// Position::undo_move() unmakes a move. When it returns, the position should
+/// be restored to exactly the same state as before the move was made. It is
/// important that Position::undo_move is called with the same move and UndoInfo
/// object as the earlier call to Position::do_move.
/// Position::do_null_move makes() a "null move": It switches the side to move
/// and updates the hash key without executing any move on the board.
-void Position::do_null_move(UndoInfo &u) {
+void Position::do_null_move(UndoInfo& u) {
assert(is_ok());
assert(!is_check());
}
-/// Position::see() is a static exchange evaluator: It tries to estimate the
-/// material gain or loss resulting from a move. There are two versions of
-/// this function: One which takes a move as input, and one which takes a
-/// 'from' and a 'to' square. The function does not yet understand promotions
-/// or en passant captures.
+/// 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.
+
+int Position::see(Square to) const {
+
+ assert(square_is_ok(to));
+ return see(SQ_NONE, to);
+}
int Position::see(Move m) const {
int Position::see(Square from, Square to) const {
- // Approximate material values, with pawn = 1
+ // Material values
static const int seeValues[18] = {
- 0, 1, 3, 3, 5, 10, 100, 0, 0, 1, 3, 3, 5, 10, 100, 0, 0, 0
+ 0, PawnValueMidgame, KnightValueMidgame, BishopValueMidgame,
+ RookValueMidgame, QueenValueMidgame, QueenValueMidgame*10, 0,
+ 0, PawnValueMidgame, KnightValueMidgame, BishopValueMidgame,
+ RookValueMidgame, QueenValueMidgame, QueenValueMidgame*10, 0,
+ 0, 0
};
Bitboard attackers, occ, b;
- assert(square_is_ok(from));
+ assert(square_is_ok(from) || from == SQ_NONE);
assert(square_is_ok(to));
// Initialize colors
- Color us = color_of_piece_on(from);
+ Color us = (from != SQ_NONE ? color_of_piece_on(from) : opposite_color(color_of_piece_on(to)));
Color them = opposite_color(us);
// Initialize pieces
// Find all attackers to the destination square, with the moving piece
// removed, but possibly an X-ray attacker added behind it.
occ = occupied_squares();
- clear_bit(&occ, from);
- attackers = (rook_attacks_bb(to, occ) & rooks_and_queens())
- | (bishop_attacks_bb(to, occ) & bishops_and_queens())
- | (piece_attacks<KNIGHT>(to) & knights())
- | (piece_attacks<KING>(to) & kings())
- | (pawn_attacks(WHITE, to) & pawns(BLACK))
- | (pawn_attacks(BLACK, to) & pawns(WHITE));
-
- // If the opponent has no attackers, we are finished
+
+ // Handle en passant moves
+ if (epSquare == to && type_of_piece_on(from) == PAWN)
+ {
+ assert(capture == EMPTY);
+
+ Square capQq = (side_to_move() == WHITE)? (to - DELTA_N) : (to - DELTA_S);
+ capture = piece_on(capQq);
+
+ assert(type_of_piece_on(capQq) == PAWN);
+
+ // Remove the captured pawn
+ clear_bit(&occ, capQq);
+ }
+
+ while (true)
+ {
+ clear_bit(&occ, from);
+ attackers = (rook_attacks_bb(to, occ) & rooks_and_queens())
+ | (bishop_attacks_bb(to, occ) & bishops_and_queens())
+ | (piece_attacks<KNIGHT>(to) & knights())
+ | (piece_attacks<KING>(to) & kings())
+ | (pawn_attacks(WHITE, to) & pawns(BLACK))
+ | (pawn_attacks(BLACK, to) & pawns(WHITE));
+
+ if (from != SQ_NONE)
+ break;
+
+ // If we don't have any attacker we are finished
+ if ((attackers & pieces_of_color(us)) == EmptyBoardBB)
+ return 0;
+
+ // Locate the least valuable attacker to the destination square
+ // and use it to initialize from square.
+ PieceType pt;
+ for (pt = PAWN; !(attackers & pieces_of_color_and_type(us, pt)); pt++)
+ assert(pt < KING);
+
+ from = first_1(attackers & pieces_of_color_and_type(us, pt));
+ piece = piece_on(from);
+ }
+
+ // If the opponent has no attackers we are finished
if ((attackers & pieces_of_color(them)) == EmptyBoardBB)
return seeValues[capture];
}
-/// Position::reset_game_ply() simply sets gamePly to 0. It is used from the
+/// Position::reset_game_ply() simply sets gamePly to 0. It is used from the
/// UCI interface code, whenever a non-reversible move is made in a
/// 'position fen <fen> moves m1 m2 ...' command. This makes it possible
/// for the program to handle games of arbitrary length, as long as the GUI
}
-/// Position::compute_pawn_key() computes the hash key of the position. The
+/// 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
/// Position::compute_mg_value() and Position::compute_eg_value() compute the
-/// incremental scores for the middle game and the endgame. These functions
+/// 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.
/// Position::compute_non_pawn_material() computes the total non-pawn middle
-/// game material score for the given side. Material scores are updated
+/// 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.
/// side to move is checkmated. Note that this function is currently very
/// slow, and shouldn't be used frequently inside the search.
-bool Position::is_mate() {
+bool Position::is_mate() const {
if (is_check())
{
/// Position::is_draw() tests whether the position is drawn by material,
-/// repetition, or the 50 moves rule. It does not detect stalemates, this
+/// repetition, or the 50 moves rule. It does not detect stalemates, this
/// must be done by the search.
bool Position::is_draw() const {
/// Position::flipped_copy() makes a copy of the input position, but with
-/// the white and black sides reversed. This is only useful for debugging,
+/// 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) {
if (type_of_piece_on(s) == KING)
kingCount[color_of_piece_on(s)]++;
- if(kingCount[0] != 1 || kingCount[1] != 1)
+ if (kingCount[0] != 1 || kingCount[1] != 1)
return false;
}
if (failedStep) (*failedStep)++;
if (debugNonPawnMaterial)
{
- if(npMaterial[WHITE] != compute_non_pawn_material(WHITE))
+ if (npMaterial[WHITE] != compute_non_pawn_material(WHITE))
return false;
- if(npMaterial[BLACK] != compute_non_pawn_material(BLACK))
+ if (npMaterial[BLACK] != compute_non_pawn_material(BLACK))
return false;
}
projects / stockfish / blobdiff