i++;
// En passant square
- if ( i < fen.length() - 2
+ 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));
castleRightsMask[make_square(initialQRFile, RANK_8)] ^= BLACK_OOO;
find_checkers();
- find_hidden_checks();
st->key = compute_key();
st->pawnKey = compute_pawn_key();
}
-/// Position:hidden_checks<>() returns a bitboard of all pinned (against the
+/// 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 pinned pieces of opposite color
-/// that are, indeed, the pieces candidate for a discovery check.
+/// 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.
-template<PieceType Piece, bool FindPinned>
-Bitboard Position::hidden_checks(Color c, Square ksq, Bitboard& pinners) const {
- Square s;
- Bitboard sliders, result = EmptyBoardBB;
+template<bool FindPinned>
+Bitboard Position::hidden_checkers(Color c) const {
- if (Piece == ROOK) // Resolved at compile time
- sliders = rooks_and_queens(FindPinned ? opposite_color(c) : c) & RookPseudoAttacks[ksq];
- else
- sliders = bishops_and_queens(FindPinned ? opposite_color(c) : c) & BishopPseudoAttacks[ksq];
+ Bitboard pinners, result = EmptyBoardBB;
+
+ // Pinned pieces protect our king, dicovery checks attack
+ // the enemy king.
+ Square ksq = king_square(FindPinned ? c : opposite_color(c));
- if (sliders && (!FindPinned || (sliders & ~st->checkersBB)))
+ // Pinners are sliders, not checkers, that give check when
+ // candidate pinned is removed.
+ pinners = (rooks_and_queens(FindPinned ? opposite_color(c) : c) & RookPseudoAttacks[ksq])
+ | (bishops_and_queens(FindPinned ? opposite_color(c) : c) & BishopPseudoAttacks[ksq]);
+
+ if (FindPinned && pinners)
+ pinners &= ~st->checkersBB;
+
+ while (pinners)
{
- // King blockers are candidate pinned pieces
- Bitboard candidate_pinned = piece_attacks<Piece>(ksq) & pieces_of_color(c);
-
- // Pinners are sliders, not checkers, that give check when
- // candidate pinned are removed.
- pinners = (FindPinned ? sliders & ~st->checkersBB : sliders);
-
- if (Piece == ROOK)
- pinners &= rook_attacks_bb(ksq, occupied_squares() ^ candidate_pinned);
- else
- pinners &= bishop_attacks_bb(ksq, occupied_squares() ^ candidate_pinned);
-
- // Finally for each pinner find the corresponding pinned piece (if same color of king)
- // or discovery checker (if opposite color) among the candidates.
- Bitboard p = pinners;
- while (p)
- {
- s = pop_1st_bit(&p);
- result |= (squares_between(s, ksq) & candidate_pinned);
- }
- }
- else
- pinners = EmptyBoardBB;
+ Square s = pop_1st_bit(&pinners);
+ Bitboard b = squares_between(s, ksq) & occupied_squares();
+ assert(b);
+
+ if ( !(b & (b - 1)) // Only one bit set?
+ && (b & pieces_of_color(c))) // Is an our piece?
+ result |= b;
+ }
return result;
}
+/// Position:pinned_pieces() returns a bitboard of all pinned (against the
+/// king) pieces for the given color.
+
+Bitboard Position::pinned_pieces(Color c) const {
+
+ return hidden_checkers<true>(c);
+}
+
+
+/// Position:discovered_check_candidates() returns a bitboard containing all
+/// pieces for the given side which are candidates for giving a discovered
+/// check.
+
+Bitboard Position::discovered_check_candidates(Color c) const {
+
+ return hidden_checkers<false>(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
st->checkersBB = attacks_to(king_square(us), opposite_color(us));
}
-/// Position:find_hidden_checks() computes the pinned, pinners and dcCandidates
-/// bitboards. There are two versions of this function. One takes a color and
-/// computes bitboards relative to that color only, the other computes both
-/// colors. Bitboard checkersBB must be already updated.
-
-void Position::find_hidden_checks(Color us, unsigned int types) {
- Bitboard p1, p2;
- Color them = opposite_color(us);
- Square ksq = king_square(them);
- if (types & Pinned)
- {
- st->pinned[them] = hidden_checks<ROOK, true>(them, ksq, p1) | hidden_checks<BISHOP, true>(them, ksq, p2);
- st->pinners[them] = p1 | p2;
- }
- if (types & DcCandidates)
- st->dcCandidates[us] = hidden_checks<ROOK, false>(us, ksq, p1) | hidden_checks<BISHOP, false>(us, ksq, p2);
-}
+/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal
-void Position::find_hidden_checks() {
+bool Position::pl_move_is_legal(Move m) const {
- for (Color c = WHITE; c <= BLACK; c++)
- find_hidden_checks(c, Pinned | DcCandidates);
+ return pl_move_is_legal(m, pinned_pieces(side_to_move()));
}
-
-/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal
-
-bool Position::pl_move_is_legal(Move m) const {
+bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
assert(is_ok());
assert(move_is_ok(m));
+ assert(pinned == pinned_pieces(side_to_move()));
// If we're in check, all pseudo-legal moves are legal, because our
// check evasion generator only generates true legal moves.
return true;
Color us = side_to_move();
- Color them = opposite_color(us);
Square from = move_from(m);
Square ksq = king_square(us);
// 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();
// If the moving piece is a king, check whether the destination
// square is attacked by the opponent.
if (from == ksq)
- return !(square_is_attacked(move_to(m), them));
+ return !(square_is_attacked(move_to(m), opposite_color(us)));
// A non-king move is legal if and only if it is not pinned or it
// is moving along the ray towards or away from the king.
- return ( !bit_is_set(pinned_pieces(us), from)
+ return ( !pinned
+ || !bit_is_set(pinned, from)
|| (direction_between_squares(from, ksq) == direction_between_squares(move_to(m), ksq)));
}
bool Position::move_is_check(Move m) const {
+ Bitboard dc = discovered_check_candidates(side_to_move());
+ return move_is_check(m, dc);
+}
+
+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()));
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);
- Bitboard dcCandidates = discovered_check_candidates(us);
assert(color_of_piece_on(from) == us);
assert(piece_on(ksq) == piece_of_color_and_type(them, KING));
if (bit_is_set(pawn_attacks(them, ksq), to)) // Normal check?
return true;
- if ( bit_is_set(dcCandidates, from) // Discovered check?
+ if ( dcCandidates // Discovered check?
+ && bit_is_set(dcCandidates, from)
&& (direction_between_squares(from, ksq) != direction_between_squares(to, ksq)))
return true;
}
return false;
+ // Test discovered check and normal check according to piece type
case KNIGHT:
- return bit_is_set(dcCandidates, from) // Discovered check?
- || bit_is_set(piece_attacks<KNIGHT>(ksq), to); // Normal check?
+ return (dcCandidates && bit_is_set(dcCandidates, from))
+ || bit_is_set(piece_attacks<KNIGHT>(ksq), to);
case BISHOP:
- return bit_is_set(dcCandidates, from) // Discovered check?
- || bit_is_set(piece_attacks<BISHOP>(ksq), to); // Normal check?
+ return (dcCandidates && bit_is_set(dcCandidates, from))
+ || ( direction_between_squares(ksq, to) != DIR_NONE
+ && bit_is_set(piece_attacks<BISHOP>(ksq), to));
case ROOK:
- return bit_is_set(dcCandidates, from) // Discovered check?
- || bit_is_set(piece_attacks<ROOK>(ksq), to); // Normal check?
+ return (dcCandidates && bit_is_set(dcCandidates, from))
+ || ( direction_between_squares(ksq, to) != DIR_NONE
+ && bit_is_set(piece_attacks<ROOK>(ksq), to));
case QUEEN:
// Discovered checks are impossible!
assert(!bit_is_set(dcCandidates, from));
- return bit_is_set(piece_attacks<QUEEN>(ksq), to); // Normal check?
+ return ( direction_between_squares(ksq, to) != DIR_NONE
+ && bit_is_set(piece_attacks<QUEEN>(ksq), to));
case KING:
// Discovered check?
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))
+ const bool Bishop = (Piece == QUEEN || Piece == BISHOP);
+ const bool Rook = (Piece == QUEEN || Piece == ROOK);
+ const bool Slider = Bishop || Rook;
+
+ if ( ( (Bishop && bit_is_set(BishopPseudoAttacks[ksq], to))
+ || (Rook && bit_is_set(RookPseudoAttacks[ksq], to)))
+ && bit_is_set(piece_attacks<Piece>(ksq), to)) // slow, try to early skip
+ set_bit(pCheckersBB, to);
+
+ else if ( Piece != KING
+ && !Slider
+ && bit_is_set(piece_attacks<Piece>(ksq), to))
set_bit(pCheckersBB, to);
if (Piece != QUEEN && bit_is_set(dcCandidates, from))
}
-/// Position::update_hidden_checks() udpates pinned, pinners and dcCandidates
-/// bitboards incrementally, given the move. It is called in do_move and is
-/// faster then find_hidden_checks().
-
-void Position::update_hidden_checks(Square from, Square to) {
-
- Color us = sideToMove;
- Color them = opposite_color(us);
- Square ksq = king_square(opposite_color(us));
-
- Bitboard moveSquares = EmptyBoardBB;
- set_bit(&moveSquares, from);
- set_bit(&moveSquares, to);
-
- // Our moving piece could have been a possible pinner or hidden checker behind a dcCandidates?
- bool checkerMoved = (st->dcCandidates[us] | st->pinners[them]) && (moveSquares & sliders());
-
- // If we are moving from/to an opponent king attack direction and we was a possible hidden checker
- // or there exsist some possible hidden checker on that line then recalculate the position
- // otherwise skip because our dcCandidates and opponent pinned pieces are not changed.
- if ( (moveSquares & RookPseudoAttacks[ksq]) && (checkerMoved || (rooks_and_queens(us) & RookPseudoAttacks[ksq]))
- || (moveSquares & BishopPseudoAttacks[ksq]) && (checkerMoved || (bishops_and_queens(us) & BishopPseudoAttacks[ksq])))
- find_hidden_checks(us, Pinned | DcCandidates);
-
- ksq = king_square(us);
-
- if (ksq == to)
- {
- find_hidden_checks(them, Pinned | DcCandidates);
- return;
- }
-
- // It is possible that we have captured an opponent hidden checker?
- Bitboard checkerCaptured = st->capture && (st->dcCandidates[them] || bit_is_set(st->pinners[us], to));
-
- // If we are moving from/to an our king attack direction and there was/is some possible
- // opponent hidden checker then calculate the position otherwise skip because opponent
- // dcCandidates and our pinned pieces are not changed.
- if ( (moveSquares & RookPseudoAttacks[ksq]) && (checkerCaptured || (rooks_and_queens(them) & RookPseudoAttacks[ksq]))
- || (moveSquares & BishopPseudoAttacks[ksq]) && (checkerCaptured || (bishops_and_queens(them) & BishopPseudoAttacks[ksq])))
- {
-
- // If we don't have opponent dc candidates and we are moving in the
- // attack line then won't be dc candidates also after the move.
- if ( st->dcCandidates[them]
- || bit_is_set(RookPseudoAttacks[ksq], from)
- || bit_is_set(BishopPseudoAttacks[ksq], from))
-
- find_hidden_checks(them, Pinned | DcCandidates);
- else
- find_hidden_checks(them, Pinned);
- }
-}
-
-
/// 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.
void Position::do_move(Move m, StateInfo& newSt) {
+ do_move(m, newSt, discovered_check_candidates(side_to_move()));
+}
+
+void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) {
+
assert(is_ok());
assert(move_is_ok(m));
- // Get now the current (before to move) dc candidates that we will use
- // in update_checkers().
- Bitboard oldDcCandidates = discovered_check_candidates(side_to_move());
+ // 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 epSquare;
+ Value mgValue, egValue;
+ };
- // Copy some fields of old state to our new StateInfo object (except the
- // captured piece, which is taken care of later) and switch state pointer
- // to point to the new, ready to be updated, state.
- newSt = *st;
+ memcpy(&newSt, st, sizeof(ReducedStateInfo));
newSt.capture = NO_PIECE_TYPE;
newSt.previous = st;
st = &newSt;
st->capture = type_of_piece_on(to);
if (st->capture)
- do_capture_move(m, st->capture, them, to);
+ do_capture_move(st->capture, them, to);
// Move the piece
clear_bit(&(byColorBB[us]), from);
Square ksq = king_square(them);
switch (piece)
{
- case PAWN: update_checkers<PAWN>(&st->checkersBB, ksq, from, to, oldDcCandidates); break;
- case KNIGHT: update_checkers<KNIGHT>(&st->checkersBB, ksq, from, to, oldDcCandidates); break;
- case BISHOP: update_checkers<BISHOP>(&st->checkersBB, ksq, from, to, oldDcCandidates); break;
- case ROOK: update_checkers<ROOK>(&st->checkersBB, ksq, from, to, oldDcCandidates); break;
- case QUEEN: update_checkers<QUEEN>(&st->checkersBB, ksq, from, to, oldDcCandidates); break;
- case KING: update_checkers<KING>(&st->checkersBB, ksq, from, to, oldDcCandidates); break;
+ case PAWN: update_checkers<PAWN>(&(st->checkersBB), ksq, from, to, dcCandidates); break;
+ case KNIGHT: update_checkers<KNIGHT>(&(st->checkersBB), ksq, from, to, dcCandidates); break;
+ case BISHOP: update_checkers<BISHOP>(&(st->checkersBB), ksq, from, to, dcCandidates); break;
+ case ROOK: update_checkers<ROOK>(&(st->checkersBB), ksq, from, to, dcCandidates); break;
+ case QUEEN: update_checkers<QUEEN>(&(st->checkersBB), ksq, from, to, dcCandidates); break;
+ case KING: update_checkers<KING>(&(st->checkersBB), ksq, from, to, dcCandidates); break;
default: assert(false); break;
}
-
- update_hidden_checks(from, to);
}
// Finish
/// 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(Move m, PieceType capture, Color them, Square to) {
+void Position::do_capture_move(PieceType capture, Color them, Square to) {
assert(capture != KING);
st->mgValue -= pst<MidGame>(them, capture, to);
st->egValue -= pst<EndGame>(them, capture, to);
- assert(!move_promotion(m) || capture != PAWN);
-
// Update material
if (capture != PAWN)
npMaterial[them] -= piece_value_midgame(capture);
// Update checkers BB
st->checkersBB = attacks_to(king_square(them), us);
-
- // Update hidden checks
- find_hidden_checks();
}
st->capture = type_of_piece_on(to);
if (st->capture)
- do_capture_move(m, st->capture, them, to);
+ do_capture_move(st->capture, them, to);
// Remove pawn
clear_bit(&(byColorBB[us]), from);
// Update checkers BB
st->checkersBB = attacks_to(king_square(them), us);
-
- // Update hidden checks
- find_hidden_checks();
}
// Update checkers BB
st->checkersBB = attacks_to(king_square(them), us);
-
- // Update hidden checks
- find_hidden_checks();
}
board[to] = EMPTY;
}
- // Finally point out state pointer back to the previous state
+ // Finally point our state pointer back to the previous state
st = st->previous;
assert(is_ok());
/// 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(StateInfo& newSt) {
+void Position::do_null_move(StateInfo& backupSt) {
assert(is_ok());
assert(!is_check());
// Back up the information necessary to undo the null move to the supplied
// StateInfo object. In the case of a null move, the only thing we need to
// remember is the last move made and the en passant square.
- newSt.lastMove = st->lastMove;
- newSt.epSquare = st->epSquare;
- newSt.previous = st->previous;
- st->previous = &newSt;
+ // Note that differently from normal case here backupSt is actually used as
+ // a backup storage not as a new state to be used.
+ backupSt.lastMove = st->lastMove;
+ backupSt.epSquare = st->epSquare;
+ backupSt.previous = st->previous;
+ st->previous = &backupSt;
// Save the current key to the history[] array, in order to be able to
// detect repetition draws.
assert(is_ok());
assert(!is_check());
- // Restore information from the our StateInfo object
+ // Restore information from the our backup StateInfo object
st->lastMove = st->previous->lastMove;
st->epSquare = st->previous->epSquare;
st->previous = st->previous->previous;
Color us = (from != SQ_NONE ? color_of_piece_on(from) : opposite_color(color_of_piece_on(to)));
Color them = opposite_color(us);
- // Initialize pinned and pinners bitboards
- Bitboard pinned[2], pinners[2];
- pinned[us] = pinned_pieces(us, pinners[us]);
- pinned[them] = pinned_pieces(them, pinners[them]);
-
// Initialize pieces
Piece piece = piece_on(from);
Piece capture = piece_on(to);
| (pawn_attacks(WHITE, to) & pawns(BLACK))
| (pawn_attacks(BLACK, to) & pawns(WHITE));
- // Remove our pinned pieces from attacks if the captured piece is not
- // a pinner, otherwise we could remove a valid "capture the pinner" attack.
- if (pinned[us] != EmptyBoardBB && !bit_is_set(pinners[us], to))
- attackers &= ~pinned[us];
-
- // Remove opponent pinned pieces from attacks if the moving piece is not
- // a pinner, otherwise we could remove a piece that is no more pinned
- // due to our pinner piece is moving away.
- if (pinned[them] != EmptyBoardBB && !bit_is_set(pinners[them], from))
- attackers &= ~pinned[them];
-
if (from != SQ_NONE)
break;
// Remove the attacker we just found from the 'attackers' bitboard,
// and scan for new X-ray attacks behind the attacker.
b = attackers & pieces_of_color_and_type(c, pt);
- occ ^= (b & -b);
+ occ ^= (b & (~b + 1));
attackers |= (rook_attacks_bb(to, occ) & rooks_and_queens())
| (bishop_attacks_bb(to, occ) & bishops_and_queens());
lastCapturingPieceValue = seeValues[pt];
c = opposite_color(c);
- // Remove pinned pieces from attackers
- if ( pinned[c] != EmptyBoardBB
- && !bit_is_set(pinners[c], to)
- && !(pinners[c] & attackers))
- attackers &= ~pinned[c];
-
// Stop after a king capture
if (pt == KING && (attackers & pieces_of_color(c)))
{
Value Position::compute_non_pawn_material(Color c) const {
Value result = Value(0);
- Square s;
for (PieceType pt = KNIGHT; pt <= QUEEN; pt++)
{
Bitboard b = pieces_of_color_and_type(c, pt);
- while(b)
+ while (b)
{
- s = pop_1st_bit(&b);
- assert(piece_on(s) == piece_of_color_and_type(c, pt));
+ assert(piece_on(first_1(b)) == piece_of_color_and_type(c, pt));
+ pop_1st_bit(&b);
result += piece_value_midgame(pt);
}
}
void Position::init_zobrist() {
- for (int i = 0; i < 2; i++)
- for (int j = 0; j < 8; j++)
- for (int k = 0; k < 64; k++)
- zobrist[i][j][k] = Key(genrand_int64());
+ for(Piece p = WP; p <= BK; p++)
+ for(Square s = SQ_A1; s <= SQ_H8; s++)
+ zobrist[color_of_piece(p)][type_of_piece(p)][s] = genrand_int64();
- for (int i = 0; i < 64; i++)
- zobEp[i] = Key(genrand_int64());
+ zobEp[0] = 0ULL;
+ for(int i = 1; i < 64; i++)
+ zobEp[i] = genrand_int64();
- for (int i = 0; i < 16; i++)
- zobCastle[i] = genrand_int64();
+ for(int i = 15; i >= 0; i--)
+ zobCastle[(i&8) | (i&1) | ((i&2) << 1) | ((i&4) >> 1)] = genrand_int64();
zobSideToMove = genrand_int64();
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);
+ zobMaterial[i][j][k] = (k > 0)? genrand_int64() : 0LL;
for (int i = 0; i < 16; i++)
- zobMaterial[0][KING][i] = zobMaterial[1][KING][i] = Key(0ULL);
+ zobMaterial[0][KING][i] = zobMaterial[1][KING][i] = 0ULL;
}
projects / stockfish / blobdiff