/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008 Marco Costalba
+ Copyright (C) 2008-2009 Marco Costalba
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
#include "san.h"
#include "ucioption.h"
+using std::string;
+
////
//// Variables
////
-extern SearchStack EmptySearchStack;
-
int Position::castleRightsMask[64];
Key Position::zobrist[2][8][64];
copy(pos);
}
-Position::Position(const std::string& fen) {
+Position::Position(const 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 string& fen) {
- static const std::string pieceLetters = "KQRBNPkqrbnp";
+ static const string pieceLetters = "KQRBNPkqrbnp";
static const Piece pieces[] = { WK, WQ, WR, WB, WN, WP, BK, BQ, BR, BB, BN, BP };
clear();
continue;
}
size_t idx = pieceLetters.find(fen[i]);
- if (idx == std::string::npos)
+ if (idx == string::npos)
{
std::cout << "Error in FEN at character " << i << std::endl;
return;
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();
st->materialKey = compute_material_key();
st->mgValue = compute_value<MidGame>();
st->egValue = compute_value<EndGame>();
- npMaterial[WHITE] = compute_non_pawn_material(WHITE);
- npMaterial[BLACK] = compute_non_pawn_material(BLACK);
+ st->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
+ st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
}
/// Position::to_fen() converts the position object to a FEN string. This is
/// probably only useful for debugging.
-const std::string Position::to_fen() const {
+const string Position::to_fen() const {
- static const std::string pieceLetters = " PNBRQK pnbrqk";
- std::string fen;
+ static const string pieceLetters = " PNBRQK pnbrqk";
+ string fen;
int skip;
for (Rank rank = RANK_8; rank >= RANK_1; rank--)
void Position::print(Move m) const {
- static const std::string pieceLetters = " PNBRQK PNBRQK .";
+ static const string pieceLetters = " PNBRQK PNBRQK .";
// Check for reentrancy, as example when called from inside
// MovePicker that is used also here in move_to_san()
std::cout << std::endl;
if (m != MOVE_NONE)
{
- std::string col = (color_of_piece_on(move_from(m)) == BLACK ? ".." : "");
+ 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--)
}
-/// 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;
- if (sliders && (!FindPinned || (sliders & ~st->checkersBB)))
+ // Pinned pieces protect our king, dicovery checks attack
+ // the enemy king.
+ Square ksq = king_square(FindPinned ? c : opposite_color(c));
+
+ // 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
-/// attackers for one side.
+/// attacks a given square.
Bitboard Position::attacks_to(Square s) const {
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) {
-
- Bitboard p1, p2;
- Color them = opposite_color(us);
- Square ksq = king_square(them);
- st->pinned[them] = hidden_checks<ROOK, true>(them, ksq, p1) | hidden_checks<BISHOP, true>(them, ksq, p2);
- st->pinners[them] = p1 | p2;
- 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);
+ // 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()));
}
-
-/// 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));
-
- // If we're in check, all pseudo-legal moves are legal, because our
- // check evasion generator only generates true legal moves.
- if (is_check())
- return true;
+ assert(pinned == pinned_pieces(side_to_move()));
+ assert(!is_check());
// Castling moves are checked for legality during move generation.
if (move_is_castle(m))
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_is_diagonal(ksq, to) && 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_is_straight(ksq, to) && 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_is_straight(ksq, to) && bit_is_set(piece_attacks<ROOK>(ksq), to))
+ || (direction_is_diagonal(ksq, to) && bit_is_set(piece_attacks<BISHOP>(ksq), to)));
case KING:
// Discovered check?
}
-/// Position::move_is_capture() tests whether a move from the current
-/// position is a capture. Move must not be MOVE_NONE.
-
-bool Position::move_is_capture(Move m) const {
-
- assert(m != MOVE_NONE);
-
- return ( !square_is_empty(move_to(m))
- && (color_of_piece_on(move_to(m)) != color_of_piece_on(move_from(m)))
- )
- || move_is_ep(m);
-}
-
-
/// Position::update_checkers() udpates chekers info given the move. It is called
/// in do_move() and is faster then find_checkers().
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;
+
+ // Direct checks
+ 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);
+ // Discovery checks
if (Piece != QUEEN && bit_is_set(dcCandidates, from))
{
if (Piece != ROOK)
}
-/// 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);
-
- ksq = king_square(us);
-
- if (ksq == to)
- {
- find_hidden_checks(them);
- return;
- }
-
- // It is possible that we have captured an opponent hidden checker?
- Bitboard checkerCaptured = (st->dcCandidates[them] | st->pinners[us]) && st->capture;
-
- // 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])))
- find_hidden_checks(them);
-}
-
-
/// 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;
+ Value npMaterial[2];
+ };
- // 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);
- clear_bit(&(byTypeBB[piece]), from);
- clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
- set_bit(&(byColorBB[us]), to);
- set_bit(&(byTypeBB[piece]), to);
- set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
+ Bitboard move_bb = make_move_bb(from, to);
+ do_move_bb(&(byColorBB[us]), move_bb);
+ do_move_bb(&(byTypeBB[piece]), move_bb);
+ do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares
+
board[to] = board[from];
board[from] = EMPTY;
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);
// Remove captured piece
clear_bit(&(byColorBB[them]), to);
clear_bit(&(byTypeBB[capture]), to);
+ clear_bit(&(byTypeBB[0]), to);
// Update hash key
st->key ^= zobrist[them][capture][to];
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);
+ st->npMaterial[them] -= piece_value_midgame(capture);
// Update material hash key
st->materialKey ^= zobMaterial[them][capture][pieceCount[them][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);
st->egValue += pst<EndGame>(us, promotion, to);
// Update material
- npMaterial[us] += piece_value_midgame(promotion);
+ st->npMaterial[us] += piece_value_midgame(promotion);
// Clear the en passant square
if (st->epSquare != SQ_NONE)
// 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();
}
assert(color_of_piece_on(to) == us);
// Put the piece back at the source square
+ Bitboard move_bb = make_move_bb(to, from);
piece = type_of_piece_on(to);
- set_bit(&(byColorBB[us]), from);
- set_bit(&(byTypeBB[piece]), from);
- set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
+ do_move_bb(&(byColorBB[us]), move_bb);
+ do_move_bb(&(byTypeBB[piece]), move_bb);
+ do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares
board[from] = piece_of_color_and_type(us, piece);
- // Clear the destination square
- clear_bit(&(byColorBB[us]), to);
- clear_bit(&(byTypeBB[piece]), to);
- clear_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
-
// If the moving piece was a king, update the king square
if (piece == KING)
kingSquare[us] = from;
{
assert(st->capture != KING);
- // Replace the captured piece
+ // Restore the captured piece
set_bit(&(byColorBB[them]), to);
set_bit(&(byTypeBB[st->capture]), to);
set_bit(&(byTypeBB[0]), to);
board[to] = piece_of_color_and_type(them, st->capture);
- // Update material
- if (st->capture != PAWN)
- npMaterial[them] += piece_value_midgame(st->capture);
-
// Update piece list
pieceList[them][st->capture][pieceCount[them][st->capture]] = to;
index[to] = pieceCount[them][st->capture];
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());
set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
board[from] = piece_of_color_and_type(us, PAWN);
- // Update material
- npMaterial[us] -= piece_value_midgame(promotion);
-
// Update piece list
pieceList[us][PAWN][pieceCount[us][PAWN]] = from;
index[from] = pieceCount[us][PAWN];
set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
board[to] = piece_of_color_and_type(them, st->capture);
- // Update material. Because the move is a promotion move, we know
- // that the captured piece cannot be a pawn.
- assert(st->capture != PAWN);
- npMaterial[them] += piece_value_midgame(st->capture);
-
// Update piece list
pieceList[them][st->capture][pieceCount[them][st->capture]] = to;
index[to] = pieceCount[them][st->capture];
set_bit(&(byTypeBB[0]), from);
board[from] = piece_of_color_and_type(us, PAWN);
- // Update piece list:
+ // Update piece list
pieceList[us][PAWN][index[to]] = from;
index[from] = index[to];
pieceList[them][PAWN][pieceCount[them][PAWN]] = capsq;
index[capsq] = pieceCount[them][PAWN];
- // Update piece count:
+ // Update piece count
pieceCount[them][PAWN]++;
}
/// Position::do_null_move makes() a "null move": It switches the side to move
/// and updates the hash key without executing any move on the board.
-void Position::do_null_move(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;
+ // 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.epSquare = st->epSquare;
+ backupSt.key = st->key;
+ backupSt.mgValue = st->mgValue;
+ backupSt.egValue = st->egValue;
+ 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
- st->lastMove = st->previous->lastMove;
+ // Restore information from the our backup StateInfo object
st->epSquare = st->previous->epSquare;
+ st->key = st->previous->key;
+ st->mgValue = st->previous->mgValue;
+ st->egValue = st->previous->egValue;
st->previous = st->previous->previous;
- if (st->epSquare != SQ_NONE)
- st->key ^= zobEp[st->epSquare];
-
// Update the necessary information
sideToMove = opposite_color(sideToMove);
st->rule50--;
gamePly--;
- st->key ^= zobSideToMove;
-
- st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
- st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
assert(is_ok());
}
0, 0
};
- Bitboard attackers, occ, b;
+ Bitboard attackers, stmAttackers, occ, b;
assert(square_is_ok(from) || from == SQ_NONE);
assert(square_is_ok(to));
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);
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
| (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;
}
// If the opponent has no attackers we are finished
- if ((attackers & pieces_of_color(them)) == EmptyBoardBB)
+ stmAttackers = attackers & pieces_of_color(them);
+ if (!stmAttackers)
return seeValues[capture];
attackers &= occ; // Remove the moving piece
// Locate the least valuable attacker for the side to move. The loop
// below looks like it is potentially infinite, but it isn't. We know
// that the side to move still has at least one attacker left.
- for (pt = PAWN; !(attackers & pieces_of_color_and_type(c, pt)); pt++)
+ for (pt = PAWN; !(stmAttackers & pieces_of_type(pt)); pt++)
assert(pt < KING);
// Remove the attacker we just found from the 'attackers' bitboard,
// and scan for new X-ray attacks behind the attacker.
- b = attackers & pieces_of_color_and_type(c, pt);
- occ ^= (b & -b);
+ b = stmAttackers & pieces_of_type(pt);
+ occ ^= (b & (~b + 1));
attackers |= (rook_attacks_bb(to, occ) & rooks_and_queens())
| (bishop_attacks_bb(to, occ) & bishops_and_queens());
// before beginning the next iteration
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];
+ stmAttackers = attackers & pieces_of_color(c);
// Stop after a king capture
- if (pt == KING && (attackers & pieces_of_color(c)))
+ if (pt == KING && stmAttackers)
{
assert(n < 32);
swapList[n++] = 100;
break;
}
- } while (attackers & pieces_of_color(c));
+ } 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
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);
}
}
}
-/// Position::is_mate() returns true or false depending on whether the
-/// side to move is checkmated. Note that this function is currently very
-/// slow, and shouldn't be used frequently inside the search.
-
-bool Position::is_mate() const {
-
- if (is_check())
- {
- MovePicker mp = MovePicker(*this, false, MOVE_NONE, EmptySearchStack, Depth(0));
- return mp.get_next_move() == MOVE_NONE;
- }
- return false;
-}
-
-
/// 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_mate() returns true or false depending on whether the
+/// side to move is checkmated.
+
+bool Position::is_mate() const {
+
+ MoveStack moves[256];
+
+ return is_check() && !generate_evasions(*this, moves, pinned_pieces(sideToMove));
+}
+
+
/// Position::has_mate_threat() tests whether a given color has a mate in one
-/// from the current position. This function is quite slow, but it doesn't
-/// matter, because it is currently only called from PV nodes, which are rare.
+/// from the current position.
bool Position::has_mate_threat(Color c) {
StateInfo st1, st2;
Color stm = side_to_move();
- // The following lines are useless and silly, but prevents gcc from
- // emitting a stupid warning stating that u1.lastMove and u1.epSquare might
- // be used uninitialized.
- st1.lastMove = st->lastMove;
- st1.epSquare = st->epSquare;
-
if (is_check())
return false;
MoveStack mlist[120];
int count;
bool result = false;
+ Bitboard dc = discovered_check_candidates(sideToMove);
+ Bitboard pinned = pinned_pieces(sideToMove);
- // Generate legal moves
- count = generate_legal_moves(*this, mlist);
+ // Generate pseudo-legal non-capture and capture check moves
+ count = generate_non_capture_checks(*this, mlist, dc);
+ count += generate_captures(*this, mlist + count);
// Loop through the moves, and see if one of them is mate
for (int i = 0; i < count; i++)
{
- do_move(mlist[i].move, st2);
+ Move move = mlist[i].move;
+
+ if (!pl_move_is_legal(move, pinned))
+ continue;
+
+ do_move(move, st2);
if (is_mate())
result = true;
- undo_move(mlist[i].move);
+ undo_move(move);
}
// Undo null move, if necessary
st->egValue = compute_value<EndGame>();
// Material
- npMaterial[WHITE] = compute_non_pawn_material(WHITE);
- npMaterial[BLACK] = compute_non_pawn_material(BLACK);
+ st->npMaterial[WHITE] = compute_non_pawn_material(WHITE);
+ st->npMaterial[BLACK] = compute_non_pawn_material(BLACK);
assert(is_ok());
}
if (failedStep) (*failedStep)++;
if (debugNonPawnMaterial)
{
- if (npMaterial[WHITE] != compute_non_pawn_material(WHITE))
+ if (st->npMaterial[WHITE] != compute_non_pawn_material(WHITE))
return false;
- if (npMaterial[BLACK] != compute_non_pawn_material(BLACK))
+ if (st->npMaterial[BLACK] != compute_non_pawn_material(BLACK))
return false;
}
projects / stockfish / blobdiff