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Unify pinned and discovery checks code 

Templates are our friends here. No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
sf_2.3.1_base
Marco Costalba 2008-10-23 20:43:48 +01:00
parent af59cb1d63
commit 1ac2f50145
2 changed files with 46 additions and 65 deletions
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106
src/position.cpp
View File

@ -296,50 +296,12 @@ void Position::copy(const Position &pos) {
}
/// Position:pinned_pieces<>() returns a bitboard of all pinned (against the
/// king) pieces for the given color and for the given pinner type.
template<PieceType Piece>
Bitboard Position::pinned_pieces(Color c, Square ksq) const {
Square s;
Bitboard sliders, pinned = EmptyBoardBB;
if (Piece == ROOK) // Resolved at compile time
sliders = rooks_and_queens(opposite_color(c)) & RookPseudoAttacks[ksq];
else
sliders = bishops_and_queens(opposite_color(c)) & BishopPseudoAttacks[ksq];
if (sliders && (sliders & ~checkersBB))
{
// Our 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.
Bitboard pinners = sliders & ~checkersBB;
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
// among the candidates.
while (pinners)
{
s = pop_1st_bit(&pinners);
pinned |= (squares_between(s, ksq) & candidate_pinned);
}
}
return pinned;
}
/// Position:pinned_pieces() returns a bitboard of all pinned (against the
/// king) pieces for the given color.
Bitboard Position::pinned_pieces(Color c) const {
Square ksq = king_square(c);
return pinned_pieces<ROOK>(c, ksq) | pinned_pieces<BISHOP>(c, ksq);
return hidden_checks<ROOK, true>(c, ksq) | hidden_checks<BISHOP, true>(c, ksq);
}
@ -349,33 +311,51 @@ Bitboard Position::pinned_pieces(Color c) const {
/// pieces.
Bitboard Position::discovered_check_candidates(Color c) const {
Bitboard b1, b2, dc, checkers, sliders;
Square ksq = king_square(opposite_color(c)), s;
dc = EmptyBoardBB;
b1 = occupied_squares();
Square ksq = king_square(opposite_color(c));
return hidden_checks<ROOK, false>(c, ksq) | hidden_checks<BISHOP, false>(c, ksq);
}
sliders = rooks_and_queens(c);
if(sliders & RookPseudoAttacks[ksq]) {
b2 = piece_attacks<ROOK>(ksq) & pieces_of_color(c);
checkers = rook_attacks_bb(ksq, b1 ^ b2) & sliders;
while(checkers) {
s = pop_1st_bit(&checkers);
dc |= (squares_between(s, ksq) & b2);
}
/// Position:hidden_checks<>() returns a bitboard of all pinned (against the
/// king) pieces for the given color and for the given pinner type. Or, when
/// template parameter FindPinned is false, the pinned pieces of opposite color
/// that are, indeed, the pieces candidate for a discovery check.
template<PieceType Piece, bool FindPinned>
Bitboard Position::hidden_checks(Color c, Square ksq) const {
Square s;
Bitboard sliders, result = EmptyBoardBB;
if (Piece == ROOK) // Resolved at compile time
sliders = rooks_and_queens(FindPinned ? opposite_color(c) : c) & RookPseudoAttacks[ksq];
else
sliders = bishops_and_queens(FindPinned ? opposite_color(c) : c) & BishopPseudoAttacks[ksq];
if (sliders && (!FindPinned || (sliders & ~checkersBB)))
{
// King blockers are candidate pinned pieces
Bitboard candidate_pinned = piece_attacks<Piece>(ksq) & pieces_of_color(c);
// Pinners are sliders, not checkers, that give check when
// candidate pinned are removed.
Bitboard pinners = (FindPinned ? sliders & ~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.
while (pinners)
{
s = pop_1st_bit(&pinners);
result |= (squares_between(s, ksq) & candidate_pinned);
}
}
sliders = bishops_and_queens(c);
if(sliders & BishopPseudoAttacks[ksq]) {
b2 = piece_attacks<BISHOP>(ksq) & pieces_of_color(c);
checkers = bishop_attacks_bb(ksq, b1 ^ b2) & sliders;
while(checkers) {
s = pop_1st_bit(&checkers);
dc |= (squares_between(s, ksq) & b2);
}
}
return dc;
return result;
}

5
src/position.h
View File

@ -197,8 +197,6 @@ public:
// Bitboards for pinned pieces and discovered check candidates
Bitboard discovered_check_candidates(Color c) const;
Bitboard pinned_pieces(Color c) const;
template<PieceType Piece>
Bitboard pinned_pieces(Color c, Square ksq) const;
// Checking pieces
Bitboard checkers() const;
@ -307,6 +305,9 @@ private:
void undo_ep_move(Move m);
void find_checkers();
template<PieceType Piece, bool FindPinned>
Bitboard hidden_checks(Color c, Square ksq) const;
// Computing hash keys from scratch (for initialization and debugging)
Key compute_key() const;
Key compute_pawn_key() const;