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Better dscovery check condition in generate_pawn_checks()

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Be more strict, is not enough dc bitboard is not empty, but
needs to inclde also at least one pawn.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2009-05-07 17:01:52 +02:00
parent 1d15b38cd8
commit 9fbe9af0a0
1 changed files with 14 additions and 10 deletions
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24
src/movegen.cpp
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@ -65,7 +65,7 @@ namespace {
template<Color Us> template<Color Us>
MoveStack* generate_pawn_noncaptures(const Position& pos, MoveStack* mlist); MoveStack* generate_pawn_noncaptures(const Position& pos, MoveStack* mlist);
template<Color, Color, Bitboard, Bitboard, SquareDelta> template<Color Us>
MoveStack* generate_pawn_checks(const Position&, Bitboard, Square, MoveStack*); MoveStack* generate_pawn_checks(const Position&, Bitboard, Square, MoveStack*);
template<Color Us, SquareDelta Direction> template<Color Us, SquareDelta Direction>
@ -88,11 +88,8 @@ namespace {
template<> template<>
inline MoveStack* generate_piece_checks<PAWN>(const Position& p, MoveStack* m, Color us, Bitboard dc, Square ksq) { inline MoveStack* generate_piece_checks<PAWN>(const Position& p, MoveStack* m, Color us, Bitboard dc, Square ksq) {
if (us == WHITE) return (us == WHITE ? generate_pawn_checks<WHITE>(p, dc, ksq, m)
return generate_pawn_checks<WHITE, BLACK, Rank8BB, Rank3BB, DELTA_N>(p, dc, ksq, m); : generate_pawn_checks<BLACK>(p, dc, ksq, m));
else
return generate_pawn_checks<BLACK, WHITE, Rank1BB, Rank6BB, DELTA_S>(p, dc, ksq, m);
} }
// Template generate_piece_moves() with specializations and overloads // Template generate_piece_moves() with specializations and overloads
@ -752,18 +749,25 @@ namespace {
} }
template<Color Us, Color Them, Bitboard TRank8BB, Bitboard TRank3BB, SquareDelta TDELTA_N> template<Color Us>
MoveStack* generate_pawn_checks(const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist) MoveStack* generate_pawn_checks(const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist)
{ {
// Calculate our parametrized parameters at compile time
const Color Them = (Us == WHITE ? BLACK : WHITE);
const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
Bitboard b1, b2, b3; Bitboard b1, b2, b3;
Bitboard empty = pos.empty_squares(); Bitboard empty = pos.empty_squares();
Bitboard pawns = pos.pawns(Us);
if (dc != EmptyBoardBB) if (dc & pawns)
{ {
// Pawn moves which gives discovered check. This is possible only if the // Pawn moves which gives discovered check. This is possible only if the
// pawn is not on the same file as the enemy king, because we don't // pawn is not on the same file as the enemy king, because we don't
// generate captures. // generate captures.
b1 = pos.pawns(Us) & ~file_bb(ksq); b1 = pawns & ~file_bb(ksq);
// Discovered checks, single pawn pushes, no promotions // Discovered checks, single pawn pushes, no promotions
b2 = b3 = move_pawns<Us, DELTA_N>(b1 & dc) & empty & ~TRank8BB; b2 = b3 = move_pawns<Us, DELTA_N>(b1 & dc) & empty & ~TRank8BB;
@ -784,7 +788,7 @@ namespace {
// Direct checks. These are possible only for pawns on neighboring files // Direct checks. These are possible only for pawns on neighboring files
// of the enemy king. // of the enemy king.
b1 = pos.pawns(Us) & neighboring_files_bb(ksq) & ~dc; b1 = pawns & neighboring_files_bb(ksq) & ~dc;
// Direct checks, single pawn pushes // Direct checks, single pawn pushes
b2 = move_pawns<Us, DELTA_N>(b1) & empty; b2 = move_pawns<Us, DELTA_N>(b1) & empty;