#include "bitcount.h"
#include "endgame.h"
-#include "pawns.h"
using std::string;
template<typename M>
void delete_endgame(const typename M::value_type& p) { delete p.second; }
+ // Fast stalemate detection with lone king
+ bool is_kxk_stalemate(const Position &pos, const Color c) {
+ if ( pos.side_to_move() == c &&
+ !pos.in_check()) {
+ const Square from = pos.king_square(c);
+ Bitboard b = pos.attacks_from<KING>(from);
+ while (b) {
+ // Assume there are no pinned pieces, as it is a lone king
+ if (pos.pl_move_is_legal(make_move(from, pop_1st_bit(&b)), 0))
+ return false;
+ }
+ return true;
+ }
+ return false;
+ }
} // namespace
assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
assert(pos.piece_count(weakerSide, PAWN) == VALUE_ZERO);
+ if (is_kxk_stalemate(pos, weakerSide)) {
+ return VALUE_DRAW;
+ }
+
Square winnerKSq = pos.king_square(strongerSide);
Square loserKSq = pos.king_square(weakerSide);
if ( pos.piece_count(strongerSide, QUEEN)
|| pos.piece_count(strongerSide, ROOK)
- || pos.piece_count(strongerSide, BISHOP) > 1)
- // TODO: check for two equal-colored bishops!
- result += VALUE_KNOWN_WIN;
+ || pos.both_color_bishops(strongerSide)) {
+ result += VALUE_KNOWN_WIN;
+ }
return strongerSide == pos.side_to_move() ? result : -result;
}
}
else
{
- wksq = flip(pos.king_square(BLACK));
- bksq = flip(pos.king_square(WHITE));
- wpsq = flip(pos.piece_list(BLACK, PAWN)[0]);
- stm = flip(pos.side_to_move());
+ wksq = ~pos.king_square(BLACK);
+ bksq = ~pos.king_square(WHITE);
+ wpsq = ~pos.piece_list(BLACK, PAWN)[0];
+ stm = ~pos.side_to_move();
}
if (file_of(wpsq) >= FILE_E)
if (strongerSide == BLACK)
{
- wksq = flip(wksq);
- wrsq = flip(wrsq);
- bksq = flip(bksq);
- bpsq = flip(bpsq);
+ wksq = ~wksq;
+ wrsq = ~wrsq;
+ bksq = ~bksq;
+ bpsq = ~bpsq;
}
Square queeningSq = make_square(file_of(bpsq), RANK_1);
&& abs(file_of(kingSq) - pawnFile) <= 1)
{
// The bishop has the wrong color, and the defending king is on the
- // file of the pawn(s) or the neighboring file. Find the rank of the
+ // file of the pawn(s) or the adjacent file. Find the rank of the
// frontmost pawn.
Rank rank;
if (strongerSide == WHITE)
// pawn is on the left half of the board.
if (strongerSide == BLACK)
{
- wksq = flip(wksq);
- wrsq = flip(wrsq);
- wpsq = flip(wpsq);
- bksq = flip(bksq);
- brsq = flip(brsq);
+ wksq = ~wksq;
+ wrsq = ~wrsq;
+ wpsq = ~wpsq;
+ bksq = ~bksq;
+ brsq = ~brsq;
}
if (file_of(wpsq) > FILE_D)
{
return SCALE_FACTOR_NONE;
case 1:
- // Pawns on neighboring files. Draw if defender firmly controls the square
+ // Pawns on adjacent files. Draw if defender firmly controls the square
// in front of the frontmost pawn's path, and the square diagonally behind
// this square on the file of the other pawn.
if ( ksq == blockSq1
if (strongerSide == BLACK)
{
- wksq = flip(wksq);
- bksq = flip(bksq);
- wpsq = flip(wpsq);
- stm = flip(stm);
+ wksq = ~wksq;
+ bksq = ~bksq;
+ wpsq = ~wpsq;
+ stm = ~stm;
}
if (file_of(wpsq) >= FILE_E)