def legal_drop_squares_mask(self):
king_bb = self.kings & self.occupied_co[self.turn]
if not king_bb:
return ~self.occupied
king_square = chess.msb(king_bb)
king_attackers = self.attackers_mask(not self.turn, king_square)
if not king_attackers:
return ~self.occupied
elif chess.popcount(king_attackers) == 1:
return chess.BB_BETWEEN[king_square][chess.msb(king_attackers)] & ~self.occupied
else:
return chess.BB_VOID
def legal_drop_squares_mask(self):
king = self.king(self.turn)
if king is None:
return ~self.occupied
king_attackers = self.attackers_mask(not self.turn, king)
if not king_attackers:
return ~self.occupied
elif chess.popcount(king_attackers) == 1:
return chess.BB_BETWEEN[king][chess.msb(king_attackers)] & ~self.occupied
else:
return chess.BB_VOID
def legal_drop_squares_mask(self) -> chess.Bitboard:
king = self.king(self.turn)
if king is None:
return ~self.occupied
king_attackers = self.attackers_mask(not self.turn, king)
if not king_attackers:
return ~self.occupied
elif chess.popcount(king_attackers) == 1:
return chess.between(king, chess.msb(king_attackers)) & ~self.occupied
else:
return chess.BB_EMPTY
def legal_drop_squares_mask(self):
king = self.king(self.turn)
if king is None:
return ~self.occupied
king_attackers = self.attackers_mask(not self.turn, king)
if not king_attackers:
return ~self.occupied
elif chess.popcount(king_attackers) == 1:
return chess.BB_BETWEEN[king][chess.msb(king_attackers)] & ~self.occupied
else:
return chess.BB_VOID
def is_variant_end(self) -> bool:
if not self.kings & chess.BB_RANK_8:
return False
black_kings = self.kings & self.occupied_co[chess.BLACK]
if self.turn == chess.WHITE or black_kings & chess.BB_RANK_8 or not black_kings:
return True
# White has reached the backrank. The game is over if black can not
# also reach the backrank on the next move. Check if there are any
# safe squares for the king.
black_king = chess.msb(black_kings)
targets = chess.BB_KING_ATTACKS[black_king] & chess.BB_RANK_8 & ~self.occupied_co[chess.BLACK]
return all(self.attackers_mask(chess.WHITE, target) for target in chess.scan_forward(targets))
def is_variant_end(self):
if not self.kings & chess.BB_RANK_8:
return False
if self.turn == chess.WHITE or self.kings & self.occupied_co[chess.BLACK] & chess.BB_RANK_8:
return True
black_kings = self.kings & self.occupied_co[chess.BLACK]
if not black_kings:
return True
black_king = chess.msb(black_kings)
# White has reached the backrank. The game is over if black can not
# also reach the backrank on the next move. Check if there are any
# safe squares for the king.
targets = chess.BB_KING_ATTACKS[black_king] & chess.BB_RANK_8
return all(self.attackers_mask(chess.WHITE, target) for target in chess.scan_forward(targets))
