- // don't prune move if a heavy enemy piece (KQR) is under attack after the exchanges
- Bitboard leftEnemies = (pos.pieces(~us, QUEEN, ROOK) | pos.pieces(~us, KING)) & occupied;
- Bitboard attacks = 0;
- occupied |= to_sq(move);
- while (leftEnemies && !attacks)
- {
- Square sq = pop_lsb(leftEnemies);
- attacks |= pos.attackers_to(sq, occupied) & pos.pieces(us) & occupied;
- // exclude Queen/Rook(s) which were already threatened before SEE
- if (attacks && (sq != pos.square<KING>(~us) && (pos.attackers_to(sq, pos.pieces()) & pos.pieces(us))))
- attacks = 0;
- }
- if (!attacks)
- continue;
- }