- b1 &= pawn_attacks_bb(Them, ksq);
- b2 &= pawn_attacks_bb(Them, ksq);
-
- // Add pawn pushes which give discovered check. This is possible only
- // if the pawn is not on the same file as the enemy king, because we
- // don't generate captures. Note that a possible discovered check
- // promotion has been already generated amongst the captures.
- Bitboard dcCandidateQuiets = pos.blockers_for_king(Them) & pawnsNotOn7;
- if (dcCandidateQuiets)
- {
- Bitboard dc1 = shift<Up>(dcCandidateQuiets) & emptySquares & ~file_bb(ksq);
- Bitboard dc2 = shift<Up>(dc1 & TRank3BB) & emptySquares;
-
- b1 |= dc1;
- b2 |= dc2;
- }
+ // To make a quiet check, you either make a direct check by pushing a pawn
+ // or push a blocker pawn that is not on the same file as the enemy king.
+ // Discovered check promotion has been already generated amongst the captures.
+ Bitboard dcCandidatePawns = pos.blockers_for_king(Them) & ~file_bb(ksq);
+ b1 &= pawn_attacks_bb(Them, ksq) | shift< Up>(dcCandidatePawns);
+ b2 &= pawn_attacks_bb(Them, ksq) | shift<Up+Up>(dcCandidatePawns);