// The bishop has the wrong color, and the defending king is on the
// file of the pawn(s) or the adjacent file. Find the rank of the
// frontmost pawn.
- Rank rank;
- if (strongerSide == WHITE)
- {
- for (rank = RANK_7; !(rank_bb(rank) & pawns); rank--) {}
- assert(rank >= RANK_2 && rank <= RANK_7);
- }
- else
- {
- for (rank = RANK_2; !(rank_bb(rank) & pawns); rank++) {}
- rank = Rank(rank ^ 7); // HACK to get the relative rank
- assert(rank >= RANK_2 && rank <= RANK_7);
- }
+ Rank rank = relative_rank(strongerSide, lsb(weakerSide, pawns));
// If the defending king has distance 1 to the promotion square or
// is placed somewhere in front of the pawn, it's a draw.
if ( square_distance(kingSq, queeningSq) <= 1
&& pos.non_pawn_material(weakerSide) == 0
&& pos.count<PAWN>(weakerSide) >= 1)
{
- // Get weaker pawn closest to opponent's queening square
- Bitboard wkPawns = pos.pieces(weakerSide, PAWN);
- Square weakerPawnSq = strongerSide == WHITE ? msb(wkPawns) : lsb(wkPawns);
+ // Get weakerSide pawn that is closest to home rank
+ Square weakerPawnSq = lsb(weakerSide, pos.pieces(weakerSide, PAWN));
Square strongerKingSq = pos.king_square(strongerSide);
Square weakerKingSq = pos.king_square(weakerSide);