diff --git a/src/position.cpp b/src/position.cpp index e51c1ba7..779c2640 100644 --- a/src/position.cpp +++ b/src/position.cpp @@ -997,20 +997,17 @@ Value Position::see(Move m) const { // If the opponent has no attackers we are finished stm = ~stm; stmAttackers = attackers & pieces(stm); - if (!stmAttackers) - return swapList[0]; + occupied ^= to; // For the case when captured piece is a pinner // Don't allow pinned pieces to attack as long all pinners (this includes also // potential ones) are on their original square. When a pinner moves to the // exchange-square or get captured on it, we fall back to standard SEE behaviour. - else if ( (stmAttackers & st->blockersForKing[stm]) - && ((st->pinnersForKing[stm] & (occupied ^ (occupied & to))) == st->pinnersForKing[stm])) - { - // Pinned pieces can't attack so remove them from attackers - stmAttackers ^= (stmAttackers & st->blockersForKing[stm]); - if (!stmAttackers) - return swapList[0]; - } + if ( (stmAttackers & pinned_pieces(stm)) + && (st->pinnersForKing[stm] & occupied) == st->pinnersForKing[stm]) + stmAttackers &= ~pinned_pieces(stm); + + if (!stmAttackers) + return swapList[0]; // The destination square is defended, which makes things rather more // difficult to compute. We proceed by building up a "swap list" containing @@ -1030,10 +1027,9 @@ Value Position::see(Move m) const { captured = min_attacker(byTypeBB, to, stmAttackers, occupied, attackers); stm = ~stm; stmAttackers = attackers & pieces(stm); - if ( stmAttackers - && (stmAttackers & st->blockersForKing[stm]) - && ((st->pinnersForKing[stm] & (occupied ^ (occupied & to))) == st->pinnersForKing[stm])) - stmAttackers ^= (stmAttackers & st->blockersForKing[stm]); + if ( (stmAttackers & pinned_pieces(stm)) + && (st->pinnersForKing[stm] & occupied) == st->pinnersForKing[stm]) + stmAttackers &= ~pinned_pieces(stm); ++slIndex;