diff --git a/src/evaluate.cpp b/src/evaluate.cpp index a2e5ef7b..2698c813 100644 --- a/src/evaluate.cpp +++ b/src/evaluate.cpp @@ -578,16 +578,33 @@ namespace { constexpr Color Them = ~Us; constexpr Direction Up = pawn_push(Us); + constexpr Direction Down = -Up; auto king_proximity = [&](Color c, Square s) { return std::min(distance(pos.square(c), s), 5); }; - Bitboard b, bb, squaresToQueen, unsafeSquares; + Bitboard b, bb, squaresToQueen, unsafeSquares, candidatePassers, leverable; Score score = SCORE_ZERO; b = pe->passed_pawns(Us); + candidatePassers = b & shift(pos.pieces(Them, PAWN)); + if (candidatePassers) + { + // Can we lever the blocker of a candidate passer? + leverable = shift(pos.pieces(Us, PAWN)) + & ~pos.pieces(Them) + & (~attackedBy2[Them] | attackedBy[Us][ALL_PIECES]) + & (~(attackedBy[Them][KNIGHT] | attackedBy[Them][BISHOP]) + | (attackedBy[Us ][KNIGHT] | attackedBy[Us ][BISHOP])); + + // Remove candidate otherwise + b &= ~candidatePassers + | shift(leverable) + | shift(leverable); + } + while (b) { Square s = pop_lsb(&b); diff --git a/src/pawns.cpp b/src/pawns.cpp index 0017b804..63bc596f 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -118,6 +118,7 @@ namespace { // (a) there is no stoppers except some levers // (b) the only stoppers are the leverPush, but we outnumber them // (c) there is only one front stopper which can be levered. + // (Refined in Evaluation::passed) passed = !(stoppers ^ lever) || ( !(stoppers ^ leverPush) && popcount(phalanx) >= popcount(leverPush))