constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
constexpr Direction Up = (Us == WHITE ? NORTH : SOUTH);
- Bitboard neighbours, stoppers, support, phalanx;
+ Bitboard neighbours, stoppers, support, phalanx, opposed;
Bitboard lever, leverPush;
Square s;
- bool opposed, backward, passed, doubled;
+ bool backward, passed, doubled;
Score score = SCORE_ZERO;
const Square* pl = pos.squares<PAWN>(Us);
Rank r = relative_rank(Us, s);
- e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s);
-
// Flag the pawn
opposed = theirPawns & forward_file_bb(Us, s);
stoppers = theirPawns & passed_pawn_span(Us, s);
backward = !(neighbours & forward_ranks_bb(Them, s))
&& (stoppers & (leverPush | (s + Up)));
+ // Span of backward pawns and span behind opposing pawns are not included
+ // in the pawnAttacksSpan bitboard.
+ if (!backward || phalanx)
+ {
+ if (opposed)
+ e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s) &
+ ~pawn_attack_span(Us, frontmost_sq(Them, opposed));
+ else
+ e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s);
+ }
+
// A pawn is passed if one of the three following conditions is true:
// (a) there is no stoppers except some levers
// (b) the only stoppers are the leverPush, but we outnumber them
// Score this pawn
if (support | phalanx)
{
- int v = Connected[r] * (2 + bool(phalanx) - opposed)
- + 17 * popcount(support);
+ int v = Connected[r] * (2 + bool(phalanx) - bool(opposed))
+ + 21 * popcount(support);
score += make_score(v, v * (r - 2) / 4);
}
else if (!neighbours)
- score -= Isolated + WeakUnopposed * !opposed;
+ score -= Isolated
+ + WeakUnopposed * !opposed;
else if (backward)
- score -= Backward + WeakUnopposed * !opposed;
+ score -= Backward
+ + WeakUnopposed * !opposed;
if (!support)
score -= Doubled * doubled
Square ksq = pos.square<KING>(Us);
kingSquares[Us] = ksq;
castlingRights[Us] = pos.castling_rights(Us);
+ auto compare = [](Score a, Score b) { return mg_value(a) < mg_value(b); };
- Score shelters[3] = { evaluate_shelter<Us>(pos, ksq),
- make_score(-VALUE_INFINITE, 0),
- make_score(-VALUE_INFINITE, 0) };
+ Score shelter = evaluate_shelter<Us>(pos, ksq);
// If we can castle use the bonus after castling if it is bigger
+
if (pos.can_castle(Us & KING_SIDE))
- shelters[1] = evaluate_shelter<Us>(pos, relative_square(Us, SQ_G1));
+ shelter = std::max(shelter, evaluate_shelter<Us>(pos, relative_square(Us, SQ_G1)), compare);
if (pos.can_castle(Us & QUEEN_SIDE))
- shelters[2] = evaluate_shelter<Us>(pos, relative_square(Us, SQ_C1));
-
- for (int i : {1, 2})
- if (mg_value(shelters[i]) > mg_value(shelters[0]))
- shelters[0] = shelters[i];
+ shelter = std::max(shelter, evaluate_shelter<Us>(pos, relative_square(Us, SQ_C1)), compare);
// In endgame we like to bring our king near our closest pawn
Bitboard pawns = pos.pieces(Us, PAWN);
else while (pawns)
minPawnDist = std::min(minPawnDist, distance(ksq, pop_lsb(&pawns)));
- return shelters[0] - make_score(0, 16 * minPawnDist);
+ return shelter - make_score(0, 16 * minPawnDist);
}
// Explicit template instantiation