Score evaluate(const Position& pos, Pawns::Entry* e) {
constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
- constexpr Direction Up = (Us == WHITE ? NORTH : SOUTH);
+ constexpr Direction Up = pawn_push(Us);
- Bitboard neighbours, stoppers, support, phalanx;
- Bitboard lever, leverPush;
+ Bitboard neighbours, stoppers, support, phalanx, opposed;
+ Bitboard lever, leverPush, blocked;
Square s;
- bool opposed, backward, passed, doubled;
+ bool backward, passed, doubled;
Score score = SCORE_ZERO;
const Square* pl = pos.squares<PAWN>(Us);
Bitboard doubleAttackThem = pawn_double_attacks_bb<Them>(theirPawns);
- e->passedPawns[Us] = e->pawnAttacksSpan[Us] = 0;
+ e->passedPawns[Us] = 0;
e->kingSquares[Us] = SQ_NONE;
- e->pawnAttacks[Us] = pawn_attacks_bb<Us>(ourPawns);
+ e->pawnAttacks[Us] = e->pawnAttacksSpan[Us] = pawn_attacks_bb<Us>(ourPawns);
// Loop through all pawns of the current color and score each pawn
while ((s = *pl++) != SQ_NONE)
Rank r = relative_rank(Us, s);
- e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s);
-
// Flag the pawn
opposed = theirPawns & forward_file_bb(Us, s);
+ blocked = theirPawns & (s + Up);
stoppers = theirPawns & passed_pawn_span(Us, s);
lever = theirPawns & PawnAttacks[Us][s];
leverPush = theirPawns & PawnAttacks[Us][s + Up];
support = neighbours & rank_bb(s - Up);
// A pawn is backward when it is behind all pawns of the same color on
- // the adjacent files and cannot safely advance. Phalanx and isolated
- // pawns will be excluded when the pawn is scored.
- backward = !(neighbours & forward_ranks_bb(Them, s))
- && (stoppers & (leverPush | (s + Up)));
+ // the adjacent files and cannot safely advance.
+ backward = !(neighbours & forward_ranks_bb(Them, s + Up))
+ && (leverPush | blocked);
+
+ // Compute additional span if pawn is not backward nor blocked
+ if (!backward && !blocked)
+ 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
passed = !(stoppers ^ lever)
|| ( !(stoppers ^ leverPush)
&& popcount(phalanx) >= popcount(leverPush))
- || ( stoppers == square_bb(s + Up) && r >= RANK_5
+ || ( stoppers == blocked && r >= RANK_5
&& (shift<Up>(support) & ~(theirPawns | doubleAttackThem)));
// Passed pawns will be properly scored later in evaluation when we have
// Score this pawn
if (support | phalanx)
{
- int v = Connected[r] * (phalanx ? 3 : 2) / (opposed ? 2 : 1)
- + 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
b = theirPawns & file_bb(f);
int theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : 0;
- int d = std::min(f, ~f);
+ File d = map_to_queenside(f);
bonus += make_score(ShelterStrength[d][ourRank], 0);
if (ourRank && (ourRank == theirRank - 1))
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