// Pawn penalties
constexpr Score Backward = S( 9, 24);
+ constexpr Score BlockedStorm = S(82, 82);
constexpr Score Doubled = S(11, 56);
constexpr Score Isolated = S( 5, 15);
constexpr Score WeakLever = S( 0, 56);
// Danger of enemy pawns moving toward our king by [distance from edge][rank].
// RANK_1 = 0 is used for files where the enemy has no pawn, or their pawn
- // is behind our king.
- // [0][1-2] accommodate opponent pawn on edge (likely blocked by our king)
+ // is behind our king. Note that UnblockedStorm[0][1-2] accommodate opponent pawn
+ // on edge, likely blocked by our king.
constexpr Value UnblockedStorm[int(FILE_NB) / 2][RANK_NB] = {
{ V( 89), V(-285), V(-185), V(93), V(57), V( 45), V( 51) },
{ V( 44), V( -18), V( 123), V(46), V(39), V( -7), V( 23) },
constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
constexpr Direction Up = (Us == WHITE ? NORTH : SOUTH);
- Bitboard neighbours, stoppers, doubled, support, phalanx;
+ Bitboard neighbours, stoppers, support, phalanx, opposed;
Bitboard lever, leverPush;
Square s;
- bool opposed, backward, passed;
+ 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] * (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 * int(!opposed);
+ score -= Isolated
+ + WeakUnopposed * !opposed;
else if (backward)
- score -= Backward + WeakUnopposed * int(!opposed);
+ score -= Backward
+ + WeakUnopposed * !opposed;
- if (doubled && !support)
- score -= Doubled;
+ if (!support)
+ score -= Doubled * doubled
+ + WeakLever * more_than_one(lever);
}
- // Penalize our unsupported pawns attacked twice by enemy pawns
- score -= WeakLever * popcount( ourPawns
- & doubleAttackThem
- & ~e->pawnAttacks[Us]);
-
return score;
}
/// penalty for a king, looking at the king file and the two closest files.
template<Color Us>
-void Entry::evaluate_shelter(const Position& pos, Square ksq, Score& shelter) {
+Score Entry::evaluate_shelter(const Position& pos, Square ksq) {
constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
for (File f = File(center - 1); f <= File(center + 1); ++f)
{
b = ourPawns & file_bb(f);
- Rank ourRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;
+ int ourRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : 0;
b = theirPawns & file_bb(f);
- Rank theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;
+ 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))
- bonus -= make_score(82 * (theirRank == RANK_3), 82 * (theirRank == RANK_3));
+ bonus -= BlockedStorm * int(theirRank == RANK_3);
else
bonus -= make_score(UnblockedStorm[d][theirRank], 0);
}
- if (mg_value(bonus) > mg_value(shelter))
- shelter = bonus;
+ return bonus;
}
kingSquares[Us] = ksq;
castlingRights[Us] = pos.castling_rights(Us);
+ Score shelters[3] = { evaluate_shelter<Us>(pos, ksq),
+ make_score(-VALUE_INFINITE, 0),
+ make_score(-VALUE_INFINITE, 0) };
+
+ // 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));
+
+ 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];
+
+ // In endgame we like to bring our king near our closest pawn
Bitboard pawns = pos.pieces(Us, PAWN);
int minPawnDist = pawns ? 8 : 0;
if (pawns & PseudoAttacks[KING][ksq])
minPawnDist = 1;
-
else while (pawns)
minPawnDist = std::min(minPawnDist, distance(ksq, pop_lsb(&pawns)));
- Score shelter = make_score(-VALUE_INFINITE, VALUE_ZERO);
- evaluate_shelter<Us>(pos, ksq, shelter);
-
- // If we can castle use the bonus after the castling if it is bigger
- if (pos.can_castle(Us | KING_SIDE))
- evaluate_shelter<Us>(pos, relative_square(Us, SQ_G1), shelter);
-
- if (pos.can_castle(Us | QUEEN_SIDE))
- evaluate_shelter<Us>(pos, relative_square(Us, SQ_C1), shelter);
-
- return shelter - make_score(VALUE_ZERO, 16 * minPawnDist);
+ return shelters[0] - make_score(0, 16 * minPawnDist);
}
// Explicit template instantiation
projects / stockfish / blobdiff