#define S(mg, eg) make_score(mg, eg)
// Pawn penalties
- constexpr Score Backward = S( 9, 24);
- constexpr Score Doubled = S(11, 56);
- constexpr Score Isolated = S( 5, 15);
- constexpr Score WeakUnopposed = S( 13, 27);
+ 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);
+ constexpr Score WeakUnopposed = S(13, 27);
// Connected pawn bonus
constexpr int Connected[RANK_NB] = { 0, 7, 8, 12, 29, 48, 86 };
// 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.
+ // 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(107), V(123), V(93), V(57), V( 45), V( 51) },
- { V( 44), V(-18), V(123), V(46), V(39), V( -7), V( 23) },
- { V( 4), V( 52), V(162), V(37), V( 7), V(-14), V( -2) },
- { V(-10), V(-14), V( 90), V(15), V( 2), V( -7), V(-16) }
+ { 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) },
+ { V( 4), V( 52), V( 162), V(37), V( 7), V(-14), V( -2) },
+ { V(-10), V( -14), V( 90), V(15), V( 2), V( -7), V(-16) }
};
#undef S
constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
constexpr Direction Up = (Us == WHITE ? NORTH : SOUTH);
- Bitboard b, neighbours, stoppers, doubled, support, phalanx;
+ Bitboard neighbours, stoppers, support, phalanx, opposed;
Bitboard lever, leverPush;
Square s;
- bool opposed, backward;
+ bool backward, passed, doubled;
Score score = SCORE_ZERO;
const Square* pl = pos.squares<PAWN>(Us);
Bitboard ourPawns = pos.pieces( Us, PAWN);
Bitboard theirPawns = pos.pieces(Them, PAWN);
+ Bitboard doubleAttackThem = pawn_double_attacks_bb<Them>(theirPawns);
+
e->passedPawns[Us] = e->pawnAttacksSpan[Us] = 0;
- e->kingSquares[Us] = SQ_NONE;
- e->pawnAttacks[Us] = pawn_attacks_bb<Us>(ourPawns);
+ e->kingSquares[Us] = SQ_NONE;
+ e->pawnAttacks[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);
stoppers = theirPawns & passed_pawn_span(Us, s);
phalanx = neighbours & rank_bb(s);
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 be safely advanced.
- backward = !(ourPawns & pawn_attack_span(Them, 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)));
- // Passed pawns will be properly scored in evaluation because we need
- // full attack info to evaluate them. Include also not passed pawns
- // which could become passed after one or two pawn pushes when are
- // not attacked more times than defended.
- if ( !(stoppers ^ lever ^ leverPush)
- && (support || !more_than_one(lever))
- && popcount(phalanx) >= popcount(leverPush))
- e->passedPawns[Us] |= s;
-
- else if (stoppers == square_bb(s + Up) && r >= RANK_5)
+ // Span of backward pawns and span behind opposing pawns are not included
+ // in the pawnAttacksSpan bitboard.
+ if (!backward || phalanx)
{
- b = shift<Up>(support) & ~theirPawns;
- while (b)
- if (!more_than_one(theirPawns & PawnAttacks[Us][pop_lsb(&b)]))
- e->passedPawns[Us] |= s;
+ 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
+ // (c) there is only one front stopper which can be levered.
+ passed = !(stoppers ^ lever)
+ || ( !(stoppers ^ leverPush)
+ && popcount(phalanx) >= popcount(leverPush))
+ || ( stoppers == square_bb(s + Up) && r >= RANK_5
+ && (shift<Up>(support) & ~(theirPawns | doubleAttackThem)));
+
+ // Passed pawns will be properly scored later in evaluation when we have
+ // full attack info.
+ if (passed)
+ e->passedPawns[Us] |= s;
+
// 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);
}
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);
- constexpr Direction Down = (Us == WHITE ? SOUTH : NORTH);
- constexpr Bitboard BlockSquares = (Rank1BB | Rank2BB | Rank7BB | Rank8BB)
- & (FileABB | FileHBB);
+ constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
Bitboard b = pos.pieces(PAWN) & ~forward_ranks_bb(Them, ksq);
Bitboard ourPawns = b & pos.pieces(Us);
Bitboard theirPawns = b & pos.pieces(Them);
- Value bonus[] = { (shift<Down>(theirPawns) & BlockSquares & ksq) ? Value(374) : Value(5),
- VALUE_ZERO };
+ Score bonus = make_score(5, 5);
File center = clamp(file_of(ksq), FILE_B, FILE_G);
for (File f = File(center - 1); f <= File(center + 1); ++f)
{
b = ourPawns & file_bb(f);
- Rank ourRank = b ? relative_rank(Us, backmost_sq(Us, 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);
- bonus[MG] += ShelterStrength[d][ourRank];
+ File d = map_to_queenside(f);
+ bonus += make_score(ShelterStrength[d][ourRank], 0);
if (ourRank && (ourRank == theirRank - 1))
- bonus[MG] -= 82 * (theirRank == RANK_3), bonus[EG] -= 82 * (theirRank == RANK_3);
+ bonus -= BlockedStorm * int(theirRank == RANK_3);
else
- bonus[MG] -= UnblockedStorm[d][theirRank];
+ bonus -= make_score(UnblockedStorm[d][theirRank], 0);
}
- if (bonus[MG] > mg_value(shelter))
- shelter = make_score(bonus[MG], bonus[EG]);
+ 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