constexpr Score Doubled = S(11, 56);
constexpr Score Isolated = S( 5, 15);
- // Connected pawn bonus by opposed, phalanx, #support and rank
- Score Connected[2][2][3][RANK_NB];
+ // Connected pawn bonus
+ constexpr int Connected[RANK_NB] = { 0, 7, 8, 12, 29, 48, 86 };
// Strength of pawn shelter for our king by [distance from edge][rank].
// RANK_1 = 0 is used for files where we have no pawn, or pawn is behind our king.
constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
constexpr Direction Up = (Us == WHITE ? NORTH : SOUTH);
- Bitboard b, neighbours, stoppers, doubled, supported, phalanx;
+ Bitboard b, neighbours, stoppers, doubled, support, phalanx;
Bitboard lever, leverPush;
Square s;
bool opposed, backward;
Bitboard theirPawns = pos.pieces(Them, PAWN);
e->passedPawns[Us] = e->pawnAttacksSpan[Us] = e->weakUnopposed[Us] = 0;
- e->semiopenFiles[Us] = 0xFF;
e->kingSquares[Us] = SQ_NONE;
e->pawnAttacks[Us] = pawn_attacks_bb<Us>(ourPawns);
- e->pawnsOnSquares[Us][BLACK] = popcount(ourPawns & DarkSquares);
- e->pawnsOnSquares[Us][WHITE] = pos.count<PAWN>(Us) - e->pawnsOnSquares[Us][BLACK];
// Loop through all pawns of the current color and score each pawn
while ((s = *pl++) != SQ_NONE)
assert(pos.piece_on(s) == make_piece(Us, PAWN));
File f = file_of(s);
+ Rank r = relative_rank(Us, s);
- e->semiopenFiles[Us] &= ~(1 << f);
e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s);
// Flag the pawn
opposed = theirPawns & forward_file_bb(Us, s);
- stoppers = theirPawns & passed_pawn_mask(Us, s);
+ stoppers = theirPawns & passed_pawn_span(Us, s);
lever = theirPawns & PawnAttacks[Us][s];
leverPush = theirPawns & PawnAttacks[Us][s + Up];
doubled = ourPawns & (s - Up);
neighbours = ourPawns & adjacent_files_bb(f);
phalanx = neighbours & rank_bb(s);
- supported = neighbours & rank_bb(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 be safely advanced.
// which could become passed after one or two pawn pushes when are
// not attacked more times than defended.
if ( !(stoppers ^ lever ^ leverPush)
- && popcount(supported) >= popcount(lever) - 1
- && popcount(phalanx) >= popcount(leverPush))
+ && (support || !more_than_one(lever))
+ && popcount(phalanx) >= popcount(leverPush))
e->passedPawns[Us] |= s;
- else if ( stoppers == SquareBB[s + Up]
- && relative_rank(Us, s) >= RANK_5)
+ else if (stoppers == square_bb(s + Up) && r >= RANK_5)
{
- b = shift<Up>(supported) & ~theirPawns;
+ b = shift<Up>(support) & ~theirPawns;
while (b)
if (!more_than_one(theirPawns & PawnAttacks[Us][pop_lsb(&b)]))
e->passedPawns[Us] |= s;
}
// Score this pawn
- if (supported | phalanx)
- score += Connected[opposed][bool(phalanx)][popcount(supported)][relative_rank(Us, s)];
+ if (support | phalanx)
+ {
+ int v = Connected[r] * (phalanx ? 3 : 2) / (opposed ? 2 : 1)
+ + 17 * popcount(support);
+ score += make_score(v, v * (r - 2) / 4);
+ }
else if (!neighbours)
score -= Isolated, e->weakUnopposed[Us] += !opposed;
else if (backward)
score -= Backward, e->weakUnopposed[Us] += !opposed;
- if (doubled && !supported)
+ if (doubled && !support)
score -= Doubled;
}
namespace Pawns {
-/// Pawns::init() initializes some tables needed by evaluation. Instead of using
-/// hard-coded tables, when makes sense, we prefer to calculate them with a formula
-/// to reduce independent parameters and to allow easier tuning and better insight.
-
-void init() {
-
- static constexpr int Seed[RANK_NB] = { 0, 13, 24, 18, 65, 100, 175, 330 };
-
- for (int opposed = 0; opposed <= 1; ++opposed)
- for (int phalanx = 0; phalanx <= 1; ++phalanx)
- for (int support = 0; support <= 2; ++support)
- for (Rank r = RANK_2; r < RANK_8; ++r)
- {
- int v = 17 * support;
- v += (Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0)) >> opposed;
-
- Connected[opposed][phalanx][support][r] = make_score(v, v * (r - 2) / 4);
- }
-}
-
-
/// Pawns::probe() looks up the current position's pawns configuration in
/// the pawns hash table. It returns a pointer to the Entry if the position
/// is found. Otherwise a new Entry is computed and stored there, so we don't
e->key = key;
e->scores[WHITE] = evaluate<WHITE>(pos, e);
e->scores[BLACK] = evaluate<BLACK>(pos, e);
- e->openFiles = popcount(e->semiopenFiles[WHITE] & e->semiopenFiles[BLACK]);
- e->asymmetry = popcount( (e->passedPawns[WHITE] | e->passedPawns[BLACK])
- | (e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK]));
return e;
}
/// penalty for a king, looking at the king file and the two closest files.
template<Color Us>
-Value Entry::evaluate_shelter(const Position& pos, Square ksq) {
+void Entry::evaluate_shelter(const Position& pos, Square ksq, Score& shelter) {
constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
constexpr Direction Down = (Us == WHITE ? SOUTH : NORTH);
- constexpr Bitboard BlockRanks = (Us == WHITE ? Rank1BB | Rank2BB : Rank8BB | Rank7BB);
+ constexpr Bitboard BlockSquares = (Rank1BB | Rank2BB | Rank7BB | Rank8BB)
+ & (FileABB | FileHBB);
Bitboard b = pos.pieces(PAWN) & ~forward_ranks_bb(Them, ksq);
Bitboard ourPawns = b & pos.pieces(Us);
Bitboard theirPawns = b & pos.pieces(Them);
- Value safety = (shift<Down>(theirPawns) & (FileABB | FileHBB) & BlockRanks & ksq) ?
- Value(374) : Value(5);
+ Value bonus[] = { (shift<Down>(theirPawns) & BlockSquares & ksq) ? Value(374) : Value(5),
+ VALUE_ZERO };
- File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq)));
+ 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);
- int ourRank = b ? relative_rank(Us, backmost_sq(Us, b)) : 0;
+ Rank ourRank = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1;
b = theirPawns & file_bb(f);
- int theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : 0;
+ Rank theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;
int d = std::min(f, ~f);
- safety += ShelterStrength[d][ourRank];
- safety -= (ourRank && (ourRank == theirRank - 1)) ? 66 * (theirRank == RANK_3)
- : UnblockedStorm[d][theirRank];
+ bonus[MG] += ShelterStrength[d][ourRank];
+
+ if (ourRank && (ourRank == theirRank - 1))
+ bonus[MG] -= 82 * (theirRank == RANK_3), bonus[EG] -= 82 * (theirRank == RANK_3);
+ else
+ bonus[MG] -= UnblockedStorm[d][theirRank];
}
- return safety;
+ if (bonus[MG] > mg_value(shelter))
+ shelter = make_score(bonus[MG], bonus[EG]);
}
Square ksq = pos.square<KING>(Us);
kingSquares[Us] = ksq;
- castlingRights[Us] = pos.can_castle(Us);
- int minKingPawnDistance = 0;
+ castlingRights[Us] = pos.castling_rights(Us);
Bitboard pawns = pos.pieces(Us, PAWN);
- if (pawns)
- while (!(DistanceRingBB[ksq][++minKingPawnDistance] & pawns)) {}
+ int minPawnDist = pawns ? 8 : 0;
+
+ if (pawns & PseudoAttacks[KING][ksq])
+ minPawnDist = 1;
+
+ else while (pawns)
+ minPawnDist = std::min(minPawnDist, distance(ksq, pop_lsb(&pawns)));
- Value bonus = evaluate_shelter<Us>(pos, ksq);
+ 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))
- bonus = std::max(bonus, evaluate_shelter<Us>(pos, relative_square(Us, SQ_G1)));
+ evaluate_shelter<Us>(pos, relative_square(Us, SQ_G1), shelter);
if (pos.can_castle(Us | QUEEN_SIDE))
- bonus = std::max(bonus, evaluate_shelter<Us>(pos, relative_square(Us, SQ_C1)));
+ evaluate_shelter<Us>(pos, relative_square(Us, SQ_C1), shelter);
- return make_score(bonus, -16 * minKingPawnDistance);
+ return shelter - make_score(VALUE_ZERO, 16 * minPawnDist);
}
// Explicit template instantiation
projects / stockfish / blobdiff