Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
- Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
#define V Value
#define S(mg, eg) make_score(mg, eg)
- // Isolated pawn penalty
- const Score Isolated = S(13, 18);
-
- // Backward pawn penalty
- const Score Backward = S(24, 12);
+ // Pawn penalties
+ constexpr Score Backward = S( 9, 24);
+ 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];
- // Doubled pawn penalty
- const Score Doubled = S(18, 38);
-
- // Weakness of our pawn shelter in front of the king by [isKingFile][distance from edge][rank].
- // RANK_1 = 0 is used for files where we have no pawns or our pawn is behind our king.
- const Value ShelterWeakness[][int(FILE_NB) / 2][RANK_NB] = {
- { { V( 98), V(20), V(11), V(42), V( 83), V( 84), V(101) }, // Not On King file
- { V(103), V( 8), V(33), V(86), V( 87), V(105), V(113) },
- { V(100), V( 2), V(65), V(95), V( 59), V( 89), V(115) },
- { V( 72), V( 6), V(52), V(74), V( 83), V( 84), V(112) } },
- { { V(105), V(19), V( 3), V(27), V( 85), V( 93), V( 84) }, // On King file
- { V(121), V( 7), V(33), V(95), V(112), V( 86), V( 72) },
- { V(121), V(26), V(65), V(90), V( 65), V( 76), V(117) },
- { V( 79), V( 0), V(45), V(65), V( 94), V( 92), V(105) } }
+ // 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 Value ShelterStrength[int(FILE_NB) / 2][RANK_NB] = {
+ { V( -6), V( 81), V( 93), V( 58), V( 39), V( 18), V( 25) },
+ { V(-43), V( 61), V( 35), V(-49), V(-29), V(-11), V( -63) },
+ { V(-10), V( 75), V( 23), V( -2), V( 32), V( 3), V( -45) },
+ { V(-39), V(-13), V(-29), V(-52), V(-48), V(-67), V(-166) }
};
- // Danger of enemy pawns moving toward our king by [type][distance from edge][rank].
- // For the unopposed and unblocked cases, RANK_1 = 0 is used when opponent has
- // no pawn on the given file, or their pawn is behind our king.
- const Value StormDanger[][4][RANK_NB] = {
- { { V( 0), V(-290), V(-274), V(57), V(41) }, // BlockedByKing
- { V( 0), V( 60), V( 144), V(39), V(13) },
- { V( 0), V( 65), V( 141), V(41), V(34) },
- { V( 0), V( 53), V( 127), V(56), V(14) } },
- { { V( 4), V( 73), V( 132), V(46), V(31) }, // Unopposed
- { V( 1), V( 64), V( 143), V(26), V(13) },
- { V( 1), V( 47), V( 110), V(44), V(24) },
- { V( 0), V( 72), V( 127), V(50), V(31) } },
- { { V( 0), V( 0), V( 79), V(23), V( 1) }, // BlockedByPawn
- { V( 0), V( 0), V( 148), V(27), V( 2) },
- { V( 0), V( 0), V( 161), V(16), V( 1) },
- { V( 0), V( 0), V( 171), V(22), V(15) } },
- { { V(22), V( 45), V( 104), V(62), V( 6) }, // Unblocked
- { V(31), V( 30), V( 99), V(39), V(19) },
- { V(23), V( 29), V( 96), V(41), V(15) },
- { V(21), V( 23), V( 116), V(41), V(15) } }
+ // 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.
+ 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) }
};
- // Max bonus for king safety. Corresponds to start position with all the pawns
- // in front of the king and no enemy pawn on the horizon.
- const Value MaxSafetyBonus = V(258);
-
#undef S
#undef V
template<Color Us>
Score evaluate(const Position& pos, Pawns::Entry* e) {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Direction Up = (Us == WHITE ? NORTH : SOUTH);
+ 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;
doubled = ourPawns & (s - Up);
neighbours = ourPawns & adjacent_files_bb(f);
phalanx = neighbours & rank_bb(s);
- supported = 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.
- if (!neighbours || lever || relative_rank(Us, s) >= RANK_5)
- backward = false;
- else
- {
- // Find the backmost rank with neighbours or stoppers
- b = rank_bb(backmost_sq(Us, neighbours | stoppers));
-
- // The pawn is backward when it cannot safely progress to that rank:
- // either there is a stopper in the way on this rank, or there is a
- // stopper on adjacent file which controls the way to that rank.
- backward = (b | shift<Up>(b & adjacent_files_bb(f))) & stoppers;
+ support = neighbours & rank_bb(s - Up);
- assert(!(backward && (forward_ranks_bb(Them, s + Up) & neighbours)));
- }
+ // 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))
+ && (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)
- && !(ourPawns & forward_file_bb(Us, s))
- && popcount(supported) >= popcount(lever)
- && popcount(phalanx) >= popcount(leverPush))
+ && popcount(support) >= popcount(lever) - 1
+ && popcount(phalanx) >= popcount(leverPush))
e->passedPawns[Us] |= s;
else if ( stoppers == SquareBB[s + Up]
&& relative_rank(Us, s) >= 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)
+ score += Connected[opposed][bool(phalanx)][popcount(support)][relative_rank(Us, s)];
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;
}
void init() {
- static const int Seed[RANK_NB] = { 0, 13, 24, 18, 76, 100, 175, 330 };
+ 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)
e->key = key;
e->scores[WHITE] = evaluate<WHITE>(pos, e);
e->scores[BLACK] = evaluate<BLACK>(pos, e);
- e->asymmetry = popcount(e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK]);
- 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;
}
-/// Entry::shelter_storm() calculates shelter and storm penalties for the file
-/// the king is on, as well as the two closest files.
+/// Entry::evaluate_shelter() calculates the shelter bonus and the storm
+/// penalty for a king, looking at the king file and the two closest files.
template<Color Us>
-Value Entry::shelter_storm(const Position& pos, Square ksq) {
-
- const Color Them = (Us == WHITE ? BLACK : WHITE);
+Value Entry::evaluate_shelter(const Position& pos, Square ksq) {
- enum { BlockedByKing, Unopposed, BlockedByPawn, Unblocked };
+ constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
+ constexpr Direction Down = (Us == WHITE ? SOUTH : NORTH);
+ constexpr Bitboard BlockRanks = (Us == WHITE ? Rank1BB | Rank2BB : Rank8BB | Rank7BB);
- Bitboard b = pos.pieces(PAWN) & (forward_ranks_bb(Us, ksq) | rank_bb(ksq));
+ Bitboard b = pos.pieces(PAWN) & ~forward_ranks_bb(Them, ksq);
Bitboard ourPawns = b & pos.pieces(Us);
Bitboard theirPawns = b & pos.pieces(Them);
- Value safety = MaxSafetyBonus;
- File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq)));
+ Value safety = (shift<Down>(theirPawns) & (FileABB | FileHBB) & BlockRanks & ksq) ?
+ Value(374) : Value(5);
+
+ File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq)));
for (File f = File(center - 1); f <= File(center + 1); ++f)
{
b = ourPawns & file_bb(f);
- Rank rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1;
+ Rank ourRank = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1;
b = theirPawns & file_bb(f);
- Rank rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;
+ Rank theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;
int d = std::min(f, ~f);
- safety -= ShelterWeakness[f == file_of(ksq)][d][rkUs]
- + StormDanger
- [f == file_of(ksq) && rkThem == relative_rank(Us, ksq) + 1 ? BlockedByKing :
- rkUs == RANK_1 ? Unopposed :
- rkThem == rkUs + 1 ? BlockedByPawn : Unblocked]
- [d][rkThem];
+ safety += ShelterStrength[d][ourRank];
+ safety -= (ourRank && (ourRank == theirRank - 1)) ? 66 * (theirRank == RANK_3)
+ : UnblockedStorm[d][theirRank];
}
return safety;
/// when king square changes, which is about 20% of total king_safety() calls.
template<Color Us>
-Score Entry::do_king_safety(const Position& pos, Square ksq) {
+Score Entry::do_king_safety(const Position& pos) {
+ Square ksq = pos.square<KING>(Us);
kingSquares[Us] = ksq;
- castlingRights[Us] = pos.can_castle(Us);
+ castlingRights[Us] = pos.castling_rights(Us);
int minKingPawnDistance = 0;
Bitboard pawns = pos.pieces(Us, PAWN);
if (pawns)
- while (!(DistanceRingBB[ksq][minKingPawnDistance++] & pawns)) {}
+ while (!(DistanceRingBB[ksq][++minKingPawnDistance] & pawns)) {}
- Value bonus = shelter_storm<Us>(pos, ksq);
+ Value bonus = evaluate_shelter<Us>(pos, ksq);
// If we can castle use the bonus after the castling if it is bigger
- if (pos.can_castle(MakeCastling<Us, KING_SIDE>::right))
- bonus = std::max(bonus, shelter_storm<Us>(pos, relative_square(Us, SQ_G1)));
+ if (pos.can_castle(Us | KING_SIDE))
+ bonus = std::max(bonus, evaluate_shelter<Us>(pos, relative_square(Us, SQ_G1)));
- if (pos.can_castle(MakeCastling<Us, QUEEN_SIDE>::right))
- bonus = std::max(bonus, shelter_storm<Us>(pos, relative_square(Us, SQ_C1)));
+ if (pos.can_castle(Us | QUEEN_SIDE))
+ bonus = std::max(bonus, evaluate_shelter<Us>(pos, relative_square(Us, SQ_C1)));
return make_score(bonus, -16 * minKingPawnDistance);
}
// Explicit template instantiation
-template Score Entry::do_king_safety<WHITE>(const Position& pos, Square ksq);
-template Score Entry::do_king_safety<BLACK>(const Position& pos, Square ksq);
+template Score Entry::do_king_safety<WHITE>(const Position& pos);
+template Score Entry::do_king_safety<BLACK>(const Position& pos);
} // namespace Pawns
projects / stockfish / blobdiff