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) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2015-2018 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 by opposed flag
- const Score Isolated[2] = { S(45, 40), S(30, 27) };
+ // Isolated pawn penalty
+ const Score Isolated = S(13, 18);
- // Backward pawn penalty by opposed flag
- const Score Backward[2] = { S(56, 33), S(41, 19) };
+ // Backward pawn penalty
+ const Score Backward = S(24, 12);
- // Unsupported pawn penalty for pawns which are neither isolated or backward
- const Score Unsupported = S(17, 8);
-
- // Connected pawn bonus by opposed, phalanx, twice supported and rank
- Score Connected[2][2][2][RANK_NB];
+ // 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);
-
- // Lever bonus by rank
- const Score Lever[RANK_NB] = {
- S( 0, 0), S( 0, 0), S(0, 0), S(0, 0),
- S(17, 16), S(33, 32), S(0, 0), S(0, 0)
- };
-
- // Weakness of our pawn shelter in front of the king by [distance from edge][rank]
- const Value ShelterWeakness[][RANK_NB] = {
- { V(100), V(20), V(10), V(46), V(82), V( 86), V( 98) },
- { V(116), V( 4), V(28), V(87), V(94), V(108), V(104) },
- { V(109), V( 1), V(59), V(87), V(62), V( 91), V(116) },
- { V( 75), V(12), V(43), V(59), V(90), V( 84), V(112) }
+ 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) } }
};
- // Danger of enemy pawns moving toward our king by [type][distance from edge][rank]
+ // 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( 4), V( 73), V( 132), V(46), V(31) },
+ { { 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(22), V( 45), V( 104), V(62), V( 6) },
- { 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) } },
- { { V( 0), V( 0), V( 79), V(23), V( 1) },
+ { { 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( 0), V(-290), V(-274), V(57), V(41) },
- { 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(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) } }
};
// Max bonus for king safety. Corresponds to start position with all the pawns
template<Color Us>
Score evaluate(const Position& pos, Pawns::Entry* e) {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Square Up = (Us == WHITE ? NORTH : SOUTH);
- const Square Right = (Us == WHITE ? NORTH_EAST : SOUTH_WEST);
- const Square Left = (Us == WHITE ? NORTH_WEST : SOUTH_EAST);
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Direction Up = (Us == WHITE ? NORTH : SOUTH);
Bitboard b, neighbours, stoppers, doubled, supported, phalanx;
+ Bitboard lever, leverPush;
Square s;
- bool opposed, lever, connected, backward;
+ bool opposed, backward;
Score score = SCORE_ZERO;
const Square* pl = pos.squares<PAWN>(Us);
- const Bitboard* pawnAttacksBB = StepAttacksBB[make_piece(Us, PAWN)];
- Bitboard ourPawns = pos.pieces(Us , PAWN);
+ Bitboard ourPawns = pos.pieces( Us, PAWN);
Bitboard theirPawns = pos.pieces(Them, PAWN);
- e->passedPawns[Us] = e->pawnAttacksSpan[Us] = 0;
+ e->passedPawns[Us] = e->pawnAttacksSpan[Us] = e->weakUnopposed[Us] = 0;
e->semiopenFiles[Us] = 0xFF;
e->kingSquares[Us] = SQ_NONE;
- e->pawnAttacks[Us] = shift<Right>(ourPawns) | shift<Left>(ourPawns);
+ 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];
e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s);
// Flag the pawn
- opposed = theirPawns & forward_bb(Us, s);
+ opposed = theirPawns & forward_file_bb(Us, s);
stoppers = theirPawns & passed_pawn_mask(Us, s);
- lever = theirPawns & pawnAttacksBB[s];
- doubled = ourPawns & (s + Up);
+ 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);
- connected = supported | phalanx;
// A pawn is backward when it is behind all pawns of the same color on the
// adjacent files and cannot be safely advanced.
// stopper on adjacent file which controls the way to that rank.
backward = (b | shift<Up>(b & adjacent_files_bb(f))) & stoppers;
- assert(!backward || !(pawn_attack_span(Them, s + Up) & neighbours));
+ assert(!(backward && (forward_ranks_bb(Them, s + Up) & neighbours)));
}
// Passed pawns will be properly scored in evaluation because we need
- // full attack info to evaluate them.
- if (!stoppers && !(ourPawns & forward_bb(Us, s)))
+ // 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))
e->passedPawns[Us] |= s;
- // Score this pawn
- if (!neighbours)
- score -= Isolated[opposed];
+ else if ( stoppers == SquareBB[s + Up]
+ && relative_rank(Us, s) >= RANK_5)
+ {
+ b = shift<Up>(supported) & ~theirPawns;
+ while (b)
+ if (!more_than_one(theirPawns & PawnAttacks[Us][pop_lsb(&b)]))
+ e->passedPawns[Us] |= s;
+ }
- else if (backward)
- score -= Backward[opposed];
+ if (e->passedPawns[Us] & s)
+ e->asymmetry++;
- else if (!supported)
- score -= Unsupported;
+ // Score this pawn
+ if (supported | phalanx)
+ score += Connected[opposed][bool(phalanx)][popcount(supported)][relative_rank(Us, s)];
- if (connected)
- score += Connected[opposed][!!phalanx][more_than_one(supported)][relative_rank(Us, s)];
+ else if (!neighbours)
+ score -= Isolated, e->weakUnopposed[Us] += !opposed;
- if (doubled)
- score -= Doubled;
+ else if (backward)
+ score -= Backward, e->weakUnopposed[Us] += !opposed;
- if (lever)
- score += Lever[relative_rank(Us, s)];
+ if (doubled && !supported)
+ score -= Doubled;
}
return score;
void init() {
- static const int Seed[RANK_NB] = { 0, 8, 19, 13, 71, 94, 169, 324 };
+ static const int Seed[RANK_NB] = { 0, 13, 24, 18, 76, 100, 175, 330 };
for (int opposed = 0; opposed <= 1; ++opposed)
for (int phalanx = 0; phalanx <= 1; ++phalanx)
- for (int apex = 0; apex <= 1; ++apex)
+ for (int support = 0; support <= 2; ++support)
for (Rank r = RANK_2; r < RANK_8; ++r)
{
- int v = (Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0)) >> opposed;
- v += (apex ? v / 2 : 0);
- Connected[opposed][phalanx][apex][r] = make_score(v, v * 5 / 8);
+ 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);
}
}
return e;
e->key = key;
- e->score = evaluate<WHITE>(pos, e) - evaluate<BLACK>(pos, e);
- e->asymmetry = popcount(e->semiopenFiles[WHITE] ^ e->semiopenFiles[BLACK]);
- e->openFiles = popcount(e->semiopenFiles[WHITE] & e->semiopenFiles[BLACK]);
+ e->asymmetry = 0;
+ 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]);
+
return e;
}
/// Entry::shelter_storm() calculates shelter and storm penalties for the file
-/// the king is on, as well as the two adjacent files.
+/// the king is on, as well as the two closest files.
template<Color Us>
Value Entry::shelter_storm(const Position& pos, Square ksq) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
- enum { NoFriendlyPawn, Unblocked, BlockedByPawn, BlockedByKing };
+ enum { BlockedByKing, Unopposed, BlockedByPawn, Unblocked };
- Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, rank_of(ksq)) | rank_bb(ksq));
+ Bitboard b = pos.pieces(PAWN) & (forward_ranks_bb(Us, ksq) | rank_bb(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)));
- for (File f = center - File(1); f <= center + File(1); ++f)
+ 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;
- b = theirPawns & file_bb(f);
+ b = theirPawns & file_bb(f);
Rank rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;
- safety -= ShelterWeakness[std::min(f, FILE_H - f)][rkUs]
+ 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 ? NoFriendlyPawn :
+ rkUs == RANK_1 ? Unopposed :
rkThem == rkUs + 1 ? BlockedByPawn : Unblocked]
- [std::min(f, FILE_H - f)][rkThem];
+ [d][rkThem];
}
return safety;
projects / stockfish / blobdiff