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) 2015-2017 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
Score Connected[2][2][2][RANK_NB];
// Doubled pawn penalty
- const Score Doubled = S(18,38);
+ const Score Doubled = S(18, 38);
// Lever bonus by rank
const Score Lever[RANK_NB] = {
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]
+ // Weakness of our pawn shelter in front of the king by [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[][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( 75), V(12), V(43), V(59), V(90), V( 84), V(112) }
};
- // 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
const Square Left = (Us == WHITE ? NORTH_WEST : SOUTH_EAST);
Bitboard b, neighbours, stoppers, doubled, supported, phalanx;
+ Bitboard lever, leverPush, connected;
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)];
opposed = theirPawns & forward_bb(Us, s);
stoppers = theirPawns & passed_pawn_mask(Us, s);
lever = theirPawns & pawnAttacksBB[s];
- doubled = ourPawns & (s + Up);
+ leverPush = theirPawns & pawnAttacksBB[s + Up];
+ doubled = ourPawns & (s - Up);
neighbours = ourPawns & adjacent_files_bb(f);
phalanx = neighbours & rank_bb(s);
supported = neighbours & rank_bb(s - Up);
}
// 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_bb(Us, s))
+ && popcount(supported) >= popcount(lever)
+ && popcount(phalanx) >= popcount(leverPush))
e->passedPawns[Us] |= s;
// Score this pawn
if (connected)
score += Connected[opposed][!!phalanx][more_than_one(supported)][relative_rank(Us, s)];
- if (doubled)
- score -= Doubled;
+ if (doubled && !supported)
+ score -= Doubled;
if (lever)
score += Lever[relative_rank(Us, s)];
{
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);
+ Connected[opposed][phalanx][apex][r] = make_score(v, v * (r-2) / 4);
}
}
/// 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 ourPawns = b & pos.pieces(Us);
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, FILE_H - f);
+ safety -= ShelterWeakness[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