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
S(0, 0), S(0, 0), S(176, 139), S(131, 127), S(217, 218), S(203, 215)
};
- // Threat[by minor/by rook][attacked PieceType] contains
- // bonuses according to which piece type attacks which one.
- // Attacks on lesser pieces which are pawn-defended are not considered.
- const Score Threat[][PIECE_TYPE_NB] = {
- { S(0, 0), S(0, 33), S(45, 43), S(46, 47), S(72,107), S(48,118) }, // by Minor
- { S(0, 0), S(0, 25), S(40, 62), S(40, 59), S( 0, 34), S(35, 48) } // by Rook
+ // ThreatByMinor/ByRook[attacked PieceType] contains bonuses according to
+ // which piece type attacks which one. Attacks on lesser pieces which are
+ // pawn-defended are not considered.
+ const Score ThreatByMinor[PIECE_TYPE_NB] = {
+ S(0, 0), S(0, 33), S(45, 43), S(46, 47), S(72, 107), S(48, 118)
};
- // ThreatByKing[on one/on many] contains bonuses for King attacks on
+ const Score ThreatByRook[PIECE_TYPE_NB] = {
+ S(0, 0), S(0, 25), S(40, 62), S(40, 59), S( 0, 34), S(35, 48)
+ };
+
+ // ThreatByKing[on one/on many] contains bonuses for king attacks on
// pawns or pieces which are not pawn-defended.
const Score ThreatByKing[2] = { S(3, 62), S(9, 138) };
// PassedFile[File] contains a bonus according to the file of a passed pawn
const Score PassedFile[FILE_NB] = {
S( 9, 10), S( 2, 10), S( 1, -8), S(-20,-12),
- S(-20,-12), S( 1, -8), S( 2, 10), S( 9, 10)
+ S(-20,-12), S( 1, -8), S( 2, 10), S( 9, 10)
};
// Assorted bonuses and penalties used by evaluation
const Score BishopPawns = S( 8, 12);
const Score RookOnPawn = S( 8, 24);
const Score TrappedRook = S(92, 0);
- const Score CloseEnemies = S( 7, 0);
- const Score SafeCheck = S(20, 20);
+ const Score WeakQueen = S(50, 10);
const Score OtherCheck = S(10, 10);
- const Score ThreatByHangingPawn = S(71, 61);
+ const Score CloseEnemies = S( 7, 0);
+ const Score PawnlessFlank = S(20, 80);
const Score LooseEnemies = S( 0, 25);
- const Score WeakQueen = S(35, 0);
+ const Score ThreatByHangingPawn = S(71, 61);
+ const Score ThreatByRank = S(16, 3);
const Score Hanging = S(48, 27);
const Score ThreatByPawnPush = S(38, 22);
- const Score Unstoppable = S( 0, 20);
- const Score PawnlessFlank = S(20, 80);
const Score HinderPassedPawn = S( 7, 0);
- const Score ThreatByRank = S(16, 3);
// Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
// a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
// Penalties for enemy's safe checks
const int QueenContactCheck = 997;
- const int QueenCheck = 695;
- const int RookCheck = 638;
- const int BishopCheck = 538;
- const int KnightCheck = 874;
+ const int QueenCheck = 745;
+ const int RookCheck = 688;
+ const int BishopCheck = 588;
+ const int KnightCheck = 924;
+ // Threshold for lazy evaluation
+ const Value LazyEval = Value(1500);
// eval_init() initializes king and attack bitboards for a given color
// adding pawn attacks. To be done at the beginning of the evaluation.
if (pos.non_pawn_material(Us) >= QueenValueMg)
{
ei.kingRing[Them] = b | shift<Down>(b);
- b &= ei.attackedBy[Us][PAWN];
- ei.kingAttackersCount[Us] = popcount(b);
+ ei.kingAttackersCount[Us] = popcount(b & ei.attackedBy[Us][PAWN]);
ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
}
else
template<bool DoTrace, Color Us = WHITE, PieceType Pt = KNIGHT>
Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score* mobility,
const Bitboard* mobilityArea) {
- Bitboard b, bb;
- Square s;
- Score score = SCORE_ZERO;
-
const PieceType NextPt = (Us == WHITE ? Pt : PieceType(Pt + 1));
const Color Them = (Us == WHITE ? BLACK : WHITE);
const Bitboard OutpostRanks = (Us == WHITE ? Rank4BB | Rank5BB | Rank6BB
: Rank5BB | Rank4BB | Rank3BB);
const Square* pl = pos.squares<Pt>(Us);
+ Bitboard b, bb;
+ Square s;
+ Score score = SCORE_ZERO;
+
ei.attackedBy[Us][Pt] = 0;
while ((s = *pl++) != SQ_NONE)
Square ksq = pos.square<KING>(Us);
if ( ((file_of(ksq) < FILE_E) == (file_of(s) < file_of(ksq)))
- && (rank_of(ksq) == rank_of(s) || relative_rank(Us, ksq) == RANK_1)
&& !ei.pi->semiopen_side(Us, file_of(ksq), file_of(s) < file_of(ksq)))
score -= (TrappedRook - make_score(mob * 22, 0)) * (1 + !pos.can_castle(Us));
}
// evaluate_king() assigns bonuses and penalties to a king of a given color
- const Bitboard WhiteCamp = Rank1BB | Rank2BB | Rank3BB | Rank4BB | Rank5BB;
- const Bitboard BlackCamp = Rank8BB | Rank7BB | Rank6BB | Rank5BB | Rank4BB;
- const Bitboard QueenSide = FileABB | FileBBB | FileCBB | FileDBB;
const Bitboard CenterFiles = FileCBB | FileDBB | FileEBB | FileFBB;
- const Bitboard KingSide = FileEBB | FileFBB | FileGBB | FileHBB;
- const Bitboard KingFlank[COLOR_NB][FILE_NB] = {
- { QueenSide & WhiteCamp, QueenSide & WhiteCamp, QueenSide & WhiteCamp, CenterFiles & WhiteCamp,
- CenterFiles & WhiteCamp, KingSide & WhiteCamp, KingSide & WhiteCamp, KingSide & WhiteCamp },
- { QueenSide & BlackCamp, QueenSide & BlackCamp, QueenSide & BlackCamp, CenterFiles & BlackCamp,
- CenterFiles & BlackCamp, KingSide & BlackCamp, KingSide & BlackCamp, KingSide & BlackCamp },
+ const Bitboard KingFlank[FILE_NB] = {
+ CenterFiles >> 2, CenterFiles >> 2, CenterFiles >> 2, CenterFiles, CenterFiles,
+ CenterFiles << 2, CenterFiles << 2, CenterFiles << 2
};
template<Color Us, bool DoTrace>
Score evaluate_king(const Position& pos, const EvalInfo& ei) {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Square Up = (Us == WHITE ? NORTH : SOUTH);
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Square Up = (Us == WHITE ? NORTH : SOUTH);
+ const Bitboard Camp = (Us == WHITE ? ~Bitboard(0) ^ Rank6BB ^ Rank7BB ^ Rank8BB
+ : ~Bitboard(0) ^ Rank1BB ^ Rank2BB ^ Rank3BB);
+ const Square ksq = pos.square<KING>(Us);
Bitboard undefended, b, b1, b2, safe, other;
int kingDanger;
- const Square ksq = pos.square<KING>(Us);
// King shelter and enemy pawns storm
Score score = ei.pi->king_safety<Us>(pos, ksq);
// Enemy queen safe checks
if ((b1 | b2) & ei.attackedBy[Them][QUEEN] & safe)
- kingDanger += QueenCheck, score -= SafeCheck;
+ kingDanger += QueenCheck;
// For other pieces, also consider the square safe if attacked twice,
// and only defended by a queen.
// Enemy rooks safe and other checks
if (b1 & ei.attackedBy[Them][ROOK] & safe)
- kingDanger += RookCheck, score -= SafeCheck;
+ kingDanger += RookCheck;
else if (b1 & ei.attackedBy[Them][ROOK] & other)
score -= OtherCheck;
// Enemy bishops safe and other checks
if (b2 & ei.attackedBy[Them][BISHOP] & safe)
- kingDanger += BishopCheck, score -= SafeCheck;
+ kingDanger += BishopCheck;
else if (b2 & ei.attackedBy[Them][BISHOP] & other)
score -= OtherCheck;
// Enemy knights safe and other checks
b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT];
if (b & safe)
- kingDanger += KnightCheck, score -= SafeCheck;
+ kingDanger += KnightCheck;
else if (b & other)
score -= OtherCheck;
// King tropism: firstly, find squares that opponent attacks in our king flank
File kf = file_of(ksq);
- b = ei.attackedBy[Them][ALL_PIECES] & KingFlank[Us][kf];
+ b = ei.attackedBy[Them][ALL_PIECES] & KingFlank[kf] & Camp;
assert(((Us == WHITE ? b << 4 : b >> 4) & b) == 0);
assert(popcount(Us == WHITE ? b << 4 : b >> 4) == popcount(b));
score -= CloseEnemies * popcount(b);
// Penalty when our king is on a pawnless flank
- if (!(pos.pieces(PAWN) & (KingFlank[WHITE][kf] | KingFlank[BLACK][kf])))
+ if (!(pos.pieces(PAWN) & KingFlank[kf]))
score -= PawnlessFlank;
if (DoTrace)
const Bitboard TRank2BB = (Us == WHITE ? Rank2BB : Rank7BB);
const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
- enum { Minor, Rook };
-
Bitboard b, weak, defended, safeThreats;
Score score = SCORE_ZERO;
while (b)
{
Square s = pop_lsb(&b);
- score += Threat[Minor][type_of(pos.piece_on(s))];
+ score += ThreatByMinor[type_of(pos.piece_on(s))];
if (type_of(pos.piece_on(s)) != PAWN)
score += ThreatByRank * (int)relative_rank(Them, s);
}
while (b)
{
Square s = pop_lsb(&b);
- score += Threat[Rook][type_of(pos.piece_on(s))];
+ score += ThreatByRook[type_of(pos.piece_on(s))];
if (type_of(pos.piece_on(s)) != PAWN)
score += ThreatByRank * (int)relative_rank(Them, s);
}
mbonus += rr + r * 2, ebonus += rr + r * 2;
} // rr != 0
+ // Assign a small bonus when the opponent has no pieces left
+ if (!pos.non_pawn_material(Them))
+ ebonus += 20;
+
score += make_score(mbonus, ebonus) + PassedFile[file_of(s)];
}
const Color Them = (Us == WHITE ? BLACK : WHITE);
const Bitboard SpaceMask =
- Us == WHITE ? (FileCBB | FileDBB | FileEBB | FileFBB) & (Rank2BB | Rank3BB | Rank4BB)
- : (FileCBB | FileDBB | FileEBB | FileFBB) & (Rank7BB | Rank6BB | Rank5BB);
+ Us == WHITE ? CenterFiles & (Rank2BB | Rank3BB | Rank4BB)
+ : CenterFiles & (Rank7BB | Rank6BB | Rank5BB);
// Find the safe squares for our pieces inside the area defined by
// SpaceMask. A square is unsafe if it is attacked by an enemy
return sf;
}
+
+ Value lazy_eval(Value mg, Value eg) {
+
+ if (mg > LazyEval && eg > LazyEval)
+ return LazyEval + ((mg + eg) / 2 - LazyEval) / 4;
+
+ else if (mg < -LazyEval && eg < -LazyEval)
+ return -LazyEval + ((mg + eg) / 2 + LazyEval) / 4;
+
+ return VALUE_ZERO;
+ }
+
} // namespace
ei.pi = Pawns::probe(pos);
score += ei.pi->pawns_score();
+ // We have taken into account all cheap evaluation terms.
+ // If score exceeds a threshold return a lazy evaluation.
+ Value lazy = lazy_eval(mg_value(score), eg_value(score));
+ if (lazy)
+ return pos.side_to_move() == WHITE ? lazy : -lazy;
+
// Initialize attack and king safety bitboards
ei.attackedBy[WHITE][ALL_PIECES] = ei.attackedBy[BLACK][ALL_PIECES] = 0;
ei.attackedBy[WHITE][KING] = pos.attacks_from<KING>(pos.square<KING>(WHITE));
score += evaluate_passed_pawns<WHITE, DoTrace>(pos, ei)
- evaluate_passed_pawns<BLACK, DoTrace>(pos, ei);
- // If both sides have only pawns, score for potential unstoppable pawns
- if (!pos.non_pawn_material(WHITE) && !pos.non_pawn_material(BLACK))
- {
- Bitboard b;
- if ((b = ei.pi->passed_pawns(WHITE)) != 0)
- score += Unstoppable * int(relative_rank(WHITE, frontmost_sq(WHITE, b)));
-
- if ((b = ei.pi->passed_pawns(BLACK)) != 0)
- score -= Unstoppable * int(relative_rank(BLACK, frontmost_sq(BLACK, b)));
- }
-
// Evaluate space for both sides, only during opening
if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >= 12222)
score += evaluate_space<WHITE>(pos, ei)
projects / stockfish / blobdiff