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
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
namespace Trace {
- enum Term { // First 8 entries are for PieceType
+ enum Term { // The first 8 entries are for PieceType
MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, TOTAL, TERM_NB
};
// which attack a square in the kingRing of the enemy king.
int kingAttackersCount[COLOR_NB];
- // kingAttackersWeight[color] is the sum of the "weight" of the pieces of the
+ // kingAttackersWeight[color] is the sum of the "weights" of the pieces of the
// given color which attack a square in the kingRing of the enemy king. The
// weights of the individual piece types are given by the elements in the
// KingAttackWeights array.
Pawns::Entry* pi;
};
-
- // Evaluation weights, indexed by the corresponding evaluation term
- enum { PawnStructure, PassedPawns, Space, KingSafety };
-
- const struct Weight { int mg, eg; } Weights[] = {
- {214, 203}, {193, 262}, {47, 0}, {330, 0} };
-
- Score operator*(Score s, const Weight& w) {
- return make_score(mg_value(s) * w.mg / 256, eg_value(s) * w.eg / 256);
- }
-
-
#define V(v) Value(v)
#define S(mg, eg) make_score(mg, eg)
const Score RookOnFile[2] = { S(19, 10), S(43, 21) };
// ThreatBySafePawn[PieceType] contains bonuses according to which piece
- // type is attacked by a pawn which is protected or not attacked.
+ // type is attacked by a pawn which is protected or is not attacked.
const Score ThreatBySafePawn[PIECE_TYPE_NB] = {
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.
+ // 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
};
// ThreatByKing[on one/on many] contains bonuses for King attacks on
- // pawns or pieces which are not pawn defended.
+ // pawns or pieces which are not pawn-defended.
const Score ThreatByKing[2] = { S(3, 62), S(9, 138) };
// Passed[mg/eg][Rank] contains midgame and endgame bonuses for passed pawns.
// We don't use a Score because we process the two components independently.
const Value Passed[][RANK_NB] = {
- { V(0), V( 1), V(34), V(90), V(214), V(328) },
- { V(7), V(14), V(37), V(63), V(134), V(189) }
+ { V(0), V( 1), V(26), V(68), V(161), V(247) },
+ { V(7), V(14), V(38), V(64), V(137), V(193) }
};
// PassedFile[File] contains a bonus according to the file of a passed pawn
const Score PassedFile[FILE_NB] = {
- S( 12, 10), S( 3, 10), S( 1, -8), S(-27,-12),
- S(-27,-12), S( 1, -8), S( 3, 10), S( 12, 10)
+ S( 9, 10), S( 2, 10), S( 1, -8), S(-20,-12),
+ S(-20,-12), S( 1, -8), S( 2, 10), S( 9, 10)
};
// Assorted bonuses and penalties used by evaluation
const int KnightCheck = 14;
- // eval_init() initializes king and attack bitboards for given color
+ // eval_init() initializes king and attack bitboards for a given color
// adding pawn attacks. To be done at the beginning of the evaluation.
template<Color Us>
&& (pos.pieces(PAWN) & (s + pawn_push(Us))))
score += MinorBehindPawn;
- // Penalty for pawns on same color square of bishop
+ // Penalty for pawns on the same color square as the bishop
if (Pt == BISHOP)
score -= BishopPawns * ei.pi->pawns_on_same_color_squares(Us, s);
if (ei.pi->semiopen_file(Us, file_of(s)))
score += RookOnFile[!!ei.pi->semiopen_file(Them, file_of(s))];
- // Penalize when trapped by the king, even more if king cannot castle
+ // Penalize when trapped by the king, even more if the king cannot castle
else if (mob <= 3)
{
Square ksq = pos.square<KING>(Us);
if (DoTrace)
Trace::add(Pt, Us, score);
- // Recursively call evaluate_pieces() of next piece type until KING excluded
+ // Recursively call evaluate_pieces() of next piece type until KING is excluded
return score - evaluate_pieces<DoTrace, Them, NextPt>(pos, ei, mobility, mobilityArea);
}
}
// Finally, extract the king danger score from the KingDanger[]
- // array and subtract the score from evaluation.
+ // array and subtract the score from the evaluation.
score -= KingDanger[std::max(std::min(attackUnits, 399), 0)];
}
}
- // evaluate_threats() assigns bonuses according to the type of attacking piece
- // and the type of attacked one.
+ // evaluate_threats() assigns bonuses according to the types of the attacking
+ // and the attacked pieces.
template<Color Us, bool DoTrace>
Score evaluate_threats(const Position& pos, const EvalInfo& ei) {
// assign a smaller bonus if the block square isn't attacked.
int k = !unsafeSquares ? 18 : !(unsafeSquares & blockSq) ? 8 : 0;
- // If the path to queen is fully defended, assign a big bonus.
+ // If the path to the queen is fully defended, assign a big bonus.
// Otherwise assign a smaller bonus if the block square is defended.
if (defendedSquares == squaresToQueen)
k += 6;
else if (defendedSquares & blockSq)
k += 4;
- mbonus += k * rr, ebonus += k * rr;
+ mbonus += k * rr * 3 / 4, ebonus += k * rr;
}
else if (pos.pieces(Us) & blockSq)
- mbonus += rr * 3 + r * 2 + 3, ebonus += rr + r * 2;
+ mbonus += (rr * 3 + r * 2 + 3) * 3 / 4, ebonus += rr + r * 2;
} // rr != 0
if (pos.count<PAWN>(Us) < pos.count<PAWN>(Them))
}
if (DoTrace)
- Trace::add(PASSED, Us, score * Weights[PassedPawns]);
+ Trace::add(PASSED, Us, score);
// Add the scores to the middlegame and endgame eval
- return score * Weights[PassedPawns];
+ return score;
}
int weight = pos.count<KNIGHT>(Us) + pos.count<BISHOP>(Us)
+ pos.count<KNIGHT>(Them) + pos.count<BISHOP>(Them);
- return make_score(bonus * weight * weight, 0);
+ return make_score(bonus * weight * weight * 2 / 11, 0);
}
// evaluate_initiative() computes the initiative correction value for the
- // position, i.e. second order bonus/malus based on the known attacking/defending
+ // position, i.e., second order bonus/malus based on the known attacking/defending
// status of the players.
Score evaluate_initiative(const Position& pos, int asymmetry, Value eg) {
if (pos.opposite_bishops())
{
// Endgame with opposite-colored bishops and no other pieces (ignoring pawns)
- // is almost a draw, in case of KBP vs KB is even more a draw.
+ // is almost a draw, in case of KBP vs KB, it is even more a draw.
if ( pos.non_pawn_material(WHITE) == BishopValueMg
&& pos.non_pawn_material(BLACK) == BishopValueMg)
sf = more_than_one(pos.pieces(PAWN)) ? ScaleFactor(31) : ScaleFactor(9);
// Probe the pawn hash table
ei.pi = Pawns::probe(pos);
- score += ei.pi->pawns_score() * Weights[PawnStructure];
+ score += ei.pi->pawns_score();
// Initialize attack and king safety bitboards
ei.attackedBy[WHITE][ALL_PIECES] = ei.attackedBy[BLACK][ALL_PIECES] = 0;
// 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)
- - evaluate_space<BLACK>(pos, ei)) * Weights[Space];
+ score += evaluate_space<WHITE>(pos, ei)
+ - evaluate_space<BLACK>(pos, ei);
// Evaluate position potential for the winning side
score += evaluate_initiative(pos, ei.pi->pawn_asymmetry(), eg_value(score));
{
Trace::add(MATERIAL, pos.psq_score());
Trace::add(IMBALANCE, ei.me->imbalance());
- Trace::add(PAWN, ei.pi->pawns_score() * Weights[PawnStructure]);
+ Trace::add(PAWN, ei.pi->pawns_score());
Trace::add(MOBILITY, mobility[WHITE], mobility[BLACK]);
- Trace::add(SPACE, evaluate_space<WHITE>(pos, ei) * Weights[Space]
- , evaluate_space<BLACK>(pos, ei) * Weights[Space]);
+ Trace::add(SPACE, evaluate_space<WHITE>(pos, ei)
+ , evaluate_space<BLACK>(pos, ei));
Trace::add(TOTAL, score);
}
void Eval::init() {
- const int MaxSlope = 8700;
- const int Peak = 1280000;
+ const int MaxSlope = 322;
+ const int Peak = 47410;
int t = 0;
for (int i = 0; i < 400; ++i)
{
- t = std::min(Peak, std::min(i * i * 27, t + MaxSlope));
- KingDanger[i] = make_score(t / 1000, 0) * Weights[KingSafety];
+ t = std::min(Peak, std::min(i * i - 16, t + MaxSlope));
+ KingDanger[i] = make_score(t * 268 / 7700, 0);
}
}
projects / stockfish / blobdiff