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 { Mobility, PawnStructure, PassedPawns, Space, KingSafety };
-
- const struct Weight { int mg, eg; } Weights[] = {
- {266, 334}, {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)
// MobilityBonus[PieceType][attacked] contains bonuses for middle and end
- // game, indexed by piece type and number of attacked squares not occupied by
- // friendly pieces.
+ // game, indexed by piece type and number of attacked squares in the MobilityArea.
const Score MobilityBonus[][32] = {
{}, {},
- { S(-70,-52), S(-52,-37), S( -7,-17), S( 0, -6), S( 8, 5), S( 16, 9), // Knights
- S( 23, 20), S( 31, 21), S( 36, 22) },
- { S(-49,-44), S(-22,-13), S( 16, 0), S( 27, 11), S( 38, 19), S( 52, 34), // Bishops
- S( 56, 44), S( 65, 47), S( 67, 51), S( 73, 56), S( 81, 59), S( 83, 69),
- S( 95, 72), S(100, 75) },
- { S(-49,-57), S(-22,-14), S(-10, 18), S( -5, 39), S( -4, 50), S( -2, 58), // Rooks
- S( 6, 78), S( 11, 86), S( 17, 92), S( 19,103), S( 26,111), S( 27,115),
- S( 36,119), S( 41,121), S( 50,122) },
- { S(-41,-24), S(-26, -8), S( 0, 6), S( 2, 14), S( 12, 27), S( 21, 40), // Queens
- S( 22, 45), S( 37, 55), S( 40, 57), S( 43, 63), S( 50, 68), S( 52, 74),
- S( 56, 80), S( 66, 84), S( 68, 85), S( 69, 88), S( 71, 92), S( 72, 94),
- S( 80, 96), S( 89, 98), S( 94,101), S(102,113), S(106,114), S(107,116),
- S(112,125), S(113,127), S(117,137), S(122,143) }
+ { S(-75,-76), S(-56,-54), S(- 9,-26), S( -2,-10), S( 6, 5), S( 15, 11), // Knights
+ S( 22, 26), S( 30, 28), S( 36, 29) },
+ { S(-48,-58), S(-21,-19), S( 16, -2), S( 26, 12), S( 37, 22), S( 51, 42), // Bishops
+ S( 54, 54), S( 63, 58), S( 65, 63), S( 71, 70), S( 79, 74), S( 81, 86),
+ S( 92, 90), S( 97, 94) },
+ { S(-56,-78), S(-25,-18), S(-11, 26), S( -5, 55), S( -4, 70), S( -1, 81), // Rooks
+ S( 8,109), S( 14,120), S( 21,128), S( 23,143), S( 31,154), S( 32,160),
+ S( 43,165), S( 49,168), S( 59,169) },
+ { S(-40,-35), S(-25,-12), S( 2, 7), S( 4, 19), S( 14, 37), S( 24, 55), // Queens
+ S( 25, 62), S( 40, 76), S( 43, 79), S( 47, 87), S( 54, 94), S( 56,102),
+ S( 60,111), S( 70,116), S( 72,118), S( 73,122), S( 75,128), S( 77,130),
+ S( 85,133), S( 94,136), S( 99,140), S(108,157), S(112,158), S(113,161),
+ S(118,174), S(119,177), S(123,191), S(128,199) }
};
// Outpost[knight/bishop][supported by pawn] contains bonuses for knights and
{ S( 8, 2), S(13, 4) } // Bishops
};
- // Threat[minor/rook][attacked PieceType] contains
+ // RookOnFile[semiopen/open] contains bonuses for each rook when there is no
+ // friendly pawn on the rook file.
+ 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 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.
- const Score Threat[2][PIECE_TYPE_NB] = {
- { S(0, 0), S(0, 33), S(45, 43), S(46, 47), S(72, 107), S(48,118) }, // Minor attacks
- { S(0, 0), S(0, 25), S(40, 62), S(40, 59), S( 0, 34), S(35, 48) } // Rook attacks
+ // 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
};
- // ThreatenedByPawn[PieceType] contains a penalty according to which piece
- // type is attacked by a pawn.
- const Score ThreatenedByPawn[PIECE_TYPE_NB] = {
- S(0, 0), S(0, 0), S(176, 139), S(131, 127), S(217, 218), S(203, 215)
- };
+ // 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) };
// 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[] = {
- S( 12, 10), S( 3, 10), S( 1, -8), S(-27, -12),
- S(-27, -12), S( 1, -8), S( 3, 10), S( 12, 10)
+ // 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)
};
- const Score ThreatenedByHangingPawn = S(70, 63);
-
// Assorted bonuses and penalties used by evaluation
- const Score KingOnOne = S( 3, 62);
- const Score KingOnMany = S( 9,138);
- const Score RookOnPawn = S( 7, 27);
- const Score RookOnOpenFile = S(43, 21);
- const Score RookOnSemiOpenFile = S(19, 10);
- const Score BishopPawns = S( 8, 12);
- const Score MinorBehindPawn = S(16, 0);
- const Score TrappedRook = S(92, 0);
- const Score Unstoppable = S( 0, 20);
- const Score Hanging = S(48, 28);
- const Score PawnAttackThreat = S(31, 19);
- const Score Checked = S(20, 20);
+ const Score MinorBehindPawn = S(16, 0);
+ const Score BishopPawns = S( 8, 12);
+ const Score RookOnPawn = S( 7, 27);
+ const Score TrappedRook = S(92, 0);
+ const Score Checked = S(20, 20);
+ const Score ThreatByHangingPawn = S(70, 63);
+ const Score Hanging = S(48, 28);
+ const Score ThreatByPawnPush = S(31, 19);
+ const Score Unstoppable = S( 0, 20);
// 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
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);
{
Bitboard alignedPawns = pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s];
if (alignedPawns)
- score += popcount<Max15>(alignedPawns) * RookOnPawn;
+ score += RookOnPawn * popcount<Max15>(alignedPawns);
}
// Bonus when on an open or semi-open file
if (ei.pi->semiopen_file(Us, file_of(s)))
- score += ei.pi->semiopen_file(Them, file_of(s)) ? RookOnOpenFile : RookOnSemiOpenFile;
+ score += RookOnFile[!!ei.pi->semiopen_file(Them, file_of(s))];
- // Penalize when trapped by the king, even more if king cannot castle
- if (mob <= 3 && !ei.pi->semiopen_file(Us, file_of(s)))
+ // 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) {
safeThreats = (shift_bb<Right>(b) | shift_bb<Left>(b)) & weak;
if (weak ^ safeThreats)
- score += ThreatenedByHangingPawn;
+ score += ThreatByHangingPawn;
while (safeThreats)
- score += ThreatenedByPawn[type_of(pos.piece_on(pop_lsb(&safeThreats)))];
+ score += ThreatBySafePawn[type_of(pos.piece_on(pop_lsb(&safeThreats)))];
}
// Non-pawn enemies defended by a pawn
b = weak & ei.attackedBy[Us][KING];
if (b)
- score += more_than_one(b) ? KingOnMany : KingOnOne;
+ score += ThreatByKing[more_than_one(b)];
}
// Bonus if some pawns can safely push and attack an enemy piece
& ~ei.attackedBy[Us][PAWN];
if (b)
- score += popcount<Max15>(b) * PawnAttackThreat;
+ score += ThreatByPawnPush * popcount<Max15>(b);
if (DoTrace)
Trace::add(THREAT, Us, score);
// 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);
assert(!pos.checkers());
EvalInfo ei;
- Score score, mobility[2] = { SCORE_ZERO, SCORE_ZERO };
+ Score score, mobility[COLOR_NB] = { SCORE_ZERO, SCORE_ZERO };
// Initialize score by reading the incrementally updated scores included in
// the position object (material + piece square tables). Score is computed
// 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 all pieces but king and pawns
score += evaluate_pieces<DoTrace>(pos, ei, mobility, mobilityArea);
- score += (mobility[WHITE] - mobility[BLACK]) * Weights[Mobility];
+ score += mobility[WHITE] - mobility[BLACK];
// Evaluate kings after all other pieces because we need full attack
// information when computing the king safety evaluation.
{
Bitboard b;
if ((b = ei.pi->passed_pawns(WHITE)) != 0)
- score += int(relative_rank(WHITE, frontmost_sq(WHITE, b))) * Unstoppable;
+ score += Unstoppable * int(relative_rank(WHITE, frontmost_sq(WHITE, b)));
if ((b = ei.pi->passed_pawns(BLACK)) != 0)
- score -= int(relative_rank(BLACK, frontmost_sq(BLACK, b))) * Unstoppable;
+ 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)
- - 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());
- Trace::add(MOBILITY, mobility[WHITE] * Weights[Mobility]
- , mobility[BLACK] * Weights[Mobility]);
- Trace::add(SPACE, evaluate_space<WHITE>(pos, ei) * Weights[Space]
- , evaluate_space<BLACK>(pos, ei) * Weights[Space]);
+ Trace::add(MOBILITY, mobility[WHITE], mobility[BLACK]);
+ 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