enum Tracing { NO_TRACE, TRACE };
enum Term { // The first 8 entries are reserved for PieceType
- MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, INITIATIVE, TOTAL, TERM_NB
+ MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, WINNABLE, TOTAL, TERM_NB
};
Score scores[TERM_NB][COLOR_NB];
std::ostream& operator<<(std::ostream& os, Term t) {
- if (t == MATERIAL || t == IMBALANCE || t == INITIATIVE || t == TOTAL)
+ if (t == MATERIAL || t == IMBALANCE || t == WINNABLE || t == TOTAL)
os << " ---- ----" << " | " << " ---- ----";
else
os << scores[t][WHITE] << " | " << scores[t][BLACK];
constexpr int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 81, 52, 44, 10 };
// Penalties for enemy's safe checks
- constexpr int QueenSafeCheck = 780;
- constexpr int RookSafeCheck = 1080;
- constexpr int BishopSafeCheck = 635;
- constexpr int KnightSafeCheck = 790;
+ constexpr int QueenSafeCheck = 772;
+ constexpr int RookSafeCheck = 1084;
+ constexpr int BishopSafeCheck = 645;
+ constexpr int KnightSafeCheck = 792;
#define S(mg, eg) make_score(mg, eg)
// MobilityBonus[PieceType-2][attacked] contains bonuses for middle and end game,
// indexed by piece type and number of attacked squares in the mobility area.
constexpr Score MobilityBonus[][32] = {
- { S(-62,-81), S(-53,-56), S(-12,-30), S( -4,-14), S( 3, 8), S( 13, 15), // Knight
- S( 22, 23), S( 28, 27), S( 33, 33) },
+ { S(-62,-81), S(-53,-56), S(-12,-31), S( -4,-16), S( 3, 5), S( 13, 11), // Knight
+ S( 22, 17), S( 28, 20), S( 33, 25) },
{ S(-48,-59), S(-20,-23), S( 16, -3), S( 26, 13), S( 38, 24), S( 51, 42), // Bishop
S( 55, 54), S( 63, 57), S( 63, 65), S( 68, 73), S( 81, 78), S( 81, 86),
S( 91, 88), S( 98, 97) },
- { S(-58,-76), S(-27,-18), S(-15, 28), S(-10, 55), S( -5, 69), S( -2, 82), // Rook
- S( 9,112), S( 16,118), S( 30,132), S( 29,142), S( 32,155), S( 38,165),
- S( 46,166), S( 48,169), S( 58,171) },
- { S(-39,-36), S(-21,-15), S( 3, 8), S( 3, 18), S( 14, 34), S( 22, 54), // Queen
- S( 28, 61), S( 41, 73), S( 43, 79), S( 48, 92), S( 56, 94), S( 60,104),
- S( 60,113), S( 66,120), S( 67,123), S( 70,126), S( 71,133), S( 73,136),
- S( 79,140), S( 88,143), S( 88,148), S( 99,166), S(102,170), S(102,175),
- S(106,184), S(109,191), S(113,206), S(116,212) }
+ { S(-60,-78), S(-20,-17), S( 2, 23), S( 3, 39), S( 3, 70), S( 11, 99), // Rook
+ S( 22,103), S( 31,121), S( 40,134), S( 40,139), S( 41,158), S( 48,164),
+ S( 57,168), S( 57,169), S( 62,172) },
+ { S(-30,-48), S(-12,-30), S( -8, -7), S( -9, 19), S( 20, 40), S( 23, 55), // Queen
+ S( 23, 59), S( 35, 75), S( 38, 78), S( 53, 96), S( 64, 96), S( 65,100),
+ S( 65,121), S( 66,127), S( 67,131), S( 67,133), S( 72,136), S( 72,141),
+ S( 77,147), S( 79,150), S( 93,151), S(108,168), S(108,168), S(108,171),
+ S(110,182), S(114,182), S(114,192), S(116,219) }
};
// RookOnFile[semiopen/open] contains bonuses for each rook when there is
// no (friendly) pawn on the rook file.
- constexpr Score RookOnFile[] = { S(21, 4), S(47, 25) };
+ constexpr Score RookOnFile[] = { S(19, 7), S(48, 29) };
// ThreatByMinor/ByRook[attacked PieceType] contains bonuses according to
// which piece type attacks which one. Attacks on lesser pieces which are
};
constexpr Score ThreatByRook[PIECE_TYPE_NB] = {
- S(0, 0), S(2, 44), S(36, 71), S(36, 61), S(0, 38), S(51, 38)
+ S(0, 0), S(3, 46), S(37, 68), S(42, 60), S(0, 38), S(58, 41)
};
// PassedRank[Rank] contains a bonus according to the rank of a passed pawn
};
// Assorted bonuses and penalties
+ constexpr Score BishopKingProtector = S( 6, 9);
+ constexpr Score BishopOnKingRing = S( 24, 0);
+ constexpr Score BishopOutpost = S( 30, 23);
constexpr Score BishopPawns = S( 3, 7);
+ constexpr Score BishopXRayPawns = S( 4, 5);
constexpr Score CorneredBishop = S( 50, 50);
constexpr Score FlankAttacks = S( 8, 0);
constexpr Score Hanging = S( 69, 36);
- constexpr Score KingProtector = S( 7, 8);
- constexpr Score KnightOnQueen = S( 16, 12);
+ constexpr Score KnightKingProtector = S( 8, 9);
+ constexpr Score KnightOnQueen = S( 16, 11);
+ constexpr Score KnightOutpost = S( 56, 36);
constexpr Score LongDiagonalBishop = S( 45, 0);
constexpr Score MinorBehindPawn = S( 18, 3);
- constexpr Score Outpost = S( 30, 21);
constexpr Score PassedFile = S( 11, 8);
constexpr Score PawnlessFlank = S( 17, 95);
+ constexpr Score QueenInfiltration = S( -2, 14);
+ constexpr Score ReachableOutpost = S( 31, 22);
constexpr Score RestrictedPiece = S( 7, 7);
- constexpr Score RookOnQueenFile = S( 7, 6);
- constexpr Score SliderOnQueen = S( 59, 18);
+ constexpr Score RookOnKingRing = S( 16, 0);
+ constexpr Score RookOnQueenFile = S( 6, 11);
+ constexpr Score SliderOnQueen = S( 60, 18);
constexpr Score ThreatByKing = S( 24, 89);
constexpr Score ThreatByPawnPush = S( 48, 39);
constexpr Score ThreatBySafePawn = S(173, 94);
- constexpr Score TrappedRook = S( 52, 10);
- constexpr Score WeakQueen = S( 49, 15);
+ constexpr Score TrappedRook = S( 55, 13);
constexpr Score WeakQueenProtection = S( 14, 0);
+ constexpr Score WeakQueen = S( 56, 15);
+
#undef S
template<Color Us> Score threats() const;
template<Color Us> Score passed() const;
template<Color Us> Score space() const;
- ScaleFactor scale_factor(Value eg) const;
- Score initiative(Score score) const;
+ Value winnable(Score score) const;
const Position& pos;
Material::Entry* me;
// Evaluation::initialize() computes king and pawn attacks, and the king ring
// bitboard for a given color. This is done at the beginning of the evaluation.
+
template<Tracing T> template<Color Us>
void Evaluation<T>::initialize() {
mobilityArea[Us] = ~(b | pos.pieces(Us, KING, QUEEN) | pos.blockers_for_king(Us) | pe->pawn_attacks(Them));
// Initialize attackedBy[] for king and pawns
- attackedBy[Us][KING] = pos.attacks_from<KING>(ksq);
+ attackedBy[Us][KING] = attacks_bb<KING>(ksq);
attackedBy[Us][PAWN] = pe->pawn_attacks(Us);
attackedBy[Us][ALL_PIECES] = attackedBy[Us][KING] | attackedBy[Us][PAWN];
attackedBy2[Us] = dblAttackByPawn | (attackedBy[Us][KING] & attackedBy[Us][PAWN]);
// Init our king safety tables
Square s = make_square(Utility::clamp(file_of(ksq), FILE_B, FILE_G),
Utility::clamp(rank_of(ksq), RANK_2, RANK_7));
- kingRing[Us] = PseudoAttacks[KING][s] | s;
+ kingRing[Us] = attacks_bb<KING>(s) | s;
kingAttackersCount[Them] = popcount(kingRing[Us] & pe->pawn_attacks(Them));
kingAttacksCount[Them] = kingAttackersWeight[Them] = 0;
// Evaluation::pieces() scores pieces of a given color and type
+
template<Tracing T> template<Color Us, PieceType Pt>
Score Evaluation<T>::pieces() {
// Find attacked squares, including x-ray attacks for bishops and rooks
b = Pt == BISHOP ? attacks_bb<BISHOP>(s, pos.pieces() ^ pos.pieces(QUEEN))
: Pt == ROOK ? attacks_bb< ROOK>(s, pos.pieces() ^ pos.pieces(QUEEN) ^ pos.pieces(Us, ROOK))
- : pos.attacks_from<Pt>(s);
+ : attacks_bb<Pt>(s, pos.pieces());
if (pos.blockers_for_king(Us) & s)
- b &= LineBB[pos.square<KING>(Us)][s];
+ b &= line_bb(pos.square<KING>(Us), s);
attackedBy2[Us] |= attackedBy[Us][ALL_PIECES] & b;
attackedBy[Us][Pt] |= b;
kingAttacksCount[Us] += popcount(b & attackedBy[Them][KING]);
}
+ else if (Pt == ROOK && (file_bb(s) & kingRing[Them]))
+ score += RookOnKingRing;
+
+ else if (Pt == BISHOP && (attacks_bb<BISHOP>(s, pos.pieces(PAWN)) & kingRing[Them]))
+ score += BishopOnKingRing;
+
int mob = popcount(b & mobilityArea[Us]);
mobility[Us] += MobilityBonus[Pt - 2][mob];
// Bonus if piece is on an outpost square or can reach one
bb = OutpostRanks & attackedBy[Us][PAWN] & ~pe->pawn_attacks_span(Them);
if (bb & s)
- score += Outpost * (Pt == KNIGHT ? 2 : 1);
-
+ score += (Pt == KNIGHT) ? KnightOutpost : BishopOutpost;
else if (Pt == KNIGHT && bb & b & ~pos.pieces(Us))
- score += Outpost;
+ score += ReachableOutpost;
// Bonus for a knight or bishop shielded by pawn
if (shift<Down>(pos.pieces(PAWN)) & s)
score += MinorBehindPawn;
// Penalty if the piece is far from the king
- score -= KingProtector * distance(pos.square<KING>(Us), s);
+ score -= (Pt == KNIGHT ? KnightKingProtector
+ : BishopKingProtector) * distance(pos.square<KING>(Us), s);
if (Pt == BISHOP)
{
- // Penalty according to number of pawns on the same color square as the
+ // Penalty according to the number of our pawns on the same color square as the
// bishop, bigger when the center files are blocked with pawns and smaller
// when the bishop is outside the pawn chain.
Bitboard blocked = pos.pieces(Us, PAWN) & shift<Down>(pos.pieces());
score -= BishopPawns * pos.pawns_on_same_color_squares(Us, s)
* (!(attackedBy[Us][PAWN] & s) + popcount(blocked & CenterFiles));
+ // Penalty for all enemy pawns x-rayed
+ score -= BishopXRayPawns * popcount(attacks_bb<BISHOP>(s) & pos.pieces(Them, PAWN));
+
// Bonus for bishop on a long diagonal which can "see" both center squares
if (more_than_one(attacks_bb<BISHOP>(s, pos.pieces(PAWN)) & Center))
score += LongDiagonalBishop;
Bitboard queenPinners;
if (pos.slider_blockers(pos.pieces(Them, ROOK, BISHOP), s, queenPinners))
score -= WeakQueen;
+
+ // Bonus for queen on weak square in enemy camp
+ if (relative_rank(Us, s) > RANK_4 && (~pe->pawn_attacks_span(Them) & s))
+ score += QueenInfiltration;
}
}
if (T)
// Evaluation::king() assigns bonuses and penalties to a king of a given color
+
template<Tracing T> template<Color Us>
Score Evaluation<T>::king() const {
// Enemy rooks checks
rookChecks = b1 & safe & attackedBy[Them][ROOK];
-
if (rookChecks)
- kingDanger += RookSafeCheck;
+ kingDanger += more_than_one(rookChecks) ? RookSafeCheck * 175/100
+ : RookSafeCheck;
else
unsafeChecks |= b1 & attackedBy[Them][ROOK];
& safe
& ~attackedBy[Us][QUEEN]
& ~rookChecks;
-
if (queenChecks)
- kingDanger += QueenSafeCheck;
+ kingDanger += more_than_one(queenChecks) ? QueenSafeCheck * 145/100
+ : QueenSafeCheck;
// Enemy bishops checks: we count them only if they are from squares from
// which we can't give a queen check, because queen checks are more valuable.
& attackedBy[Them][BISHOP]
& safe
& ~queenChecks;
-
if (bishopChecks)
- kingDanger += BishopSafeCheck;
+ kingDanger += more_than_one(bishopChecks) ? BishopSafeCheck * 3/2
+ : BishopSafeCheck;
else
unsafeChecks |= b2 & attackedBy[Them][BISHOP];
// Enemy knights checks
- knightChecks = pos.attacks_from<KNIGHT>(ksq) & attackedBy[Them][KNIGHT];
-
+ knightChecks = attacks_bb<KNIGHT>(ksq) & attackedBy[Them][KNIGHT];
if (knightChecks & safe)
- kingDanger += KnightSafeCheck;
+ kingDanger += more_than_one(knightChecks & safe) ? KnightSafeCheck * 162/100
+ : KnightSafeCheck;
else
unsafeChecks |= knightChecks;
// Evaluation::threats() assigns bonuses according to the types of the
// attacking and the attacked pieces.
+
template<Tracing T> template<Color Us>
Score Evaluation<T>::threats() const {
Square s = pos.square<QUEEN>(Them);
safe = mobilityArea[Us] & ~stronglyProtected;
- b = attackedBy[Us][KNIGHT] & pos.attacks_from<KNIGHT>(s);
+ b = attackedBy[Us][KNIGHT] & attacks_bb<KNIGHT>(s);
score += KnightOnQueen * popcount(b & safe);
- b = (attackedBy[Us][BISHOP] & pos.attacks_from<BISHOP>(s))
- | (attackedBy[Us][ROOK ] & pos.attacks_from<ROOK >(s));
+ b = (attackedBy[Us][BISHOP] & attacks_bb<BISHOP>(s, pos.pieces()))
+ | (attackedBy[Us][ROOK ] & attacks_bb<ROOK >(s, pos.pieces()));
score += SliderOnQueen * popcount(b & safe & attackedBy2[Us]);
}
return std::min(distance(pos.square<KING>(c), s), 5);
};
- Bitboard b, bb, squaresToQueen, unsafeSquares, candidatePassers, leverable;
+ Bitboard b, bb, squaresToQueen, unsafeSquares, blockedPassers, helpers;
Score score = SCORE_ZERO;
b = pe->passed_pawns(Us);
- candidatePassers = b & shift<Down>(pos.pieces(Them, PAWN));
- if (candidatePassers)
+ blockedPassers = b & shift<Down>(pos.pieces(Them, PAWN));
+ if (blockedPassers)
{
- // Can we lever the blocker of a candidate passer?
- leverable = shift<Up>(pos.pieces(Us, PAWN))
- & ~pos.pieces(Them)
- & (~attackedBy2[Them] | attackedBy[Us][ALL_PIECES])
- & (~(attackedBy[Them][KNIGHT] | attackedBy[Them][BISHOP])
- | (attackedBy[Us ][KNIGHT] | attackedBy[Us ][BISHOP]));
-
- // Remove candidate otherwise
- b &= ~candidatePassers
- | shift<WEST>(leverable)
- | shift<EAST>(leverable);
+ helpers = shift<Up>(pos.pieces(Us, PAWN))
+ & ~pos.pieces(Them)
+ & (~attackedBy2[Them] | attackedBy[Us][ALL_PIECES]);
+
+ // Remove blocked candidate passers that don't have help to pass
+ b &= ~blockedPassers
+ | shift<WEST>(helpers)
+ | shift<EAST>(helpers);
}
while (b)
}
- // Evaluation::space() computes the space evaluation for a given side. The
- // space evaluation is a simple bonus based on the number of safe squares
- // available for minor pieces on the central four files on ranks 2--4. Safe
- // squares one, two or three squares behind a friendly pawn are counted
- // twice. Finally, the space bonus is multiplied by a weight. The aim is to
- // improve play on game opening.
+ // Evaluation::space() computes a space evaluation for a given side, aiming to improve game
+ // play in the opening. It is based on the number of safe squares on the 4 central files
+ // on ranks 2 to 4. Completely safe squares behind a friendly pawn are counted twice.
+ // Finally, the space bonus is multiplied by a weight which decreases according to occupancy.
template<Tracing T> template<Color Us>
Score Evaluation<T>::space() const {
+ // Early exit if, for example, both queens or 6 minor pieces have been exchanged
if (pos.non_pawn_material() < SpaceThreshold)
return SCORE_ZERO;
}
- // Evaluation::initiative() computes the initiative correction value
- // for the position. It is a second order bonus/malus based on the
- // known attacking/defending status of the players.
+ // Evaluation::winnable() adjusts the mg and eg score components based on the
+ // known attacking/defending status of the players. A single value is derived
+ // by interpolation from the mg and eg values and returned.
template<Tracing T>
- Score Evaluation<T>::initiative(Score score) const {
+ Value Evaluation<T>::winnable(Score score) const {
int outflanking = distance<File>(pos.square<KING>(WHITE), pos.square<KING>(BLACK))
- distance<Rank>(pos.square<KING>(WHITE), pos.square<KING>(BLACK));
// Compute the initiative bonus for the attacking side
int complexity = 9 * pe->passed_count()
- + 1
1 * pos.count<PAWN>()
+ + 1
2 * pos.count<PAWN>()
+ 9 * outflanking
+ 21 * pawnsOnBothFlanks
+ 24 * infiltration
// Now apply the bonus: note that we find the attacking side by extracting the
// sign of the midgame or endgame values, and that we carefully cap the bonus
// so that the midgame and endgame scores do not change sign after the bonus.
- int u = ((mg > 0) - (mg < 0)) * std::max(std::min(complexity + 50, 0), -abs(mg));
+ int u = ((mg > 0) - (mg < 0)) * Utility::clamp(complexity + 50, -abs(mg), 0);
int v = ((eg > 0) - (eg < 0)) * std::max(complexity, -abs(eg));
- if (T)
- Trace::add(INITIATIVE, make_score(u, v));
-
- return make_score(u, v);
- }
-
-
- // Evaluation::scale_factor() computes the scale factor for the winning side
-
- template<Tracing T>
- ScaleFactor Evaluation<T>::scale_factor(Value eg) const {
+ mg += u;
+ eg += v;
+ // Compute the scale factor for the winning side
Color strongSide = eg > VALUE_DRAW ? WHITE : BLACK;
int sf = me->scale_factor(pos, strongSide);
// If scale is not already specific, scale down the endgame via general heuristics
if (sf == SCALE_FACTOR_NORMAL)
{
- if ( pos.opposite_bishops()
- && pos.non_pawn_material() == 2 * BishopValueMg)
- sf = 22;
+ if (pos.opposite_bishops())
+ {
+ if ( pos.non_pawn_material(WHITE) == BishopValueMg
+ && pos.non_pawn_material(BLACK) == BishopValueMg)
+ sf = 18 + 4 * popcount(pe->passed_pawns(strongSide));
+ else
+ sf = 22 + 3 * pos.count<ALL_PIECES>(strongSide);
+ }
+ else if ( pos.non_pawn_material(WHITE) == RookValueMg
+ && pos.non_pawn_material(BLACK) == RookValueMg
+ && !pe->passed_pawns(strongSide)
+ && pos.count<PAWN>(strongSide) - pos.count<PAWN>(~strongSide) <= 1
+ && bool(KingSide & pos.pieces(strongSide, PAWN)) != bool(QueenSide & pos.pieces(strongSide, PAWN))
+ && (attacks_bb<KING>(pos.square<KING>(~strongSide)) & pos.pieces(~strongSide, PAWN)))
+ sf = 36;
+ else if (pos.count<QUEEN>() == 1)
+ sf = 37 + 3 * (pos.count<QUEEN>(WHITE) == 1 ? pos.count<BISHOP>(BLACK) + pos.count<KNIGHT>(BLACK)
+ : pos.count<BISHOP>(WHITE) + pos.count<KNIGHT>(WHITE));
else
- sf = std::min(sf, 36 + (pos.opposite_bishops() ? 2 : 7) * pos.count<PAWN>(strongSide));
+ sf = std::min(sf, 36 + 7 * pos.count<PAWN>(strongSide));
+ }
+
+ // Interpolate between the middlegame and (scaled by 'sf') endgame score
+ v = mg * int(me->game_phase())
+ + eg * int(PHASE_MIDGAME - me->game_phase()) * ScaleFactor(sf) / SCALE_FACTOR_NORMAL;
+ v /= PHASE_MIDGAME;
- sf = std::max(0, sf - (pos.rule50_count() - 12) / 4);
+ if (T)
+ {
+ Trace::add(WINNABLE, make_score(u, eg * ScaleFactor(sf) / SCALE_FACTOR_NORMAL - eg_value(score)));
+ Trace::add(TOTAL, make_score(mg, eg * ScaleFactor(sf) / SCALE_FACTOR_NORMAL));
}
- return ScaleFactor(sf);
+ return Value(v);
}
return pos.side_to_move() == WHITE ? v : -v;
// Main evaluation begins here
-
initialize<WHITE>();
initialize<BLACK>();
- // Pieces should be evaluated first (populate attack tables)
+ // Pieces evaluated first (also populates attackedBy, attackedBy2).
+ // Note that the order of evaluation of the terms is left unspecified.
score += pieces<WHITE, KNIGHT>() - pieces<BLACK, KNIGHT>()
+ pieces<WHITE, BISHOP>() - pieces<BLACK, BISHOP>()
+ pieces<WHITE, ROOK >() - pieces<BLACK, ROOK >()
score += mobility[WHITE] - mobility[BLACK];
+ // More complex interactions that require fully populated attack bitboards
score += king< WHITE>() - king< BLACK>()
+ threats<WHITE>() - threats<BLACK>()
+ passed< WHITE>() - passed< BLACK>()
+ space< WHITE>() - space< BLACK>();
- score += initiative(score);
-
- // Interpolate between a middlegame and a (scaled by 'sf') endgame score
- ScaleFactor sf = scale_factor(eg_value(score));
- v = mg_value(score) * int(me->game_phase())
- + eg_value(score) * int(PHASE_MIDGAME - me->game_phase()) * sf / SCALE_FACTOR_NORMAL;
-
- v /= PHASE_MIDGAME;
+ // Derive single value from mg and eg parts of score
+ v = winnable(score);
// In case of tracing add all remaining individual evaluation terms
if (T)
Trace::add(IMBALANCE, me->imbalance());
Trace::add(PAWN, pe->pawn_score(WHITE), pe->pawn_score(BLACK));
Trace::add(MOBILITY, mobility[WHITE], mobility[BLACK]);
- Trace::add(TOTAL, score);
}
- return (pos.side_to_move() == WHITE ? v : -v) + Tempo; // Side to move point of view
+ // Evaluation grain
+ v = (v / 16) * 16;
+
+ // Side to move point of view
+ v = (pos.side_to_move() == WHITE ? v : -v) + Tempo;
+
+ // Damp down the evaluation linearly when shuffling
+ v = v * (100 - pos.rule50_count()) / 100;
+
+ return v;
}
} // namespace
<< " Threats | " << Term(THREAT)
<< " Passed | " << Term(PASSED)
<< " Space | " << Term(SPACE)
- << " Initiative | " << Term(INITIATIVE)
+ << " Winnable | " << Term(WINNABLE)
<< " ------------+-------------+-------------+------------\n"
<< " Total | " << Term(TOTAL);
- ss << "\nTotal evaluation: " << to_cp(v) << " (white side)\n";
+ ss << "\nFinal evaluation: " << to_cp(v) << " (white side)\n";
return ss.str();
}
projects / stockfish / blobdiff