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) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2015-2018 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 {
- const Bitboard LongDiagonals = 0x8142241818244281ULL; // A1..H8 | H1..A8
- const Bitboard Center = (FileDBB | FileEBB) & (Rank4BB | Rank5BB);
- const Bitboard QueenSide = FileABB | FileBBB | FileCBB | FileDBB;
- const Bitboard CenterFiles = FileCBB | FileDBB | FileEBB | FileFBB;
- const Bitboard KingSide = FileEBB | FileFBB | FileGBB | FileHBB;
+ const Bitboard Center = (FileDBB | FileEBB) & (Rank4BB | Rank5BB);
+ const Bitboard QueenSide = FileABB | FileBBB | FileCBB | FileDBB;
+ const Bitboard CenterFiles = FileCBB | FileDBB | FileEBB | FileFBB;
+ const Bitboard KingSide = FileEBB | FileFBB | FileGBB | FileHBB;
const Bitboard KingFlank[FILE_NB] = {
QueenSide, QueenSide, QueenSide, CenterFiles, CenterFiles, KingSide, KingSide, KingSide
enum Tracing {NO_TRACE, TRACE};
enum Term { // The first 8 entries are for PieceType
- MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, TOTAL, TERM_NB
+ MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, INITIATIVE, TOTAL, TERM_NB
};
double scores[TERM_NB][COLOR_NB][PHASE_NB];
std::ostream& operator<<(std::ostream& os, Term t) {
- if (t == MATERIAL || t == IMBALANCE || t == Term(PAWN) || t == TOTAL)
+ if (t == MATERIAL || t == IMBALANCE || t == Term(PAWN) || t == INITIATIVE || t == TOTAL)
os << " --- --- | --- --- | ";
else
os << std::setw(5) << scores[t][WHITE][MG] << " "
Score mobility[COLOR_NB] = { SCORE_ZERO, SCORE_ZERO };
// attackedBy[color][piece type] is a bitboard representing all squares
- // attacked by a given color and piece type (can be also ALL_PIECES).
+ // attacked by a given color and piece type. Special "piece types" which are
+ // also calculated are QUEEN_DIAGONAL and ALL_PIECES.
Bitboard attackedBy[COLOR_NB][PIECE_TYPE_NB];
// attackedBy2[color] are the squares attacked by 2 pieces of a given color,
const Score KingProtector[] = { S(-3, -5), S(-4, -3), S(-3, 0), S(-1, 1) };
// Assorted bonuses and penalties used by evaluation
- const Score MinorBehindPawn = S( 16, 0);
- const Score BishopPawns = S( 8, 12);
- const Score LongRangedBishop = S( 22, 0);
- const Score RookOnPawn = S( 8, 24);
- const Score TrappedRook = S( 92, 0);
- const Score WeakQueen = S( 50, 10);
- const Score OtherCheck = S( 10, 10);
- const Score CloseEnemies = S( 7, 0);
- const Score PawnlessFlank = S( 20, 80);
- const Score ThreatByHangingPawn = S( 71, 61);
- const Score ThreatBySafePawn = S(182,175);
- const Score ThreatByRank = S( 16, 3);
- const Score Hanging = S( 48, 27);
- const Score WeakUnopposedPawn = S( 5, 25);
- const Score ThreatByPawnPush = S( 38, 22);
- const Score HinderPassedPawn = S( 7, 0);
- const Score TrappedBishopA1H1 = S( 50, 50);
+ const Score MinorBehindPawn = S( 16, 0);
+ const Score BishopPawns = S( 8, 12);
+ const Score LongRangedBishop = S( 22, 0);
+ const Score RookOnPawn = S( 8, 24);
+ const Score TrappedRook = S( 92, 0);
+ const Score WeakQueen = S( 50, 10);
+ const Score CloseEnemies = S( 7, 0);
+ const Score PawnlessFlank = S( 20, 80);
+ const Score ThreatBySafePawn = S(192,175);
+ const Score ThreatByRank = S( 16, 3);
+ const Score Hanging = S( 48, 27);
+ const Score WeakUnopposedPawn = S( 5, 25);
+ const Score ThreatByPawnPush = S( 38, 22);
+ const Score ThreatByAttackOnQueen = S( 38, 22);
+ const Score HinderPassedPawn = S( 7, 0);
+ const Score TrappedBishopA1H1 = S( 50, 50);
#undef S
#undef V
const int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 78, 56, 45, 11 };
// Penalties for enemy's safe checks
- const int QueenCheck = 780;
- const int RookCheck = 880;
- const int BishopCheck = 435;
- const int KnightCheck = 790;
+ const int QueenSafeCheck = 780;
+ const int RookSafeCheck = 880;
+ const int BishopSafeCheck = 435;
+ const int KnightSafeCheck = 790;
// Threshold for lazy and space evaluation
const Value LazyThreshold = Value(1500);
template<Tracing T> template<Color Us>
void Evaluation<T>::initialize() {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Square Up = (Us == WHITE ? NORTH : SOUTH);
- const Square Down = (Us == WHITE ? SOUTH : NORTH);
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Direction Up = (Us == WHITE ? NORTH : SOUTH);
+ const Direction Down = (Us == WHITE ? SOUTH : NORTH);
const Bitboard LowRanks = (Us == WHITE ? Rank2BB | Rank3BB: Rank7BB | Rank6BB);
// Find our pawns on the first two ranks, and those which are blocked
attackedBy[Us][Pt] = 0;
+ if (Pt == QUEEN)
+ attackedBy[Us][QUEEN_DIAGONAL] = 0;
+
while ((s = *pl++) != SQ_NONE)
{
// Find attacked squares, including x-ray attacks for bishops and rooks
- b = Pt == BISHOP ? attacks_bb<BISHOP>(s, pos.pieces() ^ pos.pieces(Us, QUEEN))
- : Pt == ROOK ? attacks_bb< ROOK>(s, pos.pieces() ^ pos.pieces(Us, ROOK, QUEEN))
+ 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);
if (pos.pinned_pieces(Us) & s)
attackedBy2[Us] |= attackedBy[Us][ALL_PIECES] & b;
attackedBy[Us][ALL_PIECES] |= attackedBy[Us][Pt] |= b;
+ if (Pt == QUEEN)
+ attackedBy[Us][QUEEN_DIAGONAL] |= b & PseudoAttacks[BISHOP][s];
+
if (b & kingRing[Them])
{
kingAttackersCount[Us]++;
// Bonus for outpost squares
bb = OutpostRanks & ~pe->pawn_attacks_span(Them);
if (bb & s)
- score += Outpost[Pt == BISHOP][!!(attackedBy[Us][PAWN] & s)] * 2;
+ score += Outpost[Pt == BISHOP][bool(attackedBy[Us][PAWN] & s)] * 2;
else
{
bb &= b & ~pos.pieces(Us);
if (bb)
- score += Outpost[Pt == BISHOP][!!(attackedBy[Us][PAWN] & bb)];
+ score += Outpost[Pt == BISHOP][bool(attackedBy[Us][PAWN] & bb)];
}
// Bonus when behind a pawn
// Penalty for pawns on the same color square as the bishop
score -= BishopPawns * pe->pawns_on_same_color_squares(Us, s);
- // Bonus for bishop on a long diagonal without pawns in the center
- if ( (LongDiagonals & s)
- && !(attackedBy[Them][PAWN] & s)
- && !(Center & PseudoAttacks[BISHOP][s] & pos.pieces(PAWN)))
+ // Bonus for bishop on a long diagonal which can "see" both center squares
+ if (more_than_one(Center & (attacks_bb<BISHOP>(s, pos.pieces(PAWN)) | s)))
score += LongRangedBishop;
}
&& pos.is_chess960()
&& (s == relative_square(Us, SQ_A1) || s == relative_square(Us, SQ_H1)))
{
- Square d = pawn_push(Us) + (file_of(s) == FILE_A ? EAST : WEST);
+ Direction d = pawn_push(Us) + (file_of(s) == FILE_A ? EAST : WEST);
if (pos.piece_on(s + d) == make_piece(Us, PAWN))
score -= !pos.empty(s + d + pawn_push(Us)) ? TrappedBishopA1H1 * 4
: pos.piece_on(s + d + d) == make_piece(Us, PAWN) ? TrappedBishopA1H1 * 2
// Bonus when on an open or semi-open file
if (pe->semiopen_file(Us, file_of(s)))
- score += RookOnFile[!!pe->semiopen_file(Them, file_of(s))];
+ score += RookOnFile[bool(pe->semiopen_file(Them, file_of(s)))];
// Penalty when trapped by the king, even more if the king cannot castle
else if (mob <= 3)
template<Tracing T> template<Color Us>
Score Evaluation<T>::evaluate_king() {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Square Up = (Us == WHITE ? NORTH : SOUTH);
- const Bitboard Camp = (Us == WHITE ? AllSquares ^ Rank6BB ^ Rank7BB ^ Rank8BB
- : AllSquares ^ Rank1BB ^ Rank2BB ^ Rank3BB);
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Bitboard Camp = (Us == WHITE ? AllSquares ^ Rank6BB ^ Rank7BB ^ Rank8BB
+ : AllSquares ^ Rank1BB ^ Rank2BB ^ Rank3BB);
const Square ksq = pos.square<KING>(Us);
- Bitboard kingOnlyDefended, undefended, b, b1, b2, safe, other;
- int kingDanger;
+ Bitboard weak, b, b1, b2, safe, unsafeChecks;
// King shelter and enemy pawns storm
Score score = pe->king_safety<Us>(pos, ksq);
// Main king safety evaluation
if (kingAttackersCount[Them] > (1 - pos.count<QUEEN>(Them)))
{
- // Find the attacked squares which are defended only by our king...
- kingOnlyDefended = attackedBy[Them][ALL_PIECES]
- & attackedBy[Us][KING]
- & ~attackedBy2[Us];
-
- // ... and those which are not defended at all in the larger king ring
- undefended = attackedBy[Them][ALL_PIECES]
- & ~attackedBy[Us][ALL_PIECES]
- & kingRing[Us]
- & ~pos.pieces(Them);
-
- // Initialize the 'kingDanger' variable, which will be transformed
- // later into a king danger score. The initial value is based on the
- // number and types of the enemy's attacking pieces, the number of
- // attacked and weak squares around our king, the absence of queen and
- // the quality of the pawn shelter (current 'score' value).
- kingDanger = kingAttackersCount[Them] * kingAttackersWeight[Them]
- + 102 * kingAdjacentZoneAttacksCount[Them]
- + 191 * popcount(kingOnlyDefended | undefended)
- + 143 * !!pos.pinned_pieces(Us)
- - 848 * !pos.count<QUEEN>(Them)
- - 9 * mg_value(score) / 8
- + 40;
+ // Attacked squares defended at most once by our queen or king
+ weak = attackedBy[Them][ALL_PIECES]
+ & ~attackedBy2[Us]
+ & (attackedBy[Us][KING] | attackedBy[Us][QUEEN] | ~attackedBy[Us][ALL_PIECES]);
+
+ int kingDanger = unsafeChecks = 0;
// Analyse the safe enemy's checks which are possible on next move
safe = ~pos.pieces(Them);
- safe &= ~attackedBy[Us][ALL_PIECES] | (kingOnlyDefended & attackedBy2[Them]);
+ safe &= ~attackedBy[Us][ALL_PIECES] | (weak & attackedBy2[Them]);
- b1 = pos.attacks_from< ROOK>(ksq);
- b2 = pos.attacks_from<BISHOP>(ksq);
+ b1 = attacks_bb<ROOK >(ksq, pos.pieces() ^ pos.pieces(Us, QUEEN));
+ b2 = attacks_bb<BISHOP>(ksq, pos.pieces() ^ pos.pieces(Us, QUEEN));
// Enemy queen safe checks
- if ((b1 | b2) & attackedBy[Them][QUEEN] & safe)
- kingDanger += QueenCheck;
+ if ((b1 | b2) & attackedBy[Them][QUEEN] & safe & ~attackedBy[Us][QUEEN])
+ kingDanger += QueenSafeCheck;
- // For minors and rooks, also consider the square safe if attacked twice,
- // and only defended by our queen.
- safe |= attackedBy2[Them]
- & ~(attackedBy2[Us] | pos.pieces(Them))
- & attackedBy[Us][QUEEN];
+ b1 &= attackedBy[Them][ROOK];
+ b2 &= attackedBy[Them][BISHOP];
- // Some other potential checks are also analysed, even from squares
- // currently occupied by the opponent own pieces, as long as the square
- // is not attacked by our pawns, and is not occupied by a blocked pawn.
- other = ~( attackedBy[Us][PAWN]
- | (pos.pieces(Them, PAWN) & shift<Up>(pos.pieces(PAWN))));
+ // Enemy rooks checks
+ if (b1 & safe)
+ kingDanger += RookSafeCheck;
+ else
+ unsafeChecks |= b1;
- // Enemy rooks safe and other checks
- if (b1 & attackedBy[Them][ROOK] & safe)
- kingDanger += RookCheck;
+ // Enemy bishops checks
+ if (b2 & safe)
+ kingDanger += BishopSafeCheck;
+ else
+ unsafeChecks |= b2;
- else if (b1 & attackedBy[Them][ROOK] & other)
- score -= OtherCheck;
-
- // Enemy bishops safe and other checks
- if (b2 & attackedBy[Them][BISHOP] & safe)
- kingDanger += BishopCheck;
-
- else if (b2 & attackedBy[Them][BISHOP] & other)
- score -= OtherCheck;
-
- // Enemy knights safe and other checks
+ // Enemy knights checks
b = pos.attacks_from<KNIGHT>(ksq) & attackedBy[Them][KNIGHT];
if (b & safe)
- kingDanger += KnightCheck;
-
- else if (b & other)
- score -= OtherCheck;
+ kingDanger += KnightSafeCheck;
+ else
+ unsafeChecks |= b;
+
+ // Unsafe or occupied checking squares will also be considered, as long as
+ // the square is in the attacker's mobility area.
+ unsafeChecks &= mobilityArea[Them];
+
+ kingDanger += kingAttackersCount[Them] * kingAttackersWeight[Them]
+ + 102 * kingAdjacentZoneAttacksCount[Them]
+ + 191 * popcount(kingRing[Us] & weak)
+ + 143 * popcount(pos.pinned_pieces(Us) | unsafeChecks)
+ - 848 * !pos.count<QUEEN>(Them)
+ - 9 * mg_value(score) / 8
+ + 40;
// Transform the kingDanger units into a Score, and substract it from the evaluation
if (kingDanger > 0)
+ {
+ int mobilityDanger = mg_value(mobility[Them] - mobility[Us]);
+ kingDanger = std::max(0, kingDanger + mobilityDanger);
score -= make_score(kingDanger * kingDanger / 4096, kingDanger / 16);
+ }
}
// King tropism: firstly, find squares that opponent attacks in our king flank
template<Tracing T> template<Color Us>
Score Evaluation<T>::evaluate_threats() {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Square Up = (Us == WHITE ? NORTH : SOUTH);
- const Square Left = (Us == WHITE ? NORTH_WEST : SOUTH_EAST);
- const Square Right = (Us == WHITE ? NORTH_EAST : SOUTH_WEST);
- const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Direction Up = (Us == WHITE ? NORTH : SOUTH);
+ const Direction Left = (Us == WHITE ? NORTH_WEST : SOUTH_EAST);
+ const Direction Right = (Us == WHITE ? NORTH_EAST : SOUTH_WEST);
+ const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
Bitboard b, weak, defended, stronglyProtected, safeThreats;
Score score = SCORE_ZERO;
safeThreats = (shift<Right>(b) | shift<Left>(b)) & weak;
score += ThreatBySafePawn * popcount(safeThreats);
-
- if (weak ^ safeThreats)
- score += ThreatByHangingPawn;
}
// Squares strongly protected by the opponent, either because they attack the
score += ThreatByPawnPush * popcount(b);
+ // Add a bonus for safe slider attack threats on opponent queen
+ safeThreats = ~pos.pieces(Us) & ~attackedBy2[Them] & attackedBy2[Us];
+ b = (attackedBy[Us][BISHOP] & attackedBy[Them][QUEEN_DIAGONAL])
+ | (attackedBy[Us][ROOK ] & attackedBy[Them][QUEEN] & ~attackedBy[Them][QUEEN_DIAGONAL]);
+
+ score += ThreatByAttackOnQueen * popcount(b & safeThreats);
+
if (T)
Trace::add(THREAT, Us, score);
template<Tracing T> template<Color Us>
Score Evaluation<T>::evaluate_passed_pawns() {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Square Up = (Us == WHITE ? NORTH : SOUTH);
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Direction Up = (Us == WHITE ? NORTH : SOUTH);
Bitboard b, bb, squaresToQueen, defendedSquares, unsafeSquares;
Score score = SCORE_ZERO;
// that the endgame score will never change sign after the bonus.
int v = ((eg > 0) - (eg < 0)) * std::max(initiative, -abs(eg));
+ if (T)
+ Trace::add(INITIATIVE, make_score(0, v));
+
return make_score(0, v);
}
// Initialize score by reading the incrementally updated scores included in
// the position object (material + piece square tables) and the material
// imbalance. Score is computed internally from the white point of view.
- Score score = pos.psq_score() + me->imbalance();
+ Score score = pos.psq_score() + me->imbalance() + Eval::Contempt;
// Probe the pawn hash table
pe = Pawns::probe(pos);
Trace::add(TOTAL, score);
}
- return (pos.side_to_move() == WHITE ? v : -v) + Eval::Tempo; // Side to move point of view
+ return pos.side_to_move() == WHITE ? v : -v; // Side to move point of view
}
} // namespace
+Score Eval::Contempt = SCORE_ZERO;
/// evaluate() is the evaluator for the outer world. It returns a static evaluation
/// of the position from the point of view of the side to move.
Value Eval::evaluate(const Position& pos)
{
- return Evaluation<>(pos).value();
+ return Evaluation<>(pos).value() + Eval::Tempo;
}
/// trace() is like evaluate(), but instead of returning a value, it returns
std::memset(scores, 0, sizeof(scores));
- Value v = Evaluation<TRACE>(pos).value();
+ Value v = Evaluation<TRACE>(pos).value() + Eval::Tempo;
v = pos.side_to_move() == WHITE ? v : -v; // White's point of view
std::stringstream ss;
<< " Threats | " << Term(THREAT)
<< " Passed pawns | " << Term(PASSED)
<< " Space | " << Term(SPACE)
+ << " Initiative | " << Term(INITIATIVE)
<< "----------------+-------------+-------------+-------------\n"
<< " Total | " << Term(TOTAL);
projects / stockfish / blobdiff