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 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
+ };
+
namespace Trace {
+ 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] << " "
using namespace Trace;
- // Struct EvalInfo contains various information computed and collected
+ // Evaluation class contains various information computed and collected
// by the evaluation functions.
- struct EvalInfo {
-
+ template<Tracing T = NO_TRACE>
+ class Evaluation {
+
+ public:
+ Evaluation() = delete;
+ Evaluation(const Position& p) : pos(p) {}
+ Evaluation& operator=(const Evaluation&) = delete;
+
+ Value value();
+
+ private:
+ // Evaluation helpers (used when calling value())
+ template<Color Us> void initialize();
+ template<Color Us> Score evaluate_king();
+ template<Color Us> Score evaluate_threats();
+ template<Color Us> Score evaluate_passed_pawns();
+ template<Color Us> Score evaluate_space();
+ template<Color Us, PieceType Pt> Score evaluate_pieces();
+ ScaleFactor evaluate_scale_factor(Value eg);
+ Score evaluate_initiative(Value eg);
+
+ // Data members
+ const Position& pos;
Material::Entry* me;
Pawns::Entry* pe;
Bitboard mobilityArea[COLOR_NB];
+ 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,
// kingRing[color] is the zone around the king which is considered
// by the king safety evaluation. This consists of the squares directly
- // adjacent to the king, and the three (or two, for a king on an edge file)
+ // adjacent to the king, and (only for a king on its first rank) the
// squares two ranks in front of the king. For instance, if black's king
// is on g8, kingRing[BLACK] is a bitboard containing the squares f8, h8,
// f7, g7, h7, f6, g6 and h6.
// supported by a pawn. If the minor piece occupies an outpost square
// then score is doubled.
const Score Outpost[][2] = {
- { S(22, 6), S(33, 9) }, // Knight
- { S( 9, 2), S(14, 4) } // Bishop
+ { S(22, 6), S(36,12) }, // Knight
+ { S( 9, 2), S(15, 5) } // Bishop
};
// RookOnFile[semiopen/open] contains bonuses for each rook when there is no
};
const Score ThreatByRook[PIECE_TYPE_NB] = {
- S(0, 0), S(0, 25), S(40, 62), S(40, 59), S( 0, 34), S(35, 48)
+ 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
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 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 ThreatByPawnPush = S( 38, 22);
- const Score HinderPassedPawn = S( 7, 0);
-
- // 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
- // happen in Chess960 games.
- 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);
const Value SpaceThreshold = Value(12222);
- // 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>
- void eval_init(const Position& pos, EvalInfo& ei) {
+ // initialize() computes king and pawn attacks, and the king ring bitboard
+ // for a given color. This is done at the beginning of the evaluation.
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Square Up = (Us == WHITE ? NORTH : SOUTH);
- const Square Down = (Us == WHITE ? SOUTH : NORTH);
+ template<Tracing T> template<Color Us>
+ void Evaluation<T>::initialize() {
+
+ 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
// Squares occupied by those pawns, by our king, or controlled by enemy pawns
// are excluded from the mobility area.
- ei.mobilityArea[Us] = ~(b | pos.square<KING>(Us) | ei.pe->pawn_attacks(Them));
+ mobilityArea[Us] = ~(b | pos.square<KING>(Us) | pe->pawn_attacks(Them));
// Initialise the attack bitboards with the king and pawn information
- b = ei.attackedBy[Us][KING] = pos.attacks_from<KING>(pos.square<KING>(Us));
- ei.attackedBy[Us][PAWN] = ei.pe->pawn_attacks(Us);
+ b = attackedBy[Us][KING] = pos.attacks_from<KING>(pos.square<KING>(Us));
+ attackedBy[Us][PAWN] = pe->pawn_attacks(Us);
- ei.attackedBy2[Us] = b & ei.attackedBy[Us][PAWN];
- ei.attackedBy[Us][ALL_PIECES] = b | ei.attackedBy[Us][PAWN];
+ attackedBy2[Us] = b & attackedBy[Us][PAWN];
+ attackedBy[Us][ALL_PIECES] = b | attackedBy[Us][PAWN];
// Init our king safety tables only if we are going to use them
- if (pos.non_pawn_material(Them) >= QueenValueMg)
+ if (pos.non_pawn_material(Them) >= RookValueMg + KnightValueMg)
{
- ei.kingRing[Us] = b | shift<Up>(b);
- ei.kingAttackersCount[Them] = popcount(b & ei.pe->pawn_attacks(Them));
- ei.kingAdjacentZoneAttacksCount[Them] = ei.kingAttackersWeight[Them] = 0;
+ kingRing[Us] = b;
+ if (relative_rank(Us, pos.square<KING>(Us)) == RANK_1)
+ kingRing[Us] |= shift<Up>(b);
+
+ kingAttackersCount[Them] = popcount(b & pe->pawn_attacks(Them));
+ kingAdjacentZoneAttacksCount[Them] = kingAttackersWeight[Them] = 0;
}
else
- ei.kingRing[Us] = ei.kingAttackersCount[Them] = 0;
+ kingRing[Us] = kingAttackersCount[Them] = 0;
}
// evaluate_pieces() assigns bonuses and penalties to the pieces of a given
// color and type.
- template<bool DoTrace, Color Us = WHITE, PieceType Pt = KNIGHT>
- Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score* mobility) {
+ template<Tracing T> template<Color Us, PieceType Pt>
+ Score Evaluation<T>::evaluate_pieces() {
const Color Them = (Us == WHITE ? BLACK : WHITE);
- const PieceType NextPt = (Us == WHITE ? Pt : PieceType(Pt + 1));
const Bitboard OutpostRanks = (Us == WHITE ? Rank4BB | Rank5BB | Rank6BB
: Rank5BB | Rank4BB | Rank3BB);
const Square* pl = pos.squares<Pt>(Us);
Square s;
Score score = SCORE_ZERO;
- ei.attackedBy[Us][Pt] = 0;
+ 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)
b &= LineBB[pos.square<KING>(Us)][s];
- ei.attackedBy2[Us] |= ei.attackedBy[Us][ALL_PIECES] & b;
- ei.attackedBy[Us][ALL_PIECES] |= ei.attackedBy[Us][Pt] |= b;
+ 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 & ei.kingRing[Them])
+ if (b & kingRing[Them])
{
- ei.kingAttackersCount[Us]++;
- ei.kingAttackersWeight[Us] += KingAttackWeights[Pt];
- ei.kingAdjacentZoneAttacksCount[Us] += popcount(b & ei.attackedBy[Them][KING]);
+ kingAttackersCount[Us]++;
+ kingAttackersWeight[Us] += KingAttackWeights[Pt];
+ kingAdjacentZoneAttacksCount[Us] += popcount(b & attackedBy[Them][KING]);
}
- int mob = popcount(b & ei.mobilityArea[Us]);
+ int mob = popcount(b & mobilityArea[Us]);
mobility[Us] += MobilityBonus[Pt - 2][mob];
if (Pt == BISHOP || Pt == KNIGHT)
{
// Bonus for outpost squares
- bb = OutpostRanks & ~ei.pe->pawn_attacks_span(Them);
+ bb = OutpostRanks & ~pe->pawn_attacks_span(Them);
if (bb & s)
- score += Outpost[Pt == BISHOP][!!(ei.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][!!(ei.attackedBy[Us][PAWN] & bb)];
+ score += Outpost[Pt == BISHOP][bool(attackedBy[Us][PAWN] & bb)];
}
// Bonus when behind a pawn
&& (pos.pieces(PAWN) & (s + pawn_push(Us))))
score += MinorBehindPawn;
- // Penalty for pawns on the same color square as the bishop
if (Pt == BISHOP)
- score -= BishopPawns * ei.pe->pawns_on_same_color_squares(Us, s);
+ {
+ // 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 which can "see" both center squares
+ if (more_than_one(Center & (attacks_bb<BISHOP>(s, pos.pieces(PAWN)) | s)))
+ score += LongRangedBishop;
+ }
// An important Chess960 pattern: A cornered bishop blocked by a friendly
// pawn diagonally in front of it is a very serious problem, especially
&& 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
score += RookOnPawn * popcount(pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s]);
// Bonus when on an open or semi-open file
- if (ei.pe->semiopen_file(Us, file_of(s)))
- score += RookOnFile[!!ei.pe->semiopen_file(Them, file_of(s))];
+ if (pe->semiopen_file(Us, 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)
Square ksq = pos.square<KING>(Us);
if ( ((file_of(ksq) < FILE_E) == (file_of(s) < file_of(ksq)))
- && !ei.pe->semiopen_side(Us, file_of(ksq), file_of(s) < file_of(ksq)))
+ && !pe->semiopen_side(Us, file_of(ksq), file_of(s) < file_of(ksq)))
score -= (TrappedRook - make_score(mob * 22, 0)) * (1 + !pos.can_castle(Us));
}
}
}
}
- if (DoTrace)
+ if (T)
Trace::add(Pt, Us, score);
- // Recursively call evaluate_pieces() of next piece type until KING is excluded
- return score - evaluate_pieces<DoTrace, Them, NextPt>(pos, ei, mobility);
+ return score;
}
- template<>
- Score evaluate_pieces<false, WHITE, KING>(const Position&, EvalInfo&, Score*) { return SCORE_ZERO; }
- template<>
- Score evaluate_pieces< true, WHITE, KING>(const Position&, EvalInfo&, Score*) { return SCORE_ZERO; }
-
// evaluate_king() assigns bonuses and penalties to a king of a given color
- 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
- };
-
- template<Color Us, bool DoTrace>
- Score evaluate_king(const Position& pos, const EvalInfo& ei) {
+ 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 ? ~Bitboard(0) ^ Rank6BB ^ Rank7BB ^ Rank8BB
- : ~Bitboard(0) ^ 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 undefended, b, b1, b2, safe, other;
- int kingDanger;
+ Bitboard weak, b, b1, b2, safe, unsafeChecks;
// King shelter and enemy pawns storm
- Score score = ei.pe->king_safety<Us>(pos, ksq);
+ Score score = pe->king_safety<Us>(pos, ksq);
// Main king safety evaluation
- if (ei.kingAttackersCount[Them])
+ if (kingAttackersCount[Them] > (1 - pos.count<QUEEN>(Them)))
{
- // Find the attacked squares which are defended only by our king...
- undefended = ei.attackedBy[Them][ALL_PIECES]
- & ei.attackedBy[Us][KING]
- & ~ei.attackedBy2[Us];
-
- // ... and those which are not defended at all in the larger king ring
- b = ei.attackedBy[Them][ALL_PIECES] & ~ei.attackedBy[Us][ALL_PIECES]
- & ei.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 undefended squares around our king and the quality of
- // the pawn shelter (current 'score' value).
- kingDanger = ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]
- + 102 * ei.kingAdjacentZoneAttacksCount[Them]
- + 201 * popcount(undefended)
- + 143 * (popcount(b) + !!pos.pinned_pieces(Us))
- - 848 * !pos.count<QUEEN>(Them)
- - 28 * mg_value(score) / 25 - 5;
+ // 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 &= ~ei.attackedBy[Us][ALL_PIECES] | (undefended & ei.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) & ei.attackedBy[Them][QUEEN] & safe)
- kingDanger += QueenCheck;
-
- // For minors and rooks, also consider the square safe if attacked twice,
- // and only defended by our queen.
- safe |= ei.attackedBy2[Them]
- & ~(ei.attackedBy2[Us] | pos.pieces(Them))
- & ei.attackedBy[Us][QUEEN];
-
- // 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 = ~( ei.attackedBy[Us][PAWN]
- | (pos.pieces(Them, PAWN) & shift<Up>(pos.pieces(PAWN))));
-
- // Enemy rooks safe and other checks
- if (b1 & ei.attackedBy[Them][ROOK] & safe)
- 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;
-
- 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 ((b1 | b2) & attackedBy[Them][QUEEN] & safe & ~attackedBy[Us][QUEEN])
+ kingDanger += QueenSafeCheck;
+
+ b1 &= attackedBy[Them][ROOK];
+ b2 &= attackedBy[Them][BISHOP];
+
+ // Enemy rooks checks
+ if (b1 & safe)
+ kingDanger += RookSafeCheck;
+ else
+ unsafeChecks |= b1;
+
+ // Enemy bishops checks
+ if (b2 & safe)
+ kingDanger += BishopSafeCheck;
+ else
+ unsafeChecks |= b2;
+
+ // 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)
- score -= make_score(kingDanger * kingDanger / 4096, 0);
+ score -= make_score(kingDanger * kingDanger / 4096, kingDanger / 16);
}
// King tropism: firstly, find squares that opponent attacks in our king flank
File kf = file_of(ksq);
- b = ei.attackedBy[Them][ALL_PIECES] & KingFlank[kf] & Camp;
+ b = 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));
// Secondly, add the squares which are attacked twice in that flank and
// which are not defended by our pawns.
b = (Us == WHITE ? b << 4 : b >> 4)
- | (b & ei.attackedBy2[Them] & ~ei.attackedBy[Us][PAWN]);
+ | (b & attackedBy2[Them] & ~attackedBy[Us][PAWN]);
score -= CloseEnemies * popcount(b);
if (!(pos.pieces(PAWN) & KingFlank[kf]))
score -= PawnlessFlank;
- if (DoTrace)
+ if (T)
Trace::add(KING, Us, score);
return score;
// 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) {
+ 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 TRank2BB = (Us == WHITE ? Rank2BB : Rank7BB);
- const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
+ 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;
// Non-pawn enemies attacked by a pawn
- weak = (pos.pieces(Them) ^ pos.pieces(Them, PAWN)) & ei.attackedBy[Us][PAWN];
+ weak = (pos.pieces(Them) ^ pos.pieces(Them, PAWN)) & attackedBy[Us][PAWN];
if (weak)
{
- b = pos.pieces(Us, PAWN) & ( ~ei.attackedBy[Them][ALL_PIECES]
- | ei.attackedBy[Us][ALL_PIECES]);
+ b = pos.pieces(Us, PAWN) & ( ~attackedBy[Them][ALL_PIECES]
+ | attackedBy[Us][ALL_PIECES]);
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
// square with a pawn, or because they attack the square twice and we don't.
- stronglyProtected = ei.attackedBy[Them][PAWN]
- | (ei.attackedBy2[Them] & ~ei.attackedBy2[Us]);
+ stronglyProtected = attackedBy[Them][PAWN]
+ | (attackedBy2[Them] & ~attackedBy2[Us]);
// Non-pawn enemies, strongly protected
defended = (pos.pieces(Them) ^ pos.pieces(Them, PAWN))
// Enemies not strongly protected and under our attack
weak = pos.pieces(Them)
& ~stronglyProtected
- & ei.attackedBy[Us][ALL_PIECES];
+ & attackedBy[Us][ALL_PIECES];
// Add a bonus according to the kind of attacking pieces
if (defended | weak)
{
- b = (defended | weak) & (ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]);
+ b = (defended | weak) & (attackedBy[Us][KNIGHT] | attackedBy[Us][BISHOP]);
while (b)
{
Square s = pop_lsb(&b);
score += ThreatByRank * (int)relative_rank(Them, s);
}
- b = (pos.pieces(Them, QUEEN) | weak) & ei.attackedBy[Us][ROOK];
+ b = (pos.pieces(Them, QUEEN) | weak) & attackedBy[Us][ROOK];
while (b)
{
Square s = pop_lsb(&b);
score += ThreatByRank * (int)relative_rank(Them, s);
}
- score += Hanging * popcount(weak & ~ei.attackedBy[Them][ALL_PIECES]);
+ score += Hanging * popcount(weak & ~attackedBy[Them][ALL_PIECES]);
- b = weak & ei.attackedBy[Us][KING];
+ b = weak & attackedBy[Us][KING];
if (b)
score += ThreatByKing[more_than_one(b)];
}
- // Bonus if some pawns can safely push and attack an enemy piece
- b = pos.pieces(Us, PAWN) & ~TRank7BB;
- b = shift<Up>(b | (shift<Up>(b & TRank2BB) & ~pos.pieces()));
+ // Bonus for opponent unopposed weak pawns
+ if (pos.pieces(Us, ROOK, QUEEN))
+ score += WeakUnopposedPawn * pe->weak_unopposed(Them);
+
+ // Find squares where our pawns can push on the next move
+ b = shift<Up>(pos.pieces(Us, PAWN)) & ~pos.pieces();
+ b |= shift<Up>(b & TRank3BB) & ~pos.pieces();
- b &= ~pos.pieces()
- & ~ei.attackedBy[Them][PAWN]
- & (ei.attackedBy[Us][ALL_PIECES] | ~ei.attackedBy[Them][ALL_PIECES]);
+ // Keep only the squares which are not completely unsafe
+ b &= ~attackedBy[Them][PAWN]
+ & (attackedBy[Us][ALL_PIECES] | ~attackedBy[Them][ALL_PIECES]);
+ // Add a bonus for each new pawn threats from those squares
b = (shift<Left>(b) | shift<Right>(b))
& pos.pieces(Them)
- & ~ei.attackedBy[Us][PAWN];
+ & ~attackedBy[Us][PAWN];
score += ThreatByPawnPush * popcount(b);
- if (DoTrace)
+ // 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);
return score;
}
- // evaluate_passer_pawns() evaluates the passed pawns and candidate passed
+ // evaluate_passed_pawns() evaluates the passed pawns and candidate passed
// pawns of the given color.
- template<Color Us, bool DoTrace>
- Score evaluate_passer_pawns(const Position& pos, const EvalInfo& ei) {
+ template<Tracing T> template<Color Us>
+ Score Evaluation<T>::evaluate_passed_pawns() {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Direction Up = (Us == WHITE ? NORTH : SOUTH);
Bitboard b, bb, squaresToQueen, defendedSquares, unsafeSquares;
Score score = SCORE_ZERO;
- b = ei.pe->passed_pawns(Us);
+ b = pe->passed_pawns(Us);
while (b)
{
Square s = pop_lsb(&b);
- assert(!(pos.pieces(Them, PAWN) & forward_bb(Us, s + pawn_push(Us))));
+ assert(!(pos.pieces(Them, PAWN) & forward_file_bb(Us, s + Up)));
- bb = forward_bb(Us, s) & (ei.attackedBy[Them][ALL_PIECES] | pos.pieces(Them));
+ bb = forward_file_bb(Us, s) & (attackedBy[Them][ALL_PIECES] | pos.pieces(Them));
score -= HinderPassedPawn * popcount(bb);
int r = relative_rank(Us, s) - RANK_2;
if (rr)
{
- Square blockSq = s + pawn_push(Us);
+ Square blockSq = s + Up;
// Adjust bonus based on the king's proximity
ebonus += distance(pos.square<KING>(Them), blockSq) * 5 * rr
- - distance(pos.square<KING>(Us ), blockSq) * 2 * rr;
+ - distance(pos.square<KING>( Us), blockSq) * 2 * rr;
// If blockSq is not the queening square then consider also a second push
if (relative_rank(Us, blockSq) != RANK_8)
- ebonus -= distance(pos.square<KING>(Us), blockSq + pawn_push(Us)) * rr;
+ ebonus -= distance(pos.square<KING>(Us), blockSq + Up) * rr;
// If the pawn is free to advance, then increase the bonus
if (pos.empty(blockSq))
// If there is a rook or queen attacking/defending the pawn from behind,
// consider all the squaresToQueen. Otherwise consider only the squares
// in the pawn's path attacked or occupied by the enemy.
- defendedSquares = unsafeSquares = squaresToQueen = forward_bb(Us, s);
+ defendedSquares = unsafeSquares = squaresToQueen = forward_file_bb(Us, s);
- bb = forward_bb(Them, s) & pos.pieces(ROOK, QUEEN) & pos.attacks_from<ROOK>(s);
+ bb = forward_file_bb(Them, s) & pos.pieces(ROOK, QUEEN) & pos.attacks_from<ROOK>(s);
if (!(pos.pieces(Us) & bb))
- defendedSquares &= ei.attackedBy[Us][ALL_PIECES];
+ defendedSquares &= attackedBy[Us][ALL_PIECES];
if (!(pos.pieces(Them) & bb))
- unsafeSquares &= ei.attackedBy[Them][ALL_PIECES] | pos.pieces(Them);
+ unsafeSquares &= attackedBy[Them][ALL_PIECES] | pos.pieces(Them);
// If there aren't any enemy attacks, assign a big bonus. Otherwise
// assign a smaller bonus if the block square isn't attacked.
// Scale down bonus for candidate passers which need more than one
// pawn push to become passed or have a pawn in front of them.
- if (!pos.pawn_passed(Us, s + pawn_push(Us)) || (pos.pieces(PAWN) & forward_bb(Us, s)))
+ if (!pos.pawn_passed(Us, s + Up) || (pos.pieces(PAWN) & forward_file_bb(Us, s)))
mbonus /= 2, ebonus /= 2;
score += make_score(mbonus, ebonus) + PassedFile[file_of(s)];
}
- if (DoTrace)
+ if (T)
Trace::add(PASSED, Us, score);
return score;
// 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.
- template<Color Us>
- Score evaluate_space(const Position& pos, const EvalInfo& ei) {
+
+ template<Tracing T> template<Color Us>
+ Score Evaluation<T>::evaluate_space() {
const Color Them = (Us == WHITE ? BLACK : WHITE);
const Bitboard SpaceMask =
// pawn, or if it is undefended and attacked by an enemy piece.
Bitboard safe = SpaceMask
& ~pos.pieces(Us, PAWN)
- & ~ei.attackedBy[Them][PAWN]
- & (ei.attackedBy[Us][ALL_PIECES] | ~ei.attackedBy[Them][ALL_PIECES]);
+ & ~attackedBy[Them][PAWN]
+ & (attackedBy[Us][ALL_PIECES] | ~attackedBy[Them][ALL_PIECES]);
// Find all squares which are at most three squares behind some friendly pawn
Bitboard behind = pos.pieces(Us, PAWN);
// ...count safe + (behind & safe) with a single popcount.
int bonus = popcount((Us == WHITE ? safe << 32 : safe >> 32) | (behind & safe));
- int weight = pos.count<ALL_PIECES>(Us) - 2 * ei.pe->open_files();
+ int weight = pos.count<ALL_PIECES>(Us) - 2 * pe->open_files();
return make_score(bonus * weight * weight / 16, 0);
}
// evaluate_initiative() computes the initiative correction value for the
// 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) {
+
+ template<Tracing T>
+ Score Evaluation<T>::evaluate_initiative(Value eg) {
int kingDistance = distance<File>(pos.square<KING>(WHITE), pos.square<KING>(BLACK))
- distance<Rank>(pos.square<KING>(WHITE), pos.square<KING>(BLACK));
bool bothFlanks = (pos.pieces(PAWN) & QueenSide) && (pos.pieces(PAWN) & KingSide);
// Compute the initiative bonus for the attacking side
- int initiative = 8 * (
asymmetry + kingDistance - 17) + 12 * pos.count<PAWN>() + 16 * bothFlanks;
+ int initiative = 8 * (
pe->pawn_asymmetry() + kingDistance - 17) + 12 * pos.count<PAWN>() + 16 * bothFlanks;
// Now apply the bonus: note that we find the attacking side by extracting
// the sign of the endgame value, and that we carefully cap the bonus so
// that the endgame score will never change sign after the bonus.
- int value = ((eg > 0) - (eg < 0)) * std::max(initiative, -abs(eg));
+ int v = ((eg > 0) - (eg < 0)) * std::max(initiative, -abs(eg));
- return make_score(0, value);
+ if (T)
+ Trace::add(INITIATIVE, make_score(0, v));
+
+ return make_score(0, v);
}
// evaluate_scale_factor() computes the scale factor for the winning side
- ScaleFactor evaluate_scale_factor(const Position& pos, const EvalInfo& ei, Value eg) {
+
+ template<Tracing T>
+ ScaleFactor Evaluation<T>::evaluate_scale_factor(Value eg) {
Color strongSide = eg > VALUE_DRAW ? WHITE : BLACK;
- ScaleFactor sf = ei.me->scale_factor(pos, strongSide);
+ ScaleFactor sf = me->scale_factor(pos, strongSide);
// If we don't already have an unusual scale factor, check for certain
// types of endgames, and use a lower scale for those.
return sf;
}
-} // namespace
+ // value() is the main function of the class. It computes the various parts of
+ // the evaluation and returns the value of the position from the point of view
+ // of the side to move.
-/// evaluate() is the main evaluation function. It returns a static evaluation
-/// of the position from the point of view of the side to move.
+ template<Tracing T>
+ Value Evaluation<T>::value() {
+
+ assert(!pos.checkers());
+
+ // Probe the material hash table
+ me = Material::probe(pos);
+
+ // If we have a specialized evaluation function for the current material
+ // configuration, call it and return.
+ if (me->specialized_eval_exists())
+ return me->evaluate(pos);
+
+ // 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() + Eval::Contempt;
+
+ // Probe the pawn hash table
+ pe = Pawns::probe(pos);
+ score += pe->pawns_score();
+
+ // Early exit if score is high
+ Value v = (mg_value(score) + eg_value(score)) / 2;
+ if (abs(v) > LazyThreshold)
+ return pos.side_to_move() == WHITE ? v : -v;
+
+ // Main evaluation begins here
-template<bool DoTrace>
-Value Eval::evaluate(const Position& pos) {
-
- assert(!pos.checkers());
-
- Score mobility[COLOR_NB] = { SCORE_ZERO, SCORE_ZERO };
- Value v;
- EvalInfo ei;
-
- // Probe the material hash table
- ei.me = Material::probe(pos);
-
- // If we have a specialized evaluation function for the current material
- // configuration, call it and return.
- if (ei.me->specialized_eval_exists())
- return ei.me->evaluate(pos);
-
- // 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() + ei.me->imbalance();
-
- // Probe the pawn hash table
- ei.pe = Pawns::probe(pos);
- score += ei.pe->pawns_score();
-
- // Early exit if score is high
- v = (mg_value(score) + eg_value(score)) / 2;
- if (abs(v) > LazyThreshold)
- return pos.side_to_move() == WHITE ? v : -v;
-
- // Initialize attack and king safety bitboards
- eval_init<WHITE>(pos, ei);
- eval_init<BLACK>(pos, ei);
-
- // Evaluate all pieces but king and pawns
- score += evaluate_pieces<DoTrace>(pos, ei, mobility);
- score += mobility[WHITE] - mobility[BLACK];
-
- // Evaluate kings after all other pieces because we need full attack
- // information when computing the king safety evaluation.
- score += evaluate_king<WHITE, DoTrace>(pos, ei)
- - evaluate_king<BLACK, DoTrace>(pos, ei);
-
- // Evaluate tactical threats, we need full attack information including king
- score += evaluate_threats<WHITE, DoTrace>(pos, ei)
- - evaluate_threats<BLACK, DoTrace>(pos, ei);
-
- // Evaluate passed pawns, we need full attack information including king
- score += evaluate_passer_pawns<WHITE, DoTrace>(pos, ei)
- - evaluate_passer_pawns<BLACK, DoTrace>(pos, ei);
-
- // Evaluate space for both sides, only during opening
- if (pos.non_pawn_material() >= SpaceThreshold)
- score += evaluate_space<WHITE>(pos, ei)
- - evaluate_space<BLACK>(pos, ei);
-
- // Evaluate position potential for the winning side
- score += evaluate_initiative(pos, ei.pe->pawn_asymmetry(), eg_value(score));
-
- // Evaluate scale factor for the winning side
- ScaleFactor sf = evaluate_scale_factor(pos, ei, eg_value(score));
-
- // Interpolate between a middlegame and a (scaled by 'sf') endgame score
- v = mg_value(score) * int(ei.me->game_phase())
- + eg_value(score) * int(PHASE_MIDGAME - ei.me->game_phase()) * sf / SCALE_FACTOR_NORMAL;
-
- v /= int(PHASE_MIDGAME);
-
- // In case of tracing add all remaining individual evaluation terms
- if (DoTrace)
- {
- Trace::add(MATERIAL, pos.psq_score());
- Trace::add(IMBALANCE, ei.me->imbalance());
- Trace::add(PAWN, ei.pe->pawns_score());
- Trace::add(MOBILITY, mobility[WHITE], mobility[BLACK]);
- if (pos.non_pawn_material() >= SpaceThreshold)
- Trace::add(SPACE, evaluate_space<WHITE>(pos, ei)
- , evaluate_space<BLACK>(pos, ei));
- Trace::add(TOTAL, score);
+ initialize<WHITE>();
+ initialize<BLACK>();
+
+ score += evaluate_pieces<WHITE, KNIGHT>() - evaluate_pieces<BLACK, KNIGHT>();
+ score += evaluate_pieces<WHITE, BISHOP>() - evaluate_pieces<BLACK, BISHOP>();
+ score += evaluate_pieces<WHITE, ROOK >() - evaluate_pieces<BLACK, ROOK >();
+ score += evaluate_pieces<WHITE, QUEEN >() - evaluate_pieces<BLACK, QUEEN >();
+
+ score += mobility[WHITE] - mobility[BLACK];
+
+ score += evaluate_king<WHITE>()
+ - evaluate_king<BLACK>();
+
+ score += evaluate_threats<WHITE>()
+ - evaluate_threats<BLACK>();
+
+ score += evaluate_passed_pawns<WHITE>()
+ - evaluate_passed_pawns<BLACK>();
+
+ if (pos.non_pawn_material() >= SpaceThreshold)
+ score += evaluate_space<WHITE>()
+ - evaluate_space<BLACK>();
+
+ score += evaluate_initiative(eg_value(score));
+
+ // Interpolate between a middlegame and a (scaled by 'sf') endgame score
+ ScaleFactor sf = evaluate_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 /= int(PHASE_MIDGAME);
+
+ // In case of tracing add all remaining individual evaluation terms
+ if (T)
+ {
+ Trace::add(MATERIAL, pos.psq_score());
+ Trace::add(IMBALANCE, me->imbalance());
+ Trace::add(PAWN, pe->pawns_score());
+ Trace::add(MOBILITY, mobility[WHITE], mobility[BLACK]);
+ if (pos.non_pawn_material() >= SpaceThreshold)
+ Trace::add(SPACE, evaluate_space<WHITE>()
+ , evaluate_space<BLACK>());
+ Trace::add(TOTAL, score);
+ }
+
+ return pos.side_to_move() == WHITE ? v : -v; // Side to move point of view
}
- return (pos.side_to_move() == WHITE ? v : -v) + Eval::Tempo; // Side to move point of view
-}
+} // namespace
+
+Score Eval::Contempt = SCORE_ZERO;
-// Explicit template instantiations
-template Value Eval::evaluate<true >(const Position&);
-template Value Eval::evaluate<false>(const Position&);
+/// 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() + Eval::Tempo;
+}
/// trace() is like evaluate(), but instead of returning a value, it returns
/// a string (suitable for outputting to stdout) that contains the detailed
std::memset(scores, 0, sizeof(scores));
- Value v = evaluate<true>(pos);
+ Value v = Evaluation<TRACE>(pos).value() + Eval::Tempo;
v = pos.side_to_move() == WHITE ? v : -v; // White's point of view
std::stringstream ss;
<< " Imbalance | " << Term(IMBALANCE)
<< " Pawns | " << Term(PAWN)
<< " Knights | " << Term(KNIGHT)
- << " Bishop | " << Term(BISHOP)
+ << " Bishops | " << Term(BISHOP)
<< " Rooks | " << Term(ROOK)
<< " Queens | " << Term(QUEEN)
<< " Mobility | " << Term(MOBILITY)
<< " Threats | " << Term(THREAT)
<< " Passed pawns | " << Term(PASSED)
<< " Space | " << Term(SPACE)
+ << " Initiative | " << Term(INITIATIVE)
<< "----------------+-------------+-------------+-------------\n"
<< " Total | " << Term(TOTAL);
projects / stockfish / blobdiff