diff --git a/src/evaluate.cpp b/src/evaluate.cpp
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--- /dev/null
+++ b/src/evaluate.cpp
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+/*
+ 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) 2015-2019 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
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ Stockfish is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see .
+*/
+
+#include
+#include
+#include // For std::memset
+#include
+#include
+
+#include "bitboard.h"
+#include "evaluate.h"
+#include "material.h"
+#include "pawns.h"
+#include "thread.h"
+
+namespace Trace {
+
+ 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
+ };
+
+ Score scores[TERM_NB][COLOR_NB];
+
+ double to_cp(Value v) { return double(v) / PawnValueEg; }
+
+ void add(int idx, Color c, Score s) {
+ scores[idx][c] = s;
+ }
+
+ void add(int idx, Score w, Score b = SCORE_ZERO) {
+ scores[idx][WHITE] = w;
+ scores[idx][BLACK] = b;
+ }
+
+ std::ostream& operator<<(std::ostream& os, Score s) {
+ os << std::setw(5) << to_cp(mg_value(s)) << " "
+ << std::setw(5) << to_cp(eg_value(s));
+ return os;
+ }
+
+ std::ostream& operator<<(std::ostream& os, Term t) {
+
+ if (t == MATERIAL || t == IMBALANCE || t == INITIATIVE || t == TOTAL)
+ os << " ---- ----" << " | " << " ---- ----";
+ else
+ os << scores[t][WHITE] << " | " << scores[t][BLACK];
+
+ os << " | " << scores[t][WHITE] - scores[t][BLACK] << "\n";
+ return os;
+ }
+}
+
+using namespace Trace;
+
+namespace {
+
+ // Threshold for lazy and space evaluation
+ constexpr Value LazyThreshold = Value(1400);
+ constexpr Value SpaceThreshold = Value(12222);
+
+ // KingAttackWeights[PieceType] contains king attack weights by piece type
+ constexpr int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 77, 55, 44, 10 };
+
+ // Penalties for enemy's safe checks
+ constexpr int QueenSafeCheck = 780;
+ constexpr int RookSafeCheck = 1080;
+ constexpr int BishopSafeCheck = 635;
+ constexpr int KnightSafeCheck = 790;
+
+#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), // Knights
+ S( 22, 23), S( 28, 27), S( 33, 33) },
+ { S(-48,-59), S(-20,-23), S( 16, -3), S( 26, 13), S( 38, 24), S( 51, 42), // Bishops
+ 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), // Rooks
+ 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), // Queens
+ 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) }
+ };
+
+ // RookOnFile[semiopen/open] contains bonuses for each rook when there is
+ // no (friendly) pawn on the rook file.
+ constexpr Score RookOnFile[] = { S(18, 7), S(44, 20) };
+
+ // ThreatByMinor/ByRook[attacked PieceType] contains bonuses according to
+ // which piece type attacks which one. Attacks on lesser pieces which are
+ // pawn-defended are not considered.
+ constexpr Score ThreatByMinor[PIECE_TYPE_NB] = {
+ S(0, 0), S(0, 31), S(39, 42), S(57, 44), S(68, 112), S(62, 120)
+ };
+
+ constexpr Score ThreatByRook[PIECE_TYPE_NB] = {
+ S(0, 0), S(0, 24), S(38, 71), S(38, 61), S(0, 38), S(51, 38)
+ };
+
+ // PassedRank[Rank] contains a bonus according to the rank of a passed pawn
+ constexpr Score PassedRank[RANK_NB] = {
+ S(0, 0), S(5, 18), S(12, 23), S(10, 31), S(57, 62), S(163, 167), S(271, 250)
+ };
+
+ // PassedFile[File] contains a bonus according to the file of a passed pawn
+ constexpr Score PassedFile[FILE_NB] = {
+ S( -1, 7), S( 0, 9), S(-9, -8), S(-30,-14),
+ S(-30,-14), S(-9, -8), S( 0, 9), S( -1, 7)
+ };
+
+ // Assorted bonuses and penalties
+ constexpr Score BishopPawns = S( 3, 7);
+ 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 LongDiagonalBishop = S( 45, 0);
+ constexpr Score MinorBehindPawn = S( 18, 3);
+ constexpr Score Outpost = S( 9, 3);
+ constexpr Score PawnlessFlank = S( 17, 95);
+ constexpr Score RestrictedPiece = S( 7, 7);
+ constexpr Score RookOnPawn = S( 10, 32);
+ constexpr Score SliderOnQueen = S( 59, 18);
+ constexpr Score ThreatByKing = S( 24, 89);
+ constexpr Score ThreatByPawnPush = S( 48, 39);
+ constexpr Score ThreatByRank = S( 13, 0);
+ constexpr Score ThreatBySafePawn = S(173, 94);
+ constexpr Score TrappedRook = S( 47, 4);
+ constexpr Score WeakQueen = S( 49, 15);
+ constexpr Score WeakUnopposedPawn = S( 12, 23);
+
+#undef S
+
+ // Evaluation class computes and stores attacks tables and other working data
+ template
+ class Evaluation {
+
+ public:
+ Evaluation() = delete;
+ explicit Evaluation(const Position& p) : pos(p) {}
+ Evaluation& operator=(const Evaluation&) = delete;
+ Value value();
+
+ private:
+ template void initialize();
+ template Score pieces();
+ template Score king() const;
+ template Score threats() const;
+ template Score passed() const;
+ template Score space() const;
+ ScaleFactor scale_factor(Value eg) const;
+ Score initiative(Value eg) const;
+
+ 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. Special "piece types" which
+ // is also calculated is ALL_PIECES.
+ Bitboard attackedBy[COLOR_NB][PIECE_TYPE_NB];
+
+ // attackedBy2[color] are the squares attacked by at least 2 units of a given
+ // color, including x-rays. But diagonal x-rays through pawns are not computed.
+ Bitboard attackedBy2[COLOR_NB];
+
+ // kingRing[color] are the squares adjacent to the king, plus (only for a
+ // king on its first rank) the squares two ranks in front. For instance,
+ // if black's king is on g8, kingRing[BLACK] is f8, h8, f7, g7, h7, f6, g6
+ // and h6.
+ Bitboard kingRing[COLOR_NB];
+
+ // kingAttackersCount[color] is the number of pieces of the given color
+ // which attack a square in the kingRing of the enemy king.
+ int kingAttackersCount[COLOR_NB];
+
+ // 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.
+ int kingAttackersWeight[COLOR_NB];
+
+ // kingAttacksCount[color] is the number of attacks by the given color to
+ // squares directly adjacent to the enemy king. Pieces which attack more
+ // than one square are counted multiple times. For instance, if there is
+ // a white knight on g5 and black's king is on g8, this white knight adds 2
+ // to kingAttacksCount[WHITE].
+ int kingAttacksCount[COLOR_NB];
+ };
+
+
+ // 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 template
+ void Evaluation::initialize() {
+
+ constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
+ constexpr Direction Up = (Us == WHITE ? NORTH : SOUTH);
+ constexpr Direction Down = (Us == WHITE ? SOUTH : NORTH);
+ constexpr Bitboard LowRanks = (Us == WHITE ? Rank2BB | Rank3BB: Rank7BB | Rank6BB);
+
+ const Square ksq = pos.square(Us);
+
+ Bitboard dblAttackByPawn = pawn_double_attacks_bb(pos.pieces(Us, PAWN));
+
+ // Find our pawns that are blocked or on the first two ranks
+ Bitboard b = pos.pieces(Us, PAWN) & (shift(pos.pieces()) | LowRanks);
+
+ // Squares occupied by those pawns, by our king or queen or controlled by
+ // enemy pawns are excluded from the mobility area.
+ mobilityArea[Us] = ~(b | pos.pieces(Us, KING, QUEEN) | pe->pawn_attacks(Them));
+
+ // Initialize attackedBy[] for king and pawns
+ attackedBy[Us][KING] = pos.attacks_from(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
+ kingRing[Us] = attackedBy[Us][KING];
+ if (relative_rank(Us, ksq) == RANK_1)
+ kingRing[Us] |= shift(kingRing[Us]);
+
+ if (file_of(ksq) == FILE_H)
+ kingRing[Us] |= shift(kingRing[Us]);
+
+ else if (file_of(ksq) == FILE_A)
+ kingRing[Us] |= shift(kingRing[Us]);
+
+ kingAttackersCount[Them] = popcount(kingRing[Us] & pe->pawn_attacks(Them));
+ kingAttacksCount[Them] = kingAttackersWeight[Them] = 0;
+
+ // Remove from kingRing[] the squares defended by two pawns
+ kingRing[Us] &= ~dblAttackByPawn;
+ }
+
+
+ // Evaluation::pieces() scores pieces of a given color and type
+ template template
+ Score Evaluation::pieces() {
+
+ constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
+ constexpr Direction Down = (Us == WHITE ? SOUTH : NORTH);
+ constexpr Bitboard OutpostRanks = (Us == WHITE ? Rank4BB | Rank5BB | Rank6BB
+ : Rank5BB | Rank4BB | Rank3BB);
+ const Square* pl = pos.squares(Us);
+
+ Bitboard b, bb;
+ Score score = SCORE_ZERO;
+
+ attackedBy[Us][Pt] = 0;
+
+ for (Square s = *pl; s != SQ_NONE; s = *++pl)
+ {
+ // Find attacked squares, including x-ray attacks for bishops and rooks
+ b = Pt == BISHOP ? attacks_bb(s, pos.pieces() ^ pos.pieces(QUEEN))
+ : Pt == ROOK ? attacks_bb< ROOK>(s, pos.pieces() ^ pos.pieces(QUEEN) ^ pos.pieces(Us, ROOK))
+ : pos.attacks_from(s);
+
+ if (pos.blockers_for_king(Us) & s)
+ b &= LineBB[pos.square(Us)][s];
+
+ attackedBy2[Us] |= attackedBy[Us][ALL_PIECES] & b;
+ attackedBy[Us][Pt] |= b;
+ attackedBy[Us][ALL_PIECES] |= b;
+
+ if (b & kingRing[Them])
+ {
+ kingAttackersCount[Us]++;
+ kingAttackersWeight[Us] += KingAttackWeights[Pt];
+ kingAttacksCount[Us] += popcount(b & attackedBy[Them][KING]);
+ }
+
+ int mob = popcount(b & mobilityArea[Us]);
+
+ mobility[Us] += MobilityBonus[Pt - 2][mob];
+
+ if (Pt == BISHOP || Pt == KNIGHT)
+ {
+ // Bonus if piece is on an outpost square or can reach one
+ bb = OutpostRanks & ~pe->pawn_attacks_span(Them);
+ if (bb & s)
+ score += Outpost * (Pt == KNIGHT ? 4 : 2)
+ * ((attackedBy[Us][PAWN] & s) ? 2 : 1);
+
+ else if (bb &= b & ~pos.pieces(Us))
+ score += Outpost * (Pt == KNIGHT ? 2 : 1)
+ * ((attackedBy[Us][PAWN] & bb) ? 2 : 1);
+
+ // Knight and Bishop bonus for being right behind a pawn
+ if (shift(pos.pieces(PAWN)) & s)
+ score += MinorBehindPawn;
+
+ // Penalty if the piece is far from the king
+ score -= KingProtector * distance(s, pos.square(Us));
+
+ if (Pt == BISHOP)
+ {
+ // Penalty according to number of pawns on the same color square as the
+ // bishop, bigger when the center files are blocked with pawns.
+ Bitboard blocked = pos.pieces(Us, PAWN) & shift(pos.pieces());
+
+ score -= BishopPawns * pos.pawns_on_same_color_squares(Us, s)
+ * (1 + popcount(blocked & CenterFiles));
+
+ // Bonus for bishop on a long diagonal which can "see" both center squares
+ if (more_than_one(attacks_bb(s, pos.pieces(PAWN)) & Center))
+ score += LongDiagonalBishop;
+ }
+
+ // An important Chess960 pattern: A cornered bishop blocked by a friendly
+ // pawn diagonally in front of it is a very serious problem, especially
+ // when that pawn is also blocked.
+ if ( Pt == BISHOP
+ && pos.is_chess960()
+ && (s == relative_square(Us, SQ_A1) || s == relative_square(Us, SQ_H1)))
+ {
+ 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)) ? CorneredBishop * 4
+ : pos.piece_on(s + d + d) == make_piece(Us, PAWN) ? CorneredBishop * 2
+ : CorneredBishop;
+ }
+ }
+
+ if (Pt == ROOK)
+ {
+ // Bonus for aligning rook with enemy pawns on the same rank/file
+ if (relative_rank(Us, s) >= RANK_5)
+ score += RookOnPawn * popcount(pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s]);
+
+ // Bonus for rook on an open or semi-open file
+ if (pos.is_on_semiopen_file(Us, s))
+ score += RookOnFile[bool(pos.is_on_semiopen_file(Them, s))];
+
+ // Penalty when trapped by the king, even more if the king cannot castle
+ else if (mob <= 3)
+ {
+ File kf = file_of(pos.square(Us));
+ if ((kf < FILE_E) == (file_of(s) < kf))
+ score -= TrappedRook * (1 + !pos.castling_rights(Us));
+ }
+ }
+
+ if (Pt == QUEEN)
+ {
+ // Penalty if any relative pin or discovered attack against the queen
+ Bitboard queenPinners;
+ if (pos.slider_blockers(pos.pieces(Them, ROOK, BISHOP), s, queenPinners))
+ score -= WeakQueen;
+ }
+ }
+ if (T)
+ Trace::add(Pt, Us, score);
+
+ return score;
+ }
+
+
+ // Evaluation::king() assigns bonuses and penalties to a king of a given color
+ template template
+ Score Evaluation::king() const {
+
+ constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
+ constexpr Bitboard Camp = (Us == WHITE ? AllSquares ^ Rank6BB ^ Rank7BB ^ Rank8BB
+ : AllSquares ^ Rank1BB ^ Rank2BB ^ Rank3BB);
+
+ Bitboard weak, b1, b2, safe, unsafeChecks = 0;
+ Bitboard rookChecks, queenChecks, bishopChecks, knightChecks;
+ int kingDanger = 0;
+ const Square ksq = pos.square(Us);
+
+ // Init the score with king shelter and enemy pawns storm
+ Score score = pe->king_safety(pos);
+
+ // Attacked squares defended at most once by our queen or king
+ weak = attackedBy[Them][ALL_PIECES]
+ & ~attackedBy2[Us]
+ & (~attackedBy[Us][ALL_PIECES] | attackedBy[Us][KING] | attackedBy[Us][QUEEN]);
+
+ // Analyse the safe enemy's checks which are possible on next move
+ safe = ~pos.pieces(Them);
+ safe &= ~attackedBy[Us][ALL_PIECES] | (weak & attackedBy2[Them]);
+
+ b1 = attacks_bb(ksq, pos.pieces() ^ pos.pieces(Us, QUEEN));
+ b2 = attacks_bb(ksq, pos.pieces() ^ pos.pieces(Us, QUEEN));
+
+ // Enemy rooks checks
+ rookChecks = b1 & safe & attackedBy[Them][ROOK];
+
+ if (rookChecks)
+ kingDanger += RookSafeCheck;
+ else
+ unsafeChecks |= b1 & attackedBy[Them][ROOK];
+
+ // Enemy queen safe checks: we count them only if they are from squares from
+ // which we can't give a rook check, because rook checks are more valuable.
+ queenChecks = (b1 | b2)
+ & attackedBy[Them][QUEEN]
+ & safe
+ & ~attackedBy[Us][QUEEN]
+ & ~rookChecks;
+
+ if (queenChecks)
+ kingDanger += 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.
+ bishopChecks = b2
+ & attackedBy[Them][BISHOP]
+ & safe
+ & ~queenChecks;
+
+ if (bishopChecks)
+ kingDanger += BishopSafeCheck;
+ else
+ unsafeChecks |= b2 & attackedBy[Them][BISHOP];
+
+ // Enemy knights checks
+ knightChecks = pos.attacks_from(ksq) & attackedBy[Them][KNIGHT];
+
+ if (knightChecks & safe)
+ kingDanger += KnightSafeCheck;
+ else
+ unsafeChecks |= knightChecks;
+
+ // Unsafe or occupied checking squares will also be considered, as long as
+ // the square is in the attacker's mobility area.
+ unsafeChecks &= mobilityArea[Them];
+
+ // Find the squares that opponent attacks in our king flank, and the squares
+ // which are attacked twice in that flank.
+ b1 = attackedBy[Them][ALL_PIECES] & KingFlank[file_of(ksq)] & Camp;
+ b2 = b1 & attackedBy2[Them];
+
+ int kingFlankAttacks = popcount(b1) + popcount(b2);
+
+ kingDanger += kingAttackersCount[Them] * kingAttackersWeight[Them]
+ + 69 * kingAttacksCount[Them]
+ + 185 * popcount(kingRing[Us] & weak)
+ - 100 * bool(attackedBy[Us][KNIGHT] & attackedBy[Us][KING])
+ - 35 * bool(attackedBy[Us][BISHOP] & attackedBy[Us][KING])
+ + 150 * popcount(pos.blockers_for_king(Us) | unsafeChecks)
+ - 873 * !pos.count(Them)
+ - 6 * mg_value(score) / 8
+ + mg_value(mobility[Them] - mobility[Us])
+ + 5 * kingFlankAttacks * kingFlankAttacks / 16
+ - 7;
+
+ // Transform the kingDanger units into a Score, and subtract it from the evaluation
+ if (kingDanger > 100)
+ score -= make_score(kingDanger * kingDanger / 4096, kingDanger / 16);
+
+ // Penalty when our king is on a pawnless flank
+ if (!(pos.pieces(PAWN) & KingFlank[file_of(ksq)]))
+ score -= PawnlessFlank;
+
+ // Penalty if king flank is under attack, potentially moving toward the king
+ score -= FlankAttacks * kingFlankAttacks;
+
+ if (T)
+ Trace::add(KING, Us, score);
+
+ return score;
+ }
+
+
+ // Evaluation::threats() assigns bonuses according to the types of the
+ // attacking and the attacked pieces.
+ template template
+ Score Evaluation::threats() const {
+
+ constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
+ constexpr Direction Up = (Us == WHITE ? NORTH : SOUTH);
+ constexpr Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
+
+ Bitboard b, weak, defended, nonPawnEnemies, stronglyProtected, safe;
+ Score score = SCORE_ZERO;
+
+ // Non-pawn enemies
+ nonPawnEnemies = pos.pieces(Them) & ~pos.pieces(PAWN);
+
+ // Squares strongly protected by the enemy, either because they defend the
+ // square with a pawn, or because they defend the square twice and we don't.
+ stronglyProtected = attackedBy[Them][PAWN]
+ | (attackedBy2[Them] & ~attackedBy2[Us]);
+
+ // Non-pawn enemies, strongly protected
+ defended = nonPawnEnemies & stronglyProtected;
+
+ // Enemies not strongly protected and under our attack
+ weak = pos.pieces(Them) & ~stronglyProtected & attackedBy[Us][ALL_PIECES];
+
+ // Safe or protected squares
+ safe = ~attackedBy[Them][ALL_PIECES] | attackedBy[Us][ALL_PIECES];
+
+ // Bonus according to the kind of attacking pieces
+ if (defended | weak)
+ {
+ b = (defended | weak) & (attackedBy[Us][KNIGHT] | attackedBy[Us][BISHOP]);
+ while (b)
+ {
+ Square s = pop_lsb(&b);
+ score += ThreatByMinor[type_of(pos.piece_on(s))];
+ if (type_of(pos.piece_on(s)) != PAWN)
+ score += ThreatByRank * (int)relative_rank(Them, s);
+ }
+
+ b = weak & attackedBy[Us][ROOK];
+ while (b)
+ {
+ Square s = pop_lsb(&b);
+ score += ThreatByRook[type_of(pos.piece_on(s))];
+ if (type_of(pos.piece_on(s)) != PAWN)
+ score += ThreatByRank * (int)relative_rank(Them, s);
+ }
+
+ if (weak & attackedBy[Us][KING])
+ score += ThreatByKing;
+
+ b = ~attackedBy[Them][ALL_PIECES]
+ | (nonPawnEnemies & attackedBy2[Us]);
+ score += Hanging * popcount(weak & b);
+ }
+
+ // Bonus for restricting their piece moves
+ b = attackedBy[Them][ALL_PIECES]
+ & ~stronglyProtected
+ & attackedBy[Us][ALL_PIECES];
+
+ score += RestrictedPiece * popcount(b);
+
+ // Bonus for enemy 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(pos.pieces(Us, PAWN)) & ~pos.pieces();
+ b |= shift(b & TRank3BB) & ~pos.pieces();
+
+ // Keep only the squares which are relatively safe
+ b &= ~attackedBy[Them][PAWN] & safe;
+
+ // Bonus for safe pawn threats on the next move
+ b = pawn_attacks_bb(b) & pos.pieces(Them);
+ score += ThreatByPawnPush * popcount(b);
+
+ // Our safe or protected pawns
+ b = pos.pieces(Us, PAWN) & safe;
+
+ b = pawn_attacks_bb(b) & nonPawnEnemies;
+ score += ThreatBySafePawn * popcount(b);
+
+ // Bonus for threats on the next moves against enemy queen
+ if (pos.count(Them) == 1)
+ {
+ Square s = pos.square(Them);
+ safe = mobilityArea[Us] & ~stronglyProtected;
+
+ b = attackedBy[Us][KNIGHT] & pos.attacks_from(s);
+
+ score += KnightOnQueen * popcount(b & safe);
+
+ b = (attackedBy[Us][BISHOP] & pos.attacks_from(s))
+ | (attackedBy[Us][ROOK ] & pos.attacks_from(s));
+
+ score += SliderOnQueen * popcount(b & safe & attackedBy2[Us]);
+ }
+
+ if (T)
+ Trace::add(THREAT, Us, score);
+
+ return score;
+ }
+
+ // Evaluation::passed() evaluates the passed pawns and candidate passed
+ // pawns of the given color.
+
+ template template
+ Score Evaluation::passed() const {
+
+ constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
+ constexpr Direction Up = (Us == WHITE ? NORTH : SOUTH);
+
+ auto king_proximity = [&](Color c, Square s) {
+ return std::min(distance(pos.square(c), s), 5);
+ };
+
+ Bitboard b, bb, squaresToQueen, defendedSquares, unsafeSquares;
+ Score score = SCORE_ZERO;
+
+ b = pe->passed_pawns(Us);
+
+ while (b)
+ {
+ Square s = pop_lsb(&b);
+
+ assert(!(pos.pieces(Them, PAWN) & forward_file_bb(Us, s + Up)));
+
+ int r = relative_rank(Us, s);
+
+ Score bonus = PassedRank[r];
+
+ if (r > RANK_3)
+ {
+ int w = (r-2) * (r-2) + 2;
+ Square blockSq = s + Up;
+
+ // Adjust bonus based on the king's proximity
+ bonus += make_score(0, ( king_proximity(Them, blockSq) * 5
+ - king_proximity(Us, blockSq) * 2) * w);
+
+ // If blockSq is not the queening square then consider also a second push
+ if (r != RANK_7)
+ bonus -= make_score(0, king_proximity(Us, blockSq + Up) * w);
+
+ // 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_file_bb(Us, s);
+
+ bb = forward_file_bb(Them, s) & pos.pieces(ROOK, QUEEN);
+
+ if (!(pos.pieces(Us) & bb))
+ defendedSquares &= attackedBy[Us][ALL_PIECES];
+
+ if (!(pos.pieces(Them) & bb))
+ 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.
+ int k = !unsafeSquares ? 20 : !(unsafeSquares & blockSq) ? 9 : 0;
+
+ // 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;
+
+ bonus += make_score(k * w, k * w);
+ }
+ } // r > RANK_3
+
+ // 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 + Up)
+ || (pos.pieces(PAWN) & forward_file_bb(Us, s)))
+ bonus = bonus / 2;
+
+ score += bonus + PassedFile[file_of(s)];
+ }
+
+ if (T)
+ Trace::add(PASSED, Us, score);
+
+ return score;
+ }
+
+
+ // 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.
+
+ template template
+ Score Evaluation::space() const {
+
+ if (pos.non_pawn_material() < SpaceThreshold)
+ return SCORE_ZERO;
+
+ constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
+ constexpr Direction Down = (Us == WHITE ? SOUTH : NORTH);
+ constexpr Bitboard SpaceMask =
+ Us == WHITE ? CenterFiles & (Rank2BB | Rank3BB | Rank4BB)
+ : CenterFiles & (Rank7BB | Rank6BB | Rank5BB);
+
+ // Find the available squares for our pieces inside the area defined by SpaceMask
+ Bitboard safe = SpaceMask
+ & ~pos.pieces(Us, PAWN)
+ & ~attackedBy[Them][PAWN];
+
+ // Find all squares which are at most three squares behind some friendly pawn
+ Bitboard behind = pos.pieces(Us, PAWN);
+ behind |= shift(behind);
+ behind |= shift(behind);
+
+ int bonus = popcount(safe) + popcount(behind & safe);
+ int weight = pos.count(Us) - 1;
+ Score score = make_score(bonus * weight * weight / 16, 0);
+
+ if (T)
+ Trace::add(SPACE, Us, score);
+
+ return score;
+ }
+
+
+ // 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.
+
+ template
+ Score Evaluation::initiative(Value eg) const {
+
+ int outflanking = distance(pos.square(WHITE), pos.square(BLACK))
+ - distance(pos.square(WHITE), pos.square(BLACK));
+
+ bool pawnsOnBothFlanks = (pos.pieces(PAWN) & QueenSide)
+ && (pos.pieces(PAWN) & KingSide);
+
+ // Compute the initiative bonus for the attacking side
+ int complexity = 9 * pe->passed_count()
+ + 11 * pos.count()
+ + 9 * outflanking
+ + 18 * pawnsOnBothFlanks
+ + 49 * !pos.non_pawn_material()
+ -103 ;
+
+ // 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 v = ((eg > 0) - (eg < 0)) * std::max(complexity, -abs(eg));
+
+ if (T)
+ Trace::add(INITIATIVE, make_score(0, v));
+
+ return make_score(0, v);
+ }
+
+
+ // Evaluation::scale_factor() computes the scale factor for the winning side
+
+ template
+ ScaleFactor Evaluation::scale_factor(Value eg) const {
+
+ 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 = 16 + 4 * pe->passed_count();
+ else
+ sf = std::min(40 + (pos.opposite_bishops() ? 2 : 7) * pos.count(strongSide), sf);
+
+ }
+
+ return ScaleFactor(sf);
+ }
+
+
+ // Evaluation::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.
+
+ template
+ Value Evaluation::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() + pos.this_thread()->contempt;
+
+ // Probe the pawn hash table
+ pe = Pawns::probe(pos);
+ score += pe->pawn_score(WHITE) - pe->pawn_score(BLACK);
+
+ // Early exit if score is high
+ Value v = (mg_value(score) + eg_value(score)) / 2;
+ if (abs(v) > (LazyThreshold + pos.non_pawn_material() / 64))
+ return pos.side_to_move() == WHITE ? v : -v;
+
+ // Main evaluation begins here
+
+ initialize();
+ initialize();
+
+ // Pieces should be evaluated first (populate attack tables)
+ score += pieces() - pieces()
+ + pieces() - pieces()
+ + pieces() - pieces()
+ + pieces() - pieces();
+
+ score += mobility[WHITE] - mobility[BLACK];
+
+ score += king< WHITE>() - king< BLACK>()
+ + threats() - threats()
+ + passed< WHITE>() - passed< BLACK>()
+ + space< WHITE>() - space< BLACK>();
+
+ score += initiative(eg_value(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;
+
+ // 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->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) // Side to move point of view
+ + Eval::Tempo;
+ }
+
+} // namespace
+
+
+/// 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();
+}
+
+
+/// trace() is like evaluate(), but instead of returning a value, it returns
+/// a string (suitable for outputting to stdout) that contains the detailed
+/// descriptions and values of each evaluation term. Useful for debugging.
+
+std::string Eval::trace(const Position& pos) {
+
+ std::memset(scores, 0, sizeof(scores));
+
+ pos.this_thread()->contempt = SCORE_ZERO; // Reset any dynamic contempt
+
+ Value v = Evaluation(pos).value();
+
+ v = pos.side_to_move() == WHITE ? v : -v; // Trace scores are from white's point of view
+
+ std::stringstream ss;
+ ss << std::showpoint << std::noshowpos << std::fixed << std::setprecision(2)
+ << " Term | White | Black | Total \n"
+ << " | MG EG | MG EG | MG EG \n"
+ << " ------------+-------------+-------------+------------\n"
+ << " Material | " << Term(MATERIAL)
+ << " Imbalance | " << Term(IMBALANCE)
+ << " Pawns | " << Term(PAWN)
+ << " Knights | " << Term(KNIGHT)
+ << " Bishops | " << Term(BISHOP)
+ << " Rooks | " << Term(ROOK)
+ << " Queens | " << Term(QUEEN)
+ << " Mobility | " << Term(MOBILITY)
+ << " King safety | " << Term(KING)
+ << " Threats | " << Term(THREAT)
+ << " Passed | " << Term(PASSED)
+ << " Space | " << Term(SPACE)
+ << " Initiative | " << Term(INITIATIVE)
+ << " ------------+-------------+-------------+------------\n"
+ << " Total | " << Term(TOTAL);
+
+ ss << "\nTotal evaluation: " << to_cp(v) << " (white side)\n";
+
+ return ss.str();
+}