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
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
#include <iomanip>
#include <sstream>
-#include "bitcount.h"
+#include "bitboard.h"
#include "evaluate.h"
#include "material.h"
#include "pawns.h"
namespace {
- namespace Tracing {
+ namespace Trace {
- enum Term { // First 8 entries are for PieceType
+ enum Tracing {NO_TRACE, TRACE};
+
+ enum Term { // The first 8 entries are for PieceType
MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, TOTAL, TERM_NB
};
- Score scores[COLOR_NB][TERM_NB];
+ double scores[TERM_NB][COLOR_NB][PHASE_NB];
+
+ double to_cp(Value v) { return double(v) / PawnValueEg; }
- std::ostream& operator<<(std::ostream& os, Term idx);
+ void add(int idx, Color c, Score s) {
+ scores[idx][c][MG] = to_cp(mg_value(s));
+ scores[idx][c][EG] = to_cp(eg_value(s));
+ }
+
+ void add(int idx, Score w, Score b = SCORE_ZERO) {
+ add(idx, WHITE, w); add(idx, BLACK, b);
+ }
- double to_cp(Value v);
- void write(int idx, Color c, Score s);
- void write(int idx, Score w, Score b = SCORE_ZERO);
- std::string do_trace(const Position& pos);
+ std::ostream& operator<<(std::ostream& os, Term t) {
+
+ if (t == MATERIAL || t == IMBALANCE || t == Term(PAWN) || t == TOTAL)
+ os << " --- --- | --- --- | ";
+ else
+ os << std::setw(5) << scores[t][WHITE][MG] << " "
+ << std::setw(5) << scores[t][WHITE][EG] << " | "
+ << std::setw(5) << scores[t][BLACK][MG] << " "
+ << std::setw(5) << scores[t][BLACK][EG] << " | ";
+
+ os << std::setw(5) << scores[t][WHITE][MG] - scores[t][BLACK][MG] << " "
+ << std::setw(5) << scores[t][WHITE][EG] - scores[t][BLACK][EG] << " \n";
+
+ return os;
+ }
}
+ 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 {
-
- // Pointers to material and pawn hash table entries
- Material::Entry* mi;
- Pawns::Entry* pi;
+ 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, attackedBy[color][ALL_PIECES]
- // contains all squares attacked by the given color.
+ // attacked by a given color and piece type (can be also ALL_PIECES).
Bitboard attackedBy[COLOR_NB][PIECE_TYPE_NB];
+ // attackedBy2[color] are the squares attacked by 2 pieces of a given color,
+ // possibly via x-ray or by one pawn and one piece. Diagonal x-ray through
+ // pawn or squares attacked by 2 pawns are not explicitly added.
+ Bitboard attackedBy2[COLOR_NB];
+
// 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.
// which attack a square in the kingRing of the enemy king.
int kingAttackersCount[COLOR_NB];
- // kingAttackersWeight[color] is the sum of the "weight" of the pieces of the
+ // kingAttackersWeight[color] is the sum of the "weights" of the pieces of the
// given color which attack a square in the kingRing of the enemy king. The
// weights of the individual piece types are given by the elements in the
// KingAttackWeights array.
// a white knight on g5 and black's king is on g8, this white knight adds 2
// to kingAdjacentZoneAttacksCount[WHITE].
int kingAdjacentZoneAttacksCount[COLOR_NB];
-
- Bitboard pinnedPieces[COLOR_NB];
};
-
- // Evaluation weights, indexed by the corresponding evaluation term
- enum { Mobility, PawnStructure, PassedPawns, Space, KingSafety };
-
- const struct Weight { int mg, eg; } Weights[] = {
- {289, 344}, {233, 201}, {221, 273}, {46, 0}, {322, 0}
- };
-
- Score operator*(Score s, const Weight& w) {
- return make_score(mg_value(s) * w.mg / 256, eg_value(s) * w.eg / 256);
- }
-
-
#define V(v) Value(v)
#define S(mg, eg) make_score(mg, eg)
- // MobilityBonus[PieceType][attacked] contains bonuses for middle and end
- // game, indexed by piece type and number of attacked squares not occupied by
- // friendly pieces.
+ // MobilityBonus[PieceType-2][attacked] contains bonuses for middle and end game,
+ // indexed by piece type and number of attacked squares in the mobility area.
const Score MobilityBonus[][32] = {
- {}, {},
- { S(-68,-49), S(-46,-33), S(-3,-12), S( 5, -4), S( 9, 11), S(15, 16), // Knights
- S( 23, 27), S( 33, 28), S(37, 29) },
- { S(-49,-44), S(-23,-16), S(16, 1), S(29, 16), S(40, 25), S(51, 34), // Bishops
- S( 55, 43), S( 61, 49), S(64, 51), S(68, 52), S(73, 55), S(75, 60),
- S( 80, 65), S( 86, 66) },
- { S(-50,-57), S(-28,-22), S(-11, 7), S(-1, 29), S( 0, 39), S( 1, 46), // Rooks
- S( 10, 66), S( 16, 79), S(22, 86), S(23,103), S(30,109), S(33,111),
- S( 37,115), S( 38,119), S(48,124) },
- { S(-43,-30), S(-27,-15), S( 1, -5), S( 2, -3), S(14, 10), S(18, 24), // Queens
- S( 20, 27), S( 33, 37), S(33, 38), S(34, 43), S(40, 46), S(43, 56),
- S( 46, 61), S( 52, 63), S(52, 63), S(57, 65), S(60, 70), S(61, 74),
- S( 67, 80), S( 76, 82), S(77, 88), S(82, 94), S(86, 95), S(90, 96),
- S( 94, 99), S( 96,100), S(99,111), S(99,112) }
+ { S(-75,-76), S(-57,-54), S( -9,-28), S( -2,-10), S( 6, 5), S( 14, 12), // Knights
+ S( 22, 26), S( 29, 29), S( 36, 29) },
+ { 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) }
};
- // Outpost[knight/bishop][supported by pawn] contains bonuses for knights and bishops
- // outposts, bigger if outpost piece is supported by a pawn.
+ // Outpost[knight/bishop][supported by pawn] contains bonuses for minor
+ // pieces if they can reach an outpost square, bigger if that square is
+ // supported by a pawn. If the minor piece occupies an outpost square
+ // then score is doubled.
const Score Outpost[][2] = {
- { S(28, 7), S(42,11) }, // Knights
- { S(12, 3), S(18, 5) } // Bishops
+ { S(22, 6), S(33, 9) }, // Knight
+ { S( 9, 2), S(14, 4) } // Bishop
};
- // Threat[defended/weak][minor/major attacking][attacked PieceType] contains
- // bonuses according to which piece type attacks which one.
- const Score Threat[][2][PIECE_TYPE_NB] = {
- { { S(0, 0), S( 0, 0), S(19, 37), S(24, 37), S(44, 97), S(35,106) }, // Defended Minor
- { S(0, 0), S( 0, 0), S( 9, 14), S( 9, 14), S( 7, 14), S(24, 48) } }, // Defended Major
- { { S(0, 0), S( 0,32), S(33, 41), S(31, 50), S(41,100), S(35,104) }, // Weak Minor
- { S(0, 0), S( 0,27), S(26, 57), S(26, 57), S(0 , 43), S(23, 51) } } // Weak Major
+ // RookOnFile[semiopen/open] contains bonuses for each rook when there is no
+ // friendly pawn on the rook file.
+ const Score RookOnFile[] = { S(20, 7), S(45, 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.
+ const Score ThreatByMinor[PIECE_TYPE_NB] = {
+ S(0, 0), S(0, 33), S(45, 43), S(46, 47), S(72, 107), S(48, 118)
};
- // ThreatenedByPawn[PieceType] contains a penalty according to which piece
- // type is attacked by an enemy pawn.
- const Score ThreatenedByPawn[PIECE_TYPE_NB] = {
- S(0, 0), S(0, 0), S(107, 138), S(84, 122), S(114, 203), S(121, 217)
+ const Score ThreatByRook[PIECE_TYPE_NB] = {
+ S(0, 0), S(0, 25), S(40, 62), S(40, 59), S(0, 34), S(35, 48)
};
- // PassedPawnsBonusMg[Rank] and PassedPawnsBonusEg[Rank]
- //contains bonuses for midgame and endgame for passed pawns according to
- //the rank of the pawn.
- const Value PassedPawnsBonusMg[6] = {
- V(0), V(1), V(34), V(90), V(214), V(328)
+ // ThreatByKing[on one/on many] contains bonuses for king attacks on
+ // pawns or pieces which are not pawn-defended.
+ const Score ThreatByKing[] = { S(3, 62), S(9, 138) };
+
+ // Passed[mg/eg][Rank] contains midgame and endgame bonuses for passed pawns.
+ // We don't use a Score because we process the two components independently.
+ const Value Passed[][RANK_NB] = {
+ { V(5), V( 5), V(31), V(73), V(166), V(252) },
+ { V(7), V(14), V(38), V(73), V(166), V(252) }
};
- const Value PassedPawnsBonusEg[6] = {
- V(7), V(14), V(37), V(63), V(134), V(189)
+ // PassedFile[File] contains a bonus according to the file of a passed pawn
+ const Score PassedFile[FILE_NB] = {
+ S( 9, 10), S( 2, 10), S( 1, -8), S(-20,-12),
+ S(-20,-12), S( 1, -8), S( 2, 10), S( 9, 10)
};
- const Score ThreatenedByHangingPawn = S(40, 60);
+ // KingProtector[PieceType-2] contains a bonus according to distance from king
+ const Score KingProtector[] = { S(-3, -5), S(-4, -3), S(-3, 0), S(-1, 1) };
// Assorted bonuses and penalties used by evaluation
- const Score KingOnOne = S( 2, 58);
- const Score KingOnMany = S( 6,125);
- const Score RookOnPawn = S( 7, 27);
- const Score RookOnOpenFile = S(43, 21);
- const Score RookOnSemiOpenFile = S(19, 10);
- const Score BishopPawns = S( 8, 12);
- const Score MinorBehindPawn = S(16, 0);
- const Score TrappedRook = S(92, 0);
- const Score Unstoppable = S( 0, 20);
- const Score Hanging = S(31, 26);
- const Score PawnAttackThreat = S(20, 20);
- const Score PawnSafePush = S( 5, 5);
+ 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
#undef S
#undef V
- // SpaceMask[Color] contains the area of the board which is considered
- // by the space evaluation. In the middlegame, each side is given a bonus
- // based on how many squares inside this area are safe and available for
- // friendly minor pieces.
- const Bitboard SpaceMask[COLOR_NB] = {
- (FileCBB | FileDBB | FileEBB | FileFBB) & (Rank2BB | Rank3BB | Rank4BB),
- (FileCBB | FileDBB | FileEBB | FileFBB) & (Rank7BB | Rank6BB | Rank5BB)
- };
-
- // King danger constants and variables. The king danger scores are looked-up
- // in KingDanger[]. Various little "meta-bonuses" measuring the strength
- // of the enemy attack are added up into an integer, which is used as an
- // index to KingDanger[].
- Score KingDanger[512];
-
// KingAttackWeights[PieceType] contains king attack weights by piece type
- const int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 7, 5, 4, 1 };
+ const int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 78, 56, 45, 11 };
// Penalties for enemy's safe checks
- const int QueenContactCheck = 89;
- const int RookContactCheck = 71;
- const int QueenCheck = 50;
- const int RookCheck = 37;
- const int BishopCheck = 6;
- const int KnightCheck = 14;
+ const int QueenCheck = 780;
+ const int RookCheck = 880;
+ const int BishopCheck = 435;
+ const int KnightCheck = 790;
+
+ // Threshold for lazy and space evaluation
+ const Value LazyThreshold = Value(1500);
+ const Value SpaceThreshold = Value(12222);
+
+
+ // 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() {
- // init_eval_info() initializes king bitboards for given color adding
- // pawn attacks. To be 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);
+ const Bitboard LowRanks = (Us == WHITE ? Rank2BB | Rank3BB: Rank7BB | Rank6BB);
- template<Color Us>
- void init_eval_info(const Position& pos, EvalInfo& ei) {
+ // Find our pawns on the first two ranks, and those which are blocked
+ Bitboard b = pos.pieces(Us, PAWN) & (shift<Down>(pos.pieces()) | LowRanks);
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Square Down = (Us == WHITE ? DELTA_S : DELTA_N);
+ // Squares occupied by those pawns, by our king, or controlled by enemy pawns
+ // are excluded from the mobility area.
+ mobilityArea[Us] = ~(b | pos.square<KING>(Us) | pe->pawn_attacks(Them));
- ei.pinnedPieces[Us] = pos.pinned_pieces(Us);
- ei.attackedBy[Us][ALL_PIECES] = ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);
- Bitboard b = ei.attackedBy[Them][KING] = pos.attacks_from<KING>(pos.square<KING>(Them));
+ // Initialise the attack bitboards with the king and pawn information
+ b = attackedBy[Us][KING] = pos.attacks_from<KING>(pos.square<KING>(Us));
+ attackedBy[Us][PAWN] = pe->pawn_attacks(Us);
- // Init king safety tables only if we are going to use them
- if (pos.non_pawn_material(Us) >= QueenValueMg)
+ 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) >= RookValueMg + KnightValueMg)
{
- ei.kingRing[Them] = b | shift_bb<Down>(b);
- b &= ei.attackedBy[Us][PAWN];
- ei.kingAttackersCount[Us] = b ? popcount<Max15>(b) : 0;
- ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 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[Them] = ei.kingAttackersCount[Us] = 0;
+ kingRing[Us] = kingAttackersCount[Them] = 0;
}
- // evaluate_pieces() assigns bonuses and penalties to the pieces of a given color
+ // evaluate_pieces() assigns bonuses and penalties to the pieces of a given
+ // color and type.
- template<PieceType Pt, Color Us, bool Trace>
- Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score* mobility, Bitboard* mobilityArea) {
-
- Bitboard b;
- Square s;
- Score score = SCORE_ZERO;
+ template<Tracing T> template<Color Us, PieceType Pt>
+ Score Evaluation<T>::evaluate_pieces() {
- const PieceType NextPt = (Us == WHITE ? Pt : PieceType(Pt + 1));
const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Bitboard OutpostRanks = (Us == WHITE ? Rank4BB | Rank5BB | Rank6BB
+ : Rank5BB | Rank4BB | Rank3BB);
const Square* pl = pos.squares<Pt>(Us);
- ei.attackedBy[Us][Pt] = 0;
+ Bitboard b, bb;
+ Square s;
+ Score score = SCORE_ZERO;
+
+ attackedBy[Us][Pt] = 0;
while ((s = *pl++) != SQ_NONE)
{
: Pt == ROOK ? attacks_bb< ROOK>(s, pos.pieces() ^ pos.pieces(Us, ROOK, QUEEN))
: pos.attacks_from<Pt>(s);
- if (ei.pinnedPieces[Us] & s)
+ if (pos.pinned_pieces(Us) & s)
b &= LineBB[pos.square<KING>(Us)][s];
- 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 (b & ei.kingRing[Them])
+ if (b & kingRing[Them])
{
- ei.kingAttackersCount[Us]++;
- ei.kingAttackersWeight[Us] += KingAttackWeights[Pt];
- Bitboard bb = b & ei.attackedBy[Them][KING];
- if (bb)
- ei.kingAdjacentZoneAttacksCount[Us] += popcount<Max15>(bb);
+ kingAttackersCount[Us]++;
+ kingAttackersWeight[Us] += KingAttackWeights[Pt];
+ kingAdjacentZoneAttacksCount[Us] += popcount(b & attackedBy[Them][KING]);
}
- if (Pt == QUEEN)
- b &= ~( ei.attackedBy[Them][KNIGHT]
- | ei.attackedBy[Them][BISHOP]
- | ei.attackedBy[Them][ROOK]);
+ int mob = popcount(b & mobilityArea[Us]);
- int mob = popcount<Pt == QUEEN ? Full : Max15>(b & mobilityArea[Us]);
+ mobility[Us] += MobilityBonus[Pt - 2][mob];
- mobility[Us] += MobilityBonus[Pt][mob];
+ // Bonus for this piece as a king protector
+ score += KingProtector[Pt - 2] * distance(s, pos.square<KING>(Us));
if (Pt == BISHOP || Pt == KNIGHT)
{
- // Bonus for outpost square
- if ( relative_rank(Us, s) >= RANK_4
- && !(pos.pieces(Them, PAWN) & pawn_attack_span(Us, s)))
- score += Outpost[Pt == BISHOP][!!(ei.attackedBy[Us][PAWN] & s)];
+ // Bonus for outpost squares
+ bb = OutpostRanks & ~pe->pawn_attacks_span(Them);
+ if (bb & s)
+ score += Outpost[Pt == BISHOP][!!(attackedBy[Us][PAWN] & s)] * 2;
+ else
+ {
+ bb &= b & ~pos.pieces(Us);
+ if (bb)
+ score += Outpost[Pt == BISHOP][!!(attackedBy[Us][PAWN] & bb)];
+ }
// Bonus when behind a pawn
if ( relative_rank(Us, s) < RANK_5
&& (pos.pieces(PAWN) & (s + pawn_push(Us))))
score += MinorBehindPawn;
- // Penalty for pawns on same color square of bishop
+ // Penalty for pawns on the same color square as the bishop
if (Pt == BISHOP)
- score -= BishopPawns * ei.pi->pawns_on_same_color_squares(Us, s);
+ score -= BishopPawns * pe->pawns_on_same_color_squares(Us, s);
// 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 ? DELTA_E : DELTA_W);
+ Square 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 for aligning with enemy pawns on the same rank/file
if (relative_rank(Us, s) >= RANK_5)
- {
- Bitboard alignedPawns = pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s];
- if (alignedPawns)
- score += popcount<Max15>(alignedPawns) * RookOnPawn;
- }
+ score += RookOnPawn * popcount(pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s]);
// Bonus when on an open or semi-open file
- if (ei.pi->semiopen_file(Us, file_of(s)))
- score += ei.pi->semiopen_file(Them, file_of(s)) ? RookOnOpenFile : RookOnSemiOpenFile;
+ if (pe->semiopen_file(Us, file_of(s)))
+ score += RookOnFile[!!pe->semiopen_file(Them, file_of(s))];
- // Penalize when trapped by the king, even more if king cannot castle
- if (mob <= 3 && !ei.pi->semiopen_file(Us, file_of(s)))
+ // 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)))
- && (rank_of(ksq) == rank_of(s) || relative_rank(Us, ksq) == RANK_1)
- && !ei.pi->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 (Pt == QUEEN)
+ {
+ // Penalty if any relative pin or discovered attack against the queen
+ Bitboard pinners;
+ if (pos.slider_blockers(pos.pieces(Them, ROOK, BISHOP), s, pinners))
+ score -= WeakQueen;
+ }
}
- if (Trace)
- Tracing::write(Pt, Us, score);
+ if (T)
+ Trace::add(Pt, Us, score);
- // Recursively call evaluate_pieces() of next piece type until KING excluded
- return score - evaluate_pieces<NextPt, Them, Trace>(pos, ei, mobility, mobilityArea);
+ return score;
}
- template<>
- Score evaluate_pieces<KING, WHITE, false>(const Position&, EvalInfo&, Score*, Bitboard*) { return SCORE_ZERO; }
- template<>
- Score evaluate_pieces<KING, WHITE, true>(const Position&, EvalInfo&, Score*, Bitboard*) { return SCORE_ZERO; }
-
// evaluate_king() assigns bonuses and penalties to a king of a given color
- template<Color Us, bool Trace>
- Score evaluate_king(const Position& pos, const EvalInfo& ei) {
+ const Bitboard QueenSide = FileABB | FileBBB | FileCBB | FileDBB;
+ const Bitboard CenterFiles = FileCBB | FileDBB | FileEBB | FileFBB;
+ const Bitboard KingSide = FileEBB | FileFBB | FileGBB | FileHBB;
- const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Bitboard KingFlank[FILE_NB] = {
+ QueenSide, QueenSide, QueenSide, CenterFiles, CenterFiles, KingSide, KingSide, KingSide
+ };
+
+ 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);
- Bitboard undefended, b, b1, b2, safe;
- int attackUnits;
const Square ksq = pos.square<KING>(Us);
+ Bitboard kingOnlyDefended, b, b1, b2, safe, other;
+ int kingDanger;
// King shelter and enemy pawns storm
- Score score = ei.pi->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 around the king which have no defenders
- // apart from the king itself
- undefended = ei.attackedBy[Them][ALL_PIECES]
- & ei.attackedBy[Us][KING]
- & ~( ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
- | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
- | ei.attackedBy[Us][QUEEN]);
-
- // Initialize the 'attackUnits' variable, which is used later on as an
- // index into the KingDanger[] array. 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).
- attackUnits = std::min(74, ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them])
- + 8 * ei.kingAdjacentZoneAttacksCount[Them]
- + 25 * popcount<Max15>(undefended)
- + 11 * (ei.pinnedPieces[Us] != 0)
- - mg_value(score) / 8
- - !pos.count<QUEEN>(Them) * 60;
-
- // Analyse the enemy's safe queen contact checks. Firstly, find the
- // undefended squares around the king reachable by the enemy queen...
- b = undefended & ei.attackedBy[Them][QUEEN] & ~pos.pieces(Them);
- if (b)
- {
- // ...and then remove squares not supported by another enemy piece
- b &= ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
- | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][ROOK];
-
- if (b)
- attackUnits += QueenContactCheck * popcount<Max15>(b);
- }
-
- // Analyse the enemy's safe rook contact checks. Firstly, find the
- // undefended squares around the king reachable by the enemy rooks...
- b = undefended & ei.attackedBy[Them][ROOK] & ~pos.pieces(Them);
-
- // Consider only squares where the enemy's rook gives check
- b &= PseudoAttacks[ROOK][ksq];
+ // Find the attacked squares which are defended only by our king...
+ kingOnlyDefended = attackedBy[Them][ALL_PIECES]
+ & attackedBy[Us][KING]
+ & ~attackedBy2[Us];
- if (b)
- {
- // ...and then remove squares not supported by another enemy piece
- b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
- | ei.attackedBy[Them][BISHOP]);
-
- if (b)
- attackUnits += RookContactCheck * popcount<Max15>(b);
- }
+ // ... and those which are not defended at all in the larger king ring
+ b = attackedBy[Them][ALL_PIECES] & ~attackedBy[Us][ALL_PIECES]
+ & kingRing[Us] & ~pos.pieces(Them);
- // Analyse the enemy's safe distance checks for sliders and knights
- safe = ~(ei.attackedBy[Us][ALL_PIECES] | pos.pieces(Them));
-
- b1 = pos.attacks_from<ROOK >(ksq) & safe;
- b2 = pos.attacks_from<BISHOP>(ksq) & safe;
+ // 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]
+ + 201 * popcount(kingOnlyDefended)
+ + 143 * (popcount(b) + !!pos.pinned_pieces(Us))
+ - 848 * !pos.count<QUEEN>(Them)
+ - 9 * mg_value(score) / 8
+ + 40;
+
+ // Analyse the safe enemy's checks which are possible on next move
+ safe = ~pos.pieces(Them);
+ safe &= ~attackedBy[Us][ALL_PIECES] | (kingOnlyDefended & attackedBy2[Them]);
+
+ b1 = pos.attacks_from< ROOK>(ksq);
+ b2 = pos.attacks_from<BISHOP>(ksq);
// Enemy queen safe checks
- b = (b1 | b2) & ei.attackedBy[Them][QUEEN];
- if (b)
- attackUnits += QueenCheck * popcount<Max15>(b);
+ if ((b1 | b2) & 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 |= attackedBy2[Them]
+ & ~(attackedBy2[Us] | pos.pieces(Them))
+ & 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 = ~( attackedBy[Us][PAWN]
+ | (pos.pieces(Them, PAWN) & shift<Up>(pos.pieces(PAWN))));
+
+ // Enemy rooks safe and other checks
+ if (b1 & attackedBy[Them][ROOK] & safe)
+ kingDanger += RookCheck;
+
+ 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
+ b = pos.attacks_from<KNIGHT>(ksq) & attackedBy[Them][KNIGHT];
+ if (b & safe)
+ kingDanger += KnightCheck;
+
+ else if (b & other)
+ score -= OtherCheck;
+
+ // Transform the kingDanger units into a Score, and substract it from the evaluation
+ if (kingDanger > 0)
+ score -= make_score(kingDanger * kingDanger / 4096, kingDanger / 16);
+ }
- // Enemy rooks safe checks
- b = b1 & ei.attackedBy[Them][ROOK];
- if (b)
- attackUnits += RookCheck * popcount<Max15>(b);
+ // King tropism: firstly, find squares that opponent attacks in our king flank
+ File kf = file_of(ksq);
+ b = attackedBy[Them][ALL_PIECES] & KingFlank[kf] & Camp;
- // Enemy bishops safe checks
- b = b2 & ei.attackedBy[Them][BISHOP];
- if (b)
- attackUnits += BishopCheck * popcount<Max15>(b);
+ assert(((Us == WHITE ? b << 4 : b >> 4) & b) == 0);
+ assert(popcount(Us == WHITE ? b << 4 : b >> 4) == popcount(b));
- // Enemy knights safe checks
- b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe;
- if (b)
- attackUnits += KnightCheck * popcount<Max15>(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 & attackedBy2[Them] & ~attackedBy[Us][PAWN]);
- // Finally, extract the king danger score from the KingDanger[]
- // array and subtract the score from evaluation.
- score -= KingDanger[std::max(std::min(attackUnits, 399), 0)];
- }
+ score -= CloseEnemies * popcount(b);
- if (Trace)
- Tracing::write(KING, Us, score);
+ // Penalty when our king is on a pawnless flank
+ if (!(pos.pieces(PAWN) & KingFlank[kf]))
+ score -= PawnlessFlank;
+
+ if (T)
+ Trace::add(KING, Us, score);
return score;
}
- // evaluate_threats() assigns bonuses according to the type of attacking piece
- // and the type of attacked one.
-
- template<Color Us, bool Trace>
- Score evaluate_threats(const Position& pos, const EvalInfo& ei) {
+ // evaluate_threats() assigns bonuses according to the types of the attacking
+ // and the attacked pieces.
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Square Up = (Us == WHITE ? DELTA_N : DELTA_S);
- const Square Left = (Us == WHITE ? DELTA_NW : DELTA_SE);
- const Square Right = (Us == WHITE ? DELTA_NE : DELTA_SW);
- const Bitboard TRank2BB = (Us == WHITE ? Rank2BB : Rank7BB);
- const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
+ template<Tracing T> template<Color Us>
+ Score Evaluation<T>::evaluate_threats() {
- enum { Defended, Weak };
- enum { Minor, Major };
+ 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);
- Bitboard b, weak, defended, safeThreats;
+ 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_bb<Right>(b) | shift_bb<Left>(b)) & weak;
+ safeThreats = (shift<Right>(b) | shift<Left>(b)) & weak;
- if (weak ^ safeThreats)
- score += ThreatenedByHangingPawn;
+ score += ThreatBySafePawn * popcount(safeThreats);
- while (safeThreats)
- score += ThreatenedByPawn[type_of(pos.piece_on(pop_lsb(&safeThreats)))];
+ if (weak ^ safeThreats)
+ score += ThreatByHangingPawn;
}
- // Non-pawn enemies defended by a pawn
- defended = (pos.pieces(Them) ^ pos.pieces(Them, PAWN)) & ei.attackedBy[Them][PAWN];
+ // 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 = attackedBy[Them][PAWN]
+ | (attackedBy2[Them] & ~attackedBy2[Us]);
- // Add a bonus according to the kind of attacking pieces
- if (defended)
- {
- b = defended & (ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]);
- while (b)
- score += Threat[Defended][Minor][type_of(pos.piece_on(pop_lsb(&b)))];
-
- b = defended & (ei.attackedBy[Us][ROOK]);
- while (b)
- score += Threat[Defended][Major][type_of(pos.piece_on(pop_lsb(&b)))];
- }
+ // Non-pawn enemies, strongly protected
+ defended = (pos.pieces(Them) ^ pos.pieces(Them, PAWN))
+ & stronglyProtected;
- // Enemies not defended by a pawn and under our attack
+ // Enemies not strongly protected and under our attack
weak = pos.pieces(Them)
- & ~ei.attackedBy[Them][PAWN]
- & ei.attackedBy[Us][ALL_PIECES];
+ & ~stronglyProtected
+ & attackedBy[Us][ALL_PIECES];
// Add a bonus according to the kind of attacking pieces
- if (weak)
+ if (defended | weak)
{
- b = weak & (ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]);
+ b = (defended | weak) & (attackedBy[Us][KNIGHT] | attackedBy[Us][BISHOP]);
while (b)
- score += Threat[Weak][Minor][type_of(pos.piece_on(pop_lsb(&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 & (ei.attackedBy[Us][ROOK] | ei.attackedBy[Us][QUEEN]);
+ b = (pos.pieces(Them, QUEEN) | weak) & attackedBy[Us][ROOK];
while (b)
- score += Threat[Weak][Major][type_of(pos.piece_on(pop_lsb(&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);
+ }
- b = weak & ~ei.attackedBy[Them][ALL_PIECES];
- if (b)
- score += Hanging * popcount<Max15>(b);
+ score += Hanging * popcount(weak & ~attackedBy[Them][ALL_PIECES]);
- b = weak & ei.attackedBy[Us][KING];
+ b = weak & attackedBy[Us][KING];
if (b)
- score += more_than_one(b) ? KingOnMany : KingOnOne;
+ score += ThreatByKing[more_than_one(b)];
}
- // Add a small bonus for safe pawn pushes
- b = pos.pieces(Us, PAWN) & ~TRank7BB;
- b = shift_bb<Up>(b | (shift_bb<Up>(b & TRank2BB) & ~pos.pieces()));
+ // 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]);
- if (b)
- score += popcount<Full>(b) * PawnSafePush;
-
- // Add another bonus if the pawn push attacks an enemy piece
- b = (shift_bb<Left>(b) | shift_bb<Right>(b))
+ // 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];
- if (b)
- score += popcount<Max15>(b) * PawnAttackThreat;
+ score += ThreatByPawnPush * popcount(b);
- if (Trace)
- Tracing::write(Tracing::THREAT, Us, score);
+ if (T)
+ Trace::add(THREAT, Us, score);
return score;
}
- // evaluate_passed_pawns() evaluates the passed pawns of the given color
+ // evaluate_passed_pawns() evaluates the passed pawns and candidate passed
+ // pawns of the given color.
- template<Color Us, bool Trace>
- Score evaluate_passed_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 Square Up = (Us == WHITE ? NORTH : SOUTH);
- Bitboard b, squaresToQueen, defendedSquares, unsafeSquares;
+ Bitboard b, bb, squaresToQueen, defendedSquares, unsafeSquares;
Score score = SCORE_ZERO;
- b = ei.pi->passed_pawns(Us);
+ b = pe->passed_pawns(Us);
while (b)
{
Square s = pop_lsb(&b);
- assert(pos.pawn_passed(Us, s));
+ assert(!(pos.pieces(Them, PAWN) & forward_file_bb(Us, s + Up)));
+
+ 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;
int rr = r * (r - 1);
- Value mbonus = PassedPawnsBonusMg[r],
- ebonus = PassedPawnsBonusEg[r];
+ Value mbonus = Passed[MG][r], ebonus = Passed[EG][r];
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);
- Bitboard 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.
- int k = !unsafeSquares ? 15 : !(unsafeSquares & blockSq) ? 9 : 0;
+ int k = !unsafeSquares ? 18 : !(unsafeSquares & blockSq) ? 8 : 0;
- // If the path to queen is fully defended, assign a big bonus.
+ // If the path to the queen is fully defended, assign a big bonus.
// Otherwise assign a smaller bonus if the block square is defended.
if (defendedSquares == squaresToQueen)
k += 6;
mbonus += k * rr, ebonus += k * rr;
}
else if (pos.pieces(Us) & blockSq)
- mbonus += rr * 3 + r * 2 + 3, ebonus += rr + r * 2;
+ mbonus += rr + r * 2, ebonus += rr + r * 2;
} // rr != 0
- if (pos.count<PAWN>(Us) < pos.count<PAWN>(Them))
- ebonus += ebonus / 4;
+ // 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)))
+ mbonus /= 2, ebonus /= 2;
- score += make_score(mbonus, ebonus);
+ score += make_score(mbonus, ebonus) + PassedFile[file_of(s)];
}
- if (Trace)
- Tracing::write(Tracing::PASSED, Us, score * Weights[PassedPawns]);
+ if (T)
+ Trace::add(PASSED, Us, score);
- // Add the scores to the middlegame and endgame eval
- return score * Weights[PassedPawns];
+ 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 =
+ Us == WHITE ? CenterFiles & (Rank2BB | Rank3BB | Rank4BB)
+ : CenterFiles & (Rank7BB | Rank6BB | Rank5BB);
// Find the safe squares for our pieces inside the area defined by
- // SpaceMask[]. A square is unsafe if it is attacked by an enemy
+ // SpaceMask. A square is unsafe if it is attacked by an enemy
// pawn, or if it is undefended and attacked by an enemy piece.
- Bitboard safe = SpaceMask[Us]
+ 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);
behind |= (Us == WHITE ? behind >> 8 : behind << 8);
behind |= (Us == WHITE ? behind >> 16 : behind << 16);
- // Since SpaceMask[Us] is fully on our half of the board
+ // Since SpaceMask[Us] is fully on our half of the board...
assert(unsigned(safe >> (Us == WHITE ? 32 : 0)) == 0);
- // Count safe + (behind & safe) with a single popcount
- int bonus = popcount<Full>((Us == WHITE ? safe << 32 : safe >> 32) | (behind & safe));
- int weight = pos.count<KNIGHT>(Us) + pos.count<BISHOP>(Us)
- + pos.count<KNIGHT>(Them) + pos.count<BISHOP>(Them);
+ // ...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 * pe->open_files();
- return make_score(bonus * weight * weight, 0);
+ return make_score(bonus * weight * weight / 16, 0);
}
- // do_evaluate() is the evaluation entry point, called directly from evaluate()
-
- template<bool Trace>
- Value do_evaluate(const Position& pos) {
-
- assert(!pos.checkers());
-
- EvalInfo ei;
- Score score, mobility[2] = { SCORE_ZERO, SCORE_ZERO };
-
- // Initialize score by reading the incrementally updated scores included
- // in the position object (material + piece square tables).
- // Score is computed from the point of view of white.
- score = pos.psq_score();
-
- // Probe the material hash table
- ei.mi = Material::probe(pos);
- score += ei.mi->imbalance();
-
- // If we have a specialized evaluation function for the current material
- // configuration, call it and return.
- if (ei.mi->specialized_eval_exists())
- return ei.mi->evaluate(pos);
-
- // Probe the pawn hash table
- ei.pi = Pawns::probe(pos);
- score += ei.pi->pawns_score() * Weights[PawnStructure];
-
- // Initialize attack and king safety bitboards
- init_eval_info<WHITE>(pos, ei);
- init_eval_info<BLACK>(pos, ei);
-
- ei.attackedBy[WHITE][ALL_PIECES] |= ei.attackedBy[WHITE][KING];
- ei.attackedBy[BLACK][ALL_PIECES] |= ei.attackedBy[BLACK][KING];
-
- // Pawns blocked or on ranks 2 and 3. Will be excluded from the mobility area
- Bitboard blockedPawns[] = {
- pos.pieces(WHITE, PAWN) & (shift_bb<DELTA_S>(pos.pieces()) | Rank2BB | Rank3BB),
- pos.pieces(BLACK, PAWN) & (shift_bb<DELTA_N>(pos.pieces()) | Rank7BB | Rank6BB)
- };
+ // 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.
- // Do not include in mobility squares protected by enemy pawns, or occupied
- // by our blocked pawns or king.
- Bitboard mobilityArea[] = {
- ~(ei.attackedBy[BLACK][PAWN] | blockedPawns[WHITE] | pos.square<KING>(WHITE)),
- ~(ei.attackedBy[WHITE][PAWN] | blockedPawns[BLACK] | pos.square<KING>(BLACK))
- };
+ template<Tracing T>
+ Score Evaluation<T>::evaluate_initiative(Value eg) {
- // Evaluate pieces and mobility
- score += evaluate_pieces<KNIGHT, WHITE, Trace>(pos, ei, mobility, mobilityArea);
- score += (mobility[WHITE] - mobility[BLACK]) * Weights[Mobility];
+ 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);
- // Evaluate kings after all other pieces because we need complete attack
- // information when computing the king safety evaluation.
- score += evaluate_king<WHITE, Trace>(pos, ei)
- - evaluate_king<BLACK, Trace>(pos, ei);
+ // Compute the initiative bonus for the attacking side
+ int initiative = 8 * (pe->pawn_asymmetry() + kingDistance - 17) + 12 * pos.count<PAWN>() + 16 * bothFlanks;
- // Evaluate tactical threats, we need full attack information including king
- score += evaluate_threats<WHITE, Trace>(pos, ei)
- - evaluate_threats<BLACK, Trace>(pos, ei);
+ // 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(initiative, -abs(eg));
- // Evaluate passed pawns, we need full attack information including king
- score += evaluate_passed_pawns<WHITE, Trace>(pos, ei)
- - evaluate_passed_pawns<BLACK, Trace>(pos, ei);
+ return make_score(0, v);
+ }
- // If both sides have only pawns, score for potential unstoppable pawns
- if (!pos.non_pawn_material(WHITE) && !pos.non_pawn_material(BLACK))
- {
- Bitboard b;
- if ((b = ei.pi->passed_pawns(WHITE)) != 0)
- score += int(relative_rank(WHITE, frontmost_sq(WHITE, b))) * Unstoppable;
- if ((b = ei.pi->passed_pawns(BLACK)) != 0)
- score -= int(relative_rank(BLACK, frontmost_sq(BLACK, b))) * Unstoppable;
- }
+ // evaluate_scale_factor() computes the scale factor for the winning side
- // Evaluate space for both sides, only during opening
- if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >= 11756)
- score += (evaluate_space<WHITE>(pos, ei) - evaluate_space<BLACK>(pos, ei)) * Weights[Space];
+ template<Tracing T>
+ ScaleFactor Evaluation<T>::evaluate_scale_factor(Value eg) {
- // Scale winning side if position is more drawish than it appears
- Color strongSide = eg_value(score) > VALUE_DRAW ? WHITE : BLACK;
- ScaleFactor sf = ei.mi->scale_factor(pos, strongSide);
+ Color strongSide = eg > VALUE_DRAW ? WHITE : BLACK;
+ 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.
- if ( ei.mi->game_phase() < PHASE_MIDGAME
- && (sf == SCALE_FACTOR_NORMAL || sf == SCALE_FACTOR_ONEPAWN))
+ if (sf == SCALE_FACTOR_NORMAL || sf == SCALE_FACTOR_ONEPAWN)
{
if (pos.opposite_bishops())
{
// Endgame with opposite-colored bishops and no other pieces (ignoring pawns)
- // is almost a draw, in case of KBP vs KB is even more a draw.
+ // is almost a draw, in case of KBP vs KB, it is even more a draw.
if ( pos.non_pawn_material(WHITE) == BishopValueMg
&& pos.non_pawn_material(BLACK) == BishopValueMg)
- sf = more_than_one(pos.pieces(PAWN)) ? ScaleFactor(32) : ScaleFactor(8);
+ return more_than_one(pos.pieces(PAWN)) ? ScaleFactor(31) : ScaleFactor(9);
// Endgame with opposite-colored bishops, but also other pieces. Still
// a bit drawish, but not as drawish as with only the two bishops.
- else
- sf = ScaleFactor(50 * sf / SCALE_FACTOR_NORMAL);
+ return ScaleFactor(46);
}
// Endings where weaker side can place his king in front of the opponent's
// pawns are drawish.
- else if ( abs(eg_value(score)) <= BishopValueEg
- && ei.pi->pawn_span(strongSide) <= 1
+ else if ( abs(eg) <= BishopValueEg
+ && pos.count<PAWN>(strongSide) <= 2
&& !pos.pawn_passed(~strongSide, pos.square<KING>(~strongSide)))
- sf = ei.pi->pawn_span(strongSide) ? ScaleFactor(56) : ScaleFactor(38);
- }
-
- // Interpolate between a middlegame and a (scaled by 'sf') endgame score
- Value v = mg_value(score) * int(ei.mi->game_phase())
- + eg_value(score) * int(PHASE_MIDGAME - ei.mi->game_phase()) * sf / SCALE_FACTOR_NORMAL;
-
- v /= int(PHASE_MIDGAME);
-
- // In case of tracing add all single evaluation terms for both white and black
- if (Trace)
- {
- Tracing::write(Tracing::MATERIAL, pos.psq_score());
- Tracing::write(Tracing::IMBALANCE, ei.mi->imbalance());
- Tracing::write(PAWN, ei.pi->pawns_score());
- Tracing::write(Tracing::MOBILITY, mobility[WHITE] * Weights[Mobility]
- , mobility[BLACK] * Weights[Mobility]);
- Tracing::write(Tracing::SPACE, evaluate_space<WHITE>(pos, ei) * Weights[Space]
- , evaluate_space<BLACK>(pos, ei) * Weights[Space]);
- Tracing::write(Tracing::TOTAL, score);
+ return ScaleFactor(37 + 7 * pos.count<PAWN>(strongSide));
}
- return (pos.side_to_move() == WHITE ? v : -v) + Eval::Tempo; // Side to move point of view
+ return sf;
}
- // Tracing functions
+ // 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.
- double Tracing::to_cp(Value v) { return double(v) / PawnValueEg; }
+ template<Tracing T>
+ Value Evaluation<T>::value() {
- void Tracing::write(int idx, Color c, Score s) { scores[c][idx] = s; }
-
- void Tracing::write(int idx, Score w, Score b) {
- scores[WHITE][idx] = w, scores[BLACK][idx] = b;
- }
-
- std::ostream& Tracing::operator<<(std::ostream& os, Term t) {
+ assert(!pos.checkers());
- double wScore[] = { to_cp(mg_value(scores[WHITE][t])), to_cp(eg_value(scores[WHITE][t])) };
- double bScore[] = { to_cp(mg_value(scores[BLACK][t])), to_cp(eg_value(scores[BLACK][t])) };
+ // Probe the material hash table
+ me = Material::probe(pos);
- if (t == MATERIAL || t == IMBALANCE || t == Term(PAWN) || t == TOTAL)
- os << " --- --- | --- --- | ";
- else
- os << std::setw(5) << wScore[MG] << " " << std::setw(5) << wScore[EG] << " | "
- << std::setw(5) << bScore[MG] << " " << std::setw(5) << bScore[EG] << " | ";
+ // 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);
- os << std::setw(5) << wScore[MG] - bScore[MG] << " "
- << std::setw(5) << wScore[EG] - bScore[EG] << " \n";
+ // 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();
- return os;
- }
+ // Probe the pawn hash table
+ pe = Pawns::probe(pos);
+ score += pe->pawns_score();
- std::string Tracing::do_trace(const Position& pos) {
-
- std::memset(scores, 0, sizeof(scores));
-
- Value v = do_evaluate<true>(pos);
- v = pos.side_to_move() == WHITE ? v : -v; // White's point of view
-
- std::stringstream ss;
- ss << std::showpoint << std::noshowpos << std::fixed << std::setprecision(2)
- << " Eval 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)
- << " Bishop | " << Term(BISHOP)
- << " Rooks | " << Term(ROOK)
- << " Queens | " << Term(QUEEN)
- << " Mobility | " << Term(MOBILITY)
- << " King safety | " << Term(KING)
- << " Threats | " << Term(THREAT)
- << " Passed pawns | " << Term(PASSED)
- << " Space | " << Term(SPACE)
- << "----------------+-------------+-------------+-------------\n"
- << " Total | " << Term(TOTAL);
-
- ss << "\nTotal Evaluation: " << to_cp(v) << " (white side)\n";
-
- return ss.str();
- }
+ // 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;
-} // namespace
+ // Main evaluation begins here
+ initialize<WHITE>();
+ initialize<BLACK>();
-namespace Eval {
+ 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 >();
- /// evaluate() is the main evaluation function. It returns a static evaluation
- /// of the position always from the point of view of the side to move.
+ score += mobility[WHITE] - mobility[BLACK];
- Value evaluate(const Position& pos) {
- return do_evaluate<false>(pos);
- }
+ score += evaluate_king<WHITE>()
+ - evaluate_king<BLACK>();
+ score += evaluate_threats<WHITE>()
+ - evaluate_threats<BLACK>();
- /// 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. It's mainly used for
- /// debugging.
- std::string trace(const Position& pos) {
- return Tracing::do_trace(pos);
- }
+ score += evaluate_passed_pawns<WHITE>()
+ - evaluate_passed_pawns<BLACK>();
+ if (pos.non_pawn_material() >= SpaceThreshold)
+ score += evaluate_space<WHITE>()
+ - evaluate_space<BLACK>();
- /// init() computes evaluation weights, usually at startup
+ score += evaluate_initiative(eg_value(score));
- void init() {
+ // 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;
- const int MaxSlope = 8700;
- const int Peak = 1280000;
- int t = 0;
+ v /= int(PHASE_MIDGAME);
- for (int i = 0; i < 400; ++i)
+ // In case of tracing add all remaining individual evaluation terms
+ if (T)
{
- t = std::min(Peak, std::min(i * i * 27, t + MaxSlope));
- KingDanger[i] = make_score(t / 1000, 0) * Weights[KingSafety];
+ 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) + Eval::Tempo; // Side to move point of view
}
-} // namespace Eval
+} // 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));
+
+ Value v = Evaluation<TRACE>(pos).value();
+ v = pos.side_to_move() == WHITE ? v : -v; // White's point of view
+
+ std::stringstream ss;
+ ss << std::showpoint << std::noshowpos << std::fixed << std::setprecision(2)
+ << " Eval 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 pawns | " << Term(PASSED)
+ << " Space | " << Term(SPACE)
+ << "----------------+-------------+-------------+-------------\n"
+ << " Total | " << Term(TOTAL);
+
+ ss << "\nTotal Evaluation: " << to_cp(v) << " (white side)\n";
+
+ return ss.str();
+}