/*
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) 2004-2021 The Stockfish developers (see AUTHORS file)
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 <algorithm>
#include <cassert>
+#include <cstdlib>
#include <cstring> // For std::memset
+#include <fstream>
#include <iomanip>
#include <sstream>
+#include <iostream>
+#include <streambuf>
+#include <vector>
#include "bitboard.h"
#include "evaluate.h"
#include "material.h"
+#include "misc.h"
#include "pawns.h"
+#include "thread.h"
+#include "uci.h"
+#include "incbin/incbin.h"
+
+
+// Macro to embed the default NNUE file data in the engine binary (using incbin.h, by Dale Weiler).
+// This macro invocation will declare the following three variables
+// const unsigned char gEmbeddedNNUEData[]; // a pointer to the embedded data
+// const unsigned char *const gEmbeddedNNUEEnd; // a marker to the end
+// const unsigned int gEmbeddedNNUESize; // the size of the embedded file
+// Note that this does not work in Microsof Visual Studio.
+#if !defined(_MSC_VER) && !defined(NNUE_EMBEDDING_OFF)
+ INCBIN(EmbeddedNNUE, EvalFileDefaultName);
+#else
+ const unsigned char gEmbeddedNNUEData[1] = {0x0};
+ const unsigned char *const gEmbeddedNNUEEnd = &gEmbeddedNNUEData[1];
+ const unsigned int gEmbeddedNNUESize = 1;
+#endif
+
+
+using namespace std;
+using namespace Eval::NNUE;
+
+namespace Eval {
+
+ bool useNNUE;
+ string eval_file_loaded = "None";
+
+ /// NNUE::init() tries to load a nnue network at startup time, or when the engine
+ /// receives a UCI command "setoption name EvalFile value nn-[a-z0-9]{12}.nnue"
+ /// The name of the nnue network is always retrieved from the EvalFile option.
+ /// We search the given network in three locations: internally (the default
+ /// network may be embedded in the binary), in the active working directory and
+ /// in the engine directory. Distro packagers may define the DEFAULT_NNUE_DIRECTORY
+ /// variable to have the engine search in a special directory in their distro.
+
+ void NNUE::init() {
+
+ useNNUE = Options["Use NNUE"];
+ if (!useNNUE)
+ return;
+
+ string eval_file = string(Options["EvalFile"]);
+
+ #if defined(DEFAULT_NNUE_DIRECTORY)
+ #define stringify2(x) #x
+ #define stringify(x) stringify2(x)
+ vector<string> dirs = { "<internal>" , "" , CommandLine::binaryDirectory , stringify(DEFAULT_NNUE_DIRECTORY) };
+ #else
+ vector<string> dirs = { "<internal>" , "" , CommandLine::binaryDirectory };
+ #endif
+
+ for (string directory : dirs)
+ if (eval_file_loaded != eval_file)
+ {
+ if (directory != "<internal>")
+ {
+ ifstream stream(directory + eval_file, ios::binary);
+ if (load_eval(eval_file, stream))
+ eval_file_loaded = eval_file;
+ }
-namespace {
+ if (directory == "<internal>" && eval_file == EvalFileDefaultName)
+ {
+ // C++ way to prepare a buffer for a memory stream
+ class MemoryBuffer : public basic_streambuf<char> {
+ public: MemoryBuffer(char* p, size_t n) { setg(p, p, p + n); setp(p, p + n); }
+ };
- namespace Trace {
+ MemoryBuffer buffer(const_cast<char*>(reinterpret_cast<const char*>(gEmbeddedNNUEData)),
+ size_t(gEmbeddedNNUESize));
- enum Term { // The first 8 entries are for PieceType
- MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, TOTAL, TERM_NB
- };
+ istream stream(&buffer);
+ if (load_eval(eval_file, stream))
+ eval_file_loaded = eval_file;
+ }
+ }
+ }
- double scores[TERM_NB][COLOR_NB][PHASE_NB];
+ /// NNUE::verify() verifies that the last net used was loaded successfully
+ void NNUE::verify() {
- double to_cp(Value v) { return double(v) / PawnValueEg; }
+ string eval_file = string(Options["EvalFile"]);
- 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));
+ if (useNNUE && eval_file_loaded != eval_file)
+ {
+ UCI::OptionsMap defaults;
+ UCI::init(defaults);
+
+ string msg1 = "If the UCI option \"Use NNUE\" is set to true, network evaluation parameters compatible with the engine must be available.";
+ string msg2 = "The option is set to true, but the network file " + eval_file + " was not loaded successfully.";
+ string msg3 = "The UCI option EvalFile might need to specify the full path, including the directory name, to the network file.";
+ string msg4 = "The default net can be downloaded from: https://tests.stockfishchess.org/api/nn/" + string(defaults["EvalFile"]);
+ string msg5 = "The engine will be terminated now.";
+
+ sync_cout << "info string ERROR: " << msg1 << sync_endl;
+ sync_cout << "info string ERROR: " << msg2 << sync_endl;
+ sync_cout << "info string ERROR: " << msg3 << sync_endl;
+ sync_cout << "info string ERROR: " << msg4 << sync_endl;
+ sync_cout << "info string ERROR: " << msg5 << sync_endl;
+
+ exit(EXIT_FAILURE);
}
- void add(int idx, Score w, Score b = SCORE_ZERO) {
- add(idx, WHITE, w); add(idx, BLACK, b);
- }
+ if (useNNUE)
+ sync_cout << "info string NNUE evaluation using " << eval_file << " enabled" << sync_endl;
+ else
+ sync_cout << "info string classical evaluation enabled" << sync_endl;
+ }
+}
- std::ostream& operator<<(std::ostream& os, Term t) {
+namespace Trace {
- 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] << " | ";
+ enum Tracing { NO_TRACE, TRACE };
- os << std::setw(5) << scores[t][WHITE][MG] - scores[t][BLACK][MG] << " "
- << std::setw(5) << scores[t][WHITE][EG] - scores[t][BLACK][EG] << " \n";
+ enum Term { // The first 8 entries are reserved for PieceType
+ MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, WINNABLE, TOTAL, TERM_NB
+ };
- return os;
- }
+ 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;
}
- using namespace Trace;
+ void add(int idx, Score w, Score b = SCORE_ZERO) {
+ scores[idx][WHITE] = w;
+ scores[idx][BLACK] = b;
+ }
- // Struct EvalInfo contains various information computed and collected
- // by the evaluation functions.
- struct EvalInfo {
+ 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;
+ }
- Material::Entry* me;
- Pawns::Entry* pe;
- Bitboard mobilityArea[COLOR_NB];
+ std::ostream& operator<<(std::ostream& os, Term t) {
- // attackedBy[color][piece type] is a bitboard representing all squares
- // attacked by a given color and piece type (can be also ALL_PIECES).
- Bitboard attackedBy[COLOR_NB][PIECE_TYPE_NB];
+ if (t == MATERIAL || t == IMBALANCE || t == WINNABLE || t == TOTAL)
+ os << " ---- ----" << " | " << " ---- ----";
+ else
+ os << scores[t][WHITE] << " | " << scores[t][BLACK];
- // 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];
+ os << " | " << scores[t][WHITE] - scores[t][BLACK] << "\n";
+ return os;
+ }
+}
- // 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)
- // 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.
- Bitboard kingRing[COLOR_NB];
+using namespace Trace;
- // 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];
+namespace {
- // 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];
+ // Threshold for lazy and space evaluation
+ constexpr Value LazyThreshold1 = Value(1565);
+ constexpr Value LazyThreshold2 = Value(1102);
+ constexpr Value SpaceThreshold = Value(11551);
+ constexpr Value NNUEThreshold1 = Value(682);
+ constexpr Value NNUEThreshold2 = Value(176);
- // kingAdjacentZoneAttacksCount[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 kingAdjacentZoneAttacksCount[WHITE].
- int kingAdjacentZoneAttacksCount[COLOR_NB];
+ // KingAttackWeights[PieceType] contains king attack weights by piece type
+ constexpr int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 81, 52, 44, 10 };
+
+ // SafeCheck[PieceType][single/multiple] contains safe check bonus by piece type,
+ // higher if multiple safe checks are possible for that piece type.
+ constexpr int SafeCheck[][2] = {
+ {}, {}, {803, 1292}, {639, 974}, {1087, 1878}, {759, 1132}
};
- #define V(v) Value(v)
- #define S(mg, eg) make_score(mg, eg)
+#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.
- const Score MobilityBonus[][32] = {
- { 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(-60,-77), S(-26,-20), S(-11, 27), S( -6, 57), S( -3, 69), S( -1, 82), // Rooks
- S( 10,109), S( 16,121), S( 24,131), S( 25,143), S( 32,155), S( 32,163),
- S( 43,167), S( 48,171), S( 56,173) },
- { 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) }
+ constexpr Score MobilityBonus[][32] = {
+ { S(-62,-79), S(-53,-57), S(-12,-31), S( -3,-17), S( 3, 7), S( 12, 13), // Knight
+ S( 21, 16), S( 28, 21), S( 37, 26) },
+ { S(-47,-59), S(-20,-25), S( 14, -8), S( 29, 12), S( 39, 21), S( 53, 40), // Bishop
+ S( 53, 56), S( 60, 58), S( 62, 65), S( 69, 72), S( 78, 78), S( 83, 87),
+ S( 91, 88), S( 96, 98) },
+ { S(-60,-82), S(-24,-15), S( 0, 17) ,S( 3, 43), S( 4, 72), S( 14,100), // Rook
+ S( 20,102), S( 30,122), S( 41,133), S(41 ,139), S( 41,153), S( 45,160),
+ S( 57,165), S( 58,170), S( 67,175) },
+ { S(-29,-49), S(-16,-29), S( -8, -8), S( -8, 17), S( 18, 39), S( 25, 54), // Queen
+ S( 23, 59), S( 37, 73), S( 41, 76), S( 54, 95), S( 65, 95) ,S( 68,101),
+ S( 69,124), S( 70,128), S( 70,132), S( 70,133) ,S( 71,136), S( 72,140),
+ S( 74,147), S( 76,149), S( 90,153), S(104,169), S(105,171), S(106,171),
+ S(112,178), S(114,185), S(114,187), S(119,221) }
+ };
+
+ // BishopPawns[distance from edge] contains a file-dependent penalty for pawns on
+ // squares of the same color as our bishop.
+ constexpr Score BishopPawns[int(FILE_NB) / 2] = {
+ S(3, 8), S(3, 9), S(2, 8), S(3, 8)
};
- // 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(22, 6), S(33, 9) }, // Knight
- { S( 9, 2), S(14, 4) } // Bishop
+ // KingProtector[knight/bishop] contains penalty for each distance unit to own king
+ constexpr Score KingProtector[] = { S(8, 9), S(6, 9) };
+
+ // Outpost[knight/bishop] contains bonuses for each knight or bishop occupying a
+ // pawn protected square on rank 4 to 6 which is also safe from a pawn attack.
+ constexpr Score Outpost[] = { S(57, 38), S(31, 24) };
+
+ // PassedRank[Rank] contains a bonus according to the rank of a passed pawn
+ constexpr Score PassedRank[RANK_NB] = {
+ S(0, 0), S(7, 27), S(16, 32), S(17, 40), S(64, 71), S(170, 174), S(278, 262)
};
- // 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) };
+ constexpr Score RookOnClosedFile = S(10, 5);
+ constexpr Score RookOnOpenFile[] = { S(19, 6), S(47, 26) };
// 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)
+ constexpr Score ThreatByMinor[PIECE_TYPE_NB] = {
+ S(0, 0), S(5, 32), S(55, 41), S(77, 56), S(89, 119), S(79, 162)
};
- const Score ThreatByRook[PIECE_TYPE_NB] = {
- S(0, 0), S(0, 25), S(40, 62), S(40, 59), S( 0, 34), S(35, 48)
+ constexpr Score ThreatByRook[PIECE_TYPE_NB] = {
+ S(0, 0), S(3, 44), S(37, 68), S(42, 60), S(0, 39), S(58, 43)
};
- // 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) };
+ // Assorted bonuses and penalties
+ constexpr Score UncontestedOutpost = S( 1, 10);
+ constexpr Score BishopOnKingRing = S( 24, 0);
+ constexpr Score BishopXRayPawns = S( 4, 5);
+ constexpr Score CorneredBishop = S( 50, 50);
+ constexpr Score FlankAttacks = S( 8, 0);
+ constexpr Score Hanging = S( 69, 36);
+ constexpr Score KnightOnQueen = S( 16, 11);
+ constexpr Score LongDiagonalBishop = S( 45, 0);
+ constexpr Score MinorBehindPawn = S( 18, 3);
+ constexpr Score PassedFile = S( 11, 8);
+ constexpr Score PawnlessFlank = S( 17, 95);
+ constexpr Score ReachableOutpost = S( 31, 22);
+ constexpr Score RestrictedPiece = S( 7, 7);
+ constexpr Score RookOnKingRing = S( 16, 0);
+ constexpr Score SliderOnQueen = S( 60, 18);
+ constexpr Score ThreatByKing = S( 24, 89);
+ constexpr Score ThreatByPawnPush = S( 48, 39);
+ constexpr Score ThreatBySafePawn = S(173, 94);
+ constexpr Score TrappedRook = S( 55, 13);
+ constexpr Score WeakQueenProtection = S( 14, 0);
+ constexpr Score WeakQueen = S( 56, 15);
+
+
+#undef S
+
+ // Evaluation class computes and stores attacks tables and other working data
+ template<Tracing T>
+ class Evaluation {
+
+ public:
+ Evaluation() = delete;
+ explicit Evaluation(const Position& p) : pos(p) {}
+ Evaluation& operator=(const Evaluation&) = delete;
+ Value value();
+
+ private:
+ template<Color Us> void initialize();
+ template<Color Us, PieceType Pt> Score pieces();
+ template<Color Us> Score king() const;
+ template<Color Us> Score threats() const;
+ template<Color Us> Score passed() const;
+ template<Color Us> Score space() const;
+ Value winnable(Score score) const;
+
+ const Position& pos;
+ Material::Entry* me;
+ Pawns::Entry* pe;
+ Bitboard mobilityArea[COLOR_NB];
+ Score mobility[COLOR_NB] = { SCORE_ZERO, SCORE_ZERO };
- // 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) }
- };
+ // 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];
- // 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)
- };
+ // 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];
- // Protector[PieceType-2][distance] contains a protecting bonus for our king,
- // indexed by piece type and distance between the piece and the king.
- const Score Protector[][8] = {
- { S(0, 0), S( 7, 9), S( 7, 1), S( 1, 5), S(-10,-4), S( -1,-4), S( -7,-3), S(-16,-10) }, // Knight
- { S(0, 0), S(11, 8), S(-7,-1), S(-1,-2), S( -1,-7), S(-11,-3), S( -9,-1), S(-16, -1) }, // Bishop
- { S(0, 0), S(10, 0), S(-2, 2), S(-5, 4), S( -6, 2), S(-14,-3), S( -2,-9), S(-12, -7) }, // Rook
- { S(0, 0), S( 3,-5), S( 2,-5), S(-4, 0), S( -9,-6), S( -4, 7), S(-13,-7), S(-10, -7) } // Queen
- };
+ // kingRing[color] are the squares adjacent to the king plus some other
+ // very near squares, depending on king position.
+ Bitboard kingRing[COLOR_NB];
- // 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);
-
- #undef S
- #undef V
+ // 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];
- // KingAttackWeights[PieceType] contains king attack weights by piece type
- const int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 78, 56, 45, 11 };
+ // 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];
+ };
- // Penalties for enemy's safe checks
- const int QueenCheck = 810;
- const int RookCheck = 888;
- const int BishopCheck = 400;
- const int KnightCheck = 790;
- // Threshold for lazy and space evaluation
- const Value LazyThreshold = Value(1500);
- const Value SpaceThreshold = Value(12222);
+ // 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.
- // eval_init() initializes king and attack bitboards for a given color
- // adding pawn attacks. To be done at the beginning of the evaluation.
+ template<Tracing T> template<Color Us>
+ void Evaluation<T>::initialize() {
- template<Color Us>
- void eval_init(const Position& pos, EvalInfo& ei) {
+ constexpr Color Them = ~Us;
+ constexpr Direction Up = pawn_push(Us);
+ constexpr Direction Down = -Up;
+ constexpr Bitboard LowRanks = (Us == WHITE ? Rank2BB | Rank3BB : Rank7BB | Rank6BB);
+
+ const Square ksq = pos.square<KING>(Us);
- 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);
+ Bitboard dblAttackByPawn = pawn_double_attacks_bb<Us>(pos.pieces(Us, PAWN));
- // Find our pawns on the first two ranks, and those which are blocked
+ // Find our pawns that are blocked or on the first two ranks
Bitboard b = pos.pieces(Us, PAWN) & (shift<Down>(pos.pieces()) | LowRanks);
- // 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));
+ // Squares occupied by those pawns, by our king or queen, by blockers to attacks on our king
+ // or controlled by enemy pawns are excluded from the mobility area.
+ mobilityArea[Us] = ~(b | pos.pieces(Us, KING, QUEEN) | pos.blockers_for_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);
+ // Initialize attackedBy[] for king and pawns
+ attackedBy[Us][KING] = attacks_bb<KING>(ksq);
+ attackedBy[Us][PAWN] = pe->pawn_attacks(Us);
+ attackedBy[Us][ALL_PIECES] = attackedBy[Us][KING] | attackedBy[Us][PAWN];
+ attackedBy2[Us] = dblAttackByPawn | (attackedBy[Us][KING] & attackedBy[Us][PAWN]);
- ei.attackedBy2[Us] = b & ei.attackedBy[Us][PAWN];
- ei.attackedBy[Us][ALL_PIECES] = b | ei.attackedBy[Us][PAWN];
+ // Init our king safety tables
+ Square s = make_square(std::clamp(file_of(ksq), FILE_B, FILE_G),
+ std::clamp(rank_of(ksq), RANK_2, RANK_7));
+ kingRing[Us] = attacks_bb<KING>(s) | s;
- // Init our king safety tables only if we are going to use them
- if (pos.non_pawn_material(Them) >= QueenValueMg)
- {
- ei.kingRing[Us] = b | shift<Up>(b);
- ei.kingAttackersCount[Them] = popcount(b & ei.pe->pawn_attacks(Them));
- ei.kingAdjacentZoneAttacksCount[Them] = ei.kingAttackersWeight[Them] = 0;
- }
- else
- ei.kingRing[Us] = ei.kingAttackersCount[Them] = 0;
- }
+ 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;
+ }
- // 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) {
+ // Evaluation::pieces() scores pieces of a given color and type
- 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);
+ template<Tracing T> template<Color Us, PieceType Pt>
+ Score Evaluation<T>::pieces() {
+ constexpr Color Them = ~Us;
+ constexpr Direction Down = -pawn_push(Us);
+ constexpr Bitboard OutpostRanks = (Us == WHITE ? Rank4BB | Rank5BB | Rank6BB
+ : Rank5BB | Rank4BB | Rank3BB);
+ Bitboard b1 = pos.pieces(Us, Pt);
Bitboard b, bb;
- Square s;
Score score = SCORE_ZERO;
- ei.attackedBy[Us][Pt] = 0;
+ attackedBy[Us][Pt] = 0;
+
+ while (b1) {
+ Square s = pop_lsb(&b1);
- 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))
- : pos.attacks_from<Pt>(s);
+ 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))
+ : attacks_bb<Pt>(s, pos.pieces());
- if (pos.pinned_pieces(Us) & s)
- b &= LineBB[pos.square<KING>(Us)][s];
+ if (pos.blockers_for_king(Us) & s)
+ b &= line_bb(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][Pt] |= b;
+ attackedBy[Us][ALL_PIECES] |= b;
- 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];
+ kingAttacksCount[Us] += popcount(b & attackedBy[Them][KING]);
}
- int mob = popcount(b & ei.mobilityArea[Us]);
+ else if (Pt == ROOK && (file_bb(s) & kingRing[Them]))
+ score += RookOnKingRing;
+
+ else if (Pt == BISHOP && (attacks_bb<BISHOP>(s, pos.pieces(PAWN)) & kingRing[Them]))
+ score += BishopOnKingRing;
- mobility[Us] += MobilityBonus[Pt-2][mob];
+ int mob = popcount(b & mobilityArea[Us]);
- // Bonus for this piece as a king protector
- score += Protector[Pt-2][distance(s, pos.square<KING>(Us))];
+ mobility[Us] += MobilityBonus[Pt - 2][mob];
if (Pt == BISHOP || Pt == KNIGHT)
{
- // Bonus for outpost squares
- bb = OutpostRanks & ~ei.pe->pawn_attacks_span(Them);
- if (bb & s)
- score += Outpost[Pt == BISHOP][!!(ei.attackedBy[Us][PAWN] & s)] * 2;
- else
- {
- bb &= b & ~pos.pieces(Us);
- if (bb)
- score += Outpost[Pt == BISHOP][!!(ei.attackedBy[Us][PAWN] & bb)];
- }
-
- // Bonus when behind a pawn
- if ( relative_rank(Us, s) < RANK_5
- && (pos.pieces(PAWN) & (s + pawn_push(Us))))
+ // Bonus if the piece is on an outpost square or can reach one
+ // Bonus for knights (UncontestedOutpost) if few relevant targets
+ bb = OutpostRanks & (attackedBy[Us][PAWN] | shift<Down>(pos.pieces(PAWN)))
+ & ~pe->pawn_attacks_span(Them);
+ Bitboard targets = pos.pieces(Them) & ~pos.pieces(PAWN);
+
+ if ( Pt == KNIGHT
+ && bb & s & ~CenterFiles // on a side outpost
+ && !(b & targets) // no relevant attacks
+ && (!more_than_one(targets & (s & QueenSide ? QueenSide : KingSide))))
+ score += UncontestedOutpost * popcount(pos.pieces(PAWN) & (s & QueenSide ? QueenSide : KingSide));
+ else if (bb & s)
+ score += Outpost[Pt == BISHOP];
+ else if (Pt == KNIGHT && bb & b & ~pos.pieces(Us))
+ score += ReachableOutpost;
+
+ // Bonus for a knight or bishop shielded by pawn
+ if (shift<Down>(pos.pieces(PAWN)) & s)
score += MinorBehindPawn;
- // Penalty for pawns on the same color square as the bishop
+ // Penalty if the piece is far from the king
+ score -= KingProtector[Pt == BISHOP] * distance(pos.square<KING>(Us), s);
+
if (Pt == BISHOP)
- score -= BishopPawns * ei.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
- // when that pawn is also blocked.
- if ( Pt == BISHOP
- && 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);
- 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
- : TrappedBishopA1H1;
+ // Penalty according to the number of our pawns on the same color square as the
+ // bishop, bigger when the center files are blocked with pawns and smaller
+ // when the bishop is outside the pawn chain.
+ Bitboard blocked = pos.pieces(Us, PAWN) & shift<Down>(pos.pieces());
+
+ score -= BishopPawns[edge_distance(file_of(s))] * pos.pawns_on_same_color_squares(Us, s)
+ * (!(attackedBy[Us][PAWN] & s) + popcount(blocked & CenterFiles));
+
+ // Penalty for all enemy pawns x-rayed
+ score -= BishopXRayPawns * popcount(attacks_bb<BISHOP>(s) & pos.pieces(Them, PAWN));
+
+ // Bonus for bishop on a long diagonal which can "see" both center squares
+ if (more_than_one(attacks_bb<BISHOP>(s, pos.pieces(PAWN)) & Center))
+ score += LongDiagonalBishop;
+
+ // 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 ( 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 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 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))];
-
- // Penalty when trapped by the king, even more if the king cannot castle
- else if (mob <= 3)
+ // Bonuses for rook on a (semi-)open or closed file
+ if (pos.is_on_semiopen_file(Us, s))
{
- 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)))
- score -= (TrappedRook - make_score(mob * 22, 0)) * (1 + !pos.can_castle(Us));
+ score += RookOnOpenFile[pos.is_on_semiopen_file(Them, s)];
+ }
+ else
+ {
+ // If our pawn on this file is blocked, increase penalty
+ if ( pos.pieces(Us, PAWN)
+ & shift<Down>(pos.pieces())
+ & file_bb(s))
+ {
+ score -= RookOnClosedFile;
+ }
+
+ // Penalty when trapped by the king, even more if the king cannot castle
+ if (mob <= 3)
+ {
+ File kf = file_of(pos.square<KING>(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 pinners;
- if (pos.slider_blockers(pos.pieces(Them, ROOK, BISHOP), s, pinners))
+ Bitboard queenPinners;
+ if (pos.slider_blockers(pos.pieces(Them, ROOK, BISHOP), s, queenPinners))
score -= WeakQueen;
}
}
-
- 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; }
+ // Evaluation::king() assigns bonuses and penalties to a king of a given color
- // evaluate_king() assigns bonuses and penalties to a king of a given color
+ template<Tracing T> template<Color Us>
+ Score Evaluation<T>::king() const {
- 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) {
-
- 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);
+ constexpr Color Them = ~Us;
+ constexpr Bitboard Camp = (Us == WHITE ? AllSquares ^ Rank6BB ^ Rank7BB ^ Rank8BB
+ : AllSquares ^ Rank1BB ^ Rank2BB ^ Rank3BB);
+ Bitboard weak, b1, b2, b3, safe, unsafeChecks = 0;
+ Bitboard rookChecks, queenChecks, bishopChecks, knightChecks;
+ int kingDanger = 0;
const Square ksq = pos.square<KING>(Us);
- Bitboard undefended, b, b1, b2, safe, other;
- int kingDanger;
- // King shelter and enemy pawns storm
- Score score = ei.pe->king_safety<Us>(pos, ksq);
+ // Init the score with king shelter and enemy pawns storm
+ Score score = pe->king_safety<Us>(pos);
- // Main king safety evaluation
- if (ei.kingAttackersCount[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 = std::min(820, ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them])
- + 103 * ei.kingAdjacentZoneAttacksCount[Them]
- + 190 * popcount(undefended)
- + 142 * (popcount(b) + !!pos.pinned_pieces(Us))
- - 810 * !pos.count<QUEEN>(Them)
- - 6 * mg_value(score) / 5 - 5;
-
- // 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]);
-
- b1 = pos.attacks_from<ROOK >(ksq);
- b2 = pos.attacks_from<BISHOP>(ksq);
-
- // 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 (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, 0);
- }
+ // 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]);
- // 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;
+ // Analyse the safe enemy's checks which are possible on next move
+ safe = ~pos.pieces(Them);
+ safe &= ~attackedBy[Us][ALL_PIECES] | (weak & attackedBy2[Them]);
- assert(((Us == WHITE ? b << 4 : b >> 4) & b) == 0);
- assert(popcount(Us == WHITE ? b << 4 : b >> 4) == popcount(b));
+ b1 = attacks_bb<ROOK >(ksq, pos.pieces() ^ pos.pieces(Us, QUEEN));
+ b2 = attacks_bb<BISHOP>(ksq, pos.pieces() ^ pos.pieces(Us, QUEEN));
- // 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]);
+ // Enemy rooks checks
+ rookChecks = b1 & attackedBy[Them][ROOK] & safe;
+ if (rookChecks)
+ kingDanger += SafeCheck[ROOK][more_than_one(rookChecks)];
+ else
+ unsafeChecks |= b1 & attackedBy[Them][ROOK];
+
+ // Enemy queen safe checks: count them only if the checks are from squares from
+ // which opponent cannot give a rook check, because rook checks are more valuable.
+ queenChecks = (b1 | b2) & attackedBy[Them][QUEEN] & safe
+ & ~(attackedBy[Us][QUEEN] | rookChecks);
+ if (queenChecks)
+ kingDanger += SafeCheck[QUEEN][more_than_one(queenChecks)];
+
+ // Enemy bishops checks: count them only if they are from squares from which
+ // opponent cannot give a queen check, because queen checks are more valuable.
+ bishopChecks = b2 & attackedBy[Them][BISHOP] & safe
+ & ~queenChecks;
+ if (bishopChecks)
+ kingDanger += SafeCheck[BISHOP][more_than_one(bishopChecks)];
- score -= CloseEnemies * popcount(b);
+ else
+ unsafeChecks |= b2 & attackedBy[Them][BISHOP];
+
+ // Enemy knights checks
+ knightChecks = attacks_bb<KNIGHT>(ksq) & attackedBy[Them][KNIGHT];
+ if (knightChecks & safe)
+ kingDanger += SafeCheck[KNIGHT][more_than_one(knightChecks & safe)];
+ else
+ unsafeChecks |= knightChecks;
+
+ // Find the squares that opponent attacks in our king flank, the squares
+ // which they attack twice in that flank, and the squares that we defend.
+ b1 = attackedBy[Them][ALL_PIECES] & KingFlank[file_of(ksq)] & Camp;
+ b2 = b1 & attackedBy2[Them];
+ b3 = attackedBy[Us][ALL_PIECES] & KingFlank[file_of(ksq)] & Camp;
+
+ int kingFlankAttack = popcount(b1) + popcount(b2);
+ int kingFlankDefense = popcount(b3);
+
+ kingDanger += kingAttackersCount[Them] * kingAttackersWeight[Them] // (~10 Elo)
+ + 183 * popcount(kingRing[Us] & weak) // (~15 Elo)
+ + 148 * popcount(unsafeChecks) // (~4 Elo)
+ + 98 * popcount(pos.blockers_for_king(Us)) // (~2 Elo)
+ + 69 * kingAttacksCount[Them] // (~0.5 Elo)
+ + 3 * kingFlankAttack * kingFlankAttack / 8 // (~0.5 Elo)
+ + mg_value(mobility[Them] - mobility[Us]) // (~0.5 Elo)
+ - 873 * !pos.count<QUEEN>(Them) // (~24 Elo)
+ - 100 * bool(attackedBy[Us][KNIGHT] & attackedBy[Us][KING]) // (~5 Elo)
+ - 6 * mg_value(score) / 8 // (~8 Elo)
+ - 4 * kingFlankDefense // (~5 Elo)
+ + 37; // (~0.5 Elo)
+
+ // 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[kf]))
+ if (!(pos.pieces(PAWN) & KingFlank[file_of(ksq)]))
score -= PawnlessFlank;
- if (DoTrace)
+ // Penalty if king flank is under attack, potentially moving toward the king
+ score -= FlankAttacks * kingFlankAttack;
+
+ if (T)
Trace::add(KING, Us, score);
return score;
}
- // evaluate_threats() assigns bonuses according to the types of the attacking
- // and the attacked pieces.
+ // Evaluation::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>::threats() const {
- 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);
+ constexpr Color Them = ~Us;
+ constexpr Direction Up = pawn_push(Us);
+ constexpr Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
- Bitboard b, weak, defended, stronglyProtected, safeThreats;
+ Bitboard b, weak, defended, nonPawnEnemies, stronglyProtected, safe;
Score score = SCORE_ZERO;
- // Non-pawn enemies attacked by a pawn
- weak = (pos.pieces(Them) ^ pos.pieces(Them, PAWN)) & ei.attackedBy[Us][PAWN];
+ // Non-pawn enemies
+ nonPawnEnemies = pos.pieces(Them) & ~pos.pieces(PAWN);
- if (weak)
- {
- b = pos.pieces(Us, PAWN) & ( ~ei.attackedBy[Them][ALL_PIECES]
- | ei.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]);
+ // 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 = (pos.pieces(Them) ^ pos.pieces(Them, PAWN))
- & stronglyProtected;
+ defended = nonPawnEnemies & stronglyProtected;
// Enemies not strongly protected and under our attack
- weak = pos.pieces(Them)
- & ~stronglyProtected
- & ei.attackedBy[Us][ALL_PIECES];
+ weak = pos.pieces(Them) & ~stronglyProtected & attackedBy[Us][ALL_PIECES];
- // Add a bonus according to the kind of attacking pieces
+ // 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 += ThreatByMinor[type_of(pos.piece_on(s))];
- if (type_of(pos.piece_on(s)) != PAWN)
- score += ThreatByRank * (int)relative_rank(Them, s);
- }
+ score += ThreatByMinor[type_of(pos.piece_on(pop_lsb(&b)))];
- b = (pos.pieces(Them, QUEEN) | weak) & ei.attackedBy[Us][ROOK];
+ 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);
- }
+ score += ThreatByRook[type_of(pos.piece_on(pop_lsb(&b)))];
+
+ if (weak & attackedBy[Us][KING])
+ score += ThreatByKing;
- score += Hanging * popcount(weak & ~ei.attackedBy[Them][ALL_PIECES]);
+ b = ~attackedBy[Them][ALL_PIECES]
+ | (nonPawnEnemies & attackedBy2[Us]);
+ score += Hanging * popcount(weak & b);
- b = weak & ei.attackedBy[Us][KING];
- if (b)
- score += ThreatByKing[more_than_one(b)];
+ // Additional bonus if weak piece is only protected by a queen
+ score += WeakQueenProtection * popcount(weak & attackedBy[Them][QUEEN]);
}
- // 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 restricting their piece moves
+ b = attackedBy[Them][ALL_PIECES]
+ & ~stronglyProtected
+ & attackedBy[Us][ALL_PIECES];
+ score += RestrictedPiece * popcount(b);
- b &= ~pos.pieces()
- & ~ei.attackedBy[Them][PAWN]
- & (ei.attackedBy[Us][ALL_PIECES] | ~ei.attackedBy[Them][ALL_PIECES]);
+ // Protected or unattacked squares
+ safe = ~attackedBy[Them][ALL_PIECES] | attackedBy[Us][ALL_PIECES];
- b = (shift<Left>(b) | shift<Right>(b))
- & pos.pieces(Them)
- & ~ei.attackedBy[Us][PAWN];
+ // Bonus for attacking enemy pieces with our relatively safe pawns
+ b = pos.pieces(Us, PAWN) & safe;
+ b = pawn_attacks_bb<Us>(b) & nonPawnEnemies;
+ score += ThreatBySafePawn * popcount(b);
+ // 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();
+
+ // 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<Us>(b) & nonPawnEnemies;
score += ThreatByPawnPush * popcount(b);
- if (DoTrace)
+ // Bonus for threats on the next moves against enemy queen
+ if (pos.count<QUEEN>(Them) == 1)
+ {
+ bool queenImbalance = pos.count<QUEEN>() == 1;
+
+ Square s = pos.square<QUEEN>(Them);
+ safe = mobilityArea[Us]
+ & ~pos.pieces(Us, PAWN)
+ & ~stronglyProtected;
+
+ b = attackedBy[Us][KNIGHT] & attacks_bb<KNIGHT>(s);
+
+ score += KnightOnQueen * popcount(b & safe) * (1 + queenImbalance);
+
+ b = (attackedBy[Us][BISHOP] & attacks_bb<BISHOP>(s, pos.pieces()))
+ | (attackedBy[Us][ROOK ] & attacks_bb<ROOK >(s, pos.pieces()));
+
+ score += SliderOnQueen * popcount(b & safe & attackedBy2[Us]) * (1 + queenImbalance);
+ }
+
+ if (T)
Trace::add(THREAT, Us, score);
return score;
}
-
- // evaluate_passer_pawns() evaluates the passed pawns and candidate passed
+ // Evaluation::passed() 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>::passed() const {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
+ constexpr Color Them = ~Us;
+ constexpr Direction Up = pawn_push(Us);
+ constexpr Direction Down = -Up;
- Bitboard b, bb, squaresToQueen, defendedSquares, unsafeSquares;
+ auto king_proximity = [&](Color c, Square s) {
+ return std::min(distance(pos.square<KING>(c), s), 5);
+ };
+
+ Bitboard b, bb, squaresToQueen, unsafeSquares, blockedPassers, helpers;
Score score = SCORE_ZERO;
- b = ei.pe->passed_pawns(Us);
+ b = pe->passed_pawns(Us);
+
+ blockedPassers = b & shift<Down>(pos.pieces(Them, PAWN));
+ if (blockedPassers)
+ {
+ helpers = shift<Up>(pos.pieces(Us, PAWN))
+ & ~pos.pieces(Them)
+ & (~attackedBy2[Them] | attackedBy[Us][ALL_PIECES]);
+
+ // Remove blocked candidate passers that don't have help to pass
+ b &= ~blockedPassers
+ | shift<WEST>(helpers)
+ | shift<EAST>(helpers);
+ }
while (b)
{
Square s = pop_lsb(&b);
- assert(!(pos.pieces(PAWN) & forward_bb(Us, s)));
+ assert(!(pos.pieces(Them, PAWN) & forward_file_bb(Us, s + Up)));
- bb = forward_bb(Us, s) & (ei.attackedBy[Them][ALL_PIECES] | pos.pieces(Them));
- score -= HinderPassedPawn * popcount(bb);
+ int r = relative_rank(Us, s);
- int r = relative_rank(Us, s) - RANK_2;
- int rr = r * (r - 1);
+ Score bonus = PassedRank[r];
- Value mbonus = Passed[MG][r], ebonus = Passed[EG][r];
-
- if (rr)
+ if (r > RANK_3)
{
- Square blockSq = s + pawn_push(Us);
+ int w = 5 * r - 13;
+ 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;
+ bonus += make_score(0, ( king_proximity(Them, blockSq) * 19 / 4
+ - king_proximity(Us, blockSq) * 2) * w);
// 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;
+ 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_bb(Us, s);
-
- bb = forward_bb(Them, s) & pos.pieces(ROOK, QUEEN) & pos.attacks_from<ROOK>(s);
+ squaresToQueen = forward_file_bb(Us, s);
+ unsafeSquares = passed_pawn_span(Us, s);
- if (!(pos.pieces(Us) & bb))
- defendedSquares &= ei.attackedBy[Us][ALL_PIECES];
+ bb = forward_file_bb(Them, s) & pos.pieces(ROOK, QUEEN);
if (!(pos.pieces(Them) & bb))
- unsafeSquares &= ei.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 ? 18 : !(unsafeSquares & blockSq) ? 8 : 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;
-
- mbonus += k * rr, ebonus += k * rr;
+ unsafeSquares &= attackedBy[Them][ALL_PIECES] | pos.pieces(Them);
+
+ // If there are no enemy pieces or attacks on passed pawn span, assign a big bonus.
+ // Or if there is some, but they are all attacked by our pawns, assign a bit smaller bonus.
+ // Otherwise assign a smaller bonus if the path to queen is not attacked
+ // and even smaller bonus if it is attacked but block square is not.
+ int k = !unsafeSquares ? 36 :
+ !(unsafeSquares & ~attackedBy[Us][PAWN]) ? 30 :
+ !(unsafeSquares & squaresToQueen) ? 17 :
+ !(unsafeSquares & blockSq) ? 7 :
+ 0 ;
+
+ // Assign a larger bonus if the block square is defended
+ if ((pos.pieces(Us) & bb) || (attackedBy[Us][ALL_PIECES] & blockSq))
+ k += 5;
+
+ bonus += make_score(k * w, k * w);
}
- else if (pos.pieces(Us) & blockSq)
- mbonus += rr + r * 2, ebonus += rr + r * 2;
- } // rr != 0
-
- // Scale down bonus for candidate passers which need more than one
- // pawn push to become passed.
- if (!pos.pawn_passed(Us, s + pawn_push(Us)))
- mbonus /= 2, ebonus /= 2;
+ } // r > RANK_3
- score += make_score(mbonus, ebonus) + PassedFile[file_of(s)];
+ score += bonus - PassedFile * edge_distance(file_of(s));
}
- if (DoTrace)
+ if (T)
Trace::add(PASSED, Us, score);
return score;
}
- // evaluate_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<Color Us>
- Score evaluate_space(const Position& pos, const EvalInfo& ei) {
+ // Evaluation::space() computes a space evaluation for a given side, aiming to improve game
+ // play in the opening. It is based on the number of safe squares on the four central files
+ // on ranks 2 to 4. Completely safe squares behind a friendly pawn are counted twice.
+ // Finally, the space bonus is multiplied by a weight which decreases according to occupancy.
+
+ template<Tracing T> template<Color Us>
+ Score Evaluation<T>::space() const {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
- const Bitboard SpaceMask =
+ // Early exit if, for example, both queens or 6 minor pieces have been exchanged
+ if (pos.non_pawn_material() < SpaceThreshold)
+ return SCORE_ZERO;
+
+ constexpr Color Them = ~Us;
+ constexpr Direction Down = -pawn_push(Us);
+ constexpr 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
- // pawn, or if it is undefended and attacked by an enemy piece.
+ // Find the available squares for our pieces inside the area defined by SpaceMask
Bitboard safe = SpaceMask
& ~pos.pieces(Us, PAWN)
- & ~ei.attackedBy[Them][PAWN]
- & (ei.attackedBy[Us][ALL_PIECES] | ~ei.attackedBy[Them][ALL_PIECES]);
+ & ~attackedBy[Them][PAWN];
// 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);
+ behind |= shift<Down>(behind);
+ behind |= shift<Down+Down>(behind);
- // Since SpaceMask[Us] is fully on our half of the board...
- assert(unsigned(safe >> (Us == WHITE ? 32 : 0)) == 0);
+ // Compute space score based on the number of safe squares and number of our pieces
+ // increased with number of total blocked pawns in position.
+ int bonus = popcount(safe) + popcount(behind & safe & ~attackedBy[Them][ALL_PIECES]);
+ int weight = pos.count<ALL_PIECES>(Us) - 3 + std::min(pe->blocked_count(), 9);
+ Score score = make_score(bonus * weight * weight / 16, 0);
- // ...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();
+ if (T)
+ Trace::add(SPACE, Us, score);
- return make_score(bonus * weight * weight / 16, 0);
+ return score;
}
- // 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) {
+ // Evaluation::winnable() adjusts the midgame and endgame score components, based on
+ // the known attacking/defending status of the players. The final value is derived
+ // by interpolation from the midgame and endgame values.
- 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);
+ template<Tracing T>
+ Value Evaluation<T>::winnable(Score score) const {
- // Compute the initiative bonus for the attacking side
- int initiative = 8 * (asymmetry + kingDistance - 17) + 12 * pos.count<PAWN>() + 16 * bothFlanks;
+ int outflanking = distance<File>(pos.square<KING>(WHITE), pos.square<KING>(BLACK))
+ + int(rank_of(pos.square<KING>(WHITE)) - rank_of(pos.square<KING>(BLACK)));
- // 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));
-
- return make_score(0, value);
- }
+ bool pawnsOnBothFlanks = (pos.pieces(PAWN) & QueenSide)
+ && (pos.pieces(PAWN) & KingSide);
+ bool almostUnwinnable = outflanking < 0
+ && !pawnsOnBothFlanks;
- // evaluate_scale_factor() computes the scale factor for the winning side
- ScaleFactor evaluate_scale_factor(const Position& pos, const EvalInfo& ei, Value eg) {
+ bool infiltration = rank_of(pos.square<KING>(WHITE)) > RANK_4
+ || rank_of(pos.square<KING>(BLACK)) < RANK_5;
+ // Compute the initiative bonus for the attacking side
+ int complexity = 9 * pe->passed_count()
+ + 12 * pos.count<PAWN>()
+ + 9 * outflanking
+ + 21 * pawnsOnBothFlanks
+ + 24 * infiltration
+ + 51 * !pos.non_pawn_material()
+ - 43 * almostUnwinnable
+ -110 ;
+
+ Value mg = mg_value(score);
+ Value eg = eg_value(score);
+
+ // Now apply the bonus: note that we find the attacking side by extracting the
+ // sign of the midgame or endgame values, and that we carefully cap the bonus
+ // so that the midgame and endgame scores do not change sign after the bonus.
+ int u = ((mg > 0) - (mg < 0)) * std::clamp(complexity + 50, -abs(mg), 0);
+ int v = ((eg > 0) - (eg < 0)) * std::max(complexity, -abs(eg));
+
+ mg += u;
+ eg += v;
+
+ // Compute the scale factor for the winning side
Color strongSide = eg > VALUE_DRAW ? WHITE : BLACK;
- ScaleFactor sf = ei.me->scale_factor(pos, strongSide);
+ int 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 (sf == SCALE_FACTOR_NORMAL || sf == SCALE_FACTOR_ONEPAWN)
+ // If scale factor is not already specific, scale down via general heuristics
+ if (sf == SCALE_FACTOR_NORMAL)
{
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, it is even more a draw.
+ // For pure opposite colored bishops endgames use scale factor
+ // based on the number of passed pawns of the strong side.
if ( pos.non_pawn_material(WHITE) == BishopValueMg
&& pos.non_pawn_material(BLACK) == BishopValueMg)
- 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.
- return ScaleFactor(46);
+ sf = 18 + 4 * popcount(pe->passed_pawns(strongSide));
+ // For every other opposite colored bishops endgames use scale factor
+ // based on the number of all pieces of the strong side.
+ else
+ sf = 22 + 3 * pos.count<ALL_PIECES>(strongSide);
}
- // Endings where weaker side can place his king in front of the opponent's
- // pawns are drawish.
- else if ( abs(eg) <= BishopValueEg
- && pos.count<PAWN>(strongSide) <= 2
- && !pos.pawn_passed(~strongSide, pos.square<KING>(~strongSide)))
- return ScaleFactor(37 + 7 * pos.count<PAWN>(strongSide));
+ // For rook endgames with strong side not having overwhelming pawn number advantage
+ // and its pawns being on one flank and weak side protecting its pieces with a king
+ // use lower scale factor.
+ else if ( pos.non_pawn_material(WHITE) == RookValueMg
+ && pos.non_pawn_material(BLACK) == RookValueMg
+ && pos.count<PAWN>(strongSide) - pos.count<PAWN>(~strongSide) <= 1
+ && bool(KingSide & pos.pieces(strongSide, PAWN)) != bool(QueenSide & pos.pieces(strongSide, PAWN))
+ && (attacks_bb<KING>(pos.square<KING>(~strongSide)) & pos.pieces(~strongSide, PAWN)))
+ sf = 36;
+ // For queen vs no queen endgames use scale factor
+ // based on number of minors of side that doesn't have queen.
+ else if (pos.count<QUEEN>() == 1)
+ sf = 37 + 3 * (pos.count<QUEEN>(WHITE) == 1 ? pos.count<BISHOP>(BLACK) + pos.count<KNIGHT>(BLACK)
+ : pos.count<BISHOP>(WHITE) + pos.count<KNIGHT>(WHITE));
+ // In every other case use scale factor based on
+ // the number of pawns of the strong side reduced if pawns are on a single flank.
+ else
+ sf = std::min(sf, 36 + 7 * pos.count<PAWN>(strongSide)) - 4 * !pawnsOnBothFlanks;
+
+ // Reduce scale factor in case of pawns being on a single flank
+ sf -= 4 * !pawnsOnBothFlanks;
}
- return sf;
+ // Interpolate between the middlegame and (scaled by 'sf') endgame score
+ v = mg * int(me->game_phase())
+ + eg * int(PHASE_MIDGAME - me->game_phase()) * ScaleFactor(sf) / SCALE_FACTOR_NORMAL;
+ v /= PHASE_MIDGAME;
+
+ if (T)
+ {
+ Trace::add(WINNABLE, make_score(u, eg * ScaleFactor(sf) / SCALE_FACTOR_NORMAL - eg_value(score)));
+ Trace::add(TOTAL, make_score(mg, eg * ScaleFactor(sf) / SCALE_FACTOR_NORMAL));
+ }
+
+ return Value(v);
}
-} // namespace
+ // 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.
-/// 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() {
-template<bool DoTrace>
-Value Eval::evaluate(const Position& pos) {
+ assert(!pos.checkers());
- assert(!pos.checkers());
+ // Probe the material hash table
+ me = Material::probe(pos);
- Score mobility[COLOR_NB] = { SCORE_ZERO, SCORE_ZERO };
- Value v;
- EvalInfo ei;
+ // 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
+ auto lazy_skip = [&](Value lazyThreshold) {
+ return abs(mg_value(score) + eg_value(score)) / 2 > lazyThreshold + pos.non_pawn_material() / 64;
+ };
- // Probe the material hash table
- ei.me = Material::probe(pos);
+ if (lazy_skip(LazyThreshold1))
+ goto make_v;
- // 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);
+ // Main evaluation begins here
+ initialize<WHITE>();
+ initialize<BLACK>();
- // 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();
+ // Pieces evaluated first (also populates attackedBy, attackedBy2).
+ // Note that the order of evaluation of the terms is left unspecified.
+ score += pieces<WHITE, KNIGHT>() - pieces<BLACK, KNIGHT>()
+ + pieces<WHITE, BISHOP>() - pieces<BLACK, BISHOP>()
+ + pieces<WHITE, ROOK >() - pieces<BLACK, ROOK >()
+ + pieces<WHITE, QUEEN >() - pieces<BLACK, QUEEN >();
- // Probe the pawn hash table
- ei.pe = Pawns::probe(pos);
- score += ei.pe->pawns_score();
+ score += mobility[WHITE] - mobility[BLACK];
- // 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;
+ // More complex interactions that require fully populated attack bitboards
+ score += king< WHITE>() - king< BLACK>()
+ + passed< WHITE>() - passed< BLACK>();
- // Initialize attack and king safety bitboards
- eval_init<WHITE>(pos, ei);
- eval_init<BLACK>(pos, ei);
+ if (lazy_skip(LazyThreshold2))
+ goto make_v;
- // Evaluate all pieces but king and pawns
- score += evaluate_pieces<DoTrace>(pos, ei, mobility);
- score += mobility[WHITE] - mobility[BLACK];
+ score += threats<WHITE>() - threats<BLACK>()
+ + space< WHITE>() - space< 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);
+make_v:
+ // Derive single value from mg and eg parts of score
+ Value v = winnable(score);
- // Evaluate tactical threats, we need full attack information including king
- score += evaluate_threats<WHITE, DoTrace>(pos, ei)
- - evaluate_threats<BLACK, DoTrace>(pos, ei);
+ // 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]);
+ }
- // 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);
+ // Evaluation grain
+ v = (v / 16) * 16;
- // 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);
+ // Side to move point of view
+ v = (pos.side_to_move() == WHITE ? v : -v) + Tempo;
- // Evaluate position potential for the winning side
- score += evaluate_initiative(pos, ei.pe->pawn_asymmetry(), eg_value(score));
+ return v;
+ }
- // Evaluate scale factor for the winning side
- ScaleFactor sf = evaluate_scale_factor(pos, ei, eg_value(score));
+} // namespace
- // 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);
+/// 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.
- // In case of tracing add all remaining individual evaluation terms
- if (DoTrace)
+Value Eval::evaluate(const Position& pos) {
+
+ Value v;
+
+ if (!Eval::useNNUE)
+ v = Evaluation<NO_TRACE>(pos).value();
+ else
{
- 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);
+ // Scale and shift NNUE for compatibility with search and classical evaluation
+ auto adjusted_NNUE = [&](){
+ int mat = pos.non_pawn_material() + PawnValueMg * pos.count<PAWN>();
+ return NNUE::evaluate(pos) * (679 + mat / 32) / 1024 + Tempo;
+ };
+
+ // If there is PSQ imbalance use classical eval, with small probability if it is small
+ Value psq = Value(abs(eg_value(pos.psq_score())));
+ int r50 = 16 + pos.rule50_count();
+ bool largePsq = psq * 16 > (NNUEThreshold1 + pos.non_pawn_material() / 64) * r50;
+ bool classical = largePsq || (psq > PawnValueMg / 4 && !(pos.this_thread()->nodes & 0xB));
+
+ // Use classical evaluation for really low piece endgames.
+ // The most critical case is a bishop + A/H file pawn vs naked king draw.
+ bool strongClassical = pos.non_pawn_material() < 2 * RookValueMg && pos.count<PAWN>() < 2;
+
+ v = classical || strongClassical ? Evaluation<NO_TRACE>(pos).value() : adjusted_NNUE();
+
+ // If the classical eval is small and imbalance large, use NNUE nevertheless.
+ // For the case of opposite colored bishops, switch to NNUE eval with
+ // small probability if the classical eval is less than the threshold.
+ if ( largePsq && !strongClassical
+ && ( abs(v) * 16 < NNUEThreshold2 * r50
+ || ( pos.opposite_bishops()
+ && abs(v) * 16 < (NNUEThreshold1 + pos.non_pawn_material() / 64) * r50
+ && !(pos.this_thread()->nodes & 0xB))))
+ v = adjusted_NNUE();
}
- return (pos.side_to_move() == WHITE ? v : -v) + Eval::Tempo; // Side to move point of view
-}
+ // Damp down the evaluation linearly when shuffling
+ v = v * (100 - pos.rule50_count()) / 100;
-// Explicit template instantiations
-template Value Eval::evaluate<true >(const Position&);
-template Value Eval::evaluate<false>(const Position&);
+ // Guarantee evaluation does not hit the tablebase range
+ v = std::clamp(v, VALUE_TB_LOSS_IN_MAX_PLY + 1, VALUE_TB_WIN_IN_MAX_PLY - 1);
+ return v;
+}
/// 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.
+/// Trace scores are from white's point of view
std::string Eval::trace(const Position& pos) {
+ if (pos.checkers())
+ return "Final evaluation: none (in check)";
+
+ std::stringstream ss;
+ ss << std::showpoint << std::noshowpos << std::fixed << std::setprecision(2);
+
+ Value v;
+
std::memset(scores, 0, sizeof(scores));
- Value v = evaluate<true>(pos);
- v = pos.side_to_move() == WHITE ? v : -v; // White's point of view
+ pos.this_thread()->contempt = SCORE_ZERO; // Reset any dynamic contempt
+
+ v = Evaluation<TRACE>(pos).value();
- 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";
+ << " 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)
+ << " Winnable | " << Term(WINNABLE)
+ << " ------------+-------------+-------------+------------\n"
+ << " Total | " << Term(TOTAL);
+
+ v = pos.side_to_move() == WHITE ? v : -v;
+
+ ss << "\nClassical evaluation: " << to_cp(v) << " (white side)\n";
+
+ if (Eval::useNNUE)
+ {
+ v = NNUE::evaluate(pos);
+ v = pos.side_to_move() == WHITE ? v : -v;
+ ss << "\nNNUE evaluation: " << to_cp(v) << " (white side)\n";
+ }
+
+ v = evaluate(pos);
+ v = pos.side_to_move() == WHITE ? v : -v;
+ ss << "\nFinal evaluation: " << to_cp(v) << " (white side)\n";
return ss.str();
}