/*
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) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2004-2020 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;
+ }
+
+ 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); }
+ };
+
+ MemoryBuffer buffer(const_cast<char*>(reinterpret_cast<const char*>(gEmbeddedNNUEData)),
+ size_t(gEmbeddedNNUESize));
+
+ istream stream(&buffer);
+ if (load_eval(eval_file, stream))
+ eval_file_loaded = eval_file;
+ }
+ }
+ }
+
+ /// NNUE::verify() verifies that the last net used was loaded successfully
+ void NNUE::verify() {
+
+ string eval_file = string(Options["EvalFile"]);
+
+ 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);
+ }
+
+ if (useNNUE)
+ sync_cout << "info string NNUE evaluation using " << eval_file << " enabled" << sync_endl;
+ else
+ sync_cout << "info string classical evaluation enabled" << sync_endl;
+ }
+}
namespace Trace {
enum Tracing { NO_TRACE, TRACE };
enum Term { // The first 8 entries are reserved for PieceType
- MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, INITIATIVE, TOTAL, TERM_NB
+ MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, WINNABLE, TOTAL, TERM_NB
};
Score scores[TERM_NB][COLOR_NB];
std::ostream& operator<<(std::ostream& os, Term t) {
- if (t == MATERIAL || t == IMBALANCE || t == INITIATIVE || t == TOTAL)
+ if (t == MATERIAL || t == IMBALANCE || t == WINNABLE || t == TOTAL)
os << " ---- ----" << " | " << " ---- ----";
else
os << scores[t][WHITE] << " | " << scores[t][BLACK];
namespace {
// Threshold for lazy and space evaluation
- constexpr Value LazyThreshold = Value(1400);
+ constexpr Value LazyThreshold1 = Value(1400);
+ constexpr Value LazyThreshold2 = Value(1300);
constexpr Value SpaceThreshold = Value(12222);
+ constexpr Value NNUEThreshold1 = Value(550);
+ constexpr Value NNUEThreshold2 = Value(150);
// KingAttackWeights[PieceType] contains king attack weights by piece type
constexpr int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 81, 52, 44, 10 };
- // Penalties for enemy's safe checks
- constexpr int QueenSafeCheck = 780;
- constexpr int RookSafeCheck = 1080;
- constexpr int BishopSafeCheck = 635;
- constexpr int KnightSafeCheck = 790;
+ // 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 S(mg, eg) make_score(mg, eg)
// MobilityBonus[PieceType-2][attacked] contains bonuses for middle and end game,
// indexed by piece type and number of attacked squares in the mobility area.
constexpr Score MobilityBonus[][32] = {
- { S(-62,-81), S(-53,-56), S(-12,-30), S( -4,-14), S( 3, 8), S( 13, 15), // Knight
- S( 22, 23), S( 28, 27), S( 33, 33) },
- { S(-48,-59), S(-20,-23), S( 16, -3), S( 26, 13), S( 38, 24), S( 51, 42), // Bishop
- 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), // Rook
- 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), // Queen
- 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) }
+ { 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(1, 8), S(3, 7)
+ };
+
+ // 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(56, 34), S(31, 23) };
+
+ // PassedRank[Rank] contains a bonus according to the rank of a passed pawn
+ constexpr Score PassedRank[RANK_NB] = {
+ S(0, 0), S(9, 28), S(15, 31), S(17, 39), S(64, 70), S(171, 177), S(277, 260)
};
// RookOnFile[semiopen/open] contains bonuses for each rook when there is
// no (friendly) pawn on the rook file.
- constexpr Score RookOnFile[] = { S(21, 4), S(47, 25) };
+ constexpr Score RookOnFile[] = { S(19, 7), S(48, 27) };
// ThreatByMinor/ByRook[attacked PieceType] contains bonuses according to
// which piece type attacks which one. Attacks on lesser pieces which are
// pawn-defended are not considered.
constexpr Score ThreatByMinor[PIECE_TYPE_NB] = {
- S(0, 0), S(5, 32), S(57, 41), S(77, 56), S(88, 119), S(79, 161)
+ S(0, 0), S(5, 32), S(55, 41), S(77, 56), S(89, 119), S(79, 162)
};
constexpr Score ThreatByRook[PIECE_TYPE_NB] = {
- S(0, 0), S(2, 44), S(36, 71), S(36, 61), S(0, 38), S(51, 38)
- };
-
- // PassedRank[Rank] contains a bonus according to the rank of a passed pawn
- constexpr Score PassedRank[RANK_NB] = {
- S(0, 0), S(10, 28), S(17, 33), S(15, 41), S(62, 72), S(168, 177), S(276, 260)
+ S(0, 0), S(3, 44), S(37, 68), S(42, 60), S(0, 39), S(58, 43)
};
// Assorted bonuses and penalties
- constexpr Score BishopPawns = S( 3, 7);
+ constexpr Score BadOutpost = S( -7, 36);
+ 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 KingProtector = S( 7, 8);
- constexpr Score KnightOnQueen = S( 16, 12);
+ constexpr Score KnightOnQueen = S( 16, 11);
constexpr Score LongDiagonalBishop = S( 45, 0);
constexpr Score MinorBehindPawn = S( 18, 3);
- constexpr Score Outpost = S( 30, 21);
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 RookOnQueenFile = S( 7, 6);
- constexpr Score SliderOnQueen = S( 59, 18);
+ 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( 52, 10);
- constexpr Score WeakQueen = S( 49, 15);
+ constexpr Score TrappedRook = S( 55, 13);
constexpr Score WeakQueenProtection = S( 14, 0);
+ constexpr Score WeakQueen = S( 56, 15);
+
#undef S
template<Color Us> Score threats() const;
template<Color Us> Score passed() const;
template<Color Us> Score space() const;
- ScaleFactor scale_factor(Value eg) const;
- Score initiative(Score score) const;
+ Value winnable(Score score) const;
const Position& pos;
Material::Entry* me;
// Evaluation::initialize() computes king and pawn attacks, and the king ring
// bitboard for a given color. This is done at the beginning of the evaluation.
+
template<Tracing T> template<Color Us>
void Evaluation<T>::initialize() {
mobilityArea[Us] = ~(b | pos.pieces(Us, KING, QUEEN) | pos.blockers_for_king(Us) | pe->pawn_attacks(Them));
// Initialize attackedBy[] for king and pawns
- attackedBy[Us][KING] = pos.attacks_from<KING>(ksq);
+ 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]);
// Init our king safety tables
- Square s = make_square(Utility::clamp(file_of(ksq), FILE_B, FILE_G),
- Utility::clamp(rank_of(ksq), RANK_2, RANK_7));
- kingRing[Us] = PseudoAttacks[KING][s] | s;
+ 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;
kingAttackersCount[Them] = popcount(kingRing[Us] & pe->pawn_attacks(Them));
kingAttacksCount[Them] = kingAttackersWeight[Them] = 0;
// Evaluation::pieces() scores pieces of a given color and type
+
template<Tracing T> template<Color Us, PieceType Pt>
Score Evaluation<T>::pieces() {
// Find attacked squares, including x-ray attacks for bishops and rooks
b = Pt == BISHOP ? attacks_bb<BISHOP>(s, pos.pieces() ^ pos.pieces(QUEEN))
: Pt == ROOK ? attacks_bb< ROOK>(s, pos.pieces() ^ pos.pieces(QUEEN) ^ pos.pieces(Us, ROOK))
- : pos.attacks_from<Pt>(s);
+ : attacks_bb<Pt>(s, pos.pieces());
if (pos.blockers_for_king(Us) & s)
- b &= LineBB[pos.square<KING>(Us)][s];
+ b &= line_bb(pos.square<KING>(Us), s);
attackedBy2[Us] |= attackedBy[Us][ALL_PIECES] & b;
attackedBy[Us][Pt] |= b;
kingAttacksCount[Us] += popcount(b & attackedBy[Them][KING]);
}
+ 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;
+
int mob = popcount(b & mobilityArea[Us]);
mobility[Us] += MobilityBonus[Pt - 2][mob];
if (Pt == BISHOP || Pt == KNIGHT)
{
- // Bonus if piece is on an outpost square or can reach one
- bb = OutpostRanks & attackedBy[Us][PAWN] & ~pe->pawn_attacks_span(Them);
- if (bb & s)
- score += Outpost * (Pt == KNIGHT ? 2 : 1);
-
+ // Bonus if the piece is on an outpost square or can reach one
+ // Reduced bonus for knights (BadOutpost) 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 += BadOutpost;
+ else if (bb & s)
+ score += Outpost[Pt == BISHOP];
else if (Pt == KNIGHT && bb & b & ~pos.pieces(Us))
- score += Outpost;
+ score += ReachableOutpost;
// Bonus for a knight or bishop shielded by pawn
if (shift<Down>(pos.pieces(PAWN)) & s)
score += MinorBehindPawn;
// Penalty if the piece is far from the king
- score -= KingProtector * distance(pos.square<KING>(Us), s);
+ score -= KingProtector[Pt == BISHOP] * distance(pos.square<KING>(Us), s);
if (Pt == BISHOP)
{
- // Penalty according to number of pawns on the same color square as the
+ // 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 * pos.pawns_on_same_color_squares(Us, s)
+ 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;
if (Pt == ROOK)
{
- // Bonus for rook on the same file as a queen
- if (file_bb(s) & pos.pieces(QUEEN))
- score += RookOnQueenFile;
-
// Bonus for rook on an open or semi-open file
if (pos.is_on_semiopen_file(Us, s))
score += RookOnFile[pos.is_on_semiopen_file(Them, s)];
// Evaluation::king() assigns bonuses and penalties to a king of a given color
+
template<Tracing T> template<Color Us>
Score Evaluation<T>::king() const {
b2 = attacks_bb<BISHOP>(ksq, pos.pieces() ^ pos.pieces(Us, QUEEN));
// Enemy rooks checks
- rookChecks = b1 & safe & attackedBy[Them][ROOK];
-
+ rookChecks = b1 & attackedBy[Them][ROOK] & safe;
if (rookChecks)
- kingDanger += RookSafeCheck;
+ kingDanger += SafeCheck[ROOK][more_than_one(rookChecks)];
else
unsafeChecks |= b1 & attackedBy[Them][ROOK];
- // Enemy queen safe checks: we count them only if they are from squares from
- // which we can't give a rook check, because rook checks are more valuable.
- queenChecks = (b1 | b2)
- & attackedBy[Them][QUEEN]
- & safe
- & ~attackedBy[Us][QUEEN]
- & ~rookChecks;
-
+ // 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 += QueenSafeCheck;
+ kingDanger += SafeCheck[QUEEN][more_than_one(queenChecks)];
- // Enemy bishops checks: we count them only if they are from squares from
- // which we can't give a queen check, because queen checks are more valuable.
- bishopChecks = b2
- & attackedBy[Them][BISHOP]
- & safe
+ // 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 += BishopSafeCheck;
+ kingDanger += SafeCheck[BISHOP][more_than_one(bishopChecks)];
+
else
unsafeChecks |= b2 & attackedBy[Them][BISHOP];
// Enemy knights checks
- knightChecks = pos.attacks_from<KNIGHT>(ksq) & attackedBy[Them][KNIGHT];
-
+ knightChecks = attacks_bb<KNIGHT>(ksq) & attackedBy[Them][KNIGHT];
if (knightChecks & safe)
- kingDanger += KnightSafeCheck;
+ kingDanger += SafeCheck[KNIGHT][more_than_one(knightChecks & safe)];
else
unsafeChecks |= knightChecks;
b2 = b1 & attackedBy2[Them];
b3 = attackedBy[Us][ALL_PIECES] & KingFlank[file_of(ksq)] & Camp;
- int kingFlankAttack = popcount(b1) + popcount(b2);
+ int kingFlankAttack = popcount(b1) + popcount(b2);
int kingFlankDefense = popcount(b3);
- kingDanger += kingAttackersCount[Them] * kingAttackersWeight[Them]
- + 185 * popcount(kingRing[Us] & weak)
- + 148 * popcount(unsafeChecks)
- + 98 * popcount(pos.blockers_for_king(Us))
- + 69 * kingAttacksCount[Them]
- + 3 * kingFlankAttack * kingFlankAttack / 8
- + mg_value(mobility[Them] - mobility[Us])
- - 873 * !pos.count<QUEEN>(Them)
- - 100 * bool(attackedBy[Us][KNIGHT] & attackedBy[Us][KING])
- - 6 * mg_value(score) / 8
- - 4 * kingFlankDefense
- + 37;
+ kingDanger += kingAttackersCount[Them] * kingAttackersWeight[Them] // (~10 Elo)
+ + 185 * 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)
// Evaluation::threats() assigns bonuses according to the types of the
// attacking and the attacked pieces.
+
template<Tracing T> template<Color Us>
Score Evaluation<T>::threats() const {
// 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] & ~stronglyProtected;
+ safe = mobilityArea[Us]
+ & ~pos.pieces(Us, PAWN)
+ & ~stronglyProtected;
- b = attackedBy[Us][KNIGHT] & pos.attacks_from<KNIGHT>(s);
+ b = attackedBy[Us][KNIGHT] & attacks_bb<KNIGHT>(s);
- score += KnightOnQueen * popcount(b & safe);
+ score += KnightOnQueen * popcount(b & safe) * (1 + queenImbalance);
- b = (attackedBy[Us][BISHOP] & pos.attacks_from<BISHOP>(s))
- | (attackedBy[Us][ROOK ] & pos.attacks_from<ROOK >(s));
+ 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]);
+ score += SliderOnQueen * popcount(b & safe & attackedBy2[Us]) * (1 + queenImbalance);
}
if (T)
return std::min(distance(pos.square<KING>(c), s), 5);
};
- Bitboard b, bb, squaresToQueen, unsafeSquares, candidatePassers, leverable;
+ Bitboard b, bb, squaresToQueen, unsafeSquares, blockedPassers, helpers;
Score score = SCORE_ZERO;
b = pe->passed_pawns(Us);
- candidatePassers = b & shift<Down>(pos.pieces(Them, PAWN));
- if (candidatePassers)
+ blockedPassers = b & shift<Down>(pos.pieces(Them, PAWN));
+ if (blockedPassers)
{
- // Can we lever the blocker of a candidate passer?
- leverable = shift<Up>(pos.pieces(Us, PAWN))
- & ~pos.pieces(Them)
- & (~attackedBy2[Them] | attackedBy[Us][ALL_PIECES])
- & (~(attackedBy[Them][KNIGHT] | attackedBy[Them][BISHOP])
- | (attackedBy[Us ][KNIGHT] | attackedBy[Us ][BISHOP]));
-
- // Remove candidate otherwise
- b &= ~candidatePassers
- | shift<WEST>(leverable)
- | shift<EAST>(leverable);
+ 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 blockSq = s + Up;
// Adjust bonus based on the king's proximity
- bonus += make_score(0, ( (king_proximity(Them, blockSq) * 19) / 4
- - king_proximity(Us, blockSq) * 2) * w);
+ 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 (r != RANK_7)
}
- // Evaluation::space() computes the space evaluation for a given side. The
- // space evaluation is a simple bonus based on the number of safe squares
- // available for minor pieces on the central four files on ranks 2--4. Safe
- // squares one, two or three squares behind a friendly pawn are counted
- // twice. Finally, the space bonus is multiplied by a weight. The aim is to
- // improve play on game opening.
+ // 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 {
+ // Early exit if, for example, both queens or 6 minor pieces have been exchanged
if (pos.non_pawn_material() < SpaceThreshold)
return SCORE_ZERO;
behind |= shift<Down+Down>(behind);
int bonus = popcount(safe) + popcount(behind & safe & ~attackedBy[Them][ALL_PIECES]);
- int weight = pos.count<ALL_PIECES>(Us) - 2 + pe->blocked_count() / 2;
+ int weight = pos.count<ALL_PIECES>(Us) - 3 + std::min(pe->blocked_count(), 9);
Score score = make_score(bonus * weight * weight / 16, 0);
if (T)
}
- // Evaluation::initiative() computes the initiative correction value
- // for the position. It is a second order bonus/malus based on the
- // known attacking/defending status of the players.
+ // 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.
template<Tracing T>
- Score Evaluation<T>::initiative(Score score) const {
+ Value Evaluation<T>::winnable(Score score) const {
int outflanking = distance<File>(pos.square<KING>(WHITE), pos.square<KING>(BLACK))
- distance<Rank>(pos.square<KING>(WHITE), pos.square<KING>(BLACK));
bool almostUnwinnable = outflanking < 0
&& !pawnsOnBothFlanks;
- bool infiltration = rank_of(pos.square<KING>(WHITE)) > RANK_4
- || rank_of(pos.square<KING>(BLACK)) < RANK_5;
+ 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()
- + 1
1 * pos.count<PAWN>()
+ + 1
2 * pos.count<PAWN>()
+ 9 * outflanking
+ 21 * pawnsOnBothFlanks
+ 24 * infiltration
// 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::max(std::min(complexity + 50, 0), -abs(mg));
+ int u = ((mg > 0) - (mg < 0)) * std::clamp(complexity + 50, -abs(mg), 0);
int v = ((eg > 0) - (eg < 0)) * std::max(complexity, -abs(eg));
- if (T)
- Trace::add(INITIATIVE, make_score(u, v));
-
- return make_score(u, v);
- }
-
-
- // Evaluation::scale_factor() computes the scale factor for the winning side
-
- template<Tracing T>
- ScaleFactor Evaluation<T>::scale_factor(Value eg) const {
+ mg += u;
+ eg += v;
+ // Compute the scale factor for the winning side
Color strongSide = eg > VALUE_DRAW ? WHITE : BLACK;
int sf = me->scale_factor(pos, strongSide);
- // If scale is not already specific, scale down the endgame via general heuristics
+ // If scale factor is not already specific, scale down via general heuristics
if (sf == SCALE_FACTOR_NORMAL)
{
- if ( pos.opposite_bishops()
- && pos.non_pawn_material() == 2 * BishopValueMg)
- sf = 22;
+ if (pos.opposite_bishops())
+ {
+ if ( pos.non_pawn_material(WHITE) == BishopValueMg
+ && pos.non_pawn_material(BLACK) == BishopValueMg)
+ sf = 18 + 4 * popcount(pe->passed_pawns(strongSide));
+ else
+ sf = 22 + 3 * pos.count<ALL_PIECES>(strongSide);
+ }
+ 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;
+ 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));
else
- sf = std::min(sf, 36 + (pos.opposite_bishops() ? 2 : 7) * pos.count<PAWN>(strongSide));
+ sf = std::min(sf, 36 + 7 * pos.count<PAWN>(strongSide)) - 4 * !pawnsOnBothFlanks;
- sf = std::max(0, sf - (pos.rule50_count() - 12) / 4);
+ sf -= 4 * !pawnsOnBothFlanks;
}
- return ScaleFactor(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);
}
score += pe->pawn_score(WHITE) - pe->pawn_score(BLACK);
// Early exit if score is high
- Value v = (mg_value(score) + eg_value(score)) / 2;
- if (abs(v) > LazyThreshold + pos.non_pawn_material() / 64)
- return pos.side_to_move() == WHITE ? v : -v;
+ auto lazy_skip = [&](Value lazyThreshold) {
+ return abs(mg_value(score) + eg_value(score)) / 2 > lazyThreshold + pos.non_pawn_material() / 64;
+ };
- // Main evaluation begins here
+ if (lazy_skip(LazyThreshold1))
+ goto make_v;
+ // Main evaluation begins here
initialize<WHITE>();
initialize<BLACK>();
- // Pieces should be evaluated first (populate attack tables)
+ // 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 >()
score += mobility[WHITE] - mobility[BLACK];
+ // More complex interactions that require fully populated attack bitboards
score += king< WHITE>() - king< BLACK>()
- + threats<WHITE>() - threats<BLACK>()
- + passed< WHITE>() - passed< BLACK>()
- + space< WHITE>() - space< BLACK>();
+ + passed< WHITE>() - passed< BLACK>();
- score += initiative(score);
+ if (lazy_skip(LazyThreshold2))
+ goto make_v;
- // Interpolate between a middlegame and a (scaled by 'sf') endgame score
- ScaleFactor sf = scale_factor(eg_value(score));
- v = mg_value(score) * int(me->game_phase())
- + eg_value(score) * int(PHASE_MIDGAME - me->game_phase()) * sf / SCALE_FACTOR_NORMAL;
+ score += threats<WHITE>() - threats<BLACK>()
+ + space< WHITE>() - space< BLACK>();
- v /= PHASE_MIDGAME;
+make_v:
+ // Derive single value from mg and eg parts of score
+ Value v = winnable(score);
// In case of tracing add all remaining individual evaluation terms
if (T)
Trace::add(IMBALANCE, me->imbalance());
Trace::add(PAWN, pe->pawn_score(WHITE), pe->pawn_score(BLACK));
Trace::add(MOBILITY, mobility[WHITE], mobility[BLACK]);
- Trace::add(TOTAL, score);
}
- return (pos.side_to_move() == WHITE ? v : -v) + Tempo; // Side to move point of view
+ // Evaluation grain
+ v = (v / 16) * 16;
+
+ // Side to move point of view
+ v = (pos.side_to_move() == WHITE ? v : -v) + Tempo;
+
+ return v;
}
} // namespace
/// evaluation of the position from the point of view of the side to move.
Value Eval::evaluate(const Position& pos) {
- return Evaluation<NO_TRACE>(pos).value();
-}
+ Value v;
+
+ if (!Eval::useNNUE)
+ v = Evaluation<NO_TRACE>(pos).value();
+ else
+ {
+ // Scale and shift NNUE for compatibility with search and classical evaluation
+ auto adjusted_NNUE = [&](){
+ int mat = pos.non_pawn_material() + PieceValue[MG][PAWN] * pos.count<PAWN>();
+ return NNUE::evaluate(pos) * (720 + 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));
+
+ v = classical ? 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
+ && (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();
+ }
+
+ // Damp down the evaluation linearly when shuffling
+ v = v * (100 - pos.rule50_count()) / 100;
+
+ // 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 "Total evaluation: none (in check)";
+ 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));
pos.this_thread()->contempt = SCORE_ZERO; // Reset any dynamic contempt
- Value v = Evaluation<TRACE>(pos).value();
-
- v = pos.side_to_move() == WHITE ? v : -v; // Trace scores are from white's point of view
+ v = Evaluation<TRACE>(pos).value();
- std::stringstream ss;
ss << std::showpoint << std::noshowpos << std::fixed << std::setprecision(2)
<< " Term | White | Black | Total \n"
<< " | MG EG | MG EG | MG EG \n"
<< " Threats | " << Term(THREAT)
<< " Passed | " << Term(PASSED)
<< " Space | " << Term(SPACE)
- << " Initiative | " << Term(INITIATIVE)
+ << " Winnable | " << Term(WINNABLE)
<< " ------------+-------------+-------------+------------\n"
<< " Total | " << Term(TOTAL);
- ss << "\nTotal evaluation: " << to_cp(v) << " (white side)\n";
+ 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();
}
projects / stockfish / blobdiff