X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fevaluate.cpp;h=ef33adf5d774a56fb306a6333c4774fd3fd11daa;hp=c66938d6ac7ed65db10745dbff4a3cbd86f4b5c0;hb=8630d03dd4e1ec7e492ddf6c40d9d9e4cdba2a58;hpb=cbcb05ca092160137c166f84e7e9da3d6bb4e2d3 diff --git a/src/evaluate.cpp b/src/evaluate.cpp index c66938d6..ef33adf5 100644 --- a/src/evaluate.cpp +++ b/src/evaluate.cpp @@ -20,51 +20,126 @@ #include #include #include // For std::memset +#include #include #include #include +#include +#include #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; - std::string eval_file_loaded="None"; + 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 init_NNUE() { + void NNUE::init() { useNNUE = Options["Use NNUE"]; - std::string eval_file = std::string(Options["EvalFile"]); - if (useNNUE && eval_file_loaded != eval_file) - if (Eval::NNUE::load_eval_file(eval_file)) - eval_file_loaded = eval_file; + if (!useNNUE) + return; + + string eval_file = string(Options["EvalFile"]); + + #if defined(DEFAULT_NNUE_DIRECTORY) + #define stringify2(x) #x + #define stringify(x) stringify2(x) + vector dirs = { "" , "" , CommandLine::binaryDirectory , stringify(DEFAULT_NNUE_DIRECTORY) }; + #else + vector dirs = { "" , "" , CommandLine::binaryDirectory }; + #endif + + for (string directory : dirs) + if (eval_file_loaded != eval_file) + { + if (directory != "") + { + ifstream stream(directory + eval_file, ios::binary); + if (load_eval(eval_file, stream)) + eval_file_loaded = eval_file; + } + + if (directory == "" && eval_file == EvalFileDefaultName) + { + // C++ way to prepare a buffer for a memory stream + class MemoryBuffer : public basic_streambuf { + public: MemoryBuffer(char* p, size_t n) { setg(p, p, p + n); setp(p, p + n); } + }; + + MemoryBuffer buffer(const_cast(reinterpret_cast(gEmbeddedNNUEData)), + size_t(gEmbeddedNNUESize)); + + istream stream(&buffer); + if (load_eval(eval_file, stream)) + eval_file_loaded = eval_file; + } + } } - void verify_NNUE() { + /// NNUE::verify() verifies that the last net used was loaded successfully + void NNUE::verify() { + + string eval_file = string(Options["EvalFile"]); - std::string eval_file = std::string(Options["EvalFile"]); if (useNNUE && eval_file_loaded != eval_file) { UCI::OptionsMap defaults; UCI::init(defaults); - sync_cout << "info string ERROR: NNUE evaluation used, but the network file " << eval_file << " was not loaded successfully." << sync_endl; - sync_cout << "info string ERROR: The UCI option EvalFile might need to specify the full path, including the directory/folder name, to the file." << sync_endl; - sync_cout << "info string ERROR: The default net can be downloaded from: https://tests.stockfishchess.org/api/nn/"+std::string(defaults["EvalFile"]) << sync_endl; - sync_cout << "info string ERROR: If the UCI option Use NNUE is set to true, network evaluation parameters compatible with the program must be available." << sync_endl; - sync_cout << "info string ERROR: The engine will be terminated now." << sync_endl; - std::exit(EXIT_FAILURE); + 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; + sync_cout << "info string NNUE evaluation using " << eval_file << " enabled" << sync_endl; else - sync_cout << "info string classical evaluation enabled." << sync_endl; + sync_cout << "info string classical evaluation enabled" << sync_endl; } } @@ -112,11 +187,11 @@ using namespace Trace; namespace { // Threshold for lazy and space evaluation - 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); + 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); // KingAttackWeights[PieceType] contains king attack weights by piece type constexpr int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 81, 52, 44, 10 }; @@ -124,7 +199,7 @@ namespace { // 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] = { - {}, {}, {792, 1283}, {645, 967}, {1084, 1897}, {772, 1119} + {}, {}, {803, 1292}, {639, 974}, {1087, 1878}, {759, 1132} }; #define S(mg, eg) make_score(mg, eg) @@ -132,19 +207,25 @@ namespace { // 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,-31), S( -4,-16), S( 3, 5), S( 13, 11), // Knight - S( 22, 17), S( 28, 20), S( 33, 25) }, - { 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(-60,-78), S(-20,-17), S( 2, 23), S( 3, 39), S( 3, 70), S( 11, 99), // Rook - S( 22,103), S( 31,121), S( 40,134), S( 40,139), S( 41,158), S( 48,164), - S( 57,168), S( 57,169), S( 62,172) }, - { S(-30,-48), S(-12,-30), S( -8, -7), S( -9, 19), S( 20, 40), S( 23, 55), // Queen - S( 23, 59), S( 35, 75), S( 38, 78), S( 53, 96), S( 64, 96), S( 65,100), - S( 65,121), S( 66,127), S( 67,131), S( 67,133), S( 72,136), S( 72,141), - S( 77,147), S( 79,150), S( 93,151), S(108,168), S(108,168), S(108,171), - S(110,182), S(114,182), S(114,192), S(116,219) } + { 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 @@ -152,32 +233,30 @@ namespace { // 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, 36), S(30, 23) }; + 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(10, 28), S(17, 33), S(15, 41), S(62, 72), S(168, 177), S(276, 260) + 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(19, 7), S(48, 29) }; + constexpr Score RookOnClosedFile = S(10, 5); + constexpr Score RookOnOpenFile[] = { 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(3, 46), S(37, 68), S(42, 60), S(0, 38), S(58, 41) + S(0, 0), S(3, 44), S(37, 68), S(42, 60), S(0, 39), S(58, 43) }; // Assorted bonuses and penalties constexpr Score BadOutpost = S( -7, 36); constexpr Score BishopOnKingRing = S( 24, 0); - constexpr Score BishopPawns = S( 3, 7); constexpr Score BishopXRayPawns = S( 4, 5); constexpr Score CorneredBishop = S( 50, 50); constexpr Score FlankAttacks = S( 8, 0); @@ -190,7 +269,6 @@ namespace { constexpr Score ReachableOutpost = S( 31, 22); constexpr Score RestrictedPiece = S( 7, 7); constexpr Score RookOnKingRing = S( 16, 0); - constexpr Score RookOnQueenFile = S( 6, 11); constexpr Score SliderOnQueen = S( 60, 18); constexpr Score ThreatByKing = S( 24, 89); constexpr Score ThreatByPawnPush = S( 48, 39); @@ -288,8 +366,8 @@ namespace { 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)); + 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(s) | s; kingAttackersCount[Them] = popcount(kingRing[Us] & pe->pawn_attacks(Them)); @@ -309,15 +387,15 @@ namespace { constexpr Direction Down = -pawn_push(Us); constexpr Bitboard OutpostRanks = (Us == WHITE ? Rank4BB | Rank5BB | Rank6BB : Rank5BB | Rank4BB | Rank3BB); - const Square* pl = pos.squares(Us); - + Bitboard b1 = pos.pieces(Us, Pt); Bitboard b, bb; Score score = SCORE_ZERO; attackedBy[Us][Pt] = 0; - for (Square s = *pl; s != SQ_NONE; s = *++pl) - { + while (b1) { + Square s = pop_lsb(&b1); + // Find attacked squares, including x-ray attacks for bishops and rooks b = Pt == BISHOP ? attacks_bb(s, pos.pieces() ^ pos.pieces(QUEEN)) : Pt == ROOK ? attacks_bb< ROOK>(s, pos.pieces() ^ pos.pieces(QUEEN) ^ pos.pieces(Us, ROOK)) @@ -379,7 +457,7 @@ namespace { // when the bishop is outside the pawn chain. Bitboard blocked = pos.pieces(Us, PAWN) & shift(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 @@ -406,20 +484,28 @@ namespace { 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 + // Bonuses for rook on a (semi-)open or closed file if (pos.is_on_semiopen_file(Us, s)) - score += RookOnFile[pos.is_on_semiopen_file(Them, s)]; - - // Penalty when trapped by the king, even more if the king cannot castle - else if (mob <= 3) { - File kf = file_of(pos.square(Us)); - if ((kf < FILE_E) == (file_of(s) < kf)) - score -= TrappedRook * (1 + !pos.castling_rights(Us)); + 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(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(Us)); + if ((kf < FILE_E) == (file_of(s) < kf)) + score -= TrappedRook * (1 + !pos.castling_rights(Us)); + } } } @@ -507,18 +593,18 @@ namespace { 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(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(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) @@ -686,8 +772,8 @@ namespace { 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) @@ -731,7 +817,7 @@ namespace { // 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 4 central files + // 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. @@ -758,6 +844,8 @@ namespace { behind |= shift(behind); behind |= shift(behind); + // 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(Us) - 3 + std::min(pe->blocked_count(), 9); Score score = make_score(bonus * weight * weight / 16, 0); @@ -804,7 +892,7 @@ namespace { // 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)) * Utility::clamp(complexity + 50, -abs(mg), 0); + 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; @@ -819,23 +907,37 @@ namespace { { if (pos.opposite_bishops()) { + // 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) 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(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(strongSide) - pos.count(~strongSide) <= 1 && bool(KingSide & pos.pieces(strongSide, PAWN)) != bool(QueenSide & pos.pieces(strongSide, PAWN)) && (attacks_bb(pos.square(~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() == 1) sf = 37 + 3 * (pos.count(WHITE) == 1 ? pos.count(BLACK) + pos.count(BLACK) : pos.count(WHITE) + pos.count(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(strongSide)); + sf = std::min(sf, 36 + 7 * pos.count(strongSide)) - 4 * !pawnsOnBothFlanks; + + // Reduce scale factor in case of pawns being on a single flank + sf -= 4 * !pawnsOnBothFlanks; } // Interpolate between the middlegame and (scaled by 'sf') endgame score @@ -940,19 +1042,46 @@ make_v: Value Eval::evaluate(const Position& pos) { - bool classical = !Eval::useNNUE - || abs(eg_value(pos.psq_score())) * 16 > NNUEThreshold1 * (16 + pos.rule50_count()); - Value v = classical ? Evaluation(pos).value() - : NNUE::evaluate(pos) * 5 / 4 + Tempo; + Value v; - if (classical && Eval::useNNUE && abs(v) * 16 < NNUEThreshold2 * (16 + pos.rule50_count())) - v = NNUE::evaluate(pos) * 5 / 4 + Tempo; + if (!Eval::useNNUE) + v = Evaluation(pos).value(); + else + { + // Scale and shift NNUE for compatibility with search and classical evaluation + auto adjusted_NNUE = [&](){ + int mat = pos.non_pawn_material() + PawnValueMg * pos.count(); + 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() < 2; + + v = classical || strongClassical ? Evaluation(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(); + } // Damp down the evaluation linearly when shuffling v = v * (100 - pos.rule50_count()) / 100; - // Guarantee evalution outside of TB range - v = Utility::clamp(v, VALUE_TB_LOSS_IN_MAX_PLY + 1, VALUE_TB_WIN_IN_MAX_PLY - 1); + // 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; } @@ -1013,6 +1142,5 @@ std::string Eval::trace(const Position& pos) { v = pos.side_to_move() == WHITE ? v : -v; ss << "\nFinal evaluation: " << to_cp(v) << " (white side)\n"; - return ss.str(); }