namespace Eval {
bool useNNUE;
- string eval_file_loaded = "None";
+ string currentEvalFileName = "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"
#endif
for (string directory : dirs)
- if (eval_file_loaded != eval_file)
+ if (currentEvalFileName != eval_file)
{
if (directory != "<internal>")
{
ifstream stream(directory + eval_file, ios::binary);
if (load_eval(eval_file, stream))
- eval_file_loaded = eval_file;
+ currentEvalFileName = eval_file;
}
if (directory == "<internal>" && eval_file == EvalFileDefaultName)
istream stream(&buffer);
if (load_eval(eval_file, stream))
- eval_file_loaded = eval_file;
+ currentEvalFileName = eval_file;
}
}
}
if (eval_file.empty())
eval_file = EvalFileDefaultName;
- if (useNNUE && eval_file_loaded != eval_file)
+ if (useNNUE && currentEvalFileName != eval_file)
{
string msg1 = "If the UCI option \"Use NNUE\" is set to true, network evaluation parameters compatible with the engine must be available.";
Value v;
- if (!Eval::useNNUE)
- v = Evaluation<NO_TRACE>(pos).value();
+ // Deciding between classical and NNUE eval: for high PSQ imbalance we use classical,
+ // but we switch to NNUE during long shuffling or with high material on the board.
+
+ if ( !useNNUE
+ || abs(eg_value(pos.psq_score())) * 5 > (850 + pos.non_pawn_material() / 64) * (5 + pos.rule50_count()))
+ v = Evaluation<NO_TRACE>(pos).value(); // classical
else
{
- // Scale and shift NNUE for compatibility with search and classical evaluation
- auto adjusted_NNUE = [&]()
- {
- int scale = 883
- + 32 * pos.count<PAWN>()
- + 32 * pos.non_pawn_material() / 1024;
-
- Value nnue = NNUE::evaluate(pos, true) * scale / 1024;
-
- if (pos.is_chess960())
- nnue += fix_FRC(pos);
-
- return nnue;
- };
+ int scale = 883
+ + 32 * pos.count<PAWN>()
+ + 32 * pos.non_pawn_material() / 1024;
- // If there is PSQ imbalance we use the classical eval, but we switch to
- // NNUE eval faster when shuffling or if the material on the board is high.
- int r50 = pos.rule50_count();
- Value psq = Value(abs(eg_value(pos.psq_score())));
- bool classical = psq * 5 > (850 + pos.non_pawn_material() / 64) * (5 + r50);
+ v = NNUE::evaluate(pos, true) * scale / 1024; // NNUE
- v = classical ? Evaluation<NO_TRACE>(pos).value() // classical
- : adjusted_NNUE(); // NNUE
+ if (pos.is_chess960())
+ v += fix_FRC(pos);
}
// Damp down the evaluation linearly when shuffling