Support building for Android using NDK

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index a642357e3c4904ea0ff5f6160325cd51d52b8b59..3a620a78305fb83da36f9b9b5278be919cf685aa 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -114,7 +114,7 @@ namespace {
   constexpr Value LazyThreshold1 =  Value(1400);
   constexpr Value LazyThreshold2 =  Value(1300);
   constexpr Value SpaceThreshold = Value(12222);
-  constexpr Value NNUEThreshold  =   Value(520);
+  constexpr Value NNUEThreshold  =   Value(575);
 
   // KingAttackWeights[PieceType] contains king attack weights by piece type
   constexpr int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 81, 52, 44, 10 };
@@ -927,9 +927,6 @@ make_v:
     // Side to move point of view
     v = (pos.side_to_move() == WHITE ? v : -v) + Tempo;
 
-    // Damp down the evaluation linearly when shuffling
-    v = v * (100 - pos.rule50_count()) / 100;
-
     return v;
   }
 
@@ -941,14 +938,18 @@ make_v:
 
 Value Eval::evaluate(const Position& pos) {
 
-  if (Eval::useNNUE)
-  {
-      Value v = eg_value(pos.psq_score());
-      // Take NNUE eval only on balanced positions
-      if (abs(v) < NNUEThreshold)
-         return NNUE::evaluate(pos) + Tempo;
-  }
-  return Evaluation<NO_TRACE>(pos).value();
+  bool classical = !Eval::useNNUE
+                ||  abs(eg_value(pos.psq_score())) >= NNUEThreshold * (16 + pos.rule50_count()) / 16;
+  Value v = classical ? Evaluation<NO_TRACE>(pos).value()
+                      : NNUE::evaluate(pos) * 5 / 4 + Tempo;
+
+  // 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);
+
+  return v;
 }
 
 /// trace() is like evaluate(), but instead of returning a value, it returns