Simplify history update.

[stockfish] / src / movepick.h

diff --git a/src/movepick.h b/src/movepick.h
index 9f18997406fe63c24dcb06eb9a0a136749d7e9a5..e032b0c7c79b33e4417b8a0409ba11d0b4861d02 100644 (file)
--- a/src/movepick.h
+++ b/src/movepick.h
@@ -58,7 +58,7 @@ class StatsEntry {
         assert(abs(bonus) <= D);  // Ensure range is [-D, D]
         static_assert(D <= std::numeric_limits<T>::max(), "D overflows T");
 
-        entry += (bonus * D - entry * abs(bonus)) / (D * 5 / 4);
+        entry += bonus - entry * abs(bonus) / D;
 
         assert(abs(entry) <= D);
     }
@@ -96,11 +96,10 @@ enum StatsType {
     Captures
 };
 
-// ButterflyHistory records how often quiet moves have been successful or
-// unsuccessful during the current search, and is used for reduction and move
-// ordering decisions. It uses 2 tables (one for each color) indexed by
-// the move's from and to squares, see www.chessprogramming.org/Butterfly_Boards
-// (~11 elo)
+// ButterflyHistory records how often quiet moves have been successful or unsuccessful
+// during the current search, and is used for reduction and move ordering decisions.
+// It uses 2 tables (one for each color) indexed by the move's from and to squares,
+// see www.chessprogramming.org/Butterfly_Boards (~11 elo)
 using ButterflyHistory = Stats<int16_t, 7183, COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)>;
 
 // CounterMoveHistory stores counter moves indexed by [piece][to] of the previous