X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=a9f8f037ab92925f80a62c7a26d5dfc2be7849d7;hp=5ebd10d2d6cdfa7657c3d967716e03f8b848961f;hb=600234f2e23d1244fd38a31ac08a77f00b85a087;hpb=51330414c4a773a9c3d1dd562fdc8536344a67b8

diff --git a/src/tt.cpp b/src/tt.cpp
index 5ebd10d2..a9f8f037 100644
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -66,9 +66,9 @@ void TranspositionTable::clear() {
 /// TranspositionTable::probe() looks up the current position in the transposition
 /// table. It returns true and a pointer to the TTEntry if the position is found.
 /// Otherwise, it returns false and a pointer to an empty or least valuable TTEntry
-/// to be replaced later. TTEntry t1 is considered more valuable than TTEntry t2 if
-/// both are from the current search and the depth of t1 is greater than the depth of t2,
-/// or if t1 is from a previous search but its depth is at least 8 ply deeper than t2.
+/// to be replaced later. The replace value of an entry is calculated as its depth
+/// minus 8 times its relative age. TTEntry t1 is considered more valuable than
+/// TTEntry t2 if its replace value is greater than that of t2.
 
 TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
 
@@ -87,8 +87,8 @@ TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
   // Find an entry to be replaced according to the replacement strategy
   TTEntry* replace = tte;
   for (int i = 1; i < ClusterSize; ++i)
-      if (  ((  tte[i].genBound8 & 0xFC) == generation8) * 8 * ONE_PLY +   tte[i].depth8
-          < ((replace->genBound8 & 0xFC) == generation8) * 8 * ONE_PLY + replace->depth8)
+      if (  replace->depth8 - ((259 + generation8 - replace->genBound8) & 0xFC) * 2 * ONE_PLY
+          >   tte[i].depth8 - ((259 + generation8 -   tte[i].genBound8) & 0xFC) * 2 * ONE_PLY)
           replace = &tte[i];
 
   return found = false, replace;