Allow for general transposition table sizes. (#1341)

[stockfish] / src / tt.h

diff --git a/src/tt.h b/src/tt.h
index d2f1ce65c17053475bd1797404dc209972dd07db..e1bef323af5092474f07a96db48ff2d8fb8b4e9f 100644 (file)
--- a/src/tt.h
+++ b/src/tt.h
@@ -1,7 +1,8 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008-2016 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -38,18 +39,20 @@ struct TTEntry {
   Move  move()  const { return (Move )move16; }
   Value value() const { return (Value)value16; }
   Value eval()  const { return (Value)eval16; }
-  Depth depth() const { return (Depth)depth8; }
+  Depth depth() const { return (Depth)(depth8 * int(ONE_PLY)); }
   Bound bound() const { return (Bound)(genBound8 & 0x3); }
 
   void save(Key k, Value v, Bound b, Depth d, Move m, Value ev, uint8_t g) {
 
+    assert(d / ONE_PLY * ONE_PLY == d);
+
     // Preserve any existing move for the same position
     if (m || (k >> 48) != key16)
         move16 = (uint16_t)m;
 
     // Don't overwrite more valuable entries
     if (  (k >> 48) != key16
-        || d > depth8 - 2
+        || d / ONE_PLY > depth8 - 4
      /* || g != (genBound8 & 0xFC) // Matching non-zero keys are already refreshed by probe() */
         || b == BOUND_EXACT)
     {
@@ -57,7 +60,7 @@ struct TTEntry {
         value16   = (int16_t)v;
         eval16    = (int16_t)ev;
         genBound8 = (uint8_t)(g | b);
-        depth8    = (int8_t)d;
+        depth8    = (int8_t)(d / ONE_PLY);
     }
   }
 
@@ -101,9 +104,9 @@ public:
   void resize(size_t mbSize);
   void clear();
 
-  // The lowest order bits of the key are used to get the index of the cluster
+  // The 32 lowest order bits of the key are used to get the index of the cluster
   TTEntry* first_entry(const Key key) const {
-    return &table[(size_t)key & (clusterCount - 1)].entry[0];
+    return &table[(uint32_t(key) * uint64_t(clusterCount)) >> 32].entry[0];
   }
 
 private: