Assume network file is in little-endian byte order

[stockfish] / src / tt.h

diff --git a/src/tt.h b/src/tt.h
index 76db03dabafd744cb813b82654e3da4a3c129219..c177ca52deba7065a03cc5a65e5a9e37b0effb9d 100644 (file)
--- a/src/tt.h
+++ b/src/tt.h
@@ -1,8 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2004-2020 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -60,13 +58,12 @@ private:
 /// A TranspositionTable is an array of Cluster, of size clusterCount. Each
 /// cluster consists of ClusterSize number of TTEntry. Each non-empty TTEntry
 /// contains information on exactly one position. The size of a Cluster should
-/// divide the size of a cache line for best performance,
-/// as the cacheline is prefetched when possible.
+/// divide the size of a cache line for best performance, as the cacheline is
+/// prefetched when possible.
 
 class TranspositionTable {
 
   static constexpr int ClusterSize = 3;
-  static constexpr int ClustersPerSuperCluster = 256;
 
   struct Cluster {
     TTEntry entry[ClusterSize];
@@ -84,20 +81,13 @@ public:
   void clear();
 
   TTEntry* first_entry(const Key key) const {
-
-    // The index is computed from
-    // Idx = (K48 * SCC) / 2^40, with K48 the 48 lowest bits swizzled.
-
-    const uint64_t firstTerm =  uint32_t(key) * uint64_t(superClusterCount);
-    const uint64_t secondTerm = (uint16_t(key >> 32) * uint64_t(superClusterCount)) >> 16;
-
-    return &table[(firstTerm + secondTerm) >> 24].entry[0];
+    return &table[mul_hi64(key, clusterCount)].entry[0];
   }
 
 private:
   friend struct TTEntry;
 
-  size_t superClusterCount;
+  size_t clusterCount;
   Cluster* table;
   void* mem;
   uint8_t generation8; // Size must be not bigger than TTEntry::genBound8