X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.h;h=8b70f79787619ca4c1b6326f55cfa456a2dcf04f;hp=8b98dbd52a2006daca7933e008dad9cbb4adf3d3;hb=ddcbacd04d1c860e808202ce8c1206c8acdca627;hpb=70880b8e247c94d0a16a2fb50b41827726e00742

diff --git a/src/tt.h b/src/tt.h
index 8b98dbd5..8b70f797 100644
--- a/src/tt.h
+++ b/src/tt.h
@@ -2,7 +2,7 @@
   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) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2015-2020 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
@@ -31,7 +31,7 @@
 /// value      16 bit
 /// eval value 16 bit
 /// generation  5 bit
-/// PvNode      1 bit
+/// pv node     1 bit
 /// bound type  2 bit
 /// depth       8 bit
 
@@ -40,10 +40,10 @@ 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 * int(ONE_PLY)); }
-  bool pv_hit() const { return (bool)(genBound8 & 0x4); }
+  Depth depth() const { return (Depth)depth8 + DEPTH_OFFSET; }
+  bool is_pv()  const { return (bool)(genBound8 & 0x4); }
   Bound bound() const { return (Bound)(genBound8 & 0x3); }
-  void save(Key k, Value v, bool PvNode, Bound b, Depth d, Move m, Value ev);
+  void save(Key k, Value v, bool pv, Bound b, Depth d, Move m, Value ev);
 
 private:
   friend class TranspositionTable;
@@ -53,28 +53,26 @@ private:
   int16_t  value16;
   int16_t  eval16;
   uint8_t  genBound8;
-  int8_t   depth8;
+  uint8_t  depth8;
 };
 
 
-/// A TranspositionTable consists of a power of 2 number of clusters and each
-/// cluster consists of ClusterSize number of TTEntry. Each non-empty entry
-/// contains information of exactly one position. The size of a cluster should
-/// divide the size of a cache line size, to ensure that clusters never cross
-/// cache lines. This ensures best cache performance, as the cacheline is
-/// prefetched, as soon as possible.
+/// 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.
 
 class TranspositionTable {
 
-  static constexpr int CacheLineSize = 64;
   static constexpr int ClusterSize = 3;
 
   struct Cluster {
     TTEntry entry[ClusterSize];
-    char padding[2]; // Align to a divisor of the cache line size
+    char padding[2]; // Pad to 32 bytes
   };
 
-  static_assert(CacheLineSize % sizeof(Cluster) == 0, "Cluster size incorrect");
+  static_assert(sizeof(Cluster) == 32, "Unexpected Cluster size");
 
 public:
  ~TranspositionTable() { free(mem); }