Use 32 bit key in TT

[stockfish] / src / tt.h

diff --git a/src/tt.h b/src/tt.h
index e8dc021bafc1d537524ebdfa2b55754d98388f6b..4a8699fb2dfce4468d70b6e2a73889586d61e26d 100644 (file)
--- a/src/tt.h
+++ b/src/tt.h
@@ -1,7 +1,7 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008 Marco Costalba
+  Copyright (C) 2008-2009 Marco Costalba
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -36,12 +36,12 @@
 
 /// The TTEntry class is the class of transposition table entries
 ///
-/// A TTEntry needs 128 bits to be stored
+/// A TTEntry needs 96 bits to be stored
 ///
-/// bit    0-63: key
-/// bit   64-95: data
-/// bit  96-111: value
-/// bit 112-127: depth
+/// bit  0-31: key
+/// bit 32-63: data
+/// bit 64-79: value
+/// bit 80-95: depth
 ///
 /// the 32 bits of the data field are so defined
 ///
@@ -54,11 +54,11 @@ class TTEntry {
 
 public:
   TTEntry() {}
-  TTEntry(Key k, Value v, ValueType t, Depth d, Move m, int generation)
+  TTEntry(uint32_t k, Value v, ValueType t, Depth d, Move m, int generation)
         : key_ (k), data((m & 0x1FFFF) | (t << 20) | (generation << 23)),
           value_(int16_t(v)), depth_(int16_t(d)) {}
 
-  Key key() const { return key_; }
+  uint32_t key() const { return key_; }
   Depth depth() const { return Depth(depth_); }
   Move move() const { return Move(data & 0x1FFFF); }
   Value value() const { return Value(value_); }
@@ -66,7 +66,7 @@ public:
   int generation() const { return (data >> 23); }
 
 private:
-  Key key_;
+  uint32_t key_;
   uint32_t data;
   int16_t value_;
   int16_t depth_;
@@ -87,12 +87,19 @@ public:
   TTEntry* retrieve(const Key posKey) const;
   void new_search();
   void insert_pv(const Position& pos, Move pv[]);
+  void extract_pv(const Position& pos, Move pv[]);
   int full() const;
 
 private:
   inline TTEntry* first_entry(const Key posKey) const;
 
-  unsigned size, writes;
+  // Be sure 'writes' is at least one cacheline away
+  // from read only variables.
+  unsigned char pad_before[64 - sizeof(unsigned)];
+  unsigned writes; // heavy SMP read/write access here
+  unsigned char pad_after[64];
+
+  unsigned size;
   TTEntry* entries;
   uint8_t generation;
 };