Use 32 bit key in TT

[stockfish] / src / tt.h

diff --git a/src/tt.h b/src/tt.h
index 4ca344123e5f070ec0a7c687d8cc45fbd05ddd67..4a8699fb2dfce4468d70b6e2a73889586d61e26d 100644 (file)
--- a/src/tt.h
+++ b/src/tt.h
@@ -1,13 +1,14 @@
 /*
-  Glaurung, a UCI chess playing engine.
-  Copyright (C) 2004-2008 Tord Romstad
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2008-2009 Marco Costalba
 
-  Glaurung is free software: you can redistribute it and/or modify
+  Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
 
-  Glaurung is distributed in the hope that it will be useful,
+  Stockfish is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
@@ -33,28 +34,44 @@
 //// Types
 ////
 
-/// The TTEntry class is the class of transposition table entries.
+/// The TTEntry class is the class of transposition table entries
+///
+/// A TTEntry needs 96 bits to be stored
+///
+/// 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
+///
+/// bit  0-16: move
+/// bit 17-19: not used
+/// bit 20-22: value type
+/// bit 23-31: generation
 
 class TTEntry {
 
 public:
-  TTEntry();
-  TTEntry(Key k, Value v, ValueType t, Depth d, Move m, int generation);
-  Key key() const;
-  Depth depth() const;
-  Move move() const;
-  Value value() const;
-  ValueType type() const;
-  int generation() const;
+  TTEntry() {}
+  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)) {}
+
+  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_); }
+  ValueType type() const { return ValueType((data >> 20) & 7); }
+  int generation() const { return (data >> 23); }
 
 private:
-  Key key_;
+  uint32_t key_;
   uint32_t data;
   int16_t value_;
   int16_t depth_;
 };
 
-
 /// The transposition table class.  This is basically just a huge array
 /// containing TTEntry objects, and a few methods for writing new entries
 /// and reading new ones.
@@ -62,33 +79,29 @@ private:
 class TranspositionTable {
 
 public:
-  TranspositionTable(unsigned mbSize);
+  TranspositionTable();
   ~TranspositionTable();
   void set_size(unsigned mbSize);
   void clear();
-  void store(const Position &pos, Value v, Depth d, Move m, ValueType type);
-  bool retrieve(const Position &pos, Value *value, Depth *d, Move *move,
-                ValueType *type) const;
+  void store(const Key posKey, Value v, ValueType type, Depth d, Move m);
+  TTEntry* retrieve(const Key posKey) const;
   void new_search();
-  void insert_pv(const Position &pos, Move pv[]);
-  int full();
+  void insert_pv(const Position& pos, Move pv[]);
+  void extract_pv(const Position& pos, Move pv[]);
+  int full() const;
 
 private:
-  TTEntry* first_entry(const Position &pos) const;
+  inline TTEntry* first_entry(const Key posKey) const;
+
+  // 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;
-  int writes;
   TTEntry* entries;
   uint8_t generation;
 };
 
-
-////
-//// Constants and variables
-////
-
-// Default transposition table size, in megabytes:
-const int TTDefaultSize = 32;
-
-
 #endif // !defined(TT_H_INCLUDED)