X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.h;h=fefc8e2c29d928a819ac3437a6cea53192dbb2f3;hp=02913efe7f66f0bd1a162de084bdbf1b54cb4a38;hb=3c92f849ab940fd9ac70e838e6d941827fc69cb6;hpb=5a0581498cde3d0904924d8ef7ed25ea1a2c855a

diff --git a/src/tt.h b/src/tt.h
index 02913efe..fefc8e2c 100644
--- 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 Marco Costalba
+  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2015-2019 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
@@ -17,77 +18,86 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-
-#if !defined(TT_H_INCLUDED)
+#ifndef TT_H_INCLUDED
 #define TT_H_INCLUDED
 
-////
-//// Includes
-////
-
-#include "depth.h"
-#include "position.h"
-#include "value.h"
+#include "misc.h"
+#include "types.h"
+
+/// TTEntry struct is the 10 bytes transposition table entry, defined as below:
+///
+/// key        16 bit
+/// move       16 bit
+/// value      16 bit
+/// eval value 16 bit
+/// generation  5 bit
+/// pv node     1 bit
+/// bound type  2 bit
+/// depth       8 bit
+
+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 is_pv() const { return (bool)(genBound8 & 0x4); }
+  Bound bound() const { return (Bound)(genBound8 & 0x3); }
+  void save(Key k, Value v, bool pv, Bound b, Depth d, Move m, Value ev);
 
+private:
+  friend class TranspositionTable;
+
+  uint16_t key16;
+  uint16_t move16;
+  int16_t  value16;
+  int16_t  eval16;
+  uint8_t  genBound8;
+  int8_t   depth8;
+};
 
-////
-//// Types
-////
-
-/// The TTEntry class is the class of transposition table entries.
 
-class TTEntry {
+/// 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.
 
-public:
-  TTEntry();
-  TTEntry(Key k, Value v, ValueType t, Depth d, Move m, int generation);
-  Key key() const { return key_; }
-  Depth depth() const { return Depth(depth_); }
-  Move move() const { return Move(data & 0x7FFFF); }
-  Value value() const { return Value(value_); }
-  ValueType type() const { return ValueType((data >> 20) & 7); }
-  int generation() const { return (data >> 23); }
+class TranspositionTable {
 
-private:
-  Key key_;
-  uint32_t data;
-  int16_t value_;
-  int16_t depth_;
-};
+  static constexpr int CacheLineSize = 64;
+  static constexpr int ClusterSize = 3;
 
-/// 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.
+  struct Cluster {
+    TTEntry entry[ClusterSize];
+    char padding[2]; // Align to a divisor of the cache line size
+  };
 
-class TranspositionTable {
+  static_assert(CacheLineSize % sizeof(Cluster) == 0, "Cluster size incorrect");
 
 public:
-  TranspositionTable(unsigned mbSize);
-  ~TranspositionTable();
-  void set_size(unsigned mbSize);
+ ~TranspositionTable() { free(mem); }
+  void new_search() { generation8 += 8; } // Lower 3 bits are used by PV flag and Bound
+  TTEntry* probe(const Key key, bool& found) const;
+  int hashfull() const;
+  void resize(size_t mbSize);
   void clear();
-  void store(const Position &pos, Value v, Depth d, Move m, ValueType type);
-  TTEntry* retrieve(const Position &pos) const;
-  void new_search();
-  void insert_pv(const Position &pos, Move pv[]);
-  int full();
+
+  // 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[(uint32_t(key) * uint64_t(clusterCount)) >> 32].entry[0];
+  }
 
 private:
-  inline TTEntry* first_entry(const Position &pos) const;
+  friend struct TTEntry;
 
-  unsigned size;
-  int writes;
-  TTEntry* entries;
-  uint8_t generation;
+  size_t clusterCount;
+  Cluster* table;
+  void* mem;
+  uint8_t generation8; // Size must be not bigger than TTEntry::genBound8
 };
 
+extern TranspositionTable TT;
 
-////
-//// Constants and variables
-////
-
-// Default transposition table size, in megabytes:
-const int TTDefaultSize = 32;
-
-
-#endif // !defined(TT_H_INCLUDED)
+#endif // #ifndef TT_H_INCLUDED