X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Ftt.h;h=d915d92e43f545da1826e8408e148e952c90316a;hb=36f8d3806bb1c6e498ac8fd1a746c1714d1485a3;hp=c1dd8508c2fadde864d8eb3a4932ca1b0812d3b1;hpb=7dd0c39714cbb6829d7cbf9da36fa46995e7a61e;p=stockfish

diff --git a/src/tt.h b/src/tt.h
index c1dd8508..d915d92e 100644
--- a/src/tt.h
+++ b/src/tt.h
@@ -1,13 +1,13 @@
 /*
-  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) 2004-2021 The Stockfish developers (see AUTHORS file)
 
-  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.
@@ -16,77 +16,92 @@
   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"
 
-////
-//// Types
-////
+namespace Stockfish {
 
-/// The TTEntry class is the class of transposition table entries.
+/// TTEntry struct is the 10 bytes transposition table entry, defined as below:
+///
+/// key        16 bit
+/// depth       8 bit
+/// generation  5 bit
+/// pv node     1 bit
+/// bound type  2 bit
+/// move       16 bit
+/// value      16 bit
+/// eval value 16 bit
 
-class TTEntry {
+struct TTEntry {
 
-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) & 3); }
-  int generation() const { return (data >> 23); }
+  Move  move()  const { return (Move )move16; }
+  Value value() const { return (Value)value16; }
+  Value eval()  const { return (Value)eval16; }
+  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 pv, Bound b, Depth d, Move m, Value ev);
 
 private:
-  Key key_;
-  uint32_t data;
-  int16_t value_;
-  int16_t depth_;
+  friend class TranspositionTable;
+
+  uint16_t key16;
+  uint8_t  depth8;
+  uint8_t  genBound8;
+  uint16_t move16;
+  int16_t  value16;
+  int16_t  eval16;
 };
 
-/// 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.
+
+/// 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 ClusterSize = 3;
+
+  struct Cluster {
+    TTEntry entry[ClusterSize];
+    char padding[2]; // Pad to 32 bytes
+  };
+
+  static_assert(sizeof(Cluster) == 32, "Unexpected Cluster size");
+
+  // Constants used to refresh the hash table periodically
+  static constexpr unsigned GENERATION_BITS  = 3;                                // nb of bits reserved for other things
+  static constexpr int      GENERATION_DELTA = (1 << GENERATION_BITS);           // increment for generation field
+  static constexpr int      GENERATION_CYCLE = 255 + (1 << GENERATION_BITS);     // cycle length
+  static constexpr int      GENERATION_MASK  = (0xFF << GENERATION_BITS) & 0xFF; // mask to pull out generation number
+
 public:
-  TranspositionTable(unsigned mbSize);
-  ~TranspositionTable();
-  void set_size(unsigned mbSize);
+ ~TranspositionTable() { aligned_large_pages_free(table); }
+  void new_search() { generation8 += GENERATION_DELTA; } // Lower bits are used for other things
+  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);
-  const TTEntry* retrieve(const Position &pos) const;
-  void new_search();
-  void insert_pv(const Position &pos, Move pv[]);
-  int full();
+
+  TTEntry* first_entry(const Key key) const {
+    return &table[mul_hi64(key, clusterCount)].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;
+  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;
-
+} // namespace Stockfish
 
-#endif // !defined(TT_H_INCLUDED)
+#endif // #ifndef TT_H_INCLUDED