X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.h;h=d7f57cc098d117be657234a516ca8d3494af62ac;hp=4a8699fb2dfce4468d70b6e2a73889586d61e26d;hb=d39bc2efa197ba2fd55b68eced1c60bcfe2facc1;hpb=6f1475b6fcd3e3728d800e622ab7a22265fb8ca4

diff --git a/src/tt.h b/src/tt.h
index 4a8699fb..3a5ba5da 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) 2008-2009 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
@@ -17,91 +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"
 
-////
-//// Types
-////
-
-/// The TTEntry class is the class of transposition table entries
-///
-/// A TTEntry needs 96 bits to be stored
+/// TTEntry struct is the 10 bytes transposition table entry, defined as below:
 ///
-/// 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(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); }
+/// 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)) + 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:
-  uint32_t key_;
-  uint32_t data;
-  int16_t value_;
-  int16_t depth_;
+  friend class TranspositionTable;
+
+  uint16_t key16;
+  uint16_t move16;
+  int16_t  value16;
+  int16_t  eval16;
+  uint8_t  genBound8;
+  uint8_t  depth8;
 };
 
-/// 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 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.
 
 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
+  };
+
+  static_assert(CacheLineSize % sizeof(Cluster) == 0, "Cluster size incorrect");
+
 public:
-  TranspositionTable();
-  ~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 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[]);
-  void extract_pv(const Position& pos, Move pv[]);
-  int full() const;
 
-private:
-  inline TTEntry* first_entry(const Key posKey) const;
+  // 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];
+  }
 
-  // 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];
+private:
+  friend struct TTEntry;
 
-  unsigned size;
-  TTEntry* entries;
-  uint8_t generation;
+  size_t clusterCount;
+  Cluster* table;
+  void* mem;
+  uint8_t generation8; // Size must be not bigger than TTEntry::genBound8
 };
 
-#endif // !defined(TT_H_INCLUDED)
+extern TranspositionTable TT;
+
+#endif // #ifndef TT_H_INCLUDED