2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
6 Stockfish is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 Stockfish is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
21 #if !defined(TT_H_INCLUDED)
37 /// The TTEntry class is the class of transposition table entries
39 /// A TTEntry needs 96 bits to be stored
46 /// the 32 bits of the data field are so defined
49 /// bit 17-18: not used
50 /// bit 19-22: value type
51 /// bit 23-31: generation
57 TTEntry(uint32_t k, Value v, ValueType t, Depth d, Move m, int generation)
58 : key_ (k), data((m & 0x1FFFF) | (t << 19) | (generation << 23)),
59 value_(int16_t(v)), depth_(int16_t(d)) {}
61 uint32_t key() const { return key_; }
62 Depth depth() const { return Depth(depth_); }
63 Move move() const { return Move(data & 0x1FFFF); }
64 Value value() const { return Value(value_); }
65 ValueType type() const { return ValueType((data >> 19) & 0xF); }
66 int generation() const { return (data >> 23); }
76 /// This is the number of TTEntry slots for each position
77 const int ClusterSize = 5;
79 /// Each group of ClusterSize number of TTEntry form a TTCluster
80 /// that is indexed by a single position key. Cluster is padded
81 /// to a cache line size so to guarantee always aligned accesses.
84 TTEntry data[ClusterSize];
85 char cache_line_padding[64 - sizeof(TTEntry[ClusterSize])];
89 /// The transposition table class. This is basically just a huge array
90 /// containing TTEntry objects, and a few methods for writing new entries
91 /// and reading new ones.
93 class TranspositionTable {
97 ~TranspositionTable();
98 void set_size(size_t mbSize);
100 void store(const Key posKey, Value v, ValueType type, Depth d, Move m);
101 TTEntry* retrieve(const Key posKey) const;
102 void prefetch(const Key posKey) const;
104 void insert_pv(const Position& pos, Move pv[]);
105 void extract_pv(const Position& pos, Move pv[], const int PLY_MAX);
109 inline TTEntry* first_entry(const Key posKey) const;
111 // Be sure 'writes' is at least one cache line away
112 // from read only variables.
113 unsigned char pad_before[64 - sizeof(unsigned)];
114 unsigned writes; // heavy SMP read/write access here
115 unsigned char pad_after[64];
122 extern TranspositionTable TT;
124 #endif // !defined(TT_H_INCLUDED)