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 17-19: not used
50 /// bit 20-22: value type
51 /// bit 23-31: generation
57 TTEntry(uint32_t k, Value v, ValueType t, Depth d, Move m, int generation,
58 Value statV, Value kingD)
59 : key_ (k), data((m & 0x1FFFF) | (t << 20) | (generation << 23)),
60 value_(int16_t(v)), depth_(int16_t(d)),
61 staticValue_(int16_t(statV)), kingDanger_(int16_t(kingD)) {}
63 uint32_t key() const { return key_; }
64 Depth depth() const { return Depth(depth_); }
65 Move move() const { return Move(data & 0x1FFFF); }
66 Value value() const { return Value(value_); }
67 ValueType type() const { return ValueType((data >> 20) & 7); }
68 int generation() const { return (data >> 23); }
69 Value static_value() const { return Value(staticValue_); }
70 Value king_danger() const { return Value(kingDanger_); }
82 /// This is the number of TTEntry slots for each position
83 const int ClusterSize = 4;
85 /// Each group of ClusterSize number of TTEntry form a TTCluster
86 /// that is indexed by a single position key. TTCluster size must
87 // be not bigger then a cache line size, in case it is less then
88 /// it should be padded to guarantee always aligned accesses.
91 TTEntry data[ClusterSize];
95 /// The transposition table class. This is basically just a huge array
96 /// containing TTEntry objects, and a few methods for writing new entries
97 /// and reading new ones.
99 class TranspositionTable {
102 TranspositionTable();
103 ~TranspositionTable();
104 void set_size(size_t mbSize);
106 void store(const Key posKey, Value v, ValueType type, Depth d, Move m, Value statV, Value kingD);
107 TTEntry* retrieve(const Key posKey) const;
108 void prefetch(const Key posKey) const;
110 void insert_pv(const Position& pos, Move pv[]);
111 void extract_pv(const Position& pos, Move pv[], const int PLY_MAX);
115 inline TTEntry* first_entry(const Key posKey) const;
117 // Be sure 'writes' is at least one cache line away
118 // from read only variables.
119 unsigned char pad_before[64 - sizeof(unsigned)];
120 unsigned writes; // heavy SMP read/write access here
121 unsigned char pad_after[64];
128 extern TranspositionTable TT;
130 #endif // !defined(TT_H_INCLUDED)