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 128 bits to be stored
45 /// bit 96-111: static value
46 /// bit 112-127: margin of static value
48 /// the 32 bits of the data field are so defined
51 /// bit 17-20: not used
52 /// bit 21-22: value type
53 /// bit 23-31: generation
58 void save(uint32_t k, Value v, ValueType t, Depth d, Move m, int g, Value statV, Value kd) {
61 data = (m & 0x1FFFF) | (t << 21) | (g << 23);
64 staticValue = int16_t(statV);
65 staticValueMargin = int16_t(kd);
67 void set_generation(int g) { data = move() | (type() << 21) | (g << 23); }
69 uint32_t key() const { return key32; }
70 Depth depth() const { return Depth(depth16); }
71 Move move() const { return Move(data & 0x1FFFF); }
72 Value value() const { return Value(value16); }
73 ValueType type() const { return ValueType((data >> 21) & 3); }
74 int generation() const { return data >> 23; }
75 Value static_value() const { return Value(staticValue); }
76 Value static_value_margin() const { return Value(staticValueMargin); }
84 int16_t staticValueMargin;
88 /// This is the number of TTEntry slots for each cluster
89 const int ClusterSize = 4;
91 /// TTCluster consists of ClusterSize number of TTEntries.
92 /// Size of TTCluster must not be bigger than a cache line size.
93 /// In case it is less, it should be padded to guarantee always aligned accesses.
96 TTEntry data[ClusterSize];
100 /// The transposition table class. This is basically just a huge array
101 /// containing TTCluster objects, and a few methods for writing new entries
102 /// and reading new ones.
104 class TranspositionTable {
106 TranspositionTable(const TranspositionTable&);
107 TranspositionTable& operator=(const TranspositionTable&);
110 TranspositionTable();
111 ~TranspositionTable();
112 void set_size(size_t mbSize);
114 void store(const Key posKey, Value v, ValueType type, Depth d, Move m, Value statV, Value kingD);
115 TTEntry* retrieve(const Key posKey) const;
117 TTEntry* first_entry(const Key posKey) const;
118 void refresh(const TTEntry* tte) const;
123 uint8_t generation; // To properly compare, size must be smaller then TT stored value
126 extern TranspositionTable TT;
129 /// TranspositionTable::first_entry returns a pointer to the first
130 /// entry of a cluster given a position. The lowest order bits of the key
131 /// are used to get the index of the cluster.
133 inline TTEntry* TranspositionTable::first_entry(const Key posKey) const {
135 return entries[uint32_t(posKey) & (size - 1)].data;
139 /// TranspositionTable::refresh updates the 'generation' value of the TTEntry
140 /// to avoid aging. Normally called after a TT hit, before to return.
142 inline void TranspositionTable::refresh(const TTEntry* tte) const {
144 const_cast<TTEntry*>(tte)->set_generation(generation);
147 #endif // !defined(TT_H_INCLUDED)