2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2012 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/>.
20 #if !defined(TT_H_INCLUDED)
26 /// The TTEntry is the class of transposition table entries
28 /// A TTEntry needs 128 bits to be stored
34 /// bit 96-111: static value
35 /// bit 112-127: margin of static value
37 /// the 32 bits of the data field are so defined
40 /// bit 16-20: not used
41 /// bit 21-22: value type
42 /// bit 23-31: generation
47 void save(uint32_t k, Value v, Bound b, Depth d, Move m, int g) {
52 generation8 = (uint8_t)g;
56 void set_generation(int g) { generation8 = (uint8_t)g; }
58 uint32_t key() const { return key32; }
59 Depth depth() const { return (Depth)depth16; }
60 Move move() const { return (Move)move16; }
61 Value value() const { return (Value)value16; }
62 Bound type() const { return (Bound)bound; }
63 int generation() const { return (int)generation8; }
68 uint8_t bound, generation8;
69 int16_t value16, depth16;
73 /// This is the number of TTEntry slots for each cluster
74 const int ClusterSize = 4;
77 /// TTCluster consists of ClusterSize number of TTEntries. Size of TTCluster
78 /// must not be bigger than a cache line size. In case it is less, it should
79 /// be padded to guarantee always aligned accesses.
82 TTEntry data[ClusterSize];
86 /// The transposition table class. This is basically just a huge array containing
87 /// TTCluster objects, and a few methods for writing and reading entries.
89 class TranspositionTable {
91 TranspositionTable(const TranspositionTable&);
92 TranspositionTable& operator=(const TranspositionTable&);
96 ~TranspositionTable();
97 void set_size(size_t mbSize);
99 void store(const Key posKey, Value v, Bound type, Depth d, Move m);
100 TTEntry* probe(const Key posKey) const;
102 TTEntry* first_entry(const Key posKey) const;
103 void refresh(const TTEntry* tte) const;
108 uint8_t generation; // Size must be not bigger then TTEntry::generation8
111 extern TranspositionTable TT;
114 /// TranspositionTable::first_entry() returns a pointer to the first entry of
115 /// a cluster given a position. The lowest order bits of the key are used to
116 /// get the index of the cluster.
118 inline TTEntry* TranspositionTable::first_entry(const Key posKey) const {
120 return entries[((uint32_t)posKey) & (size - 1)].data;
124 /// TranspositionTable::refresh() updates the 'generation' value of the TTEntry
125 /// to avoid aging. Normally called after a TT hit.
127 inline void TranspositionTable::refresh(const TTEntry* tte) const {
129 const_cast<TTEntry*>(tte)->set_generation(generation);
132 #endif // !defined(TT_H_INCLUDED)