2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2013 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/>.
26 /// The TTEntry is the 128 bit transposition table entry, defined as below:
34 /// static value: 16 bit
35 /// static margin: 16 bit
39 void save(uint32_t k, Value v, Bound b, Depth d, Move m, int g, Value ev) {
44 generation8 = (uint8_t)g;
47 evalValue = (int16_t)ev;
49 void set_generation(uint8_t g) { generation8 = g; }
51 uint32_t key() const { return key32; }
52 Depth depth() const { return (Depth)depth16; }
53 Move move() const { return (Move)move16; }
54 Value value() const { return (Value)value16; }
55 Bound bound() const { return (Bound)bound8; }
56 int generation() const { return (int)generation8; }
57 Value eval_value() const { return (Value)evalValue; }
62 uint8_t bound8, generation8;
63 int16_t value16, depth16, evalValue;
67 /// A TranspositionTable consists of a power of 2 number of clusters and each
68 /// cluster consists of ClusterSize number of TTEntry. Each non-empty entry
69 /// contains information of exactly one position. Size of a cluster shall not be
70 /// bigger than a cache line size. In case it is less, it should be padded to
71 /// guarantee always aligned accesses.
73 class TranspositionTable {
75 static const unsigned ClusterSize = 4; // A cluster is 64 Bytes
78 ~TranspositionTable() { free(mem); }
79 void new_search() { ++generation; }
81 const TTEntry* probe(const Key key) const;
82 TTEntry* first_entry(const Key key) const;
83 void refresh(const TTEntry* tte) const;
84 void set_size(size_t mbSize);
86 void store(const Key key, Value v, Bound type, Depth d, Move m, Value statV);
92 uint8_t generation; // Size must be not bigger than TTEntry::generation8
95 extern TranspositionTable TT;
98 /// TranspositionTable::first_entry() returns a pointer to the first entry of
99 /// a cluster given a position. The lowest order bits of the key are used to
100 /// get the index of the cluster.
102 inline TTEntry* TranspositionTable::first_entry(const Key key) const {
104 return table + ((uint32_t)key & hashMask);
108 /// TranspositionTable::refresh() updates the 'generation' value of the TTEntry
109 /// to avoid aging. Normally called after a TT hit.
111 inline void TranspositionTable::refresh(const TTEntry* tte) const {
113 const_cast<TTEntry*>(tte)->set_generation(generation);
116 #endif // #ifndef TT_H_INCLUDED