2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2014 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 14 bytes transposition table entry, defined as below:
38 Move move() const { return (Move )move16; }
39 Bound bound() const { return (Bound)bound8; }
40 Value value() const { return (Value)value16; }
41 Depth depth() const { return (Depth)depth16; }
42 Value eval_value() const { return (Value)evalValue; }
45 friend class TranspositionTable;
47 void save(uint32_t k, Value v, Bound b, Depth d, Move m, uint8_t g, Value ev) {
52 generation8 = (uint8_t)g;
55 evalValue = (int16_t)ev;
60 uint8_t bound8, generation8;
61 int16_t value16, depth16, evalValue;
65 /// A TranspositionTable consists of a power of 2 number of clusters and each
66 /// cluster consists of ClusterSize number of TTEntry. Each non-empty entry
67 /// contains information of exactly one position. The size of a cluster should
68 /// not be bigger than a cache line size. In case it is less, it should be padded
69 /// to guarantee always aligned accesses.
71 class TranspositionTable {
73 static const unsigned ClusterSize = 4;
76 ~TranspositionTable() { free(mem); }
77 void new_search() { ++generation; }
79 const TTEntry* probe(const Key key) const;
80 TTEntry* first_entry(const Key key) const;
81 void resize(uint64_t mbSize);
83 void store(const Key key, Value v, Bound type, Depth d, Move m, Value statV);
89 uint8_t generation; // Size must be not bigger than TTEntry::generation8
92 extern TranspositionTable TT;
95 /// TranspositionTable::first_entry() returns a pointer to the first entry of
96 /// a cluster given a position. The lowest order bits of the key are used to
97 /// get the index of the cluster.
99 inline TTEntry* TranspositionTable::first_entry(const Key key) const {
101 return table + ((uint32_t)key & hashMask);
104 #endif // #ifndef TT_H_INCLUDED