2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2015 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 /// TTEntry struct is the 10 bytes transposition table entry, defined as below:
38 Move move() const { return (Move )move16; }
39 Value value() const { return (Value)value16; }
40 Value eval() const { return (Value)eval16; }
41 Depth depth() const { return (Depth)depth8; }
42 Bound bound() const { return (Bound)(genBound8 & 0x3); }
44 void save(Key k, Value v, Bound b, Depth d, Move m, Value ev, uint8_t g) {
46 if (m || (k >> 48) != key16) // Preserve any existing move for the same position
49 key16 = (uint16_t)(k >> 48);
52 genBound8 = (uint8_t)(g | b);
57 friend class TranspositionTable;
68 /// A TranspositionTable consists of a power of 2 number of clusters and each
69 /// cluster consists of ClusterSize number of TTEntry. Each non-empty entry
70 /// contains information of exactly one position. The size of a cluster should
71 /// not be bigger than a cache line size. In case it is less, it should be padded
72 /// to guarantee always aligned accesses.
74 class TranspositionTable {
76 static const int CacheLineSize = 64;
77 static const int ClusterSize = 3;
80 TTEntry entry[ClusterSize];
81 char padding[2]; // Align to the cache line size
84 static_assert(sizeof(Cluster) == CacheLineSize / 2, "Cluster size incorrect");
87 ~TranspositionTable() { free(mem); }
88 void new_search() { generation8 += 4; } // Lower 2 bits are used by Bound
89 uint8_t generation() const { return generation8; }
90 TTEntry* probe(const Key key, bool& found) const;
92 void resize(size_t mbSize);
95 // The lowest order bits of the key are used to get the index of the cluster
96 TTEntry* first_entry(const Key key) const {
97 return &table[(size_t)key & (clusterCount - 1)].entry[0];
104 uint8_t generation8; // Size must be not bigger than TTEntry::genBound8
107 extern TranspositionTable TT;
109 #endif // #ifndef TT_H_INCLUDED