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/>.
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, Value ev, Value em) {
52 generation8 = (uint8_t)g;
55 evalValue = (int16_t)ev;
56 evalMargin = (int16_t)em;
58 void set_generation(int g) { generation8 = (uint8_t)g; }
60 uint32_t key() const { return key32; }
61 Depth depth() const { return (Depth)depth16; }
62 Move move() const { return (Move)move16; }
63 Value value() const { return (Value)value16; }
64 Bound type() const { return (Bound)bound; }
65 int generation() const { return (int)generation8; }
66 Value eval_value() const { return (Value)evalValue; }
67 Value eval_margin() const { return (Value)evalMargin; }
72 uint8_t bound, generation8;
73 int16_t value16, depth16, evalValue, evalMargin;
77 /// A TranspositionTable consists of a power of 2 number of clusters and each
78 /// cluster consists of ClusterSize number of TTEntry. Each non-empty entry
79 /// contains information of exactly one position. Size of a cluster shall not be
80 /// bigger than a cache line size. In case it is less, it should be padded to
81 /// guarantee always aligned accesses.
83 class TranspositionTable {
85 static const unsigned ClusterSize = 4; // A cluster is 64 Bytes
88 ~TranspositionTable() { free(mem); }
89 void new_search() { generation++; }
91 TTEntry* probe(const Key key) const;
92 TTEntry* first_entry(const Key key) const;
93 void refresh(const TTEntry* tte) const;
94 void set_size(size_t mbSize);
96 void store(const Key key, Value v, Bound type, Depth d, Move m, Value statV, Value kingD);
102 uint8_t generation; // Size must be not bigger then TTEntry::generation8
105 extern TranspositionTable TT;
108 /// TranspositionTable::first_entry() returns a pointer to the first entry of
109 /// a cluster given a position. The lowest order bits of the key are used to
110 /// get the index of the cluster.
112 inline TTEntry* TranspositionTable::first_entry(const Key key) const {
114 return table + ((uint32_t)key & hashMask);
118 /// TranspositionTable::refresh() updates the 'generation' value of the TTEntry
119 /// to avoid aging. Normally called after a TT hit.
121 inline void TranspositionTable::refresh(const TTEntry* tte) const {
123 const_cast<TTEntry*>(tte)->set_generation(generation);
126 #endif // !defined(TT_H_INCLUDED)