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 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, Value em) {
44 generation8 = (uint8_t)g;
47 evalValue = (int16_t)ev;
48 evalMargin = (int16_t)em;
50 void set_generation(uint8_t g) { generation8 = g; }
52 uint32_t key() const { return key32; }
53 Depth depth() const { return (Depth)depth16; }
54 Move move() const { return (Move)move16; }
55 Value value() const { return (Value)value16; }
56 Bound bound() const { return (Bound)bound8; }
57 int generation() const { return (int)generation8; }
58 Value eval_value() const { return (Value)evalValue; }
59 Value eval_margin() const { return (Value)evalMargin; }
64 uint8_t bound8, generation8;
65 int16_t value16, depth16, evalValue, evalMargin;
69 /// A TranspositionTable consists of a power of 2 number of clusters and each
70 /// cluster consists of ClusterSize number of TTEntry. Each non-empty entry
71 /// contains information of exactly one position. Size of a cluster shall not be
72 /// bigger than a cache line size. In case it is less, it should be padded to
73 /// guarantee always aligned accesses.
75 class TranspositionTable {
77 static const unsigned ClusterSize = 4; // A cluster is 64 Bytes
80 ~TranspositionTable() { free(mem); }
81 void new_search() { generation++; }
83 const TTEntry* probe(const Key key) const;
84 TTEntry* first_entry(const Key key) const;
85 void refresh(const TTEntry* tte) const;
86 void set_size(size_t mbSize);
88 void store(const Key key, Value v, Bound type, Depth d, Move m, Value statV, Value kingD);
94 uint8_t generation; // Size must be not bigger than TTEntry::generation8
97 extern TranspositionTable TT;
100 /// TranspositionTable::first_entry() returns a pointer to the first entry of
101 /// a cluster given a position. The lowest order bits of the key are used to
102 /// get the index of the cluster.
104 inline TTEntry* TranspositionTable::first_entry(const Key key) const {
106 return table + ((uint32_t)key & hashMask);
110 /// TranspositionTable::refresh() updates the 'generation' value of the TTEntry
111 /// to avoid aging. Normally called after a TT hit.
113 inline void TranspositionTable::refresh(const TTEntry* tte) const {
115 const_cast<TTEntry*>(tte)->set_generation(generation);
118 #endif // !defined(TT_H_INCLUDED)