2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2010 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/>.
21 #if !defined(TT_H_INCLUDED)
37 /// The TTEntry class is the class of transposition table entries
39 /// A TTEntry needs 96 bits to be stored
46 /// the 32 bits of the data field are so defined
49 /// bit 17-19: not used
50 /// bit 20-22: value type
51 /// bit 23-31: generation
56 void save(uint32_t k, Value v, ValueType t, Depth d, Move m, int g, Value statV, Value kd) {
59 data = (m & 0x1FFFF) | (t << 20) | (g << 23);
62 staticValue = int16_t(statV);
63 kingDanger = int16_t(kd);
66 uint32_t key() const { return key32; }
67 Depth depth() const { return Depth(depth16); }
68 Move move() const { return Move(data & 0x1FFFF); }
69 Value value() const { return Value(value16); }
70 ValueType type() const { return ValueType((data >> 20) & 7); }
71 int generation() const { return data >> 23; }
72 Value static_value() const { return Value(staticValue); }
73 Value king_danger() const { return Value(kingDanger); }
85 /// This is the number of TTEntry slots for each position
86 const int ClusterSize = 4;
88 /// Each group of ClusterSize number of TTEntry form a TTCluster
89 /// that is indexed by a single position key. TTCluster size must
90 /// be not bigger then a cache line size, in case it is less then
91 /// it should be padded to guarantee always aligned accesses.
94 TTEntry data[ClusterSize];
98 /// The transposition table class. This is basically just a huge array
99 /// containing TTEntry objects, and a few methods for writing new entries
100 /// and reading new ones.
102 class TranspositionTable {
105 TranspositionTable();
106 ~TranspositionTable();
107 void set_size(size_t mbSize);
109 void store(const Key posKey, Value v, ValueType type, Depth d, Move m, Value statV, Value kingD);
110 TTEntry* retrieve(const Key posKey) const;
112 void insert_pv(const Position& pos, Move pv[]);
113 void extract_pv(const Position& pos, Move pv[], const int PLY_MAX);
115 TTEntry* first_entry(const Key posKey) const;
118 // Be sure 'writes' is at least one cache line away
119 // from read only variables.
120 unsigned char pad_before[64 - sizeof(unsigned)];
121 unsigned writes; // heavy SMP read/write access here
122 unsigned char pad_after[64];
129 extern TranspositionTable TT;
132 /// TranspositionTable::first_entry returns a pointer to the first
133 /// entry of a cluster given a position. The low 32 bits of the key
134 /// are used to get the index in the table.
136 inline TTEntry* TranspositionTable::first_entry(const Key posKey) const {
138 return entries[uint32_t(posKey) & (size - 1)].data;
141 #endif // !defined(TT_H_INCLUDED)