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/>.
20 #if !defined(TT_H_INCLUDED)
28 /// A simple fixed size hash table used to store pawns and material
29 /// configurations. It is basically just an array of Entry objects.
30 /// Without cluster concept or overwrite policy.
32 template<class Entry, int HashSize>
35 SimpleHash(const SimpleHash&);
36 SimpleHash& operator=(const SimpleHash&);
41 entries = new (std::nothrow) Entry[HashSize];
44 std::cerr << "Failed to allocate " << HashSize * sizeof(Entry)
45 << " bytes for material hash table." << std::endl;
48 memset(entries, 0, HashSize * sizeof(Entry));
51 virtual ~SimpleHash() { delete [] entries; }
53 Entry* find(Key key) const { return entries + ((uint32_t)key & (HashSize - 1)); }
54 void prefetch(Key key) const { ::prefetch((char*)find(key)); }
61 /// The TTEntry class is the class of transposition table entries
63 /// A TTEntry needs 128 bits to be stored
69 /// bit 96-111: static value
70 /// bit 112-127: margin of static value
72 /// the 32 bits of the data field are so defined
75 /// bit 16-20: not used
76 /// bit 21-22: value type
77 /// bit 23-31: generation
82 void save(uint32_t k, Value v, ValueType t, Depth d, Move m, int g, Value statV, Value statM) {
86 valueType = (uint8_t)t;
87 generation8 = (uint8_t)g;
90 staticValue = (int16_t)statV;
91 staticMargin = (int16_t)statM;
93 void set_generation(int g) { generation8 = (uint8_t)g; }
95 uint32_t key() const { return key32; }
96 Depth depth() const { return Depth(depth16); }
97 Move move() const { return Move(move16); }
98 Value value() const { return Value(value16); }
99 ValueType type() const { return ValueType(valueType); }
100 int generation() const { return generation8; }
101 Value static_value() const { return Value(staticValue); }
102 Value static_value_margin() const { return Value(staticMargin); }
112 int16_t staticMargin;
116 /// This is the number of TTEntry slots for each cluster
117 const int ClusterSize = 4;
119 /// TTCluster consists of ClusterSize number of TTEntries.
120 /// Size of TTCluster must not be bigger than a cache line size.
121 /// In case it is less, it should be padded to guarantee always aligned accesses.
124 TTEntry data[ClusterSize];
128 /// The transposition table class. This is basically just a huge array
129 /// containing TTCluster objects, and a few methods for writing new entries
130 /// and reading new ones.
132 class TranspositionTable {
134 TranspositionTable(const TranspositionTable&);
135 TranspositionTable& operator=(const TranspositionTable&);
138 TranspositionTable();
139 ~TranspositionTable();
140 void set_size(size_t mbSize);
142 void store(const Key posKey, Value v, ValueType type, Depth d, Move m, Value statV, Value kingD);
143 TTEntry* retrieve(const Key posKey) const;
145 TTEntry* first_entry(const Key posKey) const;
146 void refresh(const TTEntry* tte) const;
151 uint8_t generation; // To properly compare, size must be smaller then TT stored value
154 extern TranspositionTable TT;
157 /// TranspositionTable::first_entry returns a pointer to the first
158 /// entry of a cluster given a position. The lowest order bits of the key
159 /// are used to get the index of the cluster.
161 inline TTEntry* TranspositionTable::first_entry(const Key posKey) const {
163 return entries[((uint32_t)posKey) & (size - 1)].data;
167 /// TranspositionTable::refresh updates the 'generation' value of the TTEntry
168 /// to avoid aging. Normally called after a TT hit, before to return.
170 inline void TranspositionTable::refresh(const TTEntry* tte) const {
172 const_cast<TTEntry*>(tte)->set_generation(generation);
175 #endif // !defined(TT_H_INCLUDED)