/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008 Marco Costalba
+ Copyright (C) 2008-2009 Marco Costalba
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
/// The TTEntry class is the class of transposition table entries
///
-/// A TTEntry needs 128 bits to be stored
+/// A TTEntry needs 96 bits to be stored
///
-/// bit 0-63: key
-/// bit 64-95: data
-/// bit 96-111: value
-/// bit 112-127: depth
+/// bit 0-31: key
+/// bit 32-63: data
+/// bit 64-79: value
+/// bit 80-95: depth
///
/// the 32 bits of the data field are so defined
///
class TTEntry {
public:
- TTEntry();
- TTEntry(Key k, Value v, ValueType t, Depth d, Move m, int generation);
- Key key() const { return key_; }
+ TTEntry() {}
+ TTEntry(uint32_t k, Value v, ValueType t, Depth d, Move m, int generation)
+ : key_ (k), data((m & 0x1FFFF) | (t << 20) | (generation << 23)),
+ value_(int16_t(v)), depth_(int16_t(d)) {}
+
+ uint32_t key() const { return key_; }
Depth depth() const { return Depth(depth_); }
Move move() const { return Move(data & 0x1FFFF); }
Value value() const { return Value(value_); }
int generation() const { return (data >> 23); }
private:
- Key key_;
+ uint32_t key_;
uint32_t data;
int16_t value_;
int16_t depth_;
};
-/// The transposition table class. This is basically just a huge array
+
+/// This is the number of TTEntry slots for each position
+const int ClusterSize = 5;
+
+/// Each group of ClusterSize number of TTEntry form a TTCluster
+/// that is indexed by a single position key. Cluster is padded
+/// to a cache line size so to guarantee always aligned accesses.
+
+struct TTCluster {
+ TTEntry data[ClusterSize];
+ char cache_line_padding[64 - sizeof(TTEntry[ClusterSize])];
+};
+
+
+/// The transposition table class. This is basically just a huge array
/// containing TTEntry objects, and a few methods for writing new entries
/// and reading new ones.
class TranspositionTable {
public:
- TranspositionTable(unsigned mbSize);
+ TranspositionTable();
~TranspositionTable();
void set_size(unsigned mbSize);
void clear();
- void store(const Position &pos, Value v, Depth d, Move m, ValueType type);
- TTEntry* retrieve(const Position &pos) const;
+ void store(const Key posKey, Value v, ValueType type, Depth d, Move m);
+ TTEntry* retrieve(const Key posKey) const;
+ void prefetch(const Key posKey) const;
void new_search();
- void insert_pv(const Position &pos, Move pv[]);
- int full();
+ void insert_pv(const Position& pos, Move pv[]);
+ void extract_pv(const Position& pos, Move pv[]);
+ int full() const;
private:
- inline TTEntry* first_entry(const Position &pos) const;
+ inline TTEntry* first_entry(const Key posKey) const;
+
+ // Be sure 'writes' is at least one cache line away
+ // from read only variables.
+ unsigned char pad_before[64 - sizeof(unsigned)];
+ unsigned writes; // heavy SMP read/write access here
+ unsigned char pad_after[64];
unsigned size;
- int writes;
- TTEntry* entries;
+ TTCluster* entries;
uint8_t generation;
};
-
-////
-//// Constants and variables
-////
-
-// Default transposition table size, in megabytes:
-const int TTDefaultSize = 32;
-
+extern TranspositionTable TT;
#endif // !defined(TT_H_INCLUDED)