X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.h;h=677f38edc84e1cc0a28954168629dad09f589c6c;hp=c7c39e90cc9918d3cddb8611a12d8e66ffbf63a8;hb=01ee509a5c33e11d7d62d2f325f55720d8be9cfb;hpb=293c44bc09587259818a82e1d2afb511e552badd
diff --git a/src/tt.h b/src/tt.h
index c7c39e90..677f38ed 100644
--- a/src/tt.h
+++ b/src/tt.h
@@ -1,7 +1,8 @@
/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -17,109 +18,104 @@
along with this program. If not, see .
*/
-#if !defined(TT_H_INCLUDED)
+#ifndef TT_H_INCLUDED
#define TT_H_INCLUDED
#include "misc.h"
#include "types.h"
-/// The TTEntry is the class of transposition table entries
+/// TTEntry struct is the 10 bytes transposition table entry, defined as below:
///
-/// A TTEntry needs 128 bits to be stored
-///
-/// bit 0-31: key
-/// bit 32-63: data
-/// bit 64-79: value
-/// bit 80-95: depth
-/// bit 96-111: static value
-/// bit 112-127: margin of static value
-///
-/// the 32 bits of the data field are so defined
-///
-/// bit 0-15: move
-/// bit 16-20: not used
-/// bit 21-22: value type
-/// bit 23-31: generation
-
-class TTEntry {
-
-public:
- void save(uint32_t k, Value v, Bound b, Depth d, Move m, int g, Value ev, Value em) {
-
- key32 = (uint32_t)k;
- move16 = (uint16_t)m;
- bound = (uint8_t)b;
- generation8 = (uint8_t)g;
- value16 = (int16_t)v;
- depth16 = (int16_t)d;
- evalValue = (int16_t)ev;
- evalMargin = (int16_t)em;
+/// key 16 bit
+/// move 16 bit
+/// value 16 bit
+/// eval value 16 bit
+/// generation 6 bit
+/// bound type 2 bit
+/// depth 8 bit
+
+struct TTEntry {
+
+ Move move() const { return (Move )move16; }
+ Value value() const { return (Value)value16; }
+ Value eval() const { return (Value)eval16; }
+ Depth depth() const { return (Depth)(depth8 * int(ONE_PLY)); }
+ Bound bound() const { return (Bound)(genBound8 & 0x3); }
+
+ void save(Key k, Value v, Bound b, Depth d, Move m, Value ev, uint8_t g) {
+
+ assert(d / ONE_PLY * ONE_PLY == d);
+
+ // Preserve any existing move for the same position
+ if (m || (k >> 48) != key16)
+ move16 = (uint16_t)m;
+
+ // Don't overwrite more valuable entries
+ if ( (k >> 48) != key16
+ || d / ONE_PLY > depth8 - 4
+ /* || g != (genBound8 & 0xFC) // Matching non-zero keys are already refreshed by probe() */
+ || b == BOUND_EXACT)
+ {
+ key16 = (uint16_t)(k >> 48);
+ value16 = (int16_t)v;
+ eval16 = (int16_t)ev;
+ genBound8 = (uint8_t)(g | b);
+ depth8 = (int8_t)(d / ONE_PLY);
+ }
}
- void set_generation(int g) { generation8 = (uint8_t)g; }
-
- uint32_t key() const { return key32; }
- Depth depth() const { return (Depth)depth16; }
- Move move() const { return (Move)move16; }
- Value value() const { return (Value)value16; }
- Bound type() const { return (Bound)bound; }
- int generation() const { return (int)generation8; }
- Value eval_value() const { return (Value)evalValue; }
- Value eval_margin() const { return (Value)evalMargin; }
private:
- uint32_t key32;
+ friend class TranspositionTable;
+
+ uint16_t key16;
uint16_t move16;
- uint8_t bound, generation8;
- int16_t value16, depth16, evalValue, evalMargin;
+ int16_t value16;
+ int16_t eval16;
+ uint8_t genBound8;
+ int8_t depth8;
};
/// A TranspositionTable consists of a power of 2 number of clusters and each
/// cluster consists of ClusterSize number of TTEntry. Each non-empty entry
-/// contains information of exactly one position. Size of a cluster shall not be
-/// bigger than a cache line size. In case it is less, it should be padded to
-/// guarantee always aligned accesses.
+/// contains information of exactly one position. The size of a cluster should
+/// divide the size of a cache line size, to ensure that clusters never cross
+/// cache lines. This ensures best cache performance, as the cacheline is
+/// prefetched, as soon as possible.
class TranspositionTable {
- static const unsigned ClusterSize = 4; // A cluster is 64 Bytes
+ static const int CacheLineSize = 64;
+ static const int ClusterSize = 3;
-public:
- ~TranspositionTable() { delete [] table; }
- void new_search() { generation++; }
+ struct Cluster {
+ TTEntry entry[ClusterSize];
+ char padding[2]; // Align to a divisor of the cache line size
+ };
- TTEntry* probe(const Key key) const;
- TTEntry* first_entry(const Key key) const;
- void refresh(const TTEntry* tte) const;
- void set_size(size_t mbSize);
+ static_assert(CacheLineSize % sizeof(Cluster) == 0, "Cluster size incorrect");
+
+public:
+ ~TranspositionTable() { free(mem); }
+ void new_search() { generation8 += 4; } // Lower 2 bits are used by Bound
+ uint8_t generation() const { return generation8; }
+ TTEntry* probe(const Key key, bool& found) const;
+ int hashfull() const;
+ void resize(size_t mbSize);
void clear();
- void store(const Key key, Value v, Bound type, Depth d, Move m, Value statV, Value kingD);
+
+ // The lowest order bits of the key are used to get the index of the cluster
+ TTEntry* first_entry(const Key key) const {
+ return &table[(size_t)key & (clusterCount - 1)].entry[0];
+ }
private:
- uint32_t hashMask;
- TTEntry* table;
- uint8_t generation; // Size must be not bigger then TTEntry::generation8
+ size_t clusterCount;
+ Cluster* table;
+ void* mem;
+ uint8_t generation8; // Size must be not bigger than TTEntry::genBound8
};
extern TranspositionTable TT;
-
-/// TranspositionTable::first_entry() returns a pointer to the first entry of
-/// a cluster given a position. The lowest order bits of the key are used to
-/// get the index of the cluster.
-
-inline TTEntry* TranspositionTable::first_entry(const Key key) const {
-
- return table + ((uint32_t)key & hashMask);
-}
-
-
-/// TranspositionTable::refresh() updates the 'generation' value of the TTEntry
-/// to avoid aging. Normally called after a TT hit.
-
-inline void TranspositionTable::refresh(const TTEntry* tte) const {
-
- const_cast(tte)->set_generation(generation);
-}
-
-#endif // !defined(TT_H_INCLUDED)
+#endif // #ifndef TT_H_INCLUDED