X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.h;h=a750b6c465706c1daa22947b082b42a8decbf641;hp=f3b0f2adcb327e9c096c9735a65dad8795995e3b;hb=573f0e364ff4c1e5928be2ca947f65c5d4e177d5;hpb=9b1cf3cf4360278f5485db6ba81c2cfeae746bd7
diff --git a/src/tt.h b/src/tt.h
index f3b0f2ad..a750b6c4 100644
--- a/src/tt.h
+++ b/src/tt.h
@@ -1,7 +1,6 @@
/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -17,120 +16,88 @@
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 statV, Value statM) {
-
- key32 = (uint32_t)k;
- move16 = (uint16_t)m;
- bound = (uint8_t)b;
- generation8 = (uint8_t)g;
- value16 = (int16_t)v;
- depth16 = (int16_t)d;
- staticValue = (int16_t)statV;
- staticMargin = (int16_t)statM;
- }
- 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 static_value() const { return (Value)staticValue; }
- Value static_value_margin() const { return (Value)staticMargin; }
+/// key 16 bit
+/// depth 8 bit
+/// generation 5 bit
+/// pv node 1 bit
+/// bound type 2 bit
+/// move 16 bit
+/// value 16 bit
+/// eval value 16 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 + DEPTH_OFFSET; }
+ bool is_pv() const { return (bool)(genBound8 & 0x4); }
+ Bound bound() const { return (Bound)(genBound8 & 0x3); }
+ void save(Key k, Value v, bool pv, Bound b, Depth d, Move m, Value ev);
private:
- uint32_t key32;
+ friend class TranspositionTable;
+
+ uint16_t key16;
+ uint8_t depth8;
+ uint8_t genBound8;
uint16_t move16;
- uint8_t bound, generation8;
- int16_t value16, depth16, staticValue, staticMargin;
+ int16_t value16;
+ int16_t eval16;
};
-/// This is the number of TTEntry slots for each cluster
-const int ClusterSize = 4;
-
+/// A TranspositionTable is an array of Cluster, of size clusterCount. Each
+/// cluster consists of ClusterSize number of TTEntry. Each non-empty TTEntry
+/// contains information on exactly one position. The size of a Cluster should
+/// divide the size of a cache line for best performance, as the cacheline is
+/// prefetched when possible.
-/// TTCluster consists of ClusterSize number of TTEntries. Size of TTCluster
-/// must not be bigger than a cache line size. In case it is less, it should
-/// be padded to guarantee always aligned accesses.
+class TranspositionTable {
-struct TTCluster {
- TTEntry data[ClusterSize];
-};
+ static constexpr int ClusterSize = 3;
+ struct Cluster {
+ TTEntry entry[ClusterSize];
+ char padding[2]; // Pad to 32 bytes
+ };
-/// The transposition table class. This is basically just a huge array containing
-/// TTCluster objects, and a few methods for writing and reading entries.
+ static_assert(sizeof(Cluster) == 32, "Unexpected Cluster size");
-class TranspositionTable {
-
- TranspositionTable(const TranspositionTable&);
- TranspositionTable& operator=(const TranspositionTable&);
+ // Constants used to refresh the hash table periodically
+ static constexpr unsigned GENERATION_BITS = 3; // nb of bits reserved for other things
+ static constexpr int GENERATION_DELTA = (1 << GENERATION_BITS); // increment for generation field
+ static constexpr int GENERATION_CYCLE = 255 + (1 << GENERATION_BITS); // cycle length
+ static constexpr int GENERATION_MASK = (0xFF << GENERATION_BITS) & 0xFF; // mask to pull out generation number
public:
- TranspositionTable();
- ~TranspositionTable();
- void set_size(size_t mbSize);
+ ~TranspositionTable() { aligned_large_pages_free(table); }
+ void new_search() { generation8 += GENERATION_DELTA; } // Lower bits are used for other things
+ TTEntry* probe(const Key key, bool& found) const;
+ int hashfull() const;
+ void resize(size_t mbSize);
void clear();
- void store(const Key posKey, Value v, Bound type, Depth d, Move m, Value statV, Value kingD);
- TTEntry* probe(const Key posKey) const;
- void new_search();
- TTEntry* first_entry(const Key posKey) const;
- void refresh(const TTEntry* tte) const;
+
+ TTEntry* first_entry(const Key key) const {
+ return &table[mul_hi64(key, clusterCount)].entry[0];
+ }
private:
- size_t size;
- TTCluster* entries;
- uint8_t generation; // Size must be not bigger then TTEntry::generation8
+ friend struct TTEntry;
+
+ size_t clusterCount;
+ Cluster* table;
+ 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 posKey) const {
-
- return entries[((uint32_t)posKey) & (size - 1)].data;
-}
-
-
-/// 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