/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2004-2023 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
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-
-#if !defined(TT_H_INCLUDED)
+#ifndef TT_H_INCLUDED
#define TT_H_INCLUDED
-#include <iostream>
-
-#include "depth.h"
-#include "move.h"
-#include "value.h"
-
-
-////
-//// Types
-////
-
-
-/// A simple fixed size hash table used to store pawns and material
-/// configurations. It is basically just an array of Entry objects.
-/// Without cluster concept or overwrite policy.
-
-template<class Entry, int HashSize>
-class SimpleHash {
-
- SimpleHash(const SimpleHash&);
- SimpleHash& operator=(const SimpleHash&);
-
-public:
- SimpleHash() {
-
- entries = new Entry[HashSize];
- if (!entries)
- {
- std::cerr << "Failed to allocate " << HashSize * sizeof(Entry)
- << " bytes for material hash table." << std::endl;
- exit(EXIT_FAILURE);
- }
- memset(entries, 0, HashSize * sizeof(Entry));
- }
-
- ~SimpleHash() { delete [] entries; }
-
- Entry* find(Key key) const { return entries + ((uint32_t)key & (HashSize - 1)); }
-
-protected:
- Entry* entries;
+#include <cstddef>
+#include <cstdint>
+
+#include "misc.h"
+#include "types.h"
+
+namespace Stockfish {
+
+// TTEntry struct is the 10 bytes transposition table entry, defined as below:
+//
+// 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:
+ friend class TranspositionTable;
+
+ uint16_t key16;
+ uint8_t depth8;
+ uint8_t genBound8;
+ uint16_t move16;
+ int16_t value16;
+ int16_t eval16;
};
-/// The TTEntry class is the class of transposition table entries
-///
-/// 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, ValueType t, Depth d, Move m, int g, Value statV, Value kd) {
-
- key32 = k;
- data = (m & 0xFFFF) | (t << 21) | (g << 23);
- value16 = (int16_t)v;
- depth16 = (int16_t)d;
- staticValue = (int16_t)statV;
- staticValueMargin = (int16_t)kd;
- }
- void set_generation(int g) { data = move() | (type() << 21) | (g << 23); }
-
- uint32_t key() const { return key32; }
- Depth depth() const { return Depth(depth16); }
- Move move() const { return Move(data & 0xFFFF); }
- Value value() const { return Value(value16); }
- ValueType type() const { return ValueType((data >> 21) & 3); }
- int generation() const { return data >> 23; }
- Value static_value() const { return Value(staticValue); }
- Value static_value_margin() const { return Value(staticValueMargin); }
-
-private:
- uint32_t key32;
- uint32_t data;
- int16_t value16;
- int16_t depth16;
- int16_t staticValue;
- int16_t staticValueMargin;
-};
-
-
-/// This is the number of TTEntry slots for each cluster
-const int ClusterSize = 4;
-
-/// 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.
-
-struct TTCluster {
- TTEntry data[ClusterSize];
-};
-
+// 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.
+class TranspositionTable {
-/// The transposition table class. This is basically just a huge array
-/// containing TTCluster objects, and a few methods for writing new entries
-/// and reading new ones.
+ static constexpr int ClusterSize = 3;
+
+ struct Cluster {
+ TTEntry entry[ClusterSize];
+ char padding[2]; // Pad to 32 bytes
+ };
+
+ static_assert(sizeof(Cluster) == 32, "Unexpected Cluster size");
+
+ // 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() { 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();
+
+ TTEntry* first_entry(const Key key) const {
+ return &table[mul_hi64(key, clusterCount)].entry[0];
+ }
-class TranspositionTable {
+ private:
+ friend struct TTEntry;
- TranspositionTable(const TranspositionTable&);
- TranspositionTable& operator=(const TranspositionTable&);
-
-public:
- TranspositionTable();
- ~TranspositionTable();
- void set_size(size_t mbSize);
- void clear();
- void store(const Key posKey, Value v, ValueType type, Depth d, Move m, Value statV, Value kingD);
- TTEntry* retrieve(const Key posKey) const;
- void new_search();
- TTEntry* first_entry(const Key posKey) const;
- void refresh(const TTEntry* tte) const;
-
-private:
- size_t size;
- TTCluster* entries;
- uint8_t generation; // To properly compare, size must be smaller then TT stored value
+ size_t clusterCount;
+ Cluster* table;
+ uint8_t generation8; // Size must be not bigger than TTEntry::genBound8
};
extern TranspositionTable TT;
+} // namespace Stockfish
-/// 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, before to return.
-
-inline void TranspositionTable::refresh(const TTEntry* tte) const {
-
- const_cast<TTEntry*>(tte)->set_generation(generation);
-}
-
-#endif // !defined(TT_H_INCLUDED)
+#endif // #ifndef TT_H_INCLUDED
projects / stockfish / blobdiff