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https://github.com/sockspls/badfish
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893a08a8c2
High rootDepths, selDepths and generally searches are increasingly common with long time control games, analysis, and improving hardware. In this case, depths of MAX_DEPTH/MAX_PLY (128) can be reached, and the search tree is truncated. In principle MAX_PLY can be easily increased, except for a technicality of storing depths in a signed 8 bit int in the TT. This patch increases MAX_PLY by storing the depth in an unsigned 8 bit, after shifting by the most negative depth stored in TT (DEPTH_NONE). No regression at STC: LLR: 2.96 (-2.94,2.94) [-3.00,1.00] Total: 42235 W: 9565 L: 9484 D: 23186 http://tests.stockfishchess.org/tests/view/5cdb35360ebc5925cf0595e1 Verified to reach high depths on k1b5/1p1p4/pP1Pp3/K2pPp2/1P1p1P2/3P1P2/5P2/8 w - - info depth 142 seldepth 154 multipv 1 score cp 537 nodes 26740713110 ... No bench change.
103 lines
3.2 KiB
C++
103 lines
3.2 KiB
C++
/*
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Stockfish, a UCI chess playing engine derived from Glaurung 2.1
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Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
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Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
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Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
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Stockfish is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Stockfish is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef TT_H_INCLUDED
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#define TT_H_INCLUDED
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#include "misc.h"
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#include "types.h"
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/// TTEntry struct is the 10 bytes transposition table entry, defined as below:
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///
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/// key 16 bit
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/// move 16 bit
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/// value 16 bit
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/// eval value 16 bit
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/// generation 5 bit
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/// pv node 1 bit
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/// bound type 2 bit
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/// depth 8 bit
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struct TTEntry {
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Move move() const { return (Move )move16; }
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Value value() const { return (Value)value16; }
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Value eval() const { return (Value)eval16; }
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Depth depth() const { return (Depth)(depth8 * int(ONE_PLY)) + DEPTH_NONE; }
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bool is_pv() const { return (bool)(genBound8 & 0x4); }
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Bound bound() const { return (Bound)(genBound8 & 0x3); }
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void save(Key k, Value v, bool pv, Bound b, Depth d, Move m, Value ev);
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private:
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friend class TranspositionTable;
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uint16_t key16;
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uint16_t move16;
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int16_t value16;
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int16_t eval16;
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uint8_t genBound8;
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uint8_t depth8;
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};
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/// A TranspositionTable consists of a power of 2 number of clusters and each
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/// cluster consists of ClusterSize number of TTEntry. Each non-empty entry
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/// contains information of exactly one position. The size of a cluster should
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/// divide the size of a cache line size, to ensure that clusters never cross
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/// cache lines. This ensures best cache performance, as the cacheline is
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/// prefetched, as soon as possible.
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class TranspositionTable {
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static constexpr int CacheLineSize = 64;
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static constexpr int ClusterSize = 3;
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struct Cluster {
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TTEntry entry[ClusterSize];
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char padding[2]; // Align to a divisor of the cache line size
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};
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static_assert(CacheLineSize % sizeof(Cluster) == 0, "Cluster size incorrect");
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public:
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~TranspositionTable() { free(mem); }
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void new_search() { generation8 += 8; } // Lower 3 bits are used by PV flag and Bound
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TTEntry* probe(const Key key, bool& found) const;
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int hashfull() const;
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void resize(size_t mbSize);
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void clear();
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// The 32 lowest order bits of the key are used to get the index of the cluster
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TTEntry* first_entry(const Key key) const {
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return &table[(uint32_t(key) * uint64_t(clusterCount)) >> 32].entry[0];
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}
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private:
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friend struct TTEntry;
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size_t clusterCount;
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Cluster* table;
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void* mem;
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uint8_t generation8; // Size must be not bigger than TTEntry::genBound8
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};
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extern TranspositionTable TT;
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#endif // #ifndef TT_H_INCLUDED
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