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  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
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  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
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  Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, 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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  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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  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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  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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  (at your option) any later version.
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  Move  move()  const { return (Move )move16; }
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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 value() const { return (Value)value16; }
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  Value eval()  const { return (Value)eval16; }
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  Value eval()  const { return (Value)eval16; }
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  Depth depth() const { return (Depth)(depth8 * int(ONE_PLY)); }
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  Depth depth() const { return (Depth)(depth8 * int(ONE_PLY)); }
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  Bound bound() const { return (Bound)(genBound8 & 0x3); }
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  Bound bound() const { return (Bound)(genBound8 & 0x3); }
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  void save(Key k, Value v, Bound b, Depth d, Move m, Value ev, uint8_t g) {
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  void save(Key k, Value v, Bound b, Depth d, Move m, Value ev);
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    assert(d / ONE_PLY * ONE_PLY == d);
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    // Preserve any existing move for the same position
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    if (m || (k >> 48) != key16)
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        move16 = (uint16_t)m;
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    // Don't overwrite more valuable entries
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    if (  (k >> 48) != key16
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        || d / ONE_PLY > depth8 - 4
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     /* || g != (genBound8 & 0xFC) // Matching non-zero keys are already refreshed by probe() */
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        || b == BOUND_EXACT)
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    {
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        key16     = (uint16_t)(k >> 48);
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        value16   = (int16_t)v;
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        eval16    = (int16_t)ev;
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        genBound8 = (uint8_t)(g | b);
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        depth8    = (int8_t)(d / ONE_PLY);
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    }
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  }
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private:
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private:
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  friend class TranspositionTable;
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  friend class TranspositionTable;
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  uint16_t key16;
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  uint16_t key16;
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  int16_t  value16;
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  int16_t  value16;
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  int16_t  eval16;
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  int16_t  eval16;
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  uint8_t  genBound8;
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  uint8_t  genBound8;
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  int8_t   depth8;
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  int8_t   depth8;
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};
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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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/// 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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/// 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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/// 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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/// 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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/// cache lines. This ensures best cache performance, as the cacheline is
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/// prefetched, as soon as possible.
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/// prefetched, as soon as possible.
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class TranspositionTable {
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class TranspositionTable {
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  static const int CacheLineSize = 64;
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  static constexpr int CacheLineSize = 64;
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  static const int ClusterSize = 3;
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  static constexpr int ClusterSize = 3;
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  struct Cluster {
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  struct Cluster {
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    TTEntry entry[ClusterSize];
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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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    char padding[2]; // Align to a divisor of the cache line size
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  };
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  };
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  static_assert(CacheLineSize % sizeof(Cluster) == 0, "Cluster size incorrect");
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  static_assert(CacheLineSize % sizeof(Cluster) == 0, "Cluster size incorrect");
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public:
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public:
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 ~TranspositionTable() { free(mem); }
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 ~TranspositionTable() { free(mem); }
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  void new_search() { generation8 += 4; } // Lower 2 bits are used by Bound
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  void new_search() { generation8 += 4; } // Lower 2 bits are used by Bound
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  uint8_t generation() const { return generation8; }
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  TTEntry* probe(const Key key, bool& found) const;
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  TTEntry* probe(const Key key, bool& found) const;
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  int hashfull() const;
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  int hashfull() const;
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  void resize(size_t mbSize);
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  void resize(size_t mbSize);
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  void clear();
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  void clear();
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  TTEntry* first_entry(const Key key) const {
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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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    return &table[(uint32_t(key) * uint64_t(clusterCount)) >> 32].entry[0];
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  }
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  }
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private:
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private:
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  friend struct TTEntry;
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  size_t clusterCount;
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  size_t clusterCount;
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  Cluster* table;
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  Cluster* table;
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  void* mem;
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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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  uint8_t generation8; // Size must be not bigger than TTEntry::genBound8
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};
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};