X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.h;h=70283fca29bff341fd7d06d23ac12bacfdf8a66e;hp=bd6aae99b9e2918a4b008e28af9abc2f17e75f4e;hb=77fa960f8923ca83ba0391835d50f4230ac6a345;hpb=00e86078a550631e3d045d882ab27f827d3f2378 diff --git a/src/tt.h b/src/tt.h index bd6aae99..70283fca 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) 2008-2010 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 @@ -17,120 +18,102 @@ along with this program. If not, see . */ - -#if !defined(TT_H_INCLUDED) +#ifndef TT_H_INCLUDED #define TT_H_INCLUDED -//// -//// Includes -//// - -#include "depth.h" -#include "position.h" -#include "value.h" - +#include "misc.h" +#include "types.h" -//// -//// Types -//// - -/// 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: king danger value +/// TTEntry struct is the 10 bytes transposition table entry, defined as below: /// -/// the 32 bits of the data field are so defined -/// -/// bit 0-16: move -/// bit 17-19: not used -/// bit 20-22: 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 & 0x1FFFF) | (t << 20) | (g << 23); - value16 = int16_t(v); - depth16 = int16_t(d); - staticValue = int16_t(statV); - kingDanger = int16_t(kd); +/// 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; } + Bound bound() const { return (Bound)(genBound8 & 0x3); } + + void save(Key k, Value v, Bound b, Depth d, Move m, Value ev, uint8_t g) { + + // 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 > 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; + } } - uint32_t key() const { return key32; } - Depth depth() const { return Depth(depth16); } - Move move() const { return Move(data & 0x1FFFF); } - Value value() const { return Value(value16); } - ValueType type() const { return ValueType((data >> 20) & 7); } - int generation() const { return data >> 23; } - Value static_value() const { return Value(staticValue); } - Value king_danger() const { return Value(kingDanger); } - private: - uint32_t key32; - uint32_t data; - int16_t value16; - int16_t depth16; - int16_t staticValue; - int16_t kingDanger; + friend class TranspositionTable; + + uint16_t key16; + uint16_t move16; + int16_t value16; + int16_t eval16; + uint8_t genBound8; + int8_t depth8; }; -/// This is the number of TTEntry slots for each position -const int ClusterSize = 4; +/// 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. 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. -/// Each group of ClusterSize number of TTEntry form a TTCluster -/// that is indexed by a single position key. TTCluster size must -/// be not bigger then a cache line size, in case it is less then -/// it should be padded to guarantee always aligned accesses. +class TranspositionTable { -struct TTCluster { - TTEntry data[ClusterSize]; -}; + static const int CacheLineSize = 64; + static const int ClusterSize = 3; + struct Cluster { + TTEntry entry[ClusterSize]; + char padding[2]; // Align to a divisor of the cache line size + }; -/// The transposition table class. This is basically just a huge array -/// containing TTEntry objects, and a few methods for writing new entries -/// and reading new ones. - -class TranspositionTable { + static_assert(CacheLineSize % sizeof(Cluster) == 0, "Cluster size incorrect"); public: - TranspositionTable(); - ~TranspositionTable(); - void set_size(size_t mbSize); + ~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 posKey, Value v, ValueType type, Depth d, Move m, Value statV, Value kingD); - TTEntry* retrieve(const Key posKey) const; - void new_search(); - void insert_pv(const Position& pos, Move pv[]); - void extract_pv(const Position& pos, Move bestMove, Move pv[], const int PLY_MAX); - TTEntry* first_entry(const Key posKey) const; + + // 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: - size_t size; - TTCluster* entries; - uint8_t generation; + 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 low 32 bits of the key -/// are used to get the index in the table. - -inline TTEntry* TranspositionTable::first_entry(const Key posKey) const { - - return entries[uint32_t(posKey) & (size - 1)].data; -} - -#endif // !defined(TT_H_INCLUDED) +#endif // #ifndef TT_H_INCLUDED