X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=151b71f58df6ac789a87ac200b543169a6fe5c6b;hp=773f03ccbac463929faf254ec4cb8e591d42c224;hb=29b5842da8d5477c0aea924cfd364c9e619456a2;hpb=b366c7dc38145278a00c51a560a4f7b6e03a0b2a
diff --git a/src/tt.cpp b/src/tt.cpp
index 773f03cc..151b71f5 100644
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -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
@@ -17,143 +18,100 @@
along with this program. If not, see .
*/
-
-////
-//// Includes
-////
-
-#include
-#include
+#include // For std::memset
#include
+#include "bitboard.h"
#include "tt.h"
-// The main transposition table
-TranspositionTable TT;
-
-////
-//// Functions
-////
-
-TranspositionTable::TranspositionTable() {
-
- size = 0;
- entries = 0;
- generation = 0;
-}
+TranspositionTable TT; // Our global transposition table
-TranspositionTable::~TranspositionTable() {
- delete [] entries;
-}
+/// TranspositionTable::resize() sets the size of the transposition table,
+/// measured in megabytes. Transposition table consists of a power of 2 number
+/// of clusters and each cluster consists of ClusterSize number of TTEntry.
+void TranspositionTable::resize(size_t mbSize) {
-/// TranspositionTable::set_size sets the size of the transposition table,
-/// measured in megabytes.
+ size_t newClusterCount = size_t(1) << msb((mbSize * 1024 * 1024) / sizeof(Cluster));
-void TranspositionTable::set_size(size_t mbSize) {
+ if (newClusterCount == clusterCount)
+ return;
- size_t newSize = 1024;
+ clusterCount = newClusterCount;
- // Transposition table consists of clusters and each cluster consists
- // of ClusterSize number of TTEntries. Each non-empty entry contains
- // information of exactly one position and newSize is the number of
- // clusters we are going to allocate.
- while (2ULL * newSize * sizeof(TTCluster) <= (mbSize << 20))
- newSize *= 2;
+ free(mem);
+ mem = calloc(clusterCount * sizeof(Cluster) + CacheLineSize - 1, 1);
- if (newSize != size)
+ if (!mem)
{
- size = newSize;
- delete [] entries;
- entries = new (std::nothrow) TTCluster[size];
- if (!entries)
- {
- std::cerr << "Failed to allocate " << mbSize
- << " MB for transposition table." << std::endl;
- exit(EXIT_FAILURE);
- }
- clear();
+ std::cerr << "Failed to allocate " << mbSize
+ << "MB for transposition table." << std::endl;
+ exit(EXIT_FAILURE);
}
+
+ table = (Cluster*)((uintptr_t(mem) + CacheLineSize - 1) & ~(CacheLineSize - 1));
}
-/// TranspositionTable::clear overwrites the entire transposition table
-/// with zeroes. It is called whenever the table is resized, or when the
+/// TranspositionTable::clear() overwrites the entire transposition table
+/// with zeros. It is called whenever the table is resized, or when the
/// user asks the program to clear the table (from the UCI interface).
-/// Perhaps we should also clear it when the "ucinewgame" command is received?
void TranspositionTable::clear() {
- memset(entries, 0, size * sizeof(TTCluster));
+ std::memset(table, 0, clusterCount * sizeof(Cluster));
}
-/// TranspositionTable::store writes a new entry containing position key and
-/// valuable information of current position.
-/// The Lowest order bits of position key are used to decide on which cluster
-/// the position will be placed.
-/// When a new entry is written and there are no empty entries available in cluster,
-/// it replaces the least valuable of entries.
-/// A TTEntry t1 is considered to be more valuable than a TTEntry t2 if t1 is from the
-/// current search and t2 is from a previous search, or if the depth of t1
-/// is bigger than the depth of t2.
+/// TranspositionTable::probe() looks up the current position in the transposition
+/// table. It returns true and a pointer to the TTEntry if the position is found.
+/// Otherwise, it returns false and a pointer to an empty or least valuable TTEntry
+/// to be replaced later. The replace value of an entry is calculated as its depth
+/// minus 8 times its relative age. TTEntry t1 is considered more valuable than
+/// TTEntry t2 if its replace value is greater than that of t2.
-void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d, Move m, Value statV, Value kingD) {
+TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
- int c1, c2, c3;
- TTEntry *tte, *replace;
- uint32_t posKey32 = posKey >> 32; // Use the high 32 bits as key
+ TTEntry* const tte = first_entry(key);
+ const uint16_t key16 = key >> 48; // Use the high 16 bits as key inside the cluster
- tte = replace = first_entry(posKey);
- for (int i = 0; i < ClusterSize; i++, tte++)
- {
- if (!tte->key() || tte->key() == posKey32) // empty or overwrite old
+ for (int i = 0; i < ClusterSize; ++i)
+ if (!tte[i].key16 || tte[i].key16 == key16)
{
- // Preserve any existing ttMove
- if (m == MOVE_NONE)
- m = tte->move();
+ if ((tte[i].genBound8 & 0xFC) != generation8 && tte[i].key16)
+ tte[i].genBound8 = uint8_t(generation8 | tte[i].bound()); // Refresh
- tte->save(posKey32, v, t, d, m, generation, statV, kingD);
- return;
+ return found = (bool)tte[i].key16, &tte[i];
}
- if (i == 0) // Replacing first entry is default and already set before entering for-loop
- continue;
-
- c1 = (replace->generation() == generation ? 2 : 0);
- c2 = (tte->generation() == generation || tte->type() == VALUE_TYPE_EXACT ? -2 : 0);
- c3 = (tte->depth() < replace->depth() ? 1 : 0);
-
- if (c1 + c2 + c3 > 0)
- replace = tte;
- }
- replace->save(posKey32, v, t, d, m, generation, statV, kingD);
+ // Find an entry to be replaced according to the replacement strategy
+ TTEntry* replace = tte;
+ for (int i = 1; i < ClusterSize; ++i)
+ // Due to our packed storage format for generation and its cyclic
+ // nature we add 259 (256 is the modulus plus 3 to keep the lowest
+ // two bound bits from affecting the result) to calculate the entry
+ // age correctly even after generation8 overflows into the next cycle.
+ if ( replace->depth8 - ((259 + generation8 - replace->genBound8) & 0xFC) * 2 * ONE_PLY
+ > tte[i].depth8 - ((259 + generation8 - tte[i].genBound8) & 0xFC) * 2 * ONE_PLY)
+ replace = &tte[i];
+
+ return found = false, replace;
}
-/// TranspositionTable::retrieve looks up the current position in the
-/// transposition table. Returns a pointer to the TTEntry or NULL
-/// if position is not found.
-
-TTEntry* TranspositionTable::retrieve(const Key posKey) const {
+/// Returns an approximation of the hashtable occupation during a search. The
+/// hash is x permill full, as per UCI protocol.
- uint32_t posKey32 = posKey >> 32;
- TTEntry* tte = first_entry(posKey);
-
- for (int i = 0; i < ClusterSize; i++, tte++)
- if (tte->key() == posKey32)
- return tte;
-
- return NULL;
-}
-
-
-/// TranspositionTable::new_search() is called at the beginning of every new
-/// search. It increments the "generation" variable, which is used to
-/// distinguish transposition table entries from previous searches from
-/// entries from the current search.
-
-void TranspositionTable::new_search() {
- generation++;
+int TranspositionTable::hashfull() const
+{
+ int cnt = 0;
+ for (int i = 0; i < 1000 / ClusterSize; i++)
+ {
+ const TTEntry* tte = &table[i].entry[0];
+ for (int j = 0; j < ClusterSize; j++)
+ if ((tte[j].genBound8 & 0xFC) == generation8)
+ cnt++;
+ }
+ return cnt;
}