/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2009 Marco Costalba
+ Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, 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
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-
-////
-//// Includes
-////
-
-#include <cassert>
-#include <cmath>
#include <cstring>
+#include <iostream>
-#include "movegen.h"
+#include "bitboard.h"
#include "tt.h"
-#if defined(_MSC_VER)
-#include <xmmintrin.h>
-#endif
-
-// This is the number of TTEntry slots for each position
-static const int ClusterSize = 5;
-
-// The main transposition table
-TranspositionTable TT;
+TranspositionTable TT; // Our global transposition table
-////
-//// Functions
-////
-TranspositionTable::TranspositionTable() {
+/// 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 TTClusterSize number of TTEntry.
- size = writes = 0;
- entries = 0;
- generation = 0;
-}
-
-TranspositionTable::~TranspositionTable() {
-
- delete [] entries;
-}
+void TranspositionTable::resize(size_t mbSize) {
+ size_t newClusterCount = size_t(1) << msb((mbSize * 1024 * 1024) / sizeof(TTCluster));
-/// TranspositionTable::set_size sets the size of the transposition table,
-/// measured in megabytes.
+ if (newClusterCount == clusterCount)
+ return;
-void TranspositionTable::set_size(unsigned mbSize) {
+ clusterCount = newClusterCount;
- assert(mbSize >= 4 && mbSize <= 4096);
+ free(mem);
+ mem = calloc(clusterCount * sizeof(TTCluster) + CACHE_LINE_SIZE - 1, 1);
- unsigned newSize = 1024;
-
- // We store a cluster of ClusterSize number of TTEntry for each position
- // and newSize is the maximum number of storable positions.
- while ((2 * newSize) * ClusterSize * (sizeof(TTEntry)) <= (mbSize << 20))
- newSize *= 2;
-
- if (newSize != size)
+ if (!mem)
{
- size = newSize;
- delete [] entries;
- entries = new TTEntry[size * ClusterSize];
- if (!entries)
- {
- std::cerr << "Failed to allocate " << mbSize
- << " MB for transposition table." << std::endl;
- Application::exit_with_failure();
- }
- clear();
+ std::cerr << "Failed to allocate " << mbSize
+ << "MB for transposition table." << std::endl;
+ exit(EXIT_FAILURE);
}
+
+ table = (TTCluster*)((uintptr_t(mem) + CACHE_LINE_SIZE - 1) & ~(CACHE_LINE_SIZE - 1));
}
-/// TranspositionTable::clear overwrites the entire transposition table
+/// TranspositionTable::clear() overwrites the entire transposition table
/// with zeroes. 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 recieved?
void TranspositionTable::clear() {
- memset(entries, 0, size * ClusterSize * sizeof(TTEntry));
+ std::memset(table, 0, clusterCount * sizeof(TTCluster));
}
-/// 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 {
+/// TranspositionTable::probe() looks up the current position in the
+/// transposition table. Returns a pointer to the TTEntry or NULL if
+/// position is not found.
- return entries + ((uint32_t(posKey) & (size - 1)) * ClusterSize);
-}
+const TTEntry* TranspositionTable::probe(const Key key) const {
+ TTEntry* const tte = first_entry(key);
+ const uint16_t key16 = key >> 48;
-/// TranspositionTable::store writes a new entry containing a position,
-/// a value, a value type, a search depth, and a best move to the
-/// transposition table. Transposition table is organized in clusters of
-/// four TTEntry objects, and when a new entry is written, it replaces
-/// the least valuable of the four entries in a cluster. 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. A TTEntry of type VALUE_TYPE_EVAL
-/// never replaces another entry for the same position.
-
-void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d, Move m) {
-
- TTEntry *tte, *replace;
- uint32_t posKey32 = posKey >> 32; // Use the high 32 bits as key
-
- tte = replace = first_entry(posKey);
- for (int i = 0; i < ClusterSize; i++, tte++)
- {
- if (!tte->key() || tte->key() == posKey32) // empty or overwrite old
+ for (unsigned i = 0; i < TTClusterSize; ++i)
+ if (tte[i].key16 == key16)
{
- // Do not overwrite when new type is VALUE_TYPE_EVAL
- if (tte->key() && t == VALUE_TYPE_EVAL)
- return;
-
- if (m == MOVE_NONE)
- m = tte->move();
-
- *tte = TTEntry(posKey32, v, t, d, m, generation);
- return;
+ tte[i].genBound8 = uint8_t(generation | tte[i].bound()); // Refresh
+ return &tte[i];
}
- else if (i == 0) // replace would be a no-op in this common case
- continue;
-
- int c1 = (replace->generation() == generation ? 2 : 0);
- int c2 = (tte->generation() == generation ? -2 : 0);
- int c3 = (tte->depth() < replace->depth() ? 1 : 0);
-
- if (c1 + c2 + c3 > 0)
- replace = tte;
- }
- *replace = TTEntry(posKey32, v, t, d, m, generation);
- writes++;
-}
-
-
-/// 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 {
-
- 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::prefetch looks up the current position in the
-/// transposition table and load it in L1/L2 cache. This is a non
-/// blocking function and do not stalls the CPU waiting for data
-/// to be loaded from RAM, that can be very slow. When we will
-/// subsequently call retrieve() the TT data will be already
-/// quickly accessible in L1/l2 CPU cache.
-
-void TranspositionTable::prefetch(const Key posKey) const {
-
-#if defined(_MSC_VER)
- _mm_prefetch((char*)first_entry(posKey), _MM_HINT_T0);
-#else
- __builtin_prefetch((const void*)first_entry(posKey), 0, 3);
-#endif
-}
-
-
-/// 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.
+/// 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 in which cluster the position will be placed.
+/// When a new entry is written and there are no empty entries available in the
+/// cluster, it replaces the least valuable of the 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.
-void TranspositionTable::new_search() {
+void TranspositionTable::store(const Key key, Value v, Bound b, Depth d, Move m, Value statV) {
- generation++;
- writes = 0;
-}
+ TTEntry* const tte = first_entry(key);
+ const uint16_t key16 = key >> 48; // Use the high 16 bits as key inside the cluster
+ for (unsigned i = 0; i < TTClusterSize; ++i)
+ if (!tte[i].key16 || tte[i].key16 == key16) // Empty or overwrite old
+ {
+ // Save preserving any existing ttMove
+ tte[i].save(key16, v, b, d, m ? m : tte[i].move(), generation, statV);
+ return;
+ }
-/// TranspositionTable::insert_pv() is called at the end of a search
-/// iteration, and inserts the PV back into the PV. This makes sure
-/// the old PV moves are searched first, even if the old TT entries
-/// have been overwritten.
-
-void TranspositionTable::insert_pv(const Position& pos, Move pv[]) {
-
- StateInfo st;
- Position p(pos);
-
- for (int i = 0; pv[i] != MOVE_NONE; i++)
- {
- store(p.get_key(), VALUE_NONE, VALUE_TYPE_NONE, Depth(-127*OnePly), pv[i]);
- p.do_move(pv[i], st);
- }
-}
-
-
-/// TranspositionTable::extract_pv() extends a PV by adding moves from the
-/// transposition table at the end. This should ensure that the PV is almost
-/// always at least two plies long, which is important, because otherwise we
-/// will often get single-move PVs when the search stops while failing high,
-/// and a single-move PV means that we don't have a ponder move.
-
-void TranspositionTable::extract_pv(const Position& pos, Move pv[]) {
-
- int ply;
- Position p(pos);
- StateInfo st[100];
-
- for (ply = 0; pv[ply] != MOVE_NONE; ply++)
- p.do_move(pv[ply], st[ply]);
-
- bool stop;
- const TTEntry* tte;
- for (stop = false, tte = retrieve(p.get_key());
- tte && tte->move() != MOVE_NONE && !stop;
- tte = retrieve(p.get_key()), ply++)
- {
- if (!move_is_legal(p, tte->move()))
- break;
- pv[ply] = tte->move();
- p.do_move(pv[ply], st[ply]);
- for (int j = 0; j < ply; j++)
- if (st[j].key == p.get_key()) stop = true;
- }
- pv[ply] = MOVE_NONE;
-}
-
-
-/// TranspositionTable::full() returns the permill of all transposition table
-/// entries which have received at least one write during the current search.
-/// It is used to display the "info hashfull ..." information in UCI.
-
-int TranspositionTable::full() const {
+ // Implement replace strategy
+ TTEntry* replace = tte;
+ for (unsigned i = 1; i < TTClusterSize; ++i)
+ if ( (( tte[i].genBound8 & 0xFC) == generation || tte[i].bound() == BOUND_EXACT)
+ - ((replace->genBound8 & 0xFC) == generation)
+ - (tte[i].depth8 < replace->depth8) < 0)
+ replace = &tte[i];
- double N = double(size) * ClusterSize;
- return int(1000 * (1 - exp(writes * log(1.0 - 1.0/N))));
+ replace->save(key16, v, b, d, m, generation, statV);
}
projects / stockfish / blobdiff