/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008 Marco Costalba
+ Copyright (C) 2008-2013 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 "bitboard.h"
#include "tt.h"
+TranspositionTable TT; // Our global transposition table
-////
-//// Functions
-////
-
-/// Constructor
-
-TranspositionTable::TranspositionTable(unsigned mbSize) {
-
- size = 0;
- generation = 0;
- writes = 0;
- entries = 0;
- set_size(mbSize);
-}
-
-
-/// Destructor
-TranspositionTable::~TranspositionTable() {
-
- delete [] entries;
-}
+/// TranspositionTable::set_size() 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::set_size(size_t mbSize) {
-/// TranspositionTable::set_size sets the size of the transposition table,
-/// measured in megabytes.
+ assert(msb((mbSize << 20) / sizeof(TTEntry)) < 32);
-void TranspositionTable::set_size(unsigned mbSize) {
+ uint32_t size = ClusterSize << msb((mbSize << 20) / sizeof(TTEntry[ClusterSize]));
- assert(mbSize >= 4 && mbSize <= 1024);
+ if (hashMask == size - ClusterSize)
+ return;
- unsigned newSize = 1024;
+ hashMask = size - ClusterSize;
+ free(mem);
+ mem = calloc(size * sizeof(TTEntry) + CACHE_LINE_SIZE - 1, 1);
- // We store a cluster of 4 TTEntry for each position and newSize is
- // the maximum number of storable positions
- for ( ; newSize * 4 * (sizeof(TTEntry)) <= (mbSize << 20); newSize *= 2);
- newSize /= 2;
- if (newSize != size)
+ if (!mem)
{
- size = newSize;
- delete [] entries;
- entries = new TTEntry[size * 4];
- if (!entries)
- {
std::cerr << "Failed to allocate " << mbSize
- << " MB for transposition table."
- << std::endl;
+ << "MB for transposition table." << std::endl;
exit(EXIT_FAILURE);
- }
- clear();
}
+
+ table = (TTEntry*)((uintptr_t(mem) + CACHE_LINE_SIZE - 1) & ~(CACHE_LINE_SIZE - 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 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 * 4 * sizeof(TTEntry));
-}
-
-
-/// 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. The 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.
-
-TTEntry* TranspositionTable::store(const Position &pos, Value v, Depth d,
- Move m, ValueType type) {
- TTEntry *tte, *replace;
-
- tte = replace = first_entry(pos);
- for (int i = 0; i < 4; i++, tte++)
- {
- if (!tte->key() || tte->key() == pos.get_key()) // empty or overwrite old
- {
- // Do not overwrite position entry when VALUE_TYPE_EVAL
- if ( tte->key()
- && type == VALUE_TYPE_EVAL)
- return NULL;
-
- if (m == MOVE_NONE)
- m = tte->move();
-
- *tte = TTEntry(pos.get_key(), v, type, d, m, generation);
- return tte;
- }
- 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(pos.get_key(), v, type, d, m, generation);
- writes++;
- return replace;
+ std::memset(table, 0, (hashMask + ClusterSize) * sizeof(TTEntry));
}
-/// TranspositionTable::retrieve looks up the current position in the
-/// transposition table. Returns a pointer to the TTEntry or NULL
-/// if position is not found.
+/// TranspositionTable::probe() 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 Position &pos) const {
+const TTEntry* TranspositionTable::probe(const Key key) const {
- TTEntry *tte = first_entry(pos);
+ const TTEntry* tte = first_entry(key);
+ uint32_t key32 = key >> 32;
- for (int i = 0; i < 4; i++, tte++)
- {
- if (tte->key() == pos.get_key())
+ for (unsigned i = 0; i < ClusterSize; i++, tte++)
+ if (tte->key() == key32)
return tte;
- }
- return NULL;
-}
-
-
-/// TranspositionTable::first_entry returns a pointer to the first
-/// entry of a cluster given a position.
-inline TTEntry* TranspositionTable::first_entry(const Position &pos) const {
-
- return entries + (int(pos.get_key() & (size - 1)) << 2);
+ 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++;
- writes = 0;
-}
+/// 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::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::store(const Key key, Value v, Bound b, Depth d, Move m, Value statV, Value evalM) {
-void TranspositionTable::insert_pv(const Position &pos, Move pv[]) {
+ int c1, c2, c3;
+ TTEntry *tte, *replace;
+ uint32_t key32 = key >> 32; // Use the high 32 bits as key inside the cluster
- StateInfo st;
- Position p(pos);
+ tte = replace = first_entry(key);
- for (int i = 0; pv[i] != MOVE_NONE; i++)
+ for (unsigned i = 0; i < ClusterSize; i++, tte++)
{
- store(p, VALUE_NONE, Depth(-127*OnePly), pv[i], VALUE_TYPE_NONE);
- p.do_move(pv[i], st);
+ if (!tte->key() || tte->key() == key32) // Empty or overwrite old
+ {
+ if (!m)
+ m = tte->move(); // Preserve any existing ttMove
+
+ replace = tte;
+ break;
+ }
+
+ // Implement replace strategy
+ c1 = (replace->generation() == generation ? 2 : 0);
+ c2 = (tte->generation() == generation || tte->bound() == BOUND_EXACT ? -2 : 0);
+ c3 = (tte->depth() < replace->depth() ? 1 : 0);
+
+ if (c1 + c2 + c3 > 0)
+ replace = tte;
}
-}
-
-
-/// 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() {
- double N = double(size) * 4.0;
- return int(1000 * (1 - exp(writes * log(1.0 - 1.0/N))));
+ replace->save(key32, v, b, d, m, generation, statV, evalM);
}
-
-
-/// Constructors
-
-TTEntry::TTEntry() {
-}
-
-TTEntry::TTEntry(Key k, Value v, ValueType t, Depth d, Move m,
- int generation) :
- key_ (k), data((m & 0x1FFFF) | (t << 20) | (generation << 23)),
- value_(int16_t(v)), depth_(int16_t(d)) {}
projects / stockfish / blobdiff