/*
- Glaurung, a UCI chess playing engine.
- Copyright (C) 2004-2008 Tord Romstad
+ Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+ Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+ Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
- Glaurung is free software: you can redistribute it and/or modify
+ Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
-
- Glaurung is distributed in the hope that it will be useful,
+
+ Stockfish is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
-
+
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <cstring>
+#include <iostream>
-////
-//// Includes
-////
-
-#include <cassert>
-#include <cmath>
-
+#include "bitboard.h"
#include "tt.h"
+TranspositionTable TT; // Our global transposition table
-////
-//// Functions
-////
+TranspositionTable::TranspositionTable() {
-/// Constructor
-
-TranspositionTable::TranspositionTable(unsigned mbSize) {
-
- size = 0;
- generation = 0;
- writes = 0;
- entries = 0;
- set_size(mbSize);
+ size = generation = 0;
+ entries = NULL;
}
-
-/// Destructor
-
TranspositionTable::~TranspositionTable() {
delete [] entries;
}
-/// TranspositionTable::set_size sets the size of the transposition table,
-/// measured in megabytes.
+/// TranspositionTable::set_size() sets the size of the transposition table,
+/// measured in megabytes. Transposition table consists of a power of 2 number of
+/// TTCluster and each cluster consists of ClusterSize number of TTEntries. Each
+/// non-empty entry contains information of exactly one position.
+
+void TranspositionTable::set_size(size_t mbSize) {
-void TranspositionTable::set_size(unsigned mbSize) {
+ size_t newSize = 1ULL << msb((mbSize << 20) / sizeof(TTCluster));
- assert(mbSize >= 4 && mbSize <= 1024);
+ if (newSize == size)
+ return;
- unsigned newSize = 1024;
+ size = newSize;
+ delete [] entries;
+ entries = new (std::nothrow) TTCluster[size];
- // 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 (!entries)
{
- 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();
}
+
+ clear(); // Operator new is not guaranteed to initialize memory to zero
}
-/// 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));
+ memset(entries, 0, size * sizeof(TTCluster));
}
-/// 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.
+/// 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.
-void TranspositionTable::store(const Position &pos, Value v, Depth d,
- Move m, ValueType type) {
- TTEntry *tte, *replace;
-
- tte = replace = entries + int(pos.get_key() & (size - 1)) * 4;
- for (int i = 0; i < 4; i++)
- {
- if ((tte+i)->key() == pos.get_key())
- {
- if (m == MOVE_NONE)
- m = (tte+i)->move();
-
- *(tte+i) = TTEntry(pos.get_key(), v, type, d, m, generation);
- return;
- }
- if (replace->generation() == generation)
- {
- if ((tte+i)->generation() != generation || (tte+i)->depth() < replace->depth())
- replace = tte+i;
- }
- else if ((tte+i)->generation() != generation && (tte+i)->depth() < replace->depth())
- replace = tte+i;
- }
- *replace = TTEntry(pos.get_key(), v, type, d, m, generation);
- writes++;
-}
+void TranspositionTable::store(const Key posKey, Value v, Bound b, Depth d, Move m) {
+ int c1, c2, c3;
+ TTEntry *tte, *replace;
+ uint32_t posKey32 = posKey >> 32; // Use the high 32 bits as key inside the cluster
-/// TranspositionTable::retrieve looks up the current position in the
-/// transposition table, and extracts the value, value type, depth and
-/// best move if the position is found. The return value is true if
-/// the position is found, and false if it isn't.
+ tte = replace = first_entry(posKey);
-bool TranspositionTable::retrieve(const Position &pos, Value *value,
- Depth *d, Move *move,
- ValueType *type) const {
- TTEntry *tte;
- bool found = false;
+ for (int i = 0; i < ClusterSize; i++, tte++)
+ {
+ if (!tte->key())
+ tte->save(posKey32, v, b, d, m, generation);
- tte = entries + int(pos.get_key() & (size - 1)) * 4;
- for (int i = 0; i < 4 && !found ; i++)
- if ((tte+i)->key() == pos.get_key())
+ if (tte->key() == posKey32)
{
- tte = tte + i;
- found = true;
- }
- if (!found) {
- *move = MOVE_NONE;
- return false;
- }
- *value = tte->value();
- *type = tte->type();
- *d = tte->depth();
- *move = tte->move();
- return true;
-}
-
-
-/// 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;
-}
+ // Preserve any existing ttMove
+ if (m == MOVE_NONE)
+ m = tte->move();
+ tte->update(v, b, d, m, generation);
+ 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[]) {
-
- UndoInfo u;
- Position p(pos);
+ // Implement replace strategy
+ c1 = (replace->generation() == generation ? 2 : 0);
+ c2 = (tte->generation() == generation || tte->type() == BOUND_EXACT ? -2 : 0);
+ c3 = (tte->depth() < replace->depth() ? 1 : 0);
- for (int i = 0; pv[i] != MOVE_NONE; i++)
- {
- store(p, VALUE_NONE, Depth(0), pv[i], VALUE_TYPE_NONE);
- p.do_move(pv[i], u);
+ if (c1 + c2 + c3 > 0)
+ replace = tte;
}
+ replace->save(posKey32, v, b, d, m, generation);
}
-/// 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() {
+/// TranspositionTable::probe() looks up the current position in the
+/// transposition table. Returns a pointer to the TTEntry or NULL if
+/// position is not found.
- double N = double(size) * 4.0;
- return int(1000 * (1 - exp(writes * log(1.0 - 1.0/N))));
-}
+TTEntry* TranspositionTable::probe(const Key posKey) const {
+ uint32_t posKey32 = posKey >> 32;
+ TTEntry* tte = first_entry(posKey);
-/// Constructors
+ for (int i = 0; i < ClusterSize; i++, tte++)
+ if (tte->key() == posKey32)
+ return tte;
-TTEntry::TTEntry() {
+ return NULL;
}
-TTEntry::TTEntry(Key k, Value v, ValueType t, Depth d, Move m,
- int generation) {
- key_ = k;
- data = (m & 0x7FFFF) | (t << 20) | (generation << 23);
- value_ = v;
- depth_ = int16_t(d);
-}
+/// 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.
-/// Functions for extracting data from TTEntry objects.
-
-inline Key TTEntry::key() const {
- return key_;
-}
-
-inline Depth TTEntry::depth() const {
- return Depth(depth_);
-}
-
-inline Move TTEntry::move() const {
- return Move(data & 0x7FFFF);
-}
-
-inline Value TTEntry::value() const {
- return Value(value_);
-}
-
-inline ValueType TTEntry::type() const {
- return ValueType((data >> 20) & 3);
-}
-
-inline int TTEntry::generation() const {
- return (data >> 23);
+void TranspositionTable::new_search() {
+ generation++;
}
projects / stockfish / blobdiff