/*
- 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 Marco Costalba
- 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 <cassert>
#include <cmath>
+#include <cstring>
#include "tt.h"
/// Constructor
TranspositionTable::TranspositionTable(unsigned mbSize) {
+
size = 0;
generation = 0;
writes = 0;
entries = 0;
- this->set_size(mbSize);
+ set_size(mbSize);
}
/// Destructor
TranspositionTable::~TranspositionTable() {
+
delete [] entries;
}
/// measured in megabytes.
void TranspositionTable::set_size(unsigned mbSize) {
- unsigned newSize;
assert(mbSize >= 4 && mbSize <= 1024);
- for(newSize = 1024; newSize * 4 * (sizeof(TTEntry)) <= (mbSize << 20);
- newSize *= 2);
- newSize /= 2;
+ unsigned newSize = 1024;
- if(newSize != 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)
+ {
size = newSize;
delete [] entries;
entries = new TTEntry[size * 4];
- if(entries == NULL) {
+ if (!entries)
+ {
std::cerr << "Failed to allocate " << mbSize
<< " MB for transposition table."
<< std::endl;
exit(EXIT_FAILURE);
}
- this->clear();
+ clear();
}
}
/// Perhaps we should also clear it when the "ucinewgame" command is recieved?
void TranspositionTable::clear() {
+
memset(entries, 0, size * 4 * sizeof(TTEntry));
}
/// 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.
+/// 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 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;
+ 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;
+
+ if (m == MOVE_NONE)
+ m = tte->move();
+
+ *tte = 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;
+ 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++;
/// 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.
-
-bool TranspositionTable::retrieve(const Position &pos, Value *value,
- Depth *d, Move *move,
- ValueType *type) const {
- TTEntry *tte;
- bool found = false;
-
- tte = entries + int(pos.get_key() & (size - 1)) * 4;
- for(int i = 0; i < 4 && !found ; i++)
- if((tte+i)->key() == pos.get_key()) {
- tte = tte + i;
- found = true;
- }
- if(!found) {
- *move = MOVE_NONE;
- return false;
- }
+/// transposition table. Returns a pointer to the TTEntry or NULL
+/// if position is not found.
- *value = tte->value();
- *type = tte->type();
- *d = tte->depth();
- *move = tte->move();
+TTEntry* TranspositionTable::retrieve(const Position &pos) const {
- return true;
+ TTEntry *tte = first_entry(pos);
+
+ for (int i = 0; i < 4; i++, tte++)
+ {
+ if (tte->key() == pos.get_key())
+ 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);
+}
+
/// 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::insert_pv() is called at the end of a search
+/// 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;
+
+ StateInfo st;
Position p(pos);
- for(int i = 0; pv[i] != MOVE_NONE; i++) {
- this->store(p, VALUE_NONE, Depth(0), pv[i], VALUE_TYPE_NONE);
- p.do_move(pv[i], u);
+ for (int i = 0; pv[i] != MOVE_NONE; i++)
+ {
+ store(p, VALUE_NONE, Depth(-127*OnePly), pv[i], VALUE_TYPE_NONE);
+ p.do_move(pv[i], st);
}
}
/// 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))));
}
}
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);
-}
-
-
-/// Functions for extracting data from TTEntry objects.
-
-Key TTEntry::key() const {
- return key_;
-}
-
-Depth TTEntry::depth() const {
- return Depth(depth_);
-}
-
-Move TTEntry::move() const {
- return Move(data & 0x7FFFF);
-}
-
-Value TTEntry::value() const {
- return Value(value_);
-}
-
-ValueType TTEntry::type() const {
- return ValueType((data >> 20) & 3);
-}
-
-int TTEntry::generation() const {
- return (data >> 23);
-}
+ int generation) :
+ key_ (k), data((m & 0x1FFFF) | (t << 20) | (generation << 23)),
+ value_(int16_t(v)), depth_(int16_t(d)) {}
projects / stockfish / blobdiff