/*
- 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) 2008-2010 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.
////
#include <cassert>
-#include <cmath>
+#include <cstring>
+#include <iostream>
#include "tt.h"
+// The main transposition table
+TranspositionTable TT;
////
//// Functions
////
-/// Constructor
-
-TranspositionTable::TranspositionTable(unsigned mbSize) {
+TranspositionTable::TranspositionTable() {
size = 0;
- generation = 0;
- writes = 0;
entries = 0;
- set_size(mbSize);
+ generation = 0;
}
-
-/// Destructor
-
TranspositionTable::~TranspositionTable() {
delete [] entries;
/// TranspositionTable::set_size sets the size of the transposition table,
/// measured in megabytes.
-void TranspositionTable::set_size(unsigned mbSize) {
+void TranspositionTable::set_size(size_t mbSize) {
- assert(mbSize >= 4 && mbSize <= 1024);
+ size_t newSize = 1024;
- unsigned newSize = 1024;
+ // Transposition table consists of clusters and
+ // each cluster consists of ClusterSize number of TTEntries.
+ // Each non-empty entry contains information of exactly one position.
+ // newSize is the number of clusters we are going to allocate.
+ while ((2 * newSize) * sizeof(TTCluster) <= (mbSize << 20))
+ newSize *= 2;
- // 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)
- {
- std::cerr << "Failed to allocate " << mbSize
- << " MB for transposition table."
- << std::endl;
- exit(EXIT_FAILURE);
- }
- clear();
+ size = newSize;
+ delete [] entries;
+ entries = new TTCluster[size];
+ if (!entries)
+ {
+ std::cerr << "Failed to allocate " << mbSize
+ << " MB for transposition table." << std::endl;
+ exit(EXIT_FAILURE);
+ }
+ clear();
}
}
/// TranspositionTable::clear overwrites the entire transposition table
-/// with zeroes. It is called whenever the table is resized, or when the
+/// 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?
+/// Perhaps we should also clear it when the "ucinewgame" command is received?
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
+/// 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) {
+void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d, Move m, Value statV, Value kingD) {
+
+ int c1, c2, c3;
TTEntry *tte, *replace;
+ uint32_t posKey32 = posKey >> 32; // Use the high 32 bits as key
- tte = replace = first_entry(pos);
- for (int i = 0; i < 4; i++)
+ tte = replace = first_entry(posKey);
+ for (int i = 0; i < ClusterSize; i++, tte++)
{
- if (!(tte+i)->key()) // still empty
- {
- *(tte+i) = TTEntry(pos.get_key(), v, type, d, m, generation);
- writes++;
- return;
- }
- if ((tte+i)->key() == pos.get_key()) // overwrite old
- {
- if (m == MOVE_NONE)
- m = (tte+i)->move();
-
- *(tte+i) = TTEntry(pos.get_key(), v, type, d, m, generation);
- return;
- }
- if ( i == 0 // already is (replace == tte+i), common case
- || replace->generation() < (tte+i)->generation())
- continue;
-
- if ( replace->generation() > (tte+i)->generation()
- || (tte+i)->depth() < replace->depth())
- replace = tte+i;
- }
- *replace = TTEntry(pos.get_key(), v, type, d, m, generation);
- writes++;
-}
+ if (!tte->key() || tte->key() == posKey32) // empty or overwrite old
+ {
+ // Preserve any existing ttMove
+ if (m == MOVE_NONE)
+ m = tte->move();
+ tte->save(posKey32, v, t, d, m, generation, statV, kingD);
+ return;
+ }
-/// 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.
+ if (i == 0) // Replacing first entry is default and already set before entering for-loop
+ continue;
-bool TranspositionTable::retrieve(const Position &pos, Value *value,
- Depth *d, Move *move,
- ValueType *type) const {
- TTEntry *tte = first_entry(pos);
+ c1 = (replace->generation() == generation ? 2 : 0);
+ c2 = (tte->generation() == generation ? -2 : 0);
+ c3 = (tte->depth() < replace->depth() ? 1 : 0);
- for (int i = 0; i < 4; i++)
- {
- tte += i;
- if (tte->key() == pos.get_key())
- {
- *value = tte->value();
- *type = tte->type();
- *d = tte->depth();
- *move = tte->move();
- return true;
- }
+ if (c1 + c2 + c3 > 0)
+ replace = tte;
}
- *move = MOVE_NONE;
- return false;
+ replace->save(posKey32, v, t, d, m, generation, statV, kingD);
}
-/// TranspositionTable::first_entry returns a pointer to the first
-/// entry of a cluster given a position.
+/// 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 {
-inline TTEntry* TranspositionTable::first_entry(const Position &pos) const {
+ uint32_t posKey32 = posKey >> 32;
+ TTEntry* tte = first_entry(posKey);
- return entries + (int(pos.get_key() & (size - 1)) << 2);
+ 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
+/// 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
-/// 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);
-
- 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);
- }
-}
-
-
-/// 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))));
-}
-
-
-/// Constructors
-
-TTEntry::TTEntry() {
-}
-
-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.
-
-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);
}