/*
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) 2008-2010 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
#include <cmath>
#include <cstring>
+#include "movegen.h"
#include "tt.h"
+// The main transposition table
+TranspositionTable TT;
////
//// Functions
TranspositionTable::TranspositionTable() {
- size = writes = 0;
+ size = overwrites = 0;
entries = 0;
generation = 0;
}
/// 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 <= 4096);
+ size_t newSize = 1024;
- unsigned newSize = 1024;
-
- // We store a cluster of 4 TTEntry for each position and newSize is
- // the maximum number of storable positions
- while ((2 * newSize) * 4 * (sizeof(TTEntry)) <= (mbSize << 20))
+ // We store a cluster of ClusterSize number of TTEntry for each position
+ // and newSize is the maximum number of storable positions.
+ while ((2 * newSize) * sizeof(TTCluster) <= (mbSize << 20))
newSize *= 2;
if (newSize != size)
{
size = newSize;
delete [] entries;
- entries = new TTEntry[size * 4];
+ entries = new TTCluster[size];
if (!entries)
{
std::cerr << "Failed to allocate " << mbSize
void TranspositionTable::clear() {
- memset(entries, 0, size * 4 * sizeof(TTEntry));
+ memset(entries, 0, size * sizeof(TTCluster));
}
/// 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) {
+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(posKey);
- for (int i = 0; i < 4; i++, tte++)
+ for (int i = 0; i < ClusterSize; i++, tte++)
{
- if (!tte->key() || tte->key() == posKey) // empty or overwrite old
+ if (!tte->key() || tte->key() == posKey32) // empty or overwrite old
{
- // Do not overwrite when new type is VALUE_TYPE_EVAL
- if (tte->key() && t == VALUE_TYPE_EVAL)
- return;
-
+ // Preserve any exsisting ttMove
if (m == MOVE_NONE)
m = tte->move();
- *tte = TTEntry(posKey, v, t, d, m, generation);
+ tte->save(posKey32, v, t, d, m, generation, statV, kingD);
return;
}
- else if (i == 0) // replace would be a no-op in this common case
+
+ 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);
+ c1 = (replace->generation() == generation ? 2 : 0);
+ c2 = (tte->generation() == generation ? -2 : 0);
+ c3 = (tte->depth() < replace->depth() ? 1 : 0);
if (c1 + c2 + c3 > 0)
replace = tte;
}
- *replace = TTEntry(posKey, v, t, d, m, generation);
- writes++;
+ replace->save(posKey32, v, t, d, m, generation, statV, kingD);
+ overwrites++;
}
TTEntry* TranspositionTable::retrieve(const Key posKey) const {
- TTEntry *tte = first_entry(posKey);
+ uint32_t posKey32 = posKey >> 32;
+ TTEntry* tte = first_entry(posKey);
- for (int i = 0; i < 4; i++, tte++)
- if (tte->key() == posKey)
+ for (int i = 0; i < ClusterSize; i++, tte++)
+ if (tte->key() == posKey32)
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 Key posKey) const {
-
- return entries + (int(posKey & (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
void TranspositionTable::new_search() {
generation++;
- writes = 0;
+ overwrites = 0;
}
void TranspositionTable::insert_pv(const Position& pos, Move pv[]) {
StateInfo st;
- Position p(pos);
+ Position p(pos, pos.thread());
for (int i = 0; pv[i] != MOVE_NONE; i++)
{
- store(p.get_key(), VALUE_NONE, VALUE_TYPE_NONE, Depth(-127*OnePly), pv[i]);
+ TTEntry *tte = retrieve(p.get_key());
+ if (!tte || tte->move() != pv[i])
+ store(p.get_key(), VALUE_NONE, VALUE_TYPE_NONE, Depth(-127*OnePly), pv[i], VALUE_NONE, VALUE_NONE);
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 bestMove, Move pv[], const int PLY_MAX) {
+
+ const TTEntry* tte;
+ StateInfo st;
+ Position p(pos, pos.thread());
+ int ply = 0;
+
+ assert(bestMove != MOVE_NONE);
+
+ pv[ply] = bestMove;
+ p.do_move(pv[ply++], st);
+
+ // Extract moves from TT when possible. We try hard to always
+ // get a ponder move, that's the reason of ply < 2 conditions.
+ while ( (tte = retrieve(p.get_key())) != NULL
+ && tte->move() != MOVE_NONE
+ && (tte->type() == VALUE_TYPE_EXACT || ply < 2)
+ && move_is_legal(p, tte->move())
+ && (!p.is_draw() || ply < 2)
+ && ply < PLY_MAX)
+ {
+ pv[ply] = tte->move();
+ p.do_move(pv[ply++], st);
+ }
+ 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.
+/// entries which have received at least one overwrite during the current search.
/// It is used to display the "info hashfull ..." information in UCI.
int TranspositionTable::full() const {
- double N = double(size) * 4.0;
- return int(1000 * (1 - exp(writes * log(1.0 - 1.0/N))));
+ double N = double(size) * ClusterSize;
+ return int(1000 * (1 - exp(overwrites * log(1.0 - 1.0/N))));
}
projects / stockfish / blobdiff