/*
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) 2008-2009 Marco Costalba
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"
+/// This is the number of TTEntry slots for each position
+static const int ClusterSize = 5;
+
+
////
//// Functions
////
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) * ClusterSize * (sizeof(TTEntry)) <= (mbSize << 20))
newSize *= 2;
if (newSize != size)
{
size = newSize;
delete [] entries;
- entries = new TTEntry[size * 4];
+ entries = new TTEntry[size * ClusterSize];
if (!entries)
{
std::cerr << "Failed to allocate " << mbSize
<< " MB for transposition table." << std::endl;
- exit(EXIT_FAILURE);
+ Application::exit_with_failure();
}
clear();
}
void TranspositionTable::clear() {
- memset(entries, 0, size * 4 * sizeof(TTEntry));
+ memset(entries, 0, size * ClusterSize * sizeof(TTEntry));
}
/// 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& p, Value v, ValueType t, Depth d, Move m) {
+void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d, Move m) {
TTEntry *tte, *replace;
+ uint32_t posKey32 = posKey >> 32; // Use the high 32 bits as key
- tte = replace = first_entry(p);
- for (int i = 0; i < 4; i++, tte++)
+ tte = replace = first_entry(posKey);
+ for (int i = 0; i < ClusterSize; i++, tte++)
{
- if (!tte->key() || tte->key() == p.get_key()) // 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)
if (m == MOVE_NONE)
m = tte->move();
- *tte = TTEntry(p.get_key(), v, t, d, m, generation);
+ *tte = TTEntry(posKey32, v, t, d, m, generation);
return;
}
else if (i == 0) // replace would be a no-op in this common case
if (c1 + c2 + c3 > 0)
replace = tte;
}
- *replace = TTEntry(p.get_key(), v, t, d, m, generation);
+ *replace = TTEntry(posKey32, v, t, d, m, generation);
writes++;
}
/// transposition table. Returns a pointer to the TTEntry or NULL
/// if position is not found.
-TTEntry* TranspositionTable::retrieve(const Position& pos) const {
+TTEntry* TranspositionTable::retrieve(const Key posKey) const {
- TTEntry *tte = first_entry(pos);
+ uint32_t posKey32 = posKey >> 32;
+ TTEntry *tte = first_entry(posKey);
- for (int i = 0; i < 4; i++, tte++)
- if (tte->key() == pos.get_key())
+ 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.
+/// entry of a cluster given a position. The low 32 bits of the key
+/// are used to get the index in the table.
-inline TTEntry* TranspositionTable::first_entry(const Position& pos) const {
+inline TTEntry* TranspositionTable::first_entry(const Key posKey) const {
- return entries + (int(pos.get_key() & (size - 1)) << 2);
+ return entries + ((uint32_t(posKey) & (size - 1)) * ClusterSize);
}
/// TranspositionTable::new_search() is called at the beginning of every new
for (int i = 0; pv[i] != MOVE_NONE; i++)
{
- store(p, VALUE_NONE, VALUE_TYPE_NONE, Depth(-127*OnePly), pv[i]);
+ store(p.get_key(), VALUE_NONE, VALUE_TYPE_NONE, Depth(-127*OnePly), pv[i]);
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 pv[]) {
+
+ int ply;
+ Position p(pos);
+ StateInfo st[100];
+
+ for (ply = 0; pv[ply] != MOVE_NONE; ply++)
+ p.do_move(pv[ply], st[ply]);
+
+ bool stop;
+ const TTEntry* tte;
+ for (stop = false, tte = retrieve(p.get_key());
+ tte && tte->move() != MOVE_NONE && !stop;
+ tte = retrieve(p.get_key()), ply++)
+ {
+ if (!move_is_legal(p, tte->move()))
+ break;
+ pv[ply] = tte->move();
+ p.do_move(pv[ply], st[ply]);
+ for (int j = 0; j < ply; j++)
+ if (st[j].key == p.get_key()) stop = true;
+ }
+ 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.
/// It is used to display the "info hashfull ..." information in UCI.
int TranspositionTable::full() const {
- double N = double(size) * 4.0;
+ double N = double(size) * ClusterSize;
return int(1000 * (1 - exp(writes * log(1.0 - 1.0/N))));
}
projects / stockfish / blobdiff