X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftt.cpp;h=9dbfcb5ac92e5fada772fd8c20a74a4a41921c63;hp=f598e3bf1318d4a57e7368d5e9b18a284f86e56b;hb=55bd27b8f08a151128d7065fa2819aa3e9605299;hpb=927f1b0bd30a5b2cfdcdf163f26f528738509064
diff --git a/src/tt.cpp b/src/tt.cpp
index f598e3bf..9dbfcb5a 100644
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -1,7 +1,7 @@
/*
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
+ Copyright (C) 2008-2012 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
@@ -17,29 +17,18 @@
along with this program. If not, see .
*/
-
-////
-//// Includes
-////
-
-#include
#include
#include
+#include "bitboard.h"
#include "tt.h"
-// The main transposition table
-TranspositionTable TT;
-
-////
-//// Functions
-////
+TranspositionTable TT; // Our global transposition table
TranspositionTable::TranspositionTable() {
- size = 0;
- entries = 0;
- generation = 0;
+ size = generation = 0;
+ entries = NULL;
}
TranspositionTable::~TranspositionTable() {
@@ -48,19 +37,14 @@ TranspositionTable::~TranspositionTable() {
}
-/// 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) {
- size_t 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 and newSize is the number of
- // clusters we are going to allocate.
- while (2ULL * newSize * sizeof(TTCluster) <= (mbSize << 20))
- newSize *= 2;
+ size_t newSize = 1ULL << msb((mbSize << 20) / sizeof(TTCluster));
if (newSize == size)
return;
@@ -68,20 +52,21 @@ void TranspositionTable::set_size(size_t mbSize) {
size = newSize;
delete [] entries;
entries = new (std::nothrow) TTCluster[size];
+
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
+/// 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 received?
void TranspositionTable::clear() {
@@ -89,23 +74,22 @@ void TranspositionTable::clear() {
}
-/// 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.
+/// 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.
+/// 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 Key posKey, Value v, ValueType t, Depth d, Move m, Value statV, Value kingD) {
+void TranspositionTable::store(const Key posKey, Value v, Bound 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
+ uint32_t posKey32 = posKey >> 32; // Use the high 32 bits as key inside the cluster
tte = replace = first_entry(posKey);
+
for (int i = 0; i < ClusterSize; i++, tte++)
{
if (!tte->key() || tte->key() == posKey32) // Empty or overwrite old
@@ -118,12 +102,9 @@ void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d,
return;
}
- // Replacing first entry is default and already set before entering for-loop
- if (i == 0)
- continue;
-
+ // Implement replace strategy
c1 = (replace->generation() == generation ? 2 : 0);
- c2 = (tte->generation() == generation ? -2 : 0);
+ c2 = (tte->generation() == generation || tte->type() == BOUND_EXACT ? -2 : 0);
c3 = (tte->depth() < replace->depth() ? 1 : 0);
if (c1 + c2 + c3 > 0)
@@ -133,11 +114,11 @@ void TranspositionTable::store(const Key posKey, Value v, ValueType t, Depth d,
}
-/// TranspositionTable::retrieve looks up the current position in the
-/// transposition table. Returns a pointer to the TTEntry or NULL
-/// if position is not found.
+/// TranspositionTable::probe() 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 {
+TTEntry* TranspositionTable::probe(const Key posKey) const {
uint32_t posKey32 = posKey >> 32;
TTEntry* tte = first_entry(posKey);