#include <cstring>
#include <iostream>
+#include "bitboard.h"
#include "tt.h"
TranspositionTable TT; // Our global transposition table
-TranspositionTable::TranspositionTable() {
-
- size = generation = 0;
- entries = NULL;
-}
-
-TranspositionTable::~TranspositionTable() {
-
- delete [] entries;
-}
-
/// TranspositionTable::set_size() sets the size of the transposition table,
-/// measured in megabytes.
+/// measured in megabytes. Transposition table consists of a power of 2 number
+/// of clusters and each cluster consists of ClusterSize number of TTEntry.
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(TTEntry[ClusterSize]));
if (newSize == size)
return;
size = newSize;
delete [] entries;
- entries = new (std::nothrow) TTCluster[size];
+ entries = new (std::nothrow) TTEntry[size * ClusterSize];
+
if (!entries)
{
std::cerr << "Failed to allocate " << mbSize
<< "MB for transposition table." << std::endl;
exit(EXIT_FAILURE);
}
- clear();
+
+ clear(); // Operator new is not guaranteed to initialize memory to zero
}
void TranspositionTable::clear() {
- memset(entries, 0, size * sizeof(TTCluster));
+ memset(entries, 0, size * sizeof(TTEntry[ClusterSize]));
}
/// 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, Bound t, Depth d, Move m, Value statV, Value kingD) {
+void TranspositionTable::store(const Key key, 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 inside the cluster
+ uint32_t key32 = key >> 32; // Use the high 32 bits as key inside the cluster
- tte = replace = first_entry(posKey);
+ tte = replace = first_entry(key);
- for (int i = 0; i < ClusterSize; i++, tte++)
+ for (unsigned i = 0; i < ClusterSize; i++, tte++)
{
- if (!tte->key() || tte->key() == posKey32) // Empty or overwrite old
+ if (!tte->key() || tte->key() == key32) // 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);
+ tte->save(key32, v, t, d, m, generation, statV, kingD);
return;
}
if (c1 + c2 + c3 > 0)
replace = tte;
}
- replace->save(posKey32, v, t, d, m, generation, statV, kingD);
+ replace->save(key32, v, t, d, m, generation, statV, kingD);
}
/// transposition table. Returns a pointer to the TTEntry or NULL if
/// position is not found.
-TTEntry* TranspositionTable::probe(const Key posKey) const {
+TTEntry* TranspositionTable::probe(const Key key) const {
- uint32_t posKey32 = posKey >> 32;
- TTEntry* tte = first_entry(posKey);
+ TTEntry* tte = first_entry(key);
+ uint32_t key32 = key >> 32;
- for (int i = 0; i < ClusterSize; i++, tte++)
- if (tte->key() == posKey32)
+ for (unsigned i = 0; i < ClusterSize; i++, tte++)
+ if (tte->key() == key32)
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
-/// distinguish transposition table entries from previous searches from
-/// entries from the current search.
-
-void TranspositionTable::new_search() {
- generation++;
-}