/// measured in megabytes. Transposition table consists of a power of 2 number
/// of clusters and each cluster consists of TTClusterSize number of TTEntry.
-void TranspositionTable::resize(uint64_t mbSize) {
+void TranspositionTable::resize(size_t mbSize) {
- assert(msb((mbSize * 1024 * 1024) / sizeof(TTCluster)) < 32);
-
- uint32_t newClusterCount = 1 << msb((mbSize * 1024 * 1024) / sizeof(TTCluster));
+ size_t newClusterCount = size_t(1) << msb((mbSize * 1024 * 1024) / sizeof(TTCluster));
if (newClusterCount == clusterCount)
return;
/// TranspositionTable::clear() overwrites the entire transposition table
-/// with zeroes. It is called whenever the table is resized, or when the
+/// with zeros. It is called whenever the table is resized, or when the
/// user asks the program to clear the table (from the UCI interface).
void TranspositionTable::clear() {
}
-/// TranspositionTable::probe() 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. It returns true and a pointer to the TTEntry if the position is found.
+/// Otherwise, it returns false and a pointer to an empty or least valuable TTEntry
+/// to be replaced later. 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.
-const TTEntry* TranspositionTable::probe(const Key key) const {
+TTEntry* TranspositionTable::probe(const Key key, bool& found) const {
- TTEntry* tte = first_entry(key);
- uint16_t key16 = key >> 48;
+ TTEntry* const tte = first_entry(key);
+ const uint16_t key16 = key >> 48; // Use the high 16 bits as key inside the cluster
- for (unsigned i = 0; i < TTClusterSize; ++i, ++tte)
- if (tte->key16 == key16)
+ for (unsigned i = 0; i < TTClusterSize; ++i)
+ if (!tte[i].key16 || tte[i].key16 == key16)
{
- tte->genBound8 = generation | tte->bound(); // Refresh
- return tte;
- }
-
- return NULL;
-}
-
-
-/// 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 in which cluster the position will be placed.
-/// When a new entry is written and there are no empty entries available in the
-/// cluster, it replaces the least valuable of the 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 key, Value v, Bound b, Depth d, Move m, Value statV) {
+ if (tte[i].key16)
+ tte[i].genBound8 = uint8_t(generation8 | tte[i].bound()); // Refresh
- TTEntry *tte, *replace;
- uint16_t key16 = key >> 48; // Use the high 16 bits as key inside the cluster
-
- tte = replace = first_entry(key);
-
- for (unsigned i = 0; i < TTClusterSize; ++i, ++tte)
- {
- if (!tte->key16 || tte->key16 == key16) // Empty or overwrite old
- {
- if (!m)
- m = tte->move(); // Preserve any existing ttMove
-
- replace = tte;
- break;
+ return found = (bool)tte[i].key16, &tte[i];
}
- // Implement replace strategy
- if ( (( tte->genBound8 & 0xFC) == generation || tte->bound() == BOUND_EXACT)
- - ((replace->genBound8 & 0xFC) == generation)
- - (tte->depth8 < replace->depth8) < 0)
- replace = tte;
- }
+ // Find an entry to be replaced according to the replacement strategy
+ TTEntry* replace = tte;
+ for (unsigned i = 1; i < TTClusterSize; ++i)
+ if ( (( tte[i].genBound8 & 0xFC) == generation8 || tte[i].bound() == BOUND_EXACT)
+ - ((replace->genBound8 & 0xFC) == generation8)
+ - (tte[i].depth8 < replace->depth8) < 0)
+ replace = &tte[i];
- replace->save(key16, v, b, d, m, generation, statV);
+ return found = false, replace;
}