class TranspositionTable {
static constexpr int ClusterSize = 3;
+ static constexpr int ClustersPerSuperCluster = 256;
struct Cluster {
TTEntry entry[ClusterSize];
void resize(size_t mbSize);
void clear();
- // The 32 lowest order bits of the key are used to get the index of the cluster
TTEntry* first_entry(const Key key) const {
- return &table[(uint32_t(key) * uint64_t(clusterCount)) >> 32].entry[0];
+
+ // The index is computed from
+ // Idx = (K48 * SCC) / 2^40, with K48 the 48 lowest bits swizzled.
+
+ const uint64_t firstTerm = uint32_t(key) * uint64_t(superClusterCount);
+ const uint64_t secondTerm = (uint16_t(key >> 32) * uint64_t(superClusterCount)) >> 16;
+
+ return &table[(firstTerm + secondTerm) >> 24].entry[0];
}
private:
friend struct TTEntry;
- size_t clusterCount;
+ size_t superClusterCount;
Cluster* table;
void* mem;
uint8_t generation8; // Size must be not bigger than TTEntry::genBound8