/// A TranspositionTable is an array of Cluster, of size clusterCount. Each
/// cluster consists of ClusterSize number of TTEntry. Each non-empty TTEntry
/// contains information on exactly one position. The size of a Cluster should
-/// divide the size of a cache line for best performance,
-/// as the cacheline is prefetched when possible.
+/// divide the size of a cache line for best performance, as the cacheline is
+/// prefetched when possible.
class TranspositionTable {
static constexpr int ClusterSize = 3;
- static constexpr int ClustersPerSuperCluster = 256;
struct Cluster {
TTEntry entry[ClusterSize];
void clear();
TTEntry* first_entry(const Key key) const {
-
- // 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];
+ return &table[mul_hi64(key, clusterCount)].entry[0];
}
private:
friend struct TTEntry;
- size_t superClusterCount;
+ size_t clusterCount;
Cluster* table;
void* mem;
uint8_t generation8; // Size must be not bigger than TTEntry::genBound8