void save(Key k, Value v, Bound b, Depth d, Move m, Value ev, uint8_t g) {
- if (m || (k >> 48) != key16) // Preserve any existing move for the same position
+ // Preserve any existing move for the same position
+ if (m || (k >> 48) != key16)
move16 = (uint16_t)m;
- key16 = (uint16_t)(k >> 48);
- value16 = (int16_t)v;
- eval16 = (int16_t)ev;
- genBound8 = (uint8_t)(g | b);
- depth8 = (int8_t)d;
+ // Don't overwrite more valuable entries
+ if ( (k >> 48) != key16
+ || d > depth8 - 2
+ /* || g != (genBound8 & 0xFC) // Matching non-zero keys are already refreshed by probe() */
+ || b == BOUND_EXACT)
+ {
+ key16 = (uint16_t)(k >> 48);
+ value16 = (int16_t)v;
+ eval16 = (int16_t)ev;
+ genBound8 = (uint8_t)(g | b);
+ depth8 = (int8_t)d;
+ }
}
private:
/// A TranspositionTable consists of a power of 2 number of clusters and each
-/// cluster consists of TTClusterSize number of TTEntry. Each non-empty entry
+/// cluster consists of ClusterSize number of TTEntry. Each non-empty entry
/// contains information of exactly one position. The size of a cluster should
/// not be bigger than a cache line size. In case it is less, it should be padded
/// to guarantee always aligned accesses.
class TranspositionTable {
static const int CacheLineSize = 64;
- static const int TTClusterSize = 3;
+ static const int ClusterSize = 3;
struct Cluster {
- TTEntry entry[TTClusterSize];
+ TTEntry entry[ClusterSize];
char padding[2]; // Align to the cache line size
};
+ static_assert(sizeof(Cluster) == CacheLineSize / 2, "Cluster size incorrect");
+
public:
~TranspositionTable() { free(mem); }
void new_search() { generation8 += 4; } // Lower 2 bits are used by Bound
uint8_t generation() const { return generation8; }
TTEntry* probe(const Key key, bool& found) const;
+ int hashfull() const;
void resize(size_t mbSize);
void clear();