/// the 32 bits of the data field are so defined
///
/// bit 0-16: move
-/// bit 17-19: not used
-/// bit 20-22: value type
+/// bit 17-20: not used
+/// bit 21-22: value type
/// bit 23-31: generation
class TTEntry {
void save(uint32_t k, Value v, ValueType t, Depth d, Move m, int g, Value statV, Value kd) {
key32 = k;
- data = (m & 0x1FFFF) | (t << 20) | (g << 23);
+ data = (m & 0x1FFFF) | (t << 21) | (g << 23);
value16 = int16_t(v);
depth16 = int16_t(d);
staticValue = int16_t(statV);
Depth depth() const { return Depth(depth16); }
Move move() const { return Move(data & 0x1FFFF); }
Value value() const { return Value(value16); }
- ValueType type() const { return ValueType((data >> 20) & 7); }
+ ValueType type() const { return ValueType((data >> 21) & 3); }
int generation() const { return data >> 23; }
Value static_value() const { return Value(staticValue); }
Value king_danger() const { return Value(kingDanger); }
};
-/// This is the number of TTEntry slots for each position
+/// This is the number of TTEntry slots for each cluster
const int ClusterSize = 4;
-/// Each group of ClusterSize number of TTEntry form a TTCluster
-/// that is indexed by a single position key. TTCluster size must
-/// be not bigger then a cache line size, in case it is less then
-/// it should be padded to guarantee always aligned accesses.
+/// TTCluster consists of ClusterSize number of TTEntries.
+/// Size of TTCluster must not be bigger than a cache line size.
+/// In case it is less, it should be padded to guarantee always aligned accesses.
struct TTCluster {
TTEntry data[ClusterSize];
/// The transposition table class. This is basically just a huge array
-/// containing TTEntry objects, and a few methods for writing new entries
+/// containing TTCluster objects, and a few methods for writing new entries
/// and reading new ones.
class TranspositionTable {
/// TranspositionTable::first_entry returns a pointer to the first
-/// entry of a cluster given a position. The low 32 bits of the key
-/// are used to get the index in the table.
+/// entry of a cluster given a position. The lowest order bits of the key
+/// are used to get the index of the cluster.
inline TTEntry* TranspositionTable::first_entry(const Key posKey) const {