int MapA1D1D4[SQUARE_NB];
int MapKK[10][SQUARE_NB]; // [MapA1D1D4][SQUARE_NB]
-int Binomial[6][SQUARE_NB]; // [k][n] k elements from a set of n elements
+int Binomial[7][SQUARE_NB]; // [k][n] k elements from a set of n elements
int LeadPawnIdx[6][SQUARE_NB]; // [leadPawnsCnt][SQUARE_NB]
int LeadPawnsSize[6][4]; // [leadPawnsCnt][FILE_A..FILE_D]
fstat(fd, &statbuf);
*mapping = statbuf.st_size;
*baseAddress = mmap(nullptr, statbuf.st_size, PROT_READ, MAP_SHARED, fd, 0);
+ madvise(*baseAddress, statbuf.st_size, MADV_RANDOM);
::close(fd);
if (*baseAddress == MAP_FAILED) {
typedef std::tuple<Key, TBTable<WDL>*, TBTable<DTZ>*> Entry;
- static const int Size = 1 << 16; // 64K table, indexed by key's 16 lsb
+ static constexpr int Size = 1 << 12; // 4K table, indexed by key's 12 lsb
+ static constexpr int Overflow = 1; // Number of elements allowed to map to the last bucket
- Entry hashTable[Size];
+ Entry hashTable[Size + Overflow];
std::deque<TBTable<WDL>> wdlTable;
std::deque<TBTable<DTZ>> dtzTable;
void insert(Key key, TBTable<WDL>* wdl, TBTable<DTZ>* dtz) {
- Entry* entry = &hashTable[(uint32_t)key & (Size - 1)];
+ uint32_t homeBucket = (uint32_t)key & (Size - 1);
+ Entry entry = std::make_tuple(key, wdl, dtz);
// Ensure last element is empty to avoid overflow when looking up
- for ( ; entry - hashTable < Size - 1; ++entry)
- if (std::get<KEY>(*entry) == key || !std::get<WDL>(*entry)) {
- *entry = std::make_tuple(key, wdl, dtz);
+ for (uint32_t bucket = homeBucket; bucket < Size + Overflow - 1; ++bucket) {
+ Key otherKey = std::get<KEY>(hashTable[bucket]);
+ if (otherKey == key || !std::get<WDL>(hashTable[bucket])) {
+ hashTable[bucket] = entry;
return;
}
+
+ // Robin Hood hashing: If we've probed for longer than this element,
+ // insert here and search for a new spot for the other element instead.
+ uint32_t otherHomeBucket = (uint32_t)otherKey & (Size - 1);
+ if (otherHomeBucket > homeBucket) {
+ swap(entry, hashTable[bucket]);
+ key = otherKey;
+ homeBucket = otherHomeBucket;
+ }
+ }
std::cerr << "TB hash table size too low!" << std::endl;
exit(1);
}
Binomial[0][0] = 1;
for (int n = 1; n < 64; n++) // Squares
- for (int k = 0; k < 6 && k <= n; ++k) // Pieces
+ for (int k = 0; k < 7 && k <= n; ++k) // Pieces
Binomial[k][n] = (k > 0 ? Binomial[k - 1][n - 1] : 0)
+ (k < n ? Binomial[k ][n - 1] : 0);