-/// A template struct, used to generate MoveStats and CounterMoveHistoryStats:
-/// MoveStats store the move that refute a previous one.
-/// CounterMoveHistoryStats is like HistoryStats, but with two consecutive moves.
-/// Entries are stored using only the moving piece and destination square, hence
-/// two moves with different origin but same destination and piece will be
-/// considered identical.
-template<typename T>
-struct Stats {
- const T* operator[](Piece pc) const { return table[pc]; }
- T* operator[](Piece pc) { return table[pc]; }
- void clear() { std::memset(table, 0, sizeof(table)); }
- void update(Piece pc, Square to, Move m) { table[pc][to] = m; }
- void update(Piece pc, Square to, Value v) {
-
- table[pc][to] -= table[pc][to] * abs(int(v)) / 936;
- table[pc][to] += int(v) * 32;
+/// ButterflyHistory records how often quiet moves have been successful or
+/// unsuccessful during the current search, and is used for reduction and move
+/// ordering decisions. It uses ButterflyBoards as backing store.
+struct ButterflyHistory : public ButterflyBoards {
+
+ void update(Color c, Move m, int bonus) {
+ StatBoards::update((*this)[c][from_to(m)], bonus, 324);