core/src/main/java/com/orientechnologies/orient/core/storage/cache/chm/FrequencySketch.java
private int indexOf(final int item, final int i) {
    long hash = SEED[i] * item;
    hash += hash >> 32;
    return ((int) hash) & tableMask;
  }
private int indexOf(final int item, final int i) {
    long hash = SEED[i] * item;
    hash += hash >> 32;
    return ((int) hash) & tableMask;
  }
Returns the table index for the counter at the specified depth.

@param item the element's hash
@param i    the counter depth

@return the table index