bubble_up Subroutine

   SUBROUTINE bubble_up(heap, first, new_pos)
      !! Balances a heap by bubbling up from the given element.
      TYPE(dbcsr_heap_type), INTENT(INOUT)               :: heap
      INTEGER, INTENT(IN)                                :: first
      INTEGER, INTENT(OUT)                               :: new_pos

      INTEGER                                            :: e, parent
      INTEGER(kind=valt)                                 :: my_value, parent_value
      LOGICAL                                            :: all_done

      DBCSR_ASSERT(0 < first .AND. first <= heap%n)

      e = first
      all_done = .FALSE.
      IF (e .GT. 1) THEN
         my_value = get_value(heap, e)
      END IF
      ! Check whether we are finished, i.e,. whether the element to
      ! bubble up is an orphan.
      new_pos = e
      DO WHILE (e .GT. 1 .AND. .NOT. all_done)
         ! Switches the parent and the current element if the current
         ! element's value is greater than the parent's value.
         parent = get_parent(e)
         parent_value = get_value(heap, parent)
         IF (my_value .LT. parent_value) THEN
            CALL dbcsr_heap_swap(heap, e, parent)
            e = parent
         ELSE
            all_done = .TRUE.
         END IF
      END DO
      new_pos = e
   END SUBROUTINE bubble_up