mg_ghost_cell_buffer_size Subroutine

  subroutine mg_ghost_cell_buffer_size(mg, n_send, n_recv, dsize)
    type(mg_t), intent(inout) :: mg
    integer, intent(out)      :: n_send(0:mg%n_cpu-1)
    integer, intent(out)      :: n_recv(0:mg%n_cpu-1)
    integer, intent(out)      :: dsize
    integer                   :: i, id, lvl, nc

    allocate(mg%comm_ghostcell%n_send(0:mg%n_cpu-1,&
        mg%first_normal_lvl:mg%highest_lvl))
    allocate(mg%comm_ghostcell%n_recv(0:mg%n_cpu-1,&
        mg%first_normal_lvl:mg%highest_lvl))

    dsize = mg%box_size**(3-1)

    do lvl = mg%first_normal_lvl, mg%highest_lvl
       nc               = mg%box_size_lvl(lvl)
       mg%buf(:)%i_send = 0
       mg%buf(:)%i_recv = 0
       mg%buf(:)%i_ix   = 0

       do i = 1, size(mg%lvls(lvl)%my_ids)
          id = mg%lvls(lvl)%my_ids(i)
          call buffer_ghost_cells(mg, id, nc, 1, dry_run=.true.)
       end do

       if (lvl > 1) then
          do i = 1, size(mg%lvls(lvl-1)%my_ref_bnds)
             id = mg%lvls(lvl-1)%my_ref_bnds(i)
             call buffer_refinement_boundaries(mg, id, nc, 1, dry_run=.true.)
          end do
       end if

       ! Set ghost cells to received data
       mg%buf(:)%i_recv = 0
       do i = 1, size(mg%lvls(lvl)%my_ids)
          id = mg%lvls(lvl)%my_ids(i)
          call set_ghost_cells(mg, id, nc, 1, dry_run=.true.)
       end do

       mg%comm_ghostcell%n_send(:, lvl) = mg%buf(:)%i_send/dsize
       mg%comm_ghostcell%n_recv(:, lvl) = mg%buf(:)%i_recv/dsize
    end do

    n_send = maxval(mg%comm_ghostcell%n_send, dim=2)
    n_recv = maxval(mg%comm_ghostcell%n_recv, dim=2)
  end subroutine mg_ghost_cell_buffer_size