read_parameters Subroutine

  subroutine read_parameters(fields_config_in)
    use file_utils, only: input_unit, error_unit, input_unit_exist
    use text_options, only: text_option, get_option_value
    use fields_implicit, only: field_subgath
    use fields_local, only: minNRow
    use fields_local, only: do_smart_update, field_local_allreduce, field_local_allreduce_sub
    use fields_local, only: field_local_tuneminnrow,  field_local_nonblocking_collectives
    use fields_arrays, only: real_response_file => response_file
    use file_utils, only: run_name
    implicit none
    type(fields_config_type), intent(in), optional :: fields_config_in    
    character(20) :: field_option
    character(len=256) :: response_dir
    character(len=256) :: response_file
    integer :: ierr, ind_slash

    if (present(fields_config_in)) fields_config = fields_config_in

    call fields_config%init(name = 'fields_knobs', requires_index = .false.)

    ! Copy out internal values into module level parameters
    do_smart_update = fields_config%do_smart_update
    dump_response = fields_config%dump_response
    field_local_allreduce = fields_config%field_local_allreduce
    field_local_allreduce_sub = fields_config%field_local_allreduce_sub
    field_local_nonblocking_collectives = fields_config%field_local_nonblocking_collectives
    field_local_tuneminnrow = fields_config%field_local_tuneminnrow
    field_option = fields_config%field_option
    field_subgath = fields_config%field_subgath
    force_maxwell_reinit = fields_config%force_maxwell_reinit
    minnrow = fields_config%minnrow
    read_response = fields_config%read_response
    remove_zonal_flows_switch = fields_config%remove_zonal_flows_switch
    response_dir = fields_config%response_dir
    response_file = fields_config%response_file

    exist = fields_config%exist
    ierr = error_unit()
    call get_option_value &
         (field_option, fieldopts, fieldopt_switch, &
         ierr, "field_option in fields_knobs",.true.)

    if (trim(response_file) == '') then
       response_file = trim(run_name)
    end if

    if(trim(response_dir).eq.'')then
       write(real_response_file,'(A)') trim(response_file)
    else
       ! Need to check if resopnse_file has a directory path in it
       ! to ensure we merge with response_dir correctly. For example,
       ! consider response_file = '../../run/input' and response_dir = 'resp'.
       ! We want to form response_file = '../../run/resp/input' and not
       ! 'resp/../../run/input' as would happen if just concatenate.
       ! Check for index of last '/'
       ind_slash = index(response_file, "/", back = .true.)
       if (ind_slash == 0) then
          write(real_response_file,'(A,"/",A)') trim(response_dir),trim(response_file)
       else
          write(real_response_file,'(A,A,"/",A)') &
               response_file(1:ind_slash), &
               trim(response_dir), &
               trim(response_file(ind_slash+1:))
       end if
    endif

    !Set the solve type specific flags
    call set_dump_and_read_response(dump_response, read_response)
  end subroutine read_parameters