transform_y5d Subroutine

  subroutine transform_y5d (xxf, yxf)
    use gs2_layouts, only: xxf_lo, yxf_lo
    use redistribute, only: gather
    use job_manage, only: time_message
    use fft_work, only: time_fft
    use array_utils, only: zero_array
    implicit none
    complex, dimension (:,xxf_lo%llim_proc:), intent (in) :: xxf
# ifdef FFT
    real, dimension (:,yxf_lo%llim_proc:), intent (out) :: yxf
# else
    real, dimension (:,yxf_lo%llim_proc:), intent(in out) :: yxf
# endif

    ! Zero out the array as the subsequent gather doesn't populate
    ! every element as we skip communicating forbidden points and
    ! we are padding our data
    call zero_array(fft)

    !Note here we're doing the communication even if we're not using
    !an FFT routine.
    call gather (x2y, xxf, fft)

#if FFT == _FFTW3_
    call time_message(.false., time_fft, ' FFT')
    call FFTW_PREFIX(_execute_dft_c2r) (yf_fft%plan, fft, yxf)
    call time_message(.false., time_fft, ' FFT')
#endif
  end subroutine transform_y5d