MODULE cuda_fft_interfaces

!--------------------------------------------------------------------------------!
! This file is part of PALM.
!
! PALM is free software: you can redistribute it and/or modify it under the terms
! of the GNU General Public License as published by the Free Software Foundation,
! either version 3 of the License, or (at your option) any later version.
!
! PALM is distributed in the hope that it will be useful, but WITHOUT ANY
! WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
! A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
!
! You should have received a copy of the GNU General Public License along with
! PALM. If not, see <http://www.gnu.org/licenses/>.
!
! Copyright 1997-2012  Leibniz University Hannover
!--------------------------------------------------------------------------------!
!
! Current revisions:
! -----------------
! 
!
! Former revisions:
! -----------------
! $Id: cuda_fft_interfaces.f90 1112 2013-03-09 00:34:37Z witha $
!
! 1111 2013-03-08 23:54:10Z raasch
! idata and odata changed from 1d- to 3d-arrays
!
! 1106 2013-03-04 05:31:38Z raasch
! Initial revision
!
! Description:
! ------------
! FORTRAN interfaces for the CUDA fft
! Routines for the fft along x and y (forward/backward) using the CUDA fft
!--------------------------------------------------------------------------------!

#if defined ( __cuda_fft )

    INTEGER :: CUFFT_FORWARD = -1,  &
               CUFFT_INVERSE =  1,  &
               CUFFT_R2C = Z'2a',   &    ! Real to Complex (interleaved)
               CUFFT_C2R = Z'2c',   &    ! Complex (interleaved) to Real
               CUFFT_C2C = Z'29',   &    ! Complex to Complex, interleaved
               CUFFT_D2Z = Z'6a',   &    ! Double to Double-Complex
               CUFFT_Z2D = Z'6c',   &    ! Double-Complex to Double
               CUFFT_Z2Z = Z'69'         ! Double-Complex to Double-Complex

    PUBLIC


!
!-- cufftPlan1d( cufftHandle *plan, int nx, cufftType type, int batch )
    INTERFACE CUFFTPLAN1D

       SUBROUTINE CUFFTPLAN1D( plan, nx, type, batch ) bind( C, name='cufftPlan1d' )

          USE ISO_C_BINDING

          INTEGER(C_INT) ::  plan
          INTEGER(C_INT), value ::  batch, nx, type

       END SUBROUTINE CUFFTPLAN1D

    END INTERFACE CUFFTPLAN1D

!
!-- cufftDestroy( cufftHandle plan )  !!! remove later if not really needed !!!
    INTERFACE CUFFTDESTROY

       SUBROUTINE CUFFTDESTROY( plan ) bind( C, name='cufftDestroy' )

          USE ISO_C_BINDING

          INTEGER(C_INT), value ::  plan

       END SUBROUTINE CUFFTDESTROY

    END INTERFACE CUFFTDESTROY


    INTERFACE CUFFTEXECZ2D

       SUBROUTINE CUFFTEXECZ2D( plan, idata, odata ) bind( C, name='cufftExecZ2D' )

          USE ISO_C_BINDING
          USE precision_kind

          INTEGER(C_INT), value ::  plan
          COMPLEX(dpk), device  ::  idata(:,:,:)
          REAL(dpk), device     ::  odata(:,:,:)

       END SUBROUTINE CUFFTEXECZ2D

    END INTERFACE CUFFTEXECZ2D


    INTERFACE CUFFTEXECD2Z

       SUBROUTINE CUFFTEXECD2Z( plan, idata, odata ) bind( C, name='cufftExecD2Z' )

          USE ISO_C_BINDING
          USE precision_kind

          INTEGER(C_INT), value ::  plan
          REAL(dpk), device     ::  idata(:,:,:)
          COMPLEX(dpk), device  ::  odata(:,:,:)

       END SUBROUTINE CUFFTEXECD2Z

    END INTERFACE CUFFTEXECD2Z

#endif
 END MODULE cuda_fft_interfaces