!> @file cuda_fft_interfaces.f90
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! Copyright 1997-2019 Leibniz Universitaet Hannover
!--------------------------------------------------------------------------------!
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! Current revisions:
! -----------------
! 
! 
! Former revisions:
! -----------------
! $Id: cuda_fft_interfaces.f90 3655 2019-01-07 16:51:22Z Giersch $
! Initial revision ( OpenACC port for SPEC )
! 
! 1683 2015-10-07 23:57:51Z knoop
!
!
! Description:
! ------------
!> FORTRAN interfaces for the CUDA fft
!> Routines for the fft along x and y (forward/backward) using the CUDA fft
!--------------------------------------------------------------------------------!
 MODULE cuda_fft_interfaces
 

#if defined ( __cuda_fft )

    USE kinds

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

    PUBLIC


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

!------------------------------------------------------------------------------!
! Description:
! ------------
!> @todo Missing subroutine description.
!------------------------------------------------------------------------------!
       SUBROUTINE CUFFTPLAN1D( plan, nx, type, batch ) bind( C, name='cufftPlan1d' )

          USE ISO_C_BINDING

          INTEGER(C_INT)        ::  plan   !< 
          INTEGER(C_INT), value ::  batch  !< 
          INTEGER(C_INT), value ::  nx     !< 
          INTEGER(C_INT), value ::  type   !< 
       END SUBROUTINE CUFFTPLAN1D

    END INTERFACE CUFFTPLAN1D

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

!------------------------------------------------------------------------------!
! Description:
! ------------
!> @todo Missing subroutine description.
!------------------------------------------------------------------------------!
       SUBROUTINE CUFFTDESTROY( plan ) bind( C, name='cufftDestroy' )

          USE ISO_C_BINDING

          INTEGER(C_INT), VALUE ::  plan

       END SUBROUTINE CUFFTDESTROY

    END INTERFACE CUFFTDESTROY


    INTERFACE CUFFTEXECZ2D

!------------------------------------------------------------------------------!
! Description:
! ------------
!> @todo Missing subroutine description.
!------------------------------------------------------------------------------!
       SUBROUTINE CUFFTEXECZ2D( plan, idata, odata ) bind( C, name='cufftExecZ2D' )

          USE ISO_C_BINDING
          USE kinds

          INTEGER(C_INT), VALUE ::  plan          !<
          COMPLEX(dp), DEVICE   ::  idata(:,:,:)  !<
          REAL(dp), DEVICE      ::  odata(:,:,:)  !<

       END SUBROUTINE CUFFTEXECZ2D

    END INTERFACE CUFFTEXECZ2D


    INTERFACE CUFFTEXECD2Z

!------------------------------------------------------------------------------!
! Description:
! ------------
!> @todo Missing subroutine description.
!------------------------------------------------------------------------------!
       SUBROUTINE CUFFTEXECD2Z( plan, idata, odata ) bind( C, name='cufftExecD2Z' )

          USE ISO_C_BINDING
          
          USE kinds

          INTEGER(C_INT), VALUE ::  plan          !<
          REAL(dp), DEVICE      ::  idata(:,:,:)  !<
          COMPLEX(dp), DEVICE   ::  odata(:,:,:)  !<

       END SUBROUTINE CUFFTEXECD2Z

    END INTERFACE CUFFTEXECD2Z

#else

    INTERFACE CUFFTdummy

!------------------------------------------------------------------------------!
! Description:
! ------------
!> Dummy interface to avoid compiler warnings in case of no bublic objects
!> declared.
!------------------------------------------------------------------------------!
       SUBROUTINE CUFFTdummy( dummy )
       
          USE kinds

          REAL(wp) ::  dummy  !<

       END SUBROUTINE CUFFTdummy

    END INTERFACE CUFFTdummy

#endif

 END MODULE cuda_fft_interfaces