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 1997-2014 Leibniz Universitaet Hannover
!--------------------------------------------------------------------------------!
!
! Current revisions:
! -----------------
! 
!
! Former revisions:
! -----------------
! $Id: cuda_fft_interfaces.f90 1321 2014-03-20 09:40:40Z witha $
!
! 1320 2014-03-20 08:40:49Z raasch
! Kind-parameters added to all INTEGER and REAL declaration statements,
! kinds are defined in new module kinds,
! old module precision_kind is removed,
! revision history before 2012 removed,
! comment fields (!:) to be used for variable explanations added to
! all variable declaration statements
!
! 1224 2013-09-16 07:27:23Z raasch
! dummy interface added to avoid compiler warnings
!
! 1166 2013-05-24 13:55:44Z raasch
! C_DOUBLE/COMPLEX reset to dpk,
! DEVICE attribut added to idata/odata arguments
!
! 1153 2013-05-10 14:33:08Z raasch
! code adjustment of data types for CUDA fft required by PGI 12.3 / CUDA 5.0
!
! 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(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

       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

       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 kinds

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

       END SUBROUTINE CUFFTEXECZ2D

    END INTERFACE CUFFTEXECZ2D


    INTERFACE CUFFTEXECD2Z

       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

!
!-- Dummy interface to avoid compiler warnings in case of no bublic objects
!-- declared
    INTERFACE CUFFTdummy

       SUBROUTINE CUFFTdummy( dummy )
       
          USE kinds

          REAL(wp) ::  dummy  !:

       END SUBROUTINE CUFFTdummy

    END INTERFACE CUFFTdummy

#endif

 END MODULE cuda_fft_interfaces