SUBROUTINE exchange_horiz_2d( ar )

!------------------------------------------------------------------------------!
! Actual revisions:
! -----------------
! 
!
! Former revisions:
! -----------------
! $Log: exchange_horiz_2d.f90,v $
! Revision 1.9  2006/05/12 19:15:52  letzel
! MPI_REAL replaced by MPI_INTEGER in exchange_horiz_2d_int
!
! Revision 1.8  2006/02/23 12:18:32  raasch
! Additional subroutine exchange_horiz_2d_int for 2D integer arrays,
! extensions for non-cyclic boundary conditions along x or y for non-parallel
! case, anz_y renamed ngp_y
!
! Revision 1.7  2003/03/16 09:30:43  raasch
! Two underscores (_) are placed in front of all define-strings
!
! Revision 1.6  2002/06/11 12:59:35  raasch
! Cyclic boundary conditions are used instead of sendrecv in case of
! pdims(..)=1. Array "feld" is renamed to "ar".
!
! Revision 1.5  2001/03/30  07:23:16  07:23:16  raasch (Siegfried Raasch)
! Translation of remaining German identifiers (variables, subroutines, etc.)
! 
! Revision 1.4  2001/01/22 06:43:50  raasch
! Module test_variables removed
!
! Revision 1.3  2000/12/20 12:09:27  letzel
! All comments translated into English.
!
! Revision 1.2  1998/07/06 12:13:53  raasch
! + USE test_variables
!
! Revision 1.1  1998/01/23 09:58:21  raasch
! Initial revision
!
!
! Description:
! ------------
! Exchange of lateral (ghost) boundaries (parallel computers) and cyclic
! boundary conditions, respectively, for 2D-arrays.
!------------------------------------------------------------------------------!

    USE control_parameters
    USE cpulog
    USE indices
    USE interfaces
    USE pegrid

    IMPLICIT NONE

    REAL ::  ar(nys-1:nyn+1,nxl-1:nxr+1)


    CALL cpu_log( log_point_s(13), 'exchange_horiz_2d', 'start' )

#if defined( __parallel )

!
!-- Exchange of lateral boundary values for parallel computers
    IF ( pdims(1) == 1 )  THEN

!
!--    One-dimensional decomposition along y, boundary values can be exchanged
!--    within the PE memory
       ar(nys:nyn,nxl-1) = ar(nys:nyn,nxr)
       ar(nys:nyn,nxr+1) = ar(nys:nyn,nxl)

    ELSE
!
!--    Send left boundary, receive right one
       CALL MPI_SENDRECV( ar(nys,nxl),   ngp_y, MPI_REAL, pleft,  0, &
                          ar(nys,nxr+1), ngp_y, MPI_REAL, pright, 0, &
                          comm2d, status, ierr )
!
!--    Send right boundary, receive left one
       CALL MPI_SENDRECV( ar(nys,nxr),   ngp_y, MPI_REAL, pright,  1, &
                          ar(nys,nxl-1), ngp_y, MPI_REAL, pleft,   1, &
                          comm2d, status, ierr )
    ENDIF

    IF ( pdims(2) == 1 )  THEN
!
!--    One-dimensional decomposition along x, boundary values can be exchanged
!--    within the PE memory
       ar(nys-1,:) = ar(nyn,:)
       ar(nyn+1,:) = ar(nys,:)

    ELSE
!
!--    Send front boundary, receive rear one
       CALL MPI_SENDRECV( ar(nys,nxl-1),   1, type_x, psouth, 0, &
                          ar(nyn+1,nxl-1), 1, type_x, pnorth, 0, &
                          comm2d, status, ierr )
!
!--    Send rear boundary, receive front one
       CALL MPI_SENDRECV( ar(nyn,nxl-1),   1, type_x, pnorth, 1, &
                          ar(nys-1,nxl-1), 1, type_x, psouth, 1, &
                          comm2d, status, ierr )
    ENDIF

#else

!
!-- Lateral boundary conditions in the non-parallel case
    IF ( bc_lr == 'cyclic' )  THEN
       ar(nys:nyn,nxl-1) = ar(nys:nyn,nxr)
       ar(nys:nyn,nxr+1) = ar(nys:nyn,nxl)
    ENDIF

    IF ( bc_ns == 'cyclic' )  THEN
       ar(nys-1,:) = ar(nyn,:)
       ar(nyn+1,:) = ar(nys,:)
    ENDIF

#endif

    CALL cpu_log( log_point_s(13), 'exchange_horiz_2d', 'stop' )

 END SUBROUTINE exchange_horiz_2d



 SUBROUTINE exchange_horiz_2d_int( ar )

!------------------------------------------------------------------------------!
! Description:
! ------------
! Exchange of lateral (ghost) boundaries (parallel computers) and cyclic
! boundary conditions, respectively, for 2D integer arrays.
!------------------------------------------------------------------------------!

    USE control_parameters
    USE cpulog
    USE indices
    USE interfaces
    USE pegrid

    IMPLICIT NONE

    INTEGER ::  ar(nys-1:nyn+1,nxl-1:nxr+1)


    CALL cpu_log( log_point_s(13), 'exchange_horiz_2d', 'start' )

#if defined( __parallel )

!
!-- Exchange of lateral boundary values for parallel computers
    IF ( pdims(1) == 1 )  THEN

!
!--    One-dimensional decomposition along y, boundary values can be exchanged
!--    within the PE memory
       ar(nys:nyn,nxl-1) = ar(nys:nyn,nxr)
       ar(nys:nyn,nxr+1) = ar(nys:nyn,nxl)

    ELSE
!
!--    Send left boundary, receive right one
       CALL MPI_SENDRECV( ar(nys,nxl),   ngp_y, MPI_INTEGER, pleft,  0, &
                          ar(nys,nxr+1), ngp_y, MPI_INTEGER, pright, 0, &
                          comm2d, status, ierr )
!
!--    Send right boundary, receive left one
       CALL MPI_SENDRECV( ar(nys,nxr),   ngp_y, MPI_INTEGER, pright,  1, &
                          ar(nys,nxl-1), ngp_y, MPI_INTEGER, pleft,   1, &
                          comm2d, status, ierr )
    ENDIF

    IF ( pdims(2) == 1 )  THEN
!
!--    One-dimensional decomposition along x, boundary values can be exchanged
!--    within the PE memory
       ar(nys-1,:) = ar(nyn,:)
       ar(nyn+1,:) = ar(nys,:)

    ELSE
!
!--    Send front boundary, receive rear one
       CALL MPI_SENDRECV( ar(nys,nxl-1),   1, type_x_int, psouth, 0, &
                          ar(nyn+1,nxl-1), 1, type_x_int, pnorth, 0, &
                          comm2d, status, ierr )
!
!--    Send rear boundary, receive front one
       CALL MPI_SENDRECV( ar(nyn,nxl-1),   1, type_x_int, pnorth, 1, &
                          ar(nys-1,nxl-1), 1, type_x_int, psouth, 1, &
                          comm2d, status, ierr )
    ENDIF

#else

!
!-- Lateral boundary conditions in the non-parallel case
    IF ( bc_lr == 'cyclic' )  THEN
       ar(nys:nyn,nxl-1) = ar(nys:nyn,nxr)
       ar(nys:nyn,nxr+1) = ar(nys:nyn,nxl)
    ENDIF

    IF ( bc_ns == 'cyclic' )  THEN
       ar(nys-1,:) = ar(nyn,:)
       ar(nyn+1,:) = ar(nys,:)
    ENDIF

#endif

    CALL cpu_log( log_point_s(13), 'exchange_horiz_2d', 'stop' )

 END SUBROUTINE exchange_horiz_2d_int