source: palm/trunk/SOURCE/exchange_horiz.f90 @ 30

 SUBROUTINE exchange_horiz( ar, xrp, ynp )

!------------------------------------------------------------------------------!
! Actual revisions:
! -----------------
! 
!
! Former revisions:
! -----------------
! $Id: exchange_horiz.f90 4 2007-02-13 11:33:16Z raasch $
! RCS Log replace by Id keyword, revision history cleaned up
!
! Revision 1.16  2006/02/23 12:19:08  raasch
! anz_yz renamed ngp_yz
!
! Revision 1.1  1997/07/24 11:13:29  raasch
! Initial revision
!
!
! Description:
! ------------
! Exchange of lateral boundary values (parallel computers) and cyclic
! lateral boundary conditions, respectively.
!------------------------------------------------------------------------------!

    USE control_parameters
    USE cpulog
    USE indices
    USE interfaces
    USE pegrid

    IMPLICIT NONE

    INTEGER ::  xrp, ynp

#if defined( __parallel )
    INTEGER                               ::  typexz
    INTEGER, DIMENSION(4)                 ::  req
    INTEGER, DIMENSION(MPI_STATUS_SIZE,4) ::  wait_stat
#endif

    REAL ::  ar(nzb:nzt+1,nys-1:nyn+ynp+1,nxl-1:nxr+xrp+1)


    CALL cpu_log( log_point_s(2), 'exchange_horiz', 'start' )

#if defined( __parallel )

!
!-- Exchange of lateral boundary values for parallel computers
    IF ( pdims(1) == 1  .OR.  mg_switch_to_pe0 )  THEN
!
!--    One-dimensional decomposition along y, boundary values can be exchanged
!--    within the PE memory
       IF ( bc_lr == 'cyclic' )  THEN
          ar(:,nys:nyn,nxl-1) = ar(:,nys:nyn,nxr)
          ar(:,nys:nyn,nxr+1) = ar(:,nys:nyn,nxl)
       ENDIF

    ELSE
       req = 0
!
!--    Send left boundary, receive right one
       CALL MPI_ISEND(                                                     &
               ar(nzb,nys-1,nxl), ngp_yz(grid_level), MPI_REAL, pleft,  0, &
                          comm2d, req(1), ierr )
       CALL MPI_IRECV(                                                       &
               ar(nzb,nys-1,nxr+1), ngp_yz(grid_level), MPI_REAL, pright, 0, &
                          comm2d, req(2), ierr )
!
!--    Send right boundary, receive left one
       CALL MPI_ISEND(                                                     &
               ar(nzb,nys-1,nxr), ngp_yz(grid_level), MPI_REAL, pright, 1, &
                          comm2d, req(3), ierr )
       CALL MPI_IRECV(                                                       &
               ar(nzb,nys-1,nxl-1), ngp_yz(grid_level), MPI_REAL, pleft,  1, &
                          comm2d, req(4), ierr )
       call MPI_Waitall (4,req,wait_stat,ierr)
    ENDIF


    IF ( pdims(2) == 1  .OR.  mg_switch_to_pe0 )  THEN
!
!--    One-dimensional decomposition along x, boundary values can be exchanged
!--    within the PE memory
       IF ( bc_ns == 'cyclic' )  THEN
          ar(:,nys-1,:) = ar(:,nyn,:)
          ar(:,nyn+1,:) = ar(:,nys,:)
       ENDIF

    ELSE
!
!--    Set the MPI data type, which depends on the size of the array
!--    (the v array has an additional gridpoint along y in case of non-cyclic
!--    boundary conditions)
       IF ( ynp == 0 )  THEN
          typexz = type_xz(grid_level)
       ELSE
          typexz = type_xz_p
       ENDIF

       req = 0
!
!--    Send front boundary, receive rear one
       CALL MPI_ISEND( ar(nzb,nys,nxl-1),   1, typexz, psouth, 0, comm2d, &
                       req(1), ierr )
       CALL MPI_IRECV( ar(nzb,nyn+1,nxl-1), 1, typexz, pnorth, 0, comm2d, &
                       req(2), ierr )
!
!--    Send rear boundary, receive front one
       CALL MPI_ISEND( ar(nzb,nyn,nxl-1),   1, typexz, pnorth, 1, comm2d, &
                       req(3), ierr )
       CALL MPI_IRECV( ar(nzb,nys-1,nxl-1), 1, typexz, psouth, 1, comm2d, &
                       req(4), ierr )
       call MPI_Waitall (4,req,wait_stat,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(2), 'exchange_horiz', 'stop' )

 END SUBROUTINE exchange_horiz