source: palm/trunk/SOURCE/exchange_horiz.f90 @ 1326

 SUBROUTINE exchange_horiz( ar, nbgp_local)

!------------------------------------------------------------------------------!
! 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: exchange_horiz.f90 1321 2014-03-20 09:40:40Z maronga $
!
! 1320 2014-03-20 08:40:49Z raasch
! ONLY-attribute added to USE-statements,
! kind-parameters added to all INTEGER and REAL declaration statements, 
! kinds are defined in new module kinds, 
! revision history before 2012 removed,
! comment fields (!:) to be used for variable explanations added to
! all variable declaration statements 
!
! 1257 2013-11-08 15:18:40Z raasch
! openacc loop and loop vector clauses removed
!
! 1128 2013-04-12 06:19:32Z raasch
! modifications for asynchronous transfer,
! local variables req, wait_stat are global now, and have been moved to module
! pegrid
!
! 1113 2013-03-10 02:48:14Z raasch
! GPU-porting for single-core (1PE) mode
!
! 1036 2012-10-22 13:43:42Z raasch
! code put under GPL (PALM 3.9)
!
! 841 2012-02-28 12:29:49Z maronga
! Excluded routine from compilation of namelist_file_check
!
! 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,                                                    &
        ONLY:  bc_lr_cyc, bc_ns_cyc, grid_level, mg_switch_to_pe0,             &
               synchronous_exchange
                
    USE cpulog,                                                                &
        ONLY:  cpu_log, log_point_s
        
    USE indices,                                                               &
        ONLY:  nxl, nxr, nyn, nys, nzb, nzt
        
    USE kinds
    
    USE pegrid

    IMPLICIT NONE


    INTEGER(iwp) ::  i           !:
    INTEGER(iwp) ::  j           !:
    INTEGER(iwp) ::  k           !:
    INTEGER(iwp) ::  nbgp_local  !:
    
    REAL(wp), DIMENSION(nzb:nzt+1,nys-nbgp_local:nyn+nbgp_local,               &
                        nxl-nbgp_local:nxr+nbgp_local) ::  ar  !:
                        

#if ! defined( __check )

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

#if defined( __parallel )

!
!-- Exchange in x-direction of lateral boundaries
    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_cyc )  THEN
          ar(:,:,nxl-nbgp_local:nxl-1) = ar(:,:,nxr-nbgp_local+1:nxr)
          ar(:,:,nxr+1:nxr+nbgp_local) = ar(:,:,nxl:nxl+nbgp_local-1)
       ENDIF

    ELSE

       IF ( synchronous_exchange )  THEN
!
!--       Send left boundary, receive right one (synchronous)
          CALL MPI_SENDRECV(                                                   &
              ar(nzb,nys-nbgp_local,nxl),   1, type_yz(grid_level), pleft,  0, &
              ar(nzb,nys-nbgp_local,nxr+1), 1, type_yz(grid_level), pright, 0, &
              comm2d, status, ierr )
!
!--       Send right boundary, receive left one (synchronous)
          CALL MPI_SENDRECV( ar(nzb,nys-nbgp_local,nxr+1-nbgp_local), 1,       &
                             type_yz(grid_level), pright, 1,                   &
                             ar(nzb,nys-nbgp_local,nxl-nbgp_local), 1,         &
                             type_yz(grid_level), pleft,  1,                   &
                             comm2d, status, ierr )

       ELSE

!
!--       In case of background communication switched on, exchange is done
!--       either along x or along y
          IF ( send_receive == 'lr'  .OR.  send_receive == 'al' )  THEN

             IF ( .NOT. sendrecv_in_background )  THEN
                req(1:4)  = 0
                req_count = 0
             ENDIF
!
!--          Send left boundary, receive right one (asynchronous)
             CALL MPI_ISEND( ar(nzb,nys-nbgp_local,nxl),   1, type_yz(grid_level), &
                             pleft, req_count, comm2d, req(req_count+1), ierr )
             CALL MPI_IRECV( ar(nzb,nys-nbgp_local,nxr+1), 1, type_yz(grid_level), &
                             pright, req_count, comm2d, req(req_count+2), ierr )
!
!--          Send right boundary, receive left one (asynchronous)
             CALL MPI_ISEND( ar(nzb,nys-nbgp_local,nxr+1-nbgp_local), 1,       &
                             type_yz(grid_level), pright, req_count+1, comm2d, &
                             req(req_count+3), ierr )
             CALL MPI_IRECV( ar(nzb,nys-nbgp_local,nxl-nbgp_local),   1,       &
                             type_yz(grid_level), pleft,  req_count+1, comm2d, &
                             req(req_count+4), ierr )

             IF ( .NOT. sendrecv_in_background )  THEN
                CALL MPI_WAITALL( 4, req, wait_stat, ierr )
             ELSE
                req_count = req_count + 4
             ENDIF

          ENDIF

       ENDIF

    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_cyc )  THEN
          ar(:,nys-nbgp_local:nys-1,:) = ar(:,nyn-nbgp_local+1:nyn,:)
          ar(:,nyn+1:nyn+nbgp_local,:) = ar(:,nys:nys+nbgp_local-1,:)
       ENDIF

    ELSE

       IF ( synchronous_exchange )  THEN
!
!--       Send front boundary, receive rear one (synchronous)
          CALL MPI_SENDRECV(                                                   &
              ar(nzb,nys,nxl-nbgp_local),   1, type_xz(grid_level), psouth, 0, &
              ar(nzb,nyn+1,nxl-nbgp_local), 1, type_xz(grid_level), pnorth, 0, &
              comm2d, status, ierr )
!
!--       Send rear boundary, receive front one (synchronous)
          CALL MPI_SENDRECV( ar(nzb,nyn-nbgp_local+1,nxl-nbgp_local), 1,       &
                             type_xz(grid_level), pnorth, 1,                   &
                             ar(nzb,nys-nbgp_local,nxl-nbgp_local),   1,       &
                             type_xz(grid_level), psouth, 1,                   &
                             comm2d, status, ierr )

       ELSE

!
!--       In case of background communication switched on, exchange is done
!--       either along x or along y
          IF ( send_receive == 'lr'  .OR.  send_receive == 'al' )  THEN

             IF ( .NOT. sendrecv_in_background )  THEN
                req(1:4)  = 0
                req_count = 0
             ENDIF

!
!--          Send front boundary, receive rear one (asynchronous)
             CALL MPI_ISEND( ar(nzb,nys,nxl-nbgp_local),   1, type_xz(grid_level), &
                             psouth, req_count, comm2d, req(req_count+1), ierr )
             CALL MPI_IRECV( ar(nzb,nyn+1,nxl-nbgp_local), 1, type_xz(grid_level), &
                             pnorth, req_count, comm2d, req(req_count+2), ierr )
!
!--          Send rear boundary, receive front one (asynchronous)
             CALL MPI_ISEND( ar(nzb,nyn-nbgp_local+1,nxl-nbgp_local), 1,       &
                             type_xz(grid_level), pnorth, req_count+1, comm2d, &
                             req(req_count+3), ierr )
             CALL MPI_IRECV( ar(nzb,nys-nbgp_local,nxl-nbgp_local),   1,       &
                             type_xz(grid_level), psouth, req_count+1, comm2d, &
                             req(req_count+4), ierr )

             IF ( .NOT. sendrecv_in_background )  THEN
                CALL MPI_WAITALL( 4, req, wait_stat, ierr )
             ELSE
                req_count = req_count + 4
             ENDIF

          ENDIF

       ENDIF

    ENDIF

#else

!
!-- Lateral boundary conditions in the non-parallel case.
!-- Case dependent, because in GPU mode still not all arrays are on device. This
!-- workaround has to be removed later. Also, since PGI compiler 12.5 has problems
!-- with array syntax, explicit loops are used.
    IF ( bc_lr == 'cyclic' )  THEN
       IF ( on_device )  THEN
          !$acc kernels present( ar )
          !$acc loop independent
          DO  i = 0, nbgp_local-1
             DO  j = nys-nbgp_local, nyn+nbgp_local
                DO  k = nzb, nzt+1
                   ar(k,j,nxl-nbgp_local+i) = ar(k,j,nxr-nbgp_local+1+i)
                   ar(k,j,nxr+1+i)          = ar(k,j,nxl+i)
                ENDDO
             ENDDO
          ENDDO
          !$acc end kernels
       ELSE
          ar(:,:,nxl-nbgp_local:nxl-1) = ar(:,:,nxr-nbgp_local+1:nxr)
          ar(:,:,nxr+1:nxr+nbgp_local) = ar(:,:,nxl:nxl+nbgp_local-1)
       ENDIF
    ENDIF

    IF ( bc_ns == 'cyclic' )  THEN
       IF ( on_device )  THEN
          !$acc kernels present( ar )
          DO  i = nxl-nbgp_local, nxr+nbgp_local
             !$acc loop independent
             DO  j = 0, nbgp_local-1
                !$acc loop independent
                DO  k = nzb, nzt+1
                   ar(k,nys-nbgp_local+j,i) = ar(k,nyn-nbgp_local+1+j,i)
                     ar(k,nyn+1+j,i)          = ar(k,nys+j,i)
                ENDDO
             ENDDO
          ENDDO
          !$acc end kernels
       ELSE
          ar(:,nys-nbgp_local:nys-1,:) = ar(:,nyn-nbgp_local+1:nyn,:)
          ar(:,nyn+1:nyn+nbgp_local,:) = ar(:,nys:nys+nbgp_local-1,:)
       ENDIF
    ENDIF

#endif
    CALL cpu_log( log_point_s(2), 'exchange_horiz', 'stop' )

#endif
 END SUBROUTINE exchange_horiz