!                          !==  IN: ptab is an array  ==!
#   if defined REAL_TYPE
#      define ARRAY_TYPE(i)    REAL(wp)         , INTENT(inout) ::   ARRAY_IN(i)
#      define TMP_TYPE(i)      REAL(wp)         , ALLOCATABLE   ::   work(i)
#      define MPI_TYPE mpi_double_precision
#   endif
#   if defined INTEGER_TYPE
#      define ARRAY_TYPE(i)    INTEGER          , INTENT(inout) ::   ARRAY_IN(i)
#      define TMP_TYPE(i)      INTEGER          , ALLOCATABLE   ::   work(i)
#      define MPI_TYPE mpi_integer
#   endif
#   if defined COMPLEX_TYPE
#      define ARRAY_TYPE(i)    COMPLEX          , INTENT(inout) ::   ARRAY_IN(i)
#      define TMP_TYPE(i)      COMPLEX          , ALLOCATABLE   ::   work(i)
#      define MPI_TYPE mpi_double_complex
#   endif
#   if defined DIM_0d
#      define ARRAY_IN(i)   ptab
#      define I_SIZE(ptab)          1
#   endif
#   if defined DIM_1d
#      define ARRAY_IN(i)   ptab(i)
#      define I_SIZE(ptab)          SIZE(ptab,1)
#   endif
#   if defined OPERATION_MAX
#      define MPI_OPERATION mpi_max
#   endif
#   if defined OPERATION_MIN
#      define MPI_OPERATION mpi_min
#   endif
#   if defined OPERATION_SUM
#      define MPI_OPERATION mpi_sum
#   endif
#   if defined OPERATION_SUM_DD
#      define MPI_OPERATION mpi_sumdd
#   endif

   SUBROUTINE ROUTINE_ALLREDUCE( cdname, ptab, kdim, kcom )
      !!----------------------------------------------------------------------
      CHARACTER(len=*),                   INTENT(in   ) ::   cdname  ! name of the calling subroutine
      ARRAY_TYPE(:)   ! array or pointer of arrays on which the boundary condition is applied
      INTEGER, OPTIONAL, INTENT(in   ) ::   kdim        ! optional pointer dimension
      INTEGER, OPTIONAL, INTENT(in   ) ::   kcom        ! optional communicator
#if defined key_mpp_mpi
      !
      INTEGER :: ipi, ii, ierr
      INTEGER :: ierror, ilocalcomm
      TMP_TYPE(:)
      !!-----------------------------------------------------------------------
      !
      IF( narea == 1 .AND. numcom == -1 ) CALL mpp_report( cdname, ld_glb = .TRUE. )
      !
      ilocalcomm = mpi_comm_oce
      IF( PRESENT(kcom) )   ilocalcomm = kcom
      !
      IF( PRESENT(kdim) ) then
         ipi = kdim
      ELSE
         ipi = I_SIZE(ptab)   ! 1st dimension
      ENDIF
      !
      ALLOCATE(work(ipi))
      IF( ln_timing ) CALL tic_tac(.TRUE., ld_global = .TRUE.)
      CALL mpi_allreduce( ARRAY_IN(:), work, ipi, MPI_TYPE, MPI_OPERATION, ilocalcomm, ierror )
      IF( ln_timing ) CALL tic_tac(.FALSE., ld_global = .TRUE.)
      DO ii = 1, ipi
         ARRAY_IN(ii) = work(ii)
      ENDDO
      DEALLOCATE(work)
#else
      ! nothing to do if non-mpp case
      RETURN
#endif

   END SUBROUTINE ROUTINE_ALLREDUCE

#undef ARRAY_TYPE
#undef ARRAY_IN
#undef I_SIZE
#undef MPI_OPERATION
#undef TMP_TYPE
#undef MPI_TYPE