! This file created from f77/coll/uallreducef.f with f77tof90

! -*- Mode: Fortran; -*- 

!

!  (C) 2003 by Argonne National Laboratory.

!      See COPYRIGHT in top-level directory.

!

!

! Test user-defined operations.  This tests a simple commutative operation

!

      subroutine uop( cin, cout, count, datatype )

      use mpi

      integer cin(*), cout(*)

      integer count, datatype

      integer i

      if (datatype .ne. MPI_INTEGER) then

         print *, 'Invalid datatype (',datatype,') passed to user_op()'

         return

      endif

      do i=1, count

         cout(i) = cin(i) + cout(i)

      enddo

      end

      program main

      use mpi

      external uop

      integer ierr, errs

      integer count, sumop, vin(65000), vout(65000), i, size

      integer comm

      errs = 0

      call mtest_init(ierr)

      call mpi_op_create( uop, .true., sumop, ierr )

      comm = MPI_COMM_WORLD

      call mpi_comm_size( comm, size, ierr )

      count = 1

      do while (count .lt. 65000) 

         do i=1, count

            vin(i) = i

            vout(i) = -1

         enddo

         call mpi_allreduce( vin, vout, count, MPI_INTEGER, sumop,  &

      &                       comm, ierr )

!         Check that all results are correct

         do i=1, count

            if (vout(i) .ne. i * size) then

               errs = errs + 1

               if (errs .lt. 10) print *, "vout(",i,") = ", vout(i)

            endif

         enddo

         count = count + count

      enddo

      call mpi_op_free( sumop, ierr )

      call mtest_finalize(errs)

      end