program main
	include 'mpif.h'
	parameter (M = 3)
	integer ierr, rank
	integer tag, status(MPI_STATUS_SIZE)
	integer size, messagesize
	real buf*(*)
	integer n, i
	integer blen

	call MPI_INIT(ierr)
	call MPI_COMM_SIZE(MPI_COMM_WORLD, size, ierr)
	call MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierr)

	if( size .ne. 2 ) then
		if( rank .eq. 0 ) then
			print *, 'Error: 2 processes required'
		endif
		call MPI_Abort(MPI_COMM_WORLD, MPI_ERR_OTHER, ierr);
	endif

	if (rank == 0) then
		blen = M * (4 + MPI_BSEND_OVERHEAD)
		call MPI_BUFFER_ATTACH(buf, blen, ierr)
		print *, 'attached ', blen, ' bytes'

		do i = 0, M - 1
			print *, 'starting send ', i
			n = i
			call MPI_BSEND(n, 1, MPI_INTEGER,
		1	1, i, MPI_COMM_WORLD, ierr)
			print *, 'complete send ', i
			call SLEEP(1)
		enddo
		call MPI_BUFFER_DETACH(buf, blen, ierr)
		print *, 'detached ', blen, ' bytes'
	else if (rank == 1) then
		do i = M - 1, 0, -1
			print *, 'starting recv ...', i
			call MPI_RECV(n, M, MPI_INTEGER,
		1	0, i, MPI_COMM_WORLD, status, ierr)
			print *, 'complete recv: ', i, ' received ', n
		enddo
	endif
	print *, 'Proc ', rank, ' finished!!'
	call MPI_FINALIZE(ierr)
	end