! This file created from f77/pt2pt/psendf.f with f77tof90

! -*- Mode: Fortran; -*-

!

!  (C) 2012 by Argonne National Laboratory.

!      See COPYRIGHT in top-level directory.

!

! This program is based on the allpair.f test from the MPICH-1 test

! (test/pt2pt/allpair.f), which in turn was inspired by a bug report from

! fsset@corelli.lerc.nasa.gov (Scott Townsend)

      program psend

      use mpi

      integer ierr, errs, comm

      logical mtestGetIntraComm

      logical verbose

      common /flags/ verbose

      errs = 0

      verbose = .false.

!      verbose = .true.

      call MTest_Init( ierr )

      do while ( mtestGetIntraComm( comm, 2, .false. ) )

         call test_pair_psend( comm, errs )

         call mtestFreeComm( comm )

      enddo

!

      call MTest_Finalize( errs )

!

      end

!

      subroutine test_pair_psend( comm, errs )

      use mpi

      integer comm, errs

      integer rank, size, ierr, next, prev, tag, count, i

      integer TEST_SIZE

      parameter (TEST_SIZE=2000)

      integer status(MPI_STATUS_SIZE)

      integer statuses(MPI_STATUS_SIZE,2), requests(2)

      real send_buf(TEST_SIZE), recv_buf(TEST_SIZE)

      logical verbose

      common /flags/ verbose

!

      if (verbose) then

         print *, ' Persistent send and recv'

      endif

!

      call mpi_comm_rank( comm, rank, ierr )

      call mpi_comm_size( comm, size, ierr )

      next = rank + 1

      if (next .ge. size) next = 0

!

      prev = rank - 1

      if (prev .lt. 0) prev = size - 1

!

      tag = 3123

      count = TEST_SIZE / 5

!

      call clear_test_data(recv_buf,TEST_SIZE)

      call MPI_Recv_init(recv_buf, TEST_SIZE, MPI_REAL, &

      &                   MPI_ANY_SOURCE, MPI_ANY_TAG, comm, &

      &                   requests(2), ierr)

!

      if (rank .eq. 0) then

!

         call init_test_data(send_buf,TEST_SIZE)

!

         call MPI_Send_init(send_buf, count, MPI_REAL, next, tag, &

      &                      comm, requests(1), ierr)

!

         call MPI_Startall(2, requests, ierr)

         call MPI_Waitall(2, requests, statuses, ierr)

!

         call msg_check( recv_buf, next, tag, count, statuses(1,2), &

      &        TEST_SIZE, 'persistent send/recv', errs )

!

         call MPI_Request_free(requests(1), ierr)

!

      else if (prev .eq. 0) then

!

         call MPI_Send_init(send_buf, count, MPI_REAL, prev, tag, &

      &                      comm, requests(1), ierr)

         call MPI_Start(requests(2), ierr)

         call MPI_Wait(requests(2), status, ierr)

!

         call msg_check( recv_buf, prev, tag, count, status, TEST_SIZE, &

      &                   'persistent send/recv', errs )

!

         do i = 1,count

            send_buf(i) = recv_buf(i)

         end do

!

         call MPI_Start(requests(1), ierr)

         call MPI_Wait(requests(1), status, ierr)

!

         call MPI_Request_free(requests(1), ierr)

      end if

!

      call dummyRef( send_buf, count, ierr )

      call MPI_Request_free(requests(2), ierr)

!

      end