!******************************************************************************
!    Hello World example:
!
!    In this example the rank 0 of MPI_COMM_WORLD waits for messages from the
!    other ranks. When a message is received it is displayed (send to stdout).
!
!    Copyright 2003 (c) Critical Software SA
!    . http://www.criticalsoftware.com
!    . http://www.criticalsoftware.com/hpc
!    . csWMPI II@criticalsoftware.com
!
!******************************************************************************

!MESSAGELENGTH The length of the messages that
!                      we are going to transmit
!TAG           The tag to use for the transmissions
!NODENAMESIZE  The size of the node name

include 'mpif.f90'

!     Main program
      program main
      use MPI
      implicit none

      integer nCommSize, nCommRank, nCounter, ierr
      integer MESSAGELENGTH, NODENAMESIZE, TAG
      parameter (MESSAGELENGTH = 128, NODENAMESIZE = 65, TAG = 100)
      character*(MESSAGELENGTH) pchMessage
      character*(NODENAMESIZE) pchNodeName
      integer   dwNodeNameSize
      character*(10) strnCommRank
      integer nCommTemp, nCount

      dwNodeNameSize = NODENAMESIZE

!     Initialize csWMPI II II:
      call MPI_INIT(ierr)

!     Determine what the world looks like and our own position in it:
      call MPI_COMM_SIZE(MPI_COMM_WORLD, nCommSize, ierr)
      call MPI_COMM_RANK(MPI_COMM_WORLD, nCommRank, ierr)
      print *, 'I am rank ', nCommRank,' of ',nCommSize,&
               ' in MPI_COMM_WORLD'

!     If I am rank 0 I'll receive messages from the other ranks in
!     MPI_COMM_WORLD and send them to stdout:
      if (nCommRank .eq. 0) then
        do nCounter = 1,nCommSize-1
!          Receive a message from a process:
            call MPI_RECV(pchMessage, MESSAGELENGTH,MPI_CHARACTER,&
                     MPI_ANY_SOURCE,TAG,MPI_COMM_WORLD,&
                     MPI_STATUS_IGNORE, ierr)

!           Display the received message:
            print *,'I received the following message: ', pchMessage
        end do
      else !I am NOT rank 0
!     Get my node name
            call MPI_GET_PROCESSOR_NAME(pchNodeName,dwNodeNameSize,ierr)
            if (trim(pchNodeName).eq.'' )then
                  pchNodeName =  'Unknown'
            end if

!           Number to string
            nCommTemp = nCommRank
            do nCount = 0,9
                  if(nCommTemp .gt. 0) then
                        strnCommRank(nCount+1:nCount+1) = &
                              char(mod(nCommTemp,10)+ichar('0'))
                else
                        strnCommRank(nCount+1:nCount+1) = ' '
                  end if
                nCommTemp = nCommTemp/10
            end do
!           Compose my message:
            pchMessage = 'Hello world from rank '//trim(strnCommRank)//&
            ' at '//pchNodeName
!           Send it:
            call MPI_SEND(pchMessage, MESSAGELENGTH, MPI_CHARACTER, 0,&
                          TAG,MPI_COMM_WORLD, ierr)
      end if

!     Pause rank 0 so that the output can be verified:
      if (nCommRank .eq. 0) then
            pause 'Press ENTER to exit...'
      end if

!     Finalize csWMPI II II:
      call MPI_FINALIZE(ierr)
      stop
      end