MPIExchangeAsync_MappedVector3D Subroutine

  subroutine MPIExchangeAsync_MappedVector3D(this,mesh)
    implicit none
    class(MappedVector3D),intent(inout) :: this
    type(Mesh3D),intent(inout) :: mesh
    ! Local
    integer :: e1,s1,e2,s2,ivar,idir
    integer :: globalSideId,r2,tag
    integer :: iError
    integer :: msgCount
    real(prec),pointer :: boundary(:,:,:,:,:,:)
    real(prec),pointer :: extboundary(:,:,:,:,:,:)

    msgCount = 0
    call c_f_pointer(this%boundary_gpu,boundary,[this%interp%N+1,this%interp%N+1,6,this%nelem,this%nvar,3])
    call c_f_pointer(this%extboundary_gpu,extboundary,[this%interp%N+1,this%interp%N+1,6,this%nelem,this%nvar,3])

    do idir = 1,3
      do ivar = 1,this%nvar
        do e1 = 1,this%nElem
          do s1 = 1,6

            e2 = mesh%sideInfo(3,s1,e1) ! Neighbor Element
            if(e2 > 0) then
              r2 = mesh%decomp%elemToRank(e2) ! Neighbor Rank

              if(r2 /= mesh%decomp%rankId) then

                s2 = mesh%sideInfo(4,s1,e1)/10
                globalSideId = abs(mesh%sideInfo(2,s1,e1))
                ! create unique tag for each side and each variable
                tag = globalsideid+mesh%nUniqueSides*(ivar-1+this%nvar*(idir-1))

                msgCount = msgCount+1
                call MPI_IRECV(extBoundary(:,:,s1,e1,ivar,idir), &
                               (this%interp%N+1)*(this%interp%N+1), &
                               mesh%decomp%mpiPrec, &
                               r2,tag, &
                               mesh%decomp%mpiComm, &
                               mesh%decomp%requests(msgCount),iError)

                msgCount = msgCount+1
                call MPI_ISEND(boundary(:,:,s1,e1,ivar,idir), &
                               (this%interp%N+1)*(this%interp%N+1), &
                               mesh%decomp%mpiPrec, &
                               r2,tag, &
                               mesh%decomp%mpiComm, &
                               mesh%decomp%requests(msgCount),iError)
              endif
            endif

          enddo
        enddo
      enddo
    enddo

    mesh%decomp%msgCount = msgCount

  endsubroutine MPIExchangeAsync_MappedVector3D