Init_DomainDecomposition Subroutine

  subroutine Init_DomainDecomposition(this)
    implicit none
    class(DomainDecomposition),intent(inout) :: this
    ! Local
    integer       :: ierror
    integer(c_int) :: num_devices,hip_err,device_id

    this%mpiComm = 0
    this%mpiPrec = prec
    this%rankId = 0
    this%nRanks = 1
    this%nElem = 0
    this%mpiEnabled = .false.

    this%mpiComm = MPI_COMM_WORLD
    print*,__FILE__," : Initializing MPI"
    call mpi_init(ierror)
    call mpi_comm_rank(this%mpiComm,this%rankId,ierror)
    call mpi_comm_size(this%mpiComm,this%nRanks,ierror)
    print*,__FILE__," : Rank ",this%rankId+1,"/",this%nRanks," checking in."

    if(this%nRanks > 1) then
      this%mpiEnabled = .true.
    else
      print*,__FILE__," : No domain decomposition used."
    endif

    if(prec == real32) then
      this%mpiPrec = MPI_FLOAT
    else
      this%mpiPrec = MPI_DOUBLE
    endif

    allocate(this%offsetElem(1:this%nRanks+1))

    hip_err = hipGetDeviceCount(num_devices)
    if(hip_err /= 0) then
      print*,'Failed to get device count on rank',this%rankId
      call MPI_Abort(MPI_COMM_WORLD,hip_err,ierror)
    endif

    ! Assign GPU device ID based on MPI rank
    device_id = modulo(this%rankId,num_devices) ! Assumes that mpi ranks are packed sequentially on a node until the node is filled up.
    hip_err = hipSetDevice(device_id)
    print*,__FILE__," : Rank ",this%rankId+1," assigned to device ",device_id
    if(hip_err /= 0) then
      print*,'Failed to set device for rank',this%rankId,'to device',device_id
      call MPI_Abort(MPI_COMM_WORLD,hip_err,ierror)
    endif

    this%initialized = .true.

  endsubroutine Init_DomainDecomposition