init_random_seed Subroutine

subroutine init_random_seed()
#ifdef PARALLEL_RANDOM
  use korc_random
#endif
  INTEGER, allocatable       :: seed(:)
  INTEGER(8), DIMENSION(8)   :: dt
  INTEGER(8)                 :: i
  INTEGER(8)                 :: istat
  INTEGER(8)                 :: pid
  INTEGER(4)                 :: n
  INTEGER(8)                 :: t

  call random_seed(size = n)
  allocate(seed(n))
  ! First try if the OS provides a random number generator
  open(default_unit_open, file="/dev/urandom", access="stream", &
       form="unformatted", action="read", status="old", iostat=istat)
  if (istat == 0) then
     read(default_unit_open) seed
     close(default_unit_open)
     
  else
     ! Fallback to XOR:ing the current time and pid. The PID is
     ! useful in case one launches multiple instances of the same
     ! program in parallel.
     call system_clock(t)
     if (t == 0) then
        call date_and_time(values=dt)
        t = (dt(1) - 1970_8) * 365_8 * 24_8 * 60_8 * 60_8 * 1000_8 &
             + dt(2) * 31_8 * 24_8 * 60_8 * 60_8 * 1000_8 &
             + dt(3) * 24_8 * 60_8 * 60_8 * 1000_8 &
             + dt(5) * 60_8 * 60_8 * 1000_8 &
             + dt(6) * 60_8 * 1000_8 &
             + dt(7) * 1000_8 &
             + dt(8)
     end if
     pid = getpid()
     write(6,'("PID: ",I15)') pid
     t = ieor(t, int(pid, kind(t)))
     do i = 1, n
        seed(i) = lcg(t)
     end do
  end if
#ifdef PARALLEL_RANDOM
  call initialize_random(seed(1))
  call initialize_random_U(seed(1))
  call initialize_random_N(seed(1))

!  call initialize_random_mkl(seed(1))
#else
  call random_seed(put=seed)
#endif
contains

  ! This simple PRNG might not be good enough for real work, but is
  ! sufficient for seeding a better PRNG.
  function lcg(s)
    INTEGER :: lcg
    INTEGER(8) :: s
    if (s == 0) then
       s = 104729_8
    else
       s = mod(s, 4294967296_8)
    end if
    s = mod(s * 279470273_8, 4294967291_8)
    lcg = int(mod(s, int(huge(0), 8)), kind(0))
  end function lcg
end subroutine init_random_seed