ADAS Subroutine xxordr

      subroutine xxordr(n, lup, xa, ia, iinva)                                         

c-----------------------------------------------------------------------
c
c  ****************** fortran77 subroutine: xxordr *******************
c
c  purpose: sorts a real*8 array xa. This is a bubble sort designed for
c           small arrays.         
c                                                                    
c
c  calling program:  general use
c
c                                                                   
c  subroutine:
c
c  input       :  (i*4)  n       = size of input arrays
c  input       :  (l*4)  lup     = .true. sort in ascending order
c                                  .false. descending order
c  input/output:  (r*8)  xa      = array to be sorted
c  output      :  (i*4)  ia      = original index of sorted xa members
c  output      :  (i*4)  iinva   = inverse of ia
c 
c  routines: none
c
c  notes: based on nsort.  subroutine sets ia(i)=i before sorting 
c
c  author:  Susan Turnbull
c
c  date:    22/08/01
c
c  version: 1.1
c  
c-----------------------------------------------------------------------
      INTEGER             IA(*),       IINVA(*),    N
      LOGICAL             LUP
      REAL*8              XA(*)