!!$ 
!!$              Parallel Sparse BLAS  v2.0
!!$    (C) Copyright 2006 Salvatore Filippone    University of Rome Tor Vergata
!!$                       Alfredo Buttari        University of Rome Tor Vergata
!!$ 
!!$  Redistribution and use in source and binary forms, with or without
!!$  modification, are permitted provided that the following conditions
!!$  are met:
!!$    1. Redistributions of source code must retain the above copyright
!!$       notice, this list of conditions and the following disclaimer.
!!$    2. Redistributions in binary form must reproduce the above copyright
!!$       notice, this list of conditions, and the following disclaimer in the
!!$       documentation and/or other materials provided with the distribution.
!!$    3. The name of the PSBLAS group or the names of its contributors may
!!$       not be used to endorse or promote products derived from this
!!$       software without specific written permission.
!!$ 
!!$  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
!!$  ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
!!$  TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
!!$  PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PSBLAS GROUP OR ITS CONTRIBUTORS
!!$  BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
!!$  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
!!$  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
!!$  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
!!$  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
!!$  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
!!$  POSSIBILITY OF SUCH DAMAGE.
!!$ 
!!$  
subroutine psi_crea_index(desc_a,index_in,index_out,glob_idx,nxch,nsnd,nrcv,info)

  use psb_realloc_mod
  use psb_descriptor_type
  use psb_error_mod
  use psb_penv_mod
  implicit none

  type(psb_desc_type), intent(in)  :: desc_a
  integer, intent(out)             :: info,nxch,nsnd,nrcv
  integer, intent(in)              :: index_in(:)
  integer, allocatable             :: index_out(:)
  logical                          :: glob_idx

  !         ....local scalars...      
  integer    :: ictxt, me, np, mode, err_act, dl_lda
  !         ...parameters...
  integer, allocatable :: dep_list(:,:), length_dl(:)
  integer,parameter    :: root=0,no_comm=-1
  logical,parameter    :: debug=.false.
  character(len=20)    :: name


  interface
    subroutine psi_sort_dl(dep_list,l_dep_list,np,info)
      integer :: np,dep_list(:,:), l_dep_list(:), info
    end subroutine psi_sort_dl
  end interface

  interface
    subroutine psi_dl_check(dep_list,dl_lda,np,length_dl)
      integer  :: np,dl_lda,length_dl(0:np)
      integer  :: dep_list(dl_lda,0:np)
    end subroutine psi_dl_check
  end interface

  interface
    subroutine psi_desc_index(desc,index_in,dep_list,&
         & length_dl,nsnd,nrcv,desc_index,&
         & isglob_in,info)
      use psb_descriptor_type
      type(psb_desc_type)  :: desc
      integer              :: index_in(:),dep_list(:)
      integer, allocatable :: desc_index(:)
      integer :: length_dl,nsnd,nrcv,info
      logical :: isglob_in
    end subroutine psi_desc_index
  end interface

  info = 0
  name='psi_crea_index'
  call psb_erractionsave(err_act)

  ictxt = psb_cd_get_context(desc_a)
  call psb_info(ictxt,me,np)
  if (np == -1) then
    info = 2010
    call psb_errpush(info,name)
    goto 9999
  endif

  ! allocate dependency list
  ! This should be computed more efficiently to save space when
  ! the number of processors becomes very high
  dl_lda=np+1

  allocate(dep_list(max(1,dl_lda),0:np),length_dl(0:np),stat=info)
  if (info /= 0) then 
    call psb_errpush(4010,name,a_err='Allocate')
    goto 9999      
  end if

  ! ...extract dependence list (ordered list of identifer process
  !    which every process must communcate with...
!!$  write(0,*) me,name,' Size of desc_in ',size(index_in)
!!$  if (size(index_in)>0) then 
!!$    write(0,*) me,name,'first item ',index_in(1)
!!$  end if
  if (debug) write(*,*) 'crea_halo: calling extract_dep_list'
  mode = 1

  call psi_extract_dep_list(desc_a%matrix_data,index_in,&
       & dep_list,length_dl,np,max(1,dl_lda),mode,info)
  if(info /= 0) then
    call psb_errpush(4010,name,a_err='extrct_dl')
    goto 9999
  end if

  if (debug) write(0,*) 'crea_index: from extract_dep_list',&
       &     me,length_dl(0),index_in(1), ':',dep_list(:length_dl(me),me)
  ! ...now process root contains dependence list of all processes...
  if (debug) write(0,*) 'crea_index: root sorting dep list'

  ! ....i must order communication in in halo
  call psi_dl_check(dep_list,max(1,dl_lda),np,length_dl)

  ! ....now i can sort dependence list......
  call psi_sort_dl(dep_list,length_dl,np,info)
  if(info /= 0) then
    call psb_errpush(4010,name,a_err='psi_sort_dl')
    goto 9999
  end if

  ! ...create desc_halo array.....
  if(debug) write(0,*)'in psi_crea_index calling psi_desc_index',&
       & size(index_out)
  call psi_desc_index(desc_a,index_in,dep_list(1:,me),&
       & length_dl(me),nsnd,nrcv, index_out,glob_idx,info)
  if(debug) write(0,*)'out of  psi_desc_index',&
       & size(index_out)
  nxch = length_dl(me)
  if(info /= 0) then
    call psb_errpush(4010,name,a_err='psi_desc_index')
    goto 9999
  end if

  deallocate(dep_list,length_dl)
  call psb_erractionrestore(err_act)
  return

9999 continue
  call psb_erractionrestore(err_act)
  if (err_act == act_abort) then
    call psb_error(ictxt)
    return
  end if
  return
end subroutine psi_crea_index