psblas3/base/internals/psi_bld_tmphalo.f90

!!$ 
!!$              Parallel Sparse BLAS  version 2.2
!!$    (C) Copyright 2006/2007/2008
!!$                       Salvatore Filippone    University of Rome Tor Vergata
!!$                       Alfredo Buttari        University of Rome Tor Vergata
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!
! File: psi_bld_tmphalo.f90
!
! Subroutine: psi_bld_tmphalo
!   Build initial versions of data exchange lists.
!   When the descriptor is for a large index space, we cannot build 
!   the data exchange lists "on-the-fly", but we also want to keep using the 
!   same format conversion routines we use in the small index space case, 
!   hence this adapter routine.
!   
! 
! Arguments: 
!    desc     - type(psb_desc_type).    The communication descriptor.        
!    info     - integer.                  return code.
!
subroutine psi_bld_tmphalo(desc,info)
  use psb_descriptor_type
  use psb_serial_mod
  use psb_const_mod
  use psb_error_mod
  use psb_penv_mod
  use psb_realloc_mod
  use psi_mod, psb_protect_name => psi_bld_tmphalo
  implicit none
  type(psb_desc_type), intent(inout) :: desc
  integer, intent(out) :: info

  integer,allocatable :: helem(:),hproc(:)
  integer,allocatable :: tmphl(:)

  integer          ::  i,j,np,me,lhalo,nhalo,&
       & n_col, err_act,  key, ih, nh, idx, nk,icomm
  integer             :: ictxt,n_row
  character(len=20)   :: name,ch_err

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

  ictxt = psb_cd_get_context(desc)
  icomm = psb_cd_get_mpic(desc)
  n_row = psb_cd_get_local_rows(desc)
  n_col = psb_cd_get_local_cols(desc)

  ! check on blacs grid 
  call psb_info(ictxt, me, np)
  if (np == -1) then
    info = 2010
    call psb_errpush(info,name)
    goto 9999
  endif

  if (.not.(psb_is_bld_desc(desc).and.psb_is_large_desc(desc))) then 
    info = 1122
    call psb_errpush(info,name)
    goto 9999
  end if

  ! Here we do not know yet who owns what, so we have 
  ! to call fnd_owner.
  nh = (n_col-n_row)
  Allocate(helem(max(1,nh)),stat=info)
  if (info /= 0) then 
    call psb_errpush(4010,name,a_err='Allocate')
    goto 9999      
  end if

  do i=1, nh
    helem(i) = n_row+i ! desc%loc_to_glob(n_row+i)
  end do

  call psb_map_l2g(helem(1:nh),desc%idxmap,info)
  if (info == 0) &
       & call psi_fnd_owner(nh,helem,hproc,desc,info)

  if (info /= 0) then 
    call psb_errpush(4010,name,a_err='fnd_owner')
    goto 9999      
  endif
  if (nh > size(hproc)) then 
    info=4010
    call psb_errpush(4010,name,a_err='nh > size(hproc)')
    goto 9999      
  end if

  allocate(tmphl((3*((n_col-n_row)+1)+1)),stat=info)
  if (info /= 0) then 
    call psb_errpush(4010,name,a_err='Allocate')
    goto 9999      
  end if
  j  = 1
  do i=1,nh
    tmphl(j+0) = hproc(i)
    if (tmphl(j+0)<0) then 
      write(0,*) 'Unrecoverable error: missing proc from asb'
    end if
    tmphl(j+1) = 1
    tmphl(j+2) = n_row+i
    j          = j + 3
  end do
  tmphl(j) = -1
  lhalo = j
  nhalo = (lhalo-1)/3

  call psb_move_alloc(tmphl,desc%halo_index,info)

  call psb_erractionrestore(err_act)
  return

9999 continue
  call psb_erractionrestore(err_act)

  if (err_act == psb_act_ret_) then
    return
  else
    call psb_error(ictxt)
  end if
  return


end subroutine psi_bld_tmphalo