SUBROUTINE lpm_write_restart_file

!------------------------------------------------------------------------------!
! Current revisions:
! ------------------
! 
!
! Former revisions:
! -----------------
! $Id: lpm_write_restart_file.f90 850 2012-03-15 12:09:25Z hoffmann $
!
! 849 2012-03-15 10:35:09Z raasch
! initial revision (former part of advec_particles)
!
!
! Description:
! ------------
! Write particle data in FORTRAN binary format on restart file
!------------------------------------------------------------------------------!

    USE control_parameters
    USE particle_attributes
    USE pegrid

    IMPLICIT NONE

    CHARACTER (LEN=10) ::  particle_binary_version
    INTEGER ::  i

!
!-- First open the output unit.
    IF ( myid_char == '' )  THEN
       OPEN ( 90, FILE='PARTICLE_RESTART_DATA_OUT'//myid_char, &
                  FORM='UNFORMATTED')
    ELSE
       IF ( myid == 0 )  CALL local_system( 'mkdir PARTICLE_RESTART_DATA_OUT' )
#if defined( __parallel )
!
!--    Set a barrier in order to allow that thereafter all other processors
!--    in the directory created by PE0 can open their file
       CALL MPI_BARRIER( comm2d, ierr )
#endif
       OPEN ( 90, FILE='PARTICLE_RESTART_DATA_OUT/'//myid_char, &
                  FORM='UNFORMATTED' )
    ENDIF

    DO  i = 0, io_blocks-1

       IF ( i == io_group )  THEN

!
!--       Write the version number of the binary format.
!--       Attention: After changes to the following output commands the version
!--       ---------  number of the variable particle_binary_version must be
!--                  changed! Also, the version number and the list of arrays
!--                  to be read in lpm_read_restart_file must be adjusted
!--                  accordingly.
          particle_binary_version = '3.0'
          WRITE ( 90 )  particle_binary_version

!
!--       Write some particle parameters, the size of the particle arrays as
!--       well as other dvrp-plot variables.
          WRITE ( 90 )  bc_par_b, bc_par_lr, bc_par_ns, bc_par_t,              &
                        maximum_number_of_particles,                           &
                        maximum_number_of_tailpoints, maximum_number_of_tails, &
                        number_of_initial_particles, number_of_particles,      &
                        number_of_particle_groups, number_of_tails,            &
                        particle_groups, time_prel, time_write_particle_data,  &
                        uniform_particles

          IF ( number_of_initial_particles /= 0 ) WRITE ( 90 ) initial_particles

          WRITE ( 90 )  prt_count, prt_start_index
          WRITE ( 90 )  particles

          IF ( use_particle_tails )  THEN
             WRITE ( 90 )  particle_tail_coordinates
          ENDIF

          CLOSE ( 90 )

       ENDIF

#if defined( __parallel )
       CALL MPI_BARRIER( comm2d, ierr )
#endif

    ENDDO


 END SUBROUTINE lpm_write_restart_file