SUBROUTINE lpm_extend_particle_array( number_of_new_particles )

!--------------------------------------------------------------------------------!
! This file is part of PALM.
!
! PALM is free software: you can redistribute it and/or modify it under the terms
! of the GNU General Public License as published by the Free Software Foundation,
! either version 3 of the License, or (at your option) any later version.
!
! PALM is distributed in the hope that it will be useful, but WITHOUT ANY
! WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
! A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
!
! You should have received a copy of the GNU General Public License along with
! PALM. If not, see <http://www.gnu.org/licenses/>.
!
! Copyright 1997-2014 Leibniz Universitaet Hannover
!--------------------------------------------------------------------------------!
!
! Current revisions:
! ------------------
!
!
! Former revisions:
! -----------------
! $Id: lpm_extend_particle_array.f90 1321 2014-03-20 09:40:40Z witha $
!
! 1320 2014-03-20 08:40:49Z raasch
! ONLY-attribute added to USE-statements,
! kind-parameters added to all INTEGER and REAL declaration statements,
! kinds are defined in new module kinds,
! comment fields (!:) to be used for variable explanations added to
! all variable declaration statements
!
! 1036 2012-10-22 13:43:42Z raasch
! code put under GPL (PALM 3.9)
!
! 849 2012-03-15 10:35:09Z raasch
! initial revision (former part of advec_particles)
!
!
! Description:
! ------------
! Allocates more memory for the particle array.
!------------------------------------------------------------------------------!

    USE kinds

    USE particle_attributes,                                                   &
        ONLY:  number_of_initial_particles, number_of_particles,               &
               maximum_number_of_particles, particles, particle_mask,          &
               particle_type, write_particle_statistics

    IMPLICIT NONE

    INTEGER(iwp) ::  new_maximum_number                              !:
    INTEGER(iwp) ::  number_of_new_particles                         !:


    LOGICAL, DIMENSION(:), ALLOCATABLE ::  tmp_particle_mask         !:

    TYPE(particle_type), DIMENSION(:), ALLOCATABLE ::  tmp_particles !:



    new_maximum_number = maximum_number_of_particles + &
                   MAX( 5*number_of_new_particles, number_of_initial_particles )

    IF ( write_particle_statistics )  THEN
       CALL check_open( 80 )
       WRITE ( 80, '(''*** Request: '', I7, '' new_maximum_number(prt)'')' ) &
                            new_maximum_number
       CALL close_file( 80 )
    ENDIF

    ALLOCATE( tmp_particles(maximum_number_of_particles), &
              tmp_particle_mask(maximum_number_of_particles) )

    tmp_particles     = particles
    tmp_particle_mask = particle_mask

    DEALLOCATE( particles, particle_mask )
    ALLOCATE( particles(new_maximum_number), particle_mask(new_maximum_number) )

    maximum_number_of_particles = new_maximum_number

    particles(1:number_of_particles) = tmp_particles(1:number_of_particles)
    particle_mask(1:number_of_particles) = &
                                       tmp_particle_mask(1:number_of_particles)
    particle_mask(number_of_particles+1:maximum_number_of_particles) = .TRUE.

    DEALLOCATE( tmp_particles, tmp_particle_mask )


 END SUBROUTINE lpm_extend_particle_array