MODULE floats
   !!======================================================================
   !!                       ***  MODULE  floats  ***
   !! Ocean floats : floats
   !!======================================================================
#if   defined key_floats   ||   defined key_esopa
   !!----------------------------------------------------------------------
   !!   'key_floats'                                     float trajectories
   !!----------------------------------------------------------------------
   !!   flo_stp   : float trajectories computation
   !!   flo_init  : initialization of float trajectories computation
   !!----------------------------------------------------------------------
   !! * Modules used
   USE flo_oce         ! floats variables
   USE lib_mpp         ! distributed memory computing
   USE flodom          ! initialisation Module 
   USE flowri          ! float output                     (flo_wri routine)
   USE flo4rk          ! Trajectories, Runge Kutta scheme (flo_4rk routine)
   USE floblk          ! Trajectories, Blanke scheme      (flo_blk routine)

   IMPLICIT NONE
   PRIVATE  

   !! * Routine accessibility
   PUBLIC flo_stp    ! routine called by step.F90
   !!----------------------------------------------------------------------
   !!   OPA 9.0 , LODYC-IPSL  (2003)
   !!----------------------------------------------------------------------

CONTAINS

   SUBROUTINE flo_stp( kt )
      !!----------------------------------------------------------------------
      !!                   ***  ROUTINE flo_stp  ***
      !!                    
      !! ** Purpose :   Compute the geographical position (lat., long., depth)
      !!      of each float at each time step with one of the algorithm.
      !! 
      !! ** Method  :   The position of a float is computed with Bruno Blanke 
      !!        algorithm by default and with a 4th order Runge-Kutta scheme
      !!        if ln_flork4 =T
      !!      
      !! History :
      !!   8.5  !  02-06  (A. Bozec, G. Madec )  F90: Free form and module
      !!----------------------------------------------------------------------
      !! * arguments
      INTEGER, INTENT( in  ) ::   kt   ! ocean time step
      !!----------------------------------------------------------------------

      IF( kt == nit000 ) THEN
         IF(lwp) WRITE(numout,*)
         IF(lwp) WRITE(numout,*) 'flo_stp : call floats routine '
         IF(lwp) WRITE(numout,*) '~~~~~~~'

         CALL flo_init           ! read the namelist of floats             

         CALL flo_dom            ! compute/read initial position of floats

         ! Initialisation of wb for computation of floats trajectories at the first time step
         wb(:,:,:) = wn(:,:,:)
      ENDIF

      IF( ln_flork4 ) THEN
         CALL flo_4rk( kt )        ! Trajectories using a 4th order Runge Kutta scheme
      ELSE
         CALL flo_blk( kt )        ! Trajectories using Blanke' algorithme
      ENDIF

      IF( lk_mpp )   CALL mppsync   ! synchronization of all the processor


      ! Writing and restart      
      
      ! trajectories file 
      IF( kt == nit000 .OR. MOD( kt, nwritefl ) == 0 )   CALL flo_wri( kt )
      ! restart file 
      IF( kt == nitend .OR. MOD( kt, nstockfl ) == 0 )   CALL flo_wri( kt )

      ! Save the old vertical velocity field
      wb(:,:,:) = wn(:,:,:)

   END SUBROUTINE flo_stp


   SUBROUTINE flo_init
      !!----------------------------------------------------------------
      !!                 ***  ROUTINE flo_init  ***
      !!                   
      !! ** Purpose :   Read the namelist of floats
      !!      
      !! History :
      !!   8.0  !         (CLIPPER)   original Code
      !!   8.5  !  02-06  (A. Bozec)  F90, Free form and module
      !!----------------------------------------------------------------------
      !! * Modules used
      USE ioipsl

      !! * Local declarations
      NAMELIST/namflo/ ln_rstflo, nwritefl, nstockfl 
      !!---------------------------------------------------------------------
      ! Namelist namflo : floats
      
      ! default values
      ln_rstflo  = .FALSE.
      nwritefl  = 150
      nstockfl  = 450
      
      ! lecture of namflo
      REWIND( numnam )
      READ  ( numnam, namflo )

      IF(lwp) THEN
         WRITE(numout,*) ' '
         WRITE(numout,*) '         Namelist floats :'
         WRITE(numout,*) '            restart                          ln_rstflo = ', ln_rstflo
         WRITE(numout,*) '            frequency of float output file   nwritefl  = ', nwritefl
         WRITE(numout,*) '            frequency of float restart file  nstockfl  = ', nstockfl
         WRITE(numout,*) ' '
      ENDIF

   END SUBROUTINE flo_init

#  else
   !!----------------------------------------------------------------------
   !!   Default option :                                       Empty module
   !!----------------------------------------------------------------------
CONTAINS
   SUBROUTINE flo_stp( kt )          ! Empty routine
      WRITE(*,*) 'flo_stp: You should not have seen this print! error?', kt
   END SUBROUTINE flo_stp
#endif

   !!======================================================================
 END MODULE floats