SUBROUTINE cpu_log( log_event, place, modus, barrierwait )

!------------------------------------------------------------------------------!
! Actual revisions:
! -----------------
! 
!
! Former revisions:
! -----------------
! $Log: cpu_log.f90,v $
! Revision 1.24  2006/06/02 15:12:17  raasch
! cpp-directives extended for lctit
!
! Revision 1.23  2004/01/28 15:08:52  raasch
! Type log changed to logpoint due to name conflict with intrinsic log
!
! Revision 1.22  2003/05/09 14:15:18  raasch
! Time measurement on linux machines included, measurements on IBM are now using
! function irtc, which allows correct measurements for jobs running over
! the 24:00 timeline
!
! Revision 1.21  2003/03/16 09:30:04  raasch
! Two underscores (_) are placed in front of all define-strings
!
! Revision 1.20  2003/03/12 16:24:18  raasch
! Time measurement on NEC implemented
!
! Revision 1.19  2002/12/20 09:38:43  raasch
! variable first is defined for all hosts
!
! Revision 1.18  2002/12/19 14:09:36  raasch
! Output of warnings in case of negative cpu-times, STOP statement replaced by
! call of subroutine local_stop
!
! Revision 1.17  2002/05/02 18:49:37  raasch
! Time measurement on IBM implemented
!
! Revision 1.16  2001/03/30 07:00:43  raasch
! Translation of remaining German identifiers (variables, subroutines, etc.)
!
! Revision 1.14  2001/01/25 06:56:49  raasch
! +cpp-directives for dec-alpha-workstations
!
! Revision 1.13  2001/01/22 08:32:46  raasch
! Module test_variables removed
!
! Revision 1.11  2000/12/20 10:18:58  letzel
! All comments translated into English.
!
! Revision 1.9  1999/11/25 16:19:07  raasch
! TIMEF jetzt als Function-Aufruf
!
! Revision 1.8  1999/03/03 09:26:14  raasch
! Zeitmessung auf T3E grundsaetzlich auf TIMEF umgestellt
!
! Revision 1.7  1998/12/15 07:32:39  raasch
! Messung der wahren I/O-Zeiten auf T3E mit TIMEF moeglich
!
! Revision 1.4  1997/09/16 06:37:24  raasch
! Zeitmessungen auf t3e umgestellt auf tsecnd (schneller als mpi_wtime)
!
! Revision 1.1  1997/07/24 11:12:29  raasch
! Initial revision
!
!
! Description:
! ------------
! Cpu-time measurements for any program part whatever.
!-------------------------------------------------------------------------------!

    USE cpulog
    USE pegrid

    IMPLICIT NONE

    CHARACTER (LEN=*)           ::  modus, place
    CHARACTER (LEN=*), OPTIONAL ::  barrierwait
    LOGICAL, SAVE               ::  first = .TRUE.
    REAL                        ::  mtime = 0.0, mtimevec = 0.0
    TYPE(logpoint)              ::  log_event

#if defined( __lcmuk ) || defined( __lctit ) || defined( __hpmuk ) || defined( __decalpha ) || defined( __nec )
    INTEGER                     ::  count, count_rate
#elif defined( __ibm )
    INTEGER(8)                  ::  IRTC
#elif defined( __t3eb )
    REAL                        ::  TIMEF
#endif


!
!-- Initialize and check, respectively, point of measurement
    IF ( log_event%place == ' ' )  THEN
       log_event%place = place
    ELSEIF ( log_event%place /= place )  THEN
       IF ( myid == 0 )  THEN
          PRINT*,'+++ cpu_log: wrong argument'
          PRINT*,'    expected: ',log_event%place,'  given: ', place
       ENDIF
       CALL local_stop
    ENDIF

!
!-- Take current time
#if defined( __lcmuk ) || defined( __lctit ) || defined( __hpmuk ) || defined( __decalpha ) || defined( __nec )
    CALL SYSTEM_CLOCK( count, count_rate )
    mtime = REAL( count ) / REAL( count_rate )
#elif defined( __ibm )
    mtime = IRTC( ) * 1E-9
!#elif defined( __vpp )
!    CALL CLOCKV ( mtimevec, mtime, 0, 2 )
#elif defined( __t3eb ) || defined( __t3eh ) || defined( __t3ej2 ) || defined( __t3ej5 )
#if defined( __parallel )
    IF ( .NOT. PRESENT( barrierwait ) )  THEN
       CALL MPI_BARRIER( comm2d, ierr )
       CONTINUE
    ENDIF
#endif
    mtime = TIMEF( )
    mtime = mtime * 0.001
#else
    IF ( myid == 0 )  THEN
       PRINT*, '+++ cpu_log: no time measurement defined on this host'
    ENDIF
    CALL local_stop
#endif

!
!-- Start, stop or pause measurement
    IF ( modus == 'start'  .OR.  modus == 'continue' )  THEN
       log_event%mtime    = mtime
       log_event%mtimevec = mtimevec
    ELSEIF ( modus == 'pause' )  THEN
       IF ( ( mtime - log_event%mtime ) < 0.0  .AND.  first )  THEN
          PRINT*,'+++ WARNING: cpu_log: negative time interval occured'
          PRINT*,'+++ PE',myid,' L=PAUSE "',TRIM(log_event%place),'" new=', &
                 mtime,' last=',log_event%mtime
          first = .FALSE.
       ENDIF
       log_event%isum     = log_event%isum + mtime - log_event%mtime
       log_event%ivect    = log_event%ivect  + mtimevec - log_event%mtimevec
    ELSEIF ( modus == 'stop' )  THEN
       IF ( ( mtime - log_event%mtime + log_event%isum ) < 0.0  .AND. &
            first )  THEN
          PRINT*,'+++ WARNING: cpu_log: negative time interval occured'
          PRINT*,'+++ PE',myid,' L=STOP "',TRIM(log_event%place),'" new=', &
                 mtime,' last=',log_event%mtime,' isum=',log_event%isum
          first = .FALSE.
       ENDIF
       log_event%mtime    = mtime    - log_event%mtime    + log_event%isum
       log_event%mtimevec = mtimevec - log_event%mtimevec + log_event%ivect
       log_event%sum      = log_event%sum  + log_event%mtime
       IF ( log_event%sum < 0.0  .AND.  first )  THEN
          PRINT*,'+++ WARNING: cpu_log: negative time interval occured'
          PRINT*,'+++ PE',myid,' L=STOP "',TRIM(log_event%place),'" sum=', &
                 log_event%sum,' mtime=',log_event%mtime
          first = .FALSE.
       ENDIF
       log_event%vector   = log_event%vector + log_event%mtimevec
       log_event%counts   = log_event%counts + 1
       log_event%isum     = 0.0
       log_event%ivect    = 0.0
    ELSE
       PRINT*, '+++ unknown modus of time measurement: ', modus
    ENDIF


 END SUBROUTINE cpu_log