SUBROUTINE cpu_log( log_event, place, modus, barrierwait )

!--------------------------------------------------------------------------------!
! 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 1997-2012  Leibniz University Hannover
!--------------------------------------------------------------------------------!
!
! Current revisions:
! -----------------
! 
!
! Former revisions:
! -----------------
! $Id: cpu_log.f90 1037 2012-10-22 14:10:22Z franke $
!
! 1036 2012-10-22 13:43:42Z raasch
! code put under GPL (PALM 3.9)
!
! 274 2009-03-26 15:11:21Z heinze
! Output of messages replaced by message handling routine.
! Type of count and count_rate changed to default INTEGER on NEC machines
!
! 225 2009-01-26 14:44:20Z raasch
! Type of count and count_rate changed to INTEGER(8)
!
! 82 2007-04-16 15:40:52Z raasch
! Preprocessor strings for different linux clusters changed to "lc",
! preprocessor directives for old systems removed
!
! RCS Log replace by Id keyword, revision history cleaned up
!
! Revision 1.24  2006/06/02 15:12:17  raasch
! cpp-directives extended for lctit
!
! Revision 1.1  1997/07/24 11:12:29  raasch
! Initial revision
!
!
! Description:
! ------------
! Cpu-time measurements for any program part whatever.
!------------------------------------------------------------------------------!

    USE control_parameters
    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( __lc ) || defined( __decalpha )
    INTEGER(8)                  ::  count, count_rate
#elif defined( __nec )
    INTEGER                     ::  count, count_rate
#elif defined( __ibm )
    INTEGER(8)                  ::  IRTC
#endif


!
!-- Initialize and check, respectively, point of measurement
    IF ( log_event%place == ' ' )  THEN
       log_event%place = place
    ELSEIF ( log_event%place /= place )  THEN
       WRITE( message_string, * ) 'wrong argument & expected: ', &
                         TRIM(log_event%place), '  given: ',  TRIM( place )
       CALL message( 'cpu_log', 'PA0174', 1, 2, 0, 6, 0 )
    ENDIF

!
!-- Take current time
#if defined( __lc ) || defined( __decalpha ) || defined( __nec )
    CALL SYSTEM_CLOCK( count, count_rate )
    mtime = REAL( count ) / REAL( count_rate )
#elif defined( __ibm )
    mtime = IRTC( ) * 1E-9
#else
    message_string = 'no time measurement defined on this host'
    CALL message( 'cpu_log', 'PA0175', 1, 2, 0, 6, 0 )
#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
          WRITE( message_string, * ) 'negative time interval occured',         &
                      ' &PE',myid,' L=PAUSE "',TRIM(log_event%place),'" new=', &
                      mtime,' last=',log_event%mtime
          CALL message( 'cpu_log', 'PA0176', 0, 1, -1, 6, 0 )
          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
          WRITE( message_string, * ) 'negative time interval occured',        &
                      ' &PE',myid,' L=STOP "',TRIM(log_event%place),'" new=', &
                      mtime,' last=',log_event%mtime,' isum=',log_event%isum
          CALL message( 'cpu_log', 'PA0177', 0, 1, -1, 6, 0 )
          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
          WRITE( message_string, * ) 'negative time interval occured',        &
                      ' &PE',myid,' L=STOP "',TRIM(log_event%place),'" sum=', &
                                      log_event%sum,' mtime=',log_event%mtime
          CALL message( 'cpu_log', 'PA0178', 0, 1, -1, 6, 0 )
          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
       message_string = 'unknown modus of time measurement: ' // TRIM( modus )
       CALL message( 'cpu_log', 'PA0179', 0, 1, -1, 6, 0 )
    ENDIF


 END SUBROUTINE cpu_log