Scheduler/ClockService: Add reltime() and reltime_type

Scheduler/ClockService.cci

@@ -83,6 +83,15 @@ prefix_ senf::ClockService::abstime_type senf::ClockService::abstime(clock_type
     return instance().abstime_m(clock);
 }
 
+prefix_ senf::ClockService::reltime_type senf::ClockService::reltime(clock_type clock)
+{
+#ifdef BOOST_DATE_TIME_POSIX_TIME_STD_CONFIG
+    return boost::posix_time::nanoseconds(clock);
+#else
+    return  boost::posix_time::microseconds((clock+500)/1000);
+#endif
+}
+
 prefix_ senf::ClockService::clock_type senf::ClockService::clock(abstime_type time)
 {
     return instance().clock_m(time);

Scheduler/ClockService.hh

@@ -86,6 +86,12 @@ namespace senf {
          */
         typedef boost::posix_time::ptime abstime_type;
 
+        /** \brief Relative time data type
+
+            Boost.DateTime datatype used to represent time intervals
+         */
+        typedef boost::posix_time::time_duration reltime_type;
+
         ///////////////////////////////////////////////////////////////////////////
 
         static clock_type now();  ///< Return current clock value
@@ -98,6 +104,12 @@ namespace senf {
                                                  monotonous, absolute time may be non-monotonous if
                                                  the system date/time is changed. */
 
+        static reltime_type reltime(clock_type clock); ///< Convert clock to relative time
+                                        /**< This member converts a clock value into a relative
+                                             Boost.DateTime time interval
+                                             \note The resolution of reltime_type might be smaller
+                                                 than the clock_type resolution */
+
         static clock_type clock(abstime_type time); ///< Convert absolute time to clock value
                                         /**< This member converst an absolute time value into the
                                              corresponding clock value.