+void xbt_os_timer_free(xbt_os_timer_t timer) {
+ free (timer);
+}
+void xbt_os_timer_start(xbt_os_timer_t timer) {
+#ifdef HAVE_GETTIMEOFDAY
+ gettimeofday(&(timer->start), NULL);
+#else
+ timer->start = (unsigned long int)(time(NULL));
+#endif
+}
+void xbt_os_timer_stop(xbt_os_timer_t timer) {
+#ifdef HAVE_GETTIMEOFDAY
+ gettimeofday(&(timer->stop), NULL);
+#else
+ timer->stop = (unsigned long int)(time(NULL));
+#endif
+}
+double xbt_os_timer_elapsed(xbt_os_timer_t timer) {
+#ifdef HAVE_GETTIMEOFDAY
+ return ((double)timer->stop.tv_sec) - ((double)timer->start.tv_sec) +
+ ((((double)timer->stop.tv_usec) - ((double)timer->start.tv_usec)) / 1000000.0);
+#else
+ return (double)timer->stop - (double)timer->start;
+#endif
+}
+