+XBT_PUBLIC(size_t) xbt_os_timer_size(void);
+
+XBT_PUBLIC(void) xbt_os_walltimer_start(xbt_os_timer_t timer);
+XBT_PUBLIC(void) xbt_os_walltimer_resume(xbt_os_timer_t timer);
+XBT_PUBLIC(void) xbt_os_walltimer_stop(xbt_os_timer_t timer);
+
+XBT_PUBLIC(void) xbt_os_cputimer_start(xbt_os_timer_t timer);
+XBT_PUBLIC(void) xbt_os_cputimer_resume(xbt_os_timer_t timer);
+XBT_PUBLIC(void) xbt_os_cputimer_stop(xbt_os_timer_t timer);