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_start(xbt_os_timer_t timer);
XBT_PUBLIC(void) xbt_os_walltimer_resume(xbt_os_timer_t timer);