-XBT_PUBLIC(xbt_os_timer_t) xbt_os_timer_new();
-XBT_PUBLIC(void) xbt_os_timer_free(xbt_os_timer_t timer);
-XBT_PUBLIC(double) xbt_os_timer_elapsed(xbt_os_timer_t timer);
-XBT_PUBLIC(size_t) xbt_os_timer_size();
+XBT_PUBLIC xbt_os_timer_t xbt_os_timer_new(void);
+XBT_PUBLIC void xbt_os_timer_free(xbt_os_timer_t timer);
+XBT_PUBLIC double xbt_os_timer_elapsed(const_xbt_os_timer_t timer);
+XBT_PUBLIC size_t xbt_os_timer_size(void);