void platform_private_start_single_hook_timer(unsigned frequency);
platform_private_start_single_hook_timer is a utility function when implementing platform_hook_single_timer on platforms that offer only one timer. platform_private_start_single_hook_timer starts the single instance of a hook timer which fires frequency times per second.
The hook timer, once active, should call platform_private_execute_hooks passing in platform_private_timer_hooks.