Function rust_libretro::environment::set_frame_time_callback

pub unsafe fn set_frame_time_callback(
    callback: retro_environment_t,
    data: retro_frame_time_callback
) -> bool

Lets the core know how much time has passed since last invocation of Core::on_run. The frontend can tamper with the timing to fake fast-forward, slow-motion, frame stepping, etc. In this case the delta time will use the reference value in retro_frame_time_callback.