Adds ability to get the current time of day

src/ffi/dynamic_data/libraries/misc_library.rs

@@ -1,10 +1,46 @@
 use crate::dynamic_data::{Gen7MiscLibrary, MiscLibrary};
 use crate::ffi::ffi_handle::FFIHandle;
+use crate::static_data::TimeOfDay;
 use std::sync::Arc;
 
 /// Instantiates a new MiscLibrary.
 #[no_mangle]
-extern "C" fn gen_7_misc_library_new() -> FFIHandle<Arc<dyn MiscLibrary>> {
-    let v: Arc<dyn MiscLibrary> = Arc::new(Gen7MiscLibrary::new());
+extern "C" fn gen_7_misc_library_new(get_time_of_day_fn: FFIGetTimeOfDayFn) -> FFIHandle<Arc<dyn MiscLibrary>> {
+    let v: Arc<dyn MiscLibrary> = Arc::new(Gen7MiscLibrary::new(Box::new(get_time_of_day_fn)));
     FFIHandle::get_handle(v.into())
 }
+
+/// Wrapper class for easier use of an external function pointer.
+#[repr(C)]
+pub(super) struct FFIGetTimeOfDayFn {
+    /// The actual C function to be called. Note that we pass the batch id as a pair of u64s. This
+    /// is because u128 does not have a stable ABI yet.
+    f: extern "C" fn() -> u8,
+}
+
+impl FFIGetTimeOfDayFn {
+    /// Calls the actual wrapped function in the correct format.
+    fn call_self(&self) -> TimeOfDay {
+        unsafe { std::mem::transmute((self.f)()) }
+    }
+}
+
+impl FnMut<()> for FFIGetTimeOfDayFn {
+    extern "rust-call" fn call_mut(&mut self, _: ()) -> Self::Output {
+        self.call_self()
+    }
+}
+
+impl FnOnce<()> for FFIGetTimeOfDayFn {
+    type Output = TimeOfDay;
+
+    extern "rust-call" fn call_once(self, _: ()) -> Self::Output {
+        self.call_self()
+    }
+}
+
+impl Fn<()> for FFIGetTimeOfDayFn {
+    extern "rust-call" fn call(&self, _: ()) -> Self::Output {
+        self.call_self()
+    }
+}