add tick

fateful_macros/src/lib.rs

@@ -83,6 +83,12 @@ pub fn peripheral(attr: TokenStream, item: TokenStream) -> TokenStream {
                 <#ident as fateful_peripheral::Peripheral>::write(&mut boxed, n, data);
             }
 
+            #[no_mangle]
+            pub unsafe extern "C" fn stateful_tick(state: *mut ::std::ffi::c_void) {
+                let mut boxed = ::std::mem::ManuallyDrop::new(::std::boxed::Box::from_raw(state as *mut #ident));
+                <#ident as fateful_peripheral::Peripheral>::tick(&mut boxed);
+            }
+
             #[no_mangle]
             pub unsafe extern "C" fn stateful_drop(state: *mut ::std::ffi::c_void) {
                 let boxed = ::std::boxed::Box::from_raw(state as *mut #ident);

src/lib.rs

@@ -89,6 +89,9 @@ pub trait Peripheral: Sized {
     /// where `ports` is the `ports` argument in [`init`](Peripheral::init)
     fn write(&mut self, port: u8, data: u8) {}
 
+    /// Called every time the CPU clock ticks (falling-edge).
+    fn tick(&mut self) {}
+
     /// Called whenever the CPU in the emulator is reset.
     /// 
     /// Implementors should make sure that the peripheral state