make the init::Resources argument optional

macros/src/trans.rs

@@ -30,9 +30,15 @@ fn init(app: &App, main: &mut Vec<Tokens>, root: &mut Vec<Tokens>) {
     let device = &app.device;
     let krate = krate();
 
+    let mut tys = vec![quote!(init::Peripherals)];
+    let mut exprs = vec![quote!(init::Peripherals::all())];
+    let mut mod_items = vec![];
+
+    if !app.resources.is_empty() {
         let mut fields = vec![];
-    let mut exprs = vec![];
         let mut lifetime = None;
+        let mut rexprs = vec![];
+
         for (name, resource) in &app.resources {
             lifetime = Some(quote!('a));
 
@@ -42,7 +48,7 @@ fn init(app: &App, main: &mut Vec<Tokens>, root: &mut Vec<Tokens>) {
                 pub #name: &'a mut #krate::Static<#ty>,
             });
 
-        exprs.push(quote! {
+            rexprs.push(quote! {
                 #name: ::#krate::Static::ref_mut(&mut *super::#name.get()),
             });
         }
@@ -53,18 +59,29 @@ fn init(app: &App, main: &mut Vec<Tokens>, root: &mut Vec<Tokens>) {
             pub struct _initResources<#lifetime> {
                 #(#fields)*
             }
+        });
 
-        mod init {
-            pub use ::#device::Peripherals;
+        mod_items.push(quote! {
             pub use ::_initResources as Resources;
 
             impl<#lifetime> Resources<#lifetime> {
                 pub unsafe fn new() -> Self {
                     Resources {
-                        #(#exprs)*
+                        #(#rexprs)*
+                    }
                 }
             }
+        });
+
+        tys.push(quote!(init::Resources));
+        exprs.push(quote!(init::Resources::new()));
     }
+
+    root.push(quote! {
+        mod init {
+            pub use ::#device::Peripherals;
+
+            #(#mod_items)*
         }
     });
 
@@ -116,10 +133,10 @@ fn init(app: &App, main: &mut Vec<Tokens>, root: &mut Vec<Tokens>) {
     let init = &app.init.path;
     main.push(quote! {
         // type check
-        let init: fn(init::Peripherals, init::Resources) = #init;
+        let init: fn(#(#tys,)*) = #init;
 
         #krate::atomic(|_cs| unsafe {
-            init(init::Peripherals::all(), init::Resources::new());
+            init(#(#exprs,)*);
 
             #(#exceptions)*
             #(#interrupts)*