Merge #394

394: use repr(fty) for enums r=therealprof a=burrbull

enums are now in C-style with `#repr(..)`

Should slightly reduce code size in debug mode when enums are used.

r? @Disasm
cc @therealprof 

Co-authored-by: Andrey Zgarbul <zgarbul.andrey@gmail.com>

Author: bors[bot]

CHANGELOG.md

@@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Changed
 
+- Enum items now associated with values (C-style), enums annotated with `repr(fty)`
 - Bump `svd-parser` dependency (0.8.1)
 
 ## [v0.16.1] - 2019-08-17

src/generate/register.rs

@@ -636,14 +636,21 @@ impl Variant {
 fn add_from_variants(mod_items: &mut Vec<TokenStream>, variants: &Vec<Variant>, pc: &Ident, f: &F, desc: &str, reset_value: Option<u64>) {
     let fty = &f.ty;
 
+    let (repr, cast) = if f.ty == "bool" {
+        (quote! { }, quote! { variant as u8 != 0 })
+    } else {
+        (quote! { #[repr(#fty)] }, quote! { variant as _ })
+    };
+
     let vars = variants
         .iter()
         .map(|v| {
             let desc = util::escape_brackets(&format!("{}: {}", v.value, v.doc));
             let pcv = &v.pc;
+            let pcval = &util::unsuffixed(v.value);
             quote! {
                 #[doc = #desc]
-                #pcv
+                #pcv = #pcval
             }
         })
         .collect::<Vec<_>>();
@@ -657,27 +664,14 @@ fn add_from_variants(mod_items: &mut Vec<TokenStream>, variants: &Vec<Variant>,
     mod_items.push(quote! {
         #[doc = #desc]
         #[derive(Clone, Copy, Debug, PartialEq)]
+        #repr
         pub enum #pc {
             #(#vars),*
         }
-    });
-
-    let arms = variants.iter().map(|v| {
-        let pcv = &v.pc;
-        let value = util::unsuffixed_or_bool(v.value, f.width);
-
-        quote! {
-            #pc::#pcv => #value
-        }
-    });
-
-    mod_items.push(quote! {
         impl From<#pc> for #fty {
             #[inline(always)]
             fn from(variant: #pc) -> Self {
-                match variant {
-                    #(#arms),*
-                }
+                #cast
             }
         }
     });