Add BinRead and BinWrite trait generation (#65)

Author: Maccraft123

src/attr.rs

@@ -15,6 +15,8 @@ pub struct Params {
     pub into: Option<syn::Path>,
     pub from: Option<syn::Path>,
     pub bits: usize,
+    pub binread: Enable,
+    pub binwrite: Enable,
     pub new: Enable,
     pub clone: Enable,
     pub debug: Enable,
@@ -41,6 +43,8 @@ impl Parse for Params {
             into: None,
             from: None,
             bits,
+            binread: Enable::No,
+            binwrite: Enable::No,
             new: Enable::Yes,
             clone: Enable::Yes,
             debug: Enable::Yes,
@@ -93,6 +97,17 @@ impl Parse for Params {
                 "conversion" => {
                     ret.conversion = syn::LitBool::parse(input)?.value;
                 }
+                "binrw" => {
+                    let enable: Enable = input.parse()?;
+                    ret.binread = enable.clone();
+                    ret.binwrite = enable;
+                }
+                "binread" => {
+                    ret.binread = input.parse()?;
+                }
+                "binwrite" => {
+                    ret.binwrite = input.parse()?;
+                }
                 _ => return Err(s_err(ident.span(), "unknown argument")),
             };
         }

src/lib.rs

@@ -30,6 +30,9 @@ fn s_err(span: proc_macro2::Span, msg: impl fmt::Display) -> syn::Error {
 /// - `from` to specify a conversion function from repr to the bitfield's integer type
 /// - `into` to specify a conversion function from the bitfield's integer type to repr
 /// - `new` to disable the `new` function generation
+/// - `binread` to enable the `BinRead` trait generation
+/// - `binwrite` to enable the `BinWrite` trait generation
+/// - `binrw` to enable both `BinRead` and `BinWrite` trait generation
 /// - `clone` to disable the `Clone` trait generation
 /// - `debug` to disable the `Debug` trait generation
 /// - `defmt` to enable the `defmt::Format` trait generation
@@ -64,6 +67,8 @@ fn bitfield_inner(args: TokenStream, input: TokenStream) -> syn::Result<TokenStr
         into,
         from,
         bits,
+        binread,
+        binwrite,
         new,
         clone,
         debug,
@@ -133,6 +138,12 @@ fn bitfield_inner(args: TokenStream, input: TokenStream) -> syn::Result<TokenStr
     if let Some(cfg) = hash.cfg() {
         impl_debug.extend(traits::hash(&name, &members, cfg));
     }
+    if let Some(cfg) = binread.cfg() {
+        impl_debug.extend(traits::binread(&name, &repr, cfg));
+    }
+    if let Some(cfg) = binwrite.cfg() {
+        impl_debug.extend(traits::binwrite(&name, cfg));
+    }
 
     let defaults = members.iter().map(Member::default).collect::<Vec<_>>();
 

src/traits.rs

@@ -131,3 +131,69 @@ pub fn hash(
         }
     }
 }
+
+/// Implements the `binrw::BinWrite` trait for the given bitfield struct.
+pub fn binwrite(
+    name: &syn::Ident,
+    cfg: Option<TokenStream>,
+) -> TokenStream {
+    let attr = cfg.map(|cfg| quote!(#[cfg(#cfg)]));
+
+    quote! {
+        #attr
+        impl binrw::BinWrite for #name {
+            type Args<'a> = ();
+
+            fn write_options<W: binrw::io::Write + binrw::io::Seek>(
+                &self,
+                writer: &mut W,
+                endian: binrw::Endian,
+                args: Self::Args<'_>,
+            ) -> binrw::BinResult<()> {
+                let raw = self.into_bits();
+
+                let bytes = match endian {
+                    binrw::Endian::Big => raw.to_be_bytes(),
+                    binrw::Endian::Little => raw.to_le_bytes(),
+                };
+
+                writer.write_all(&bytes)?;
+
+                Ok(())
+            }
+        }
+    }
+}
+
+/// Implements the `binrw::BinRead` trait for the given bitfield struct.
+pub fn binread(
+    name: &syn::Ident,
+    repr: &syn::Type,
+    cfg: Option<TokenStream>,
+) -> TokenStream {
+    let attr = cfg.map(|cfg| quote!(#[cfg(#cfg)]));
+
+    quote! {
+        #attr
+        impl binrw::BinRead for #name {
+            type Args<'a> = ();
+
+            fn read_options<R: binrw::io::Read + binrw::io::Seek>(
+                reader: &mut R,
+                endian: binrw::Endian,
+                args: Self::Args<'_>,
+            ) -> binrw::BinResult<Self> {
+                let mut buf = [0u8; core::mem::size_of::<#repr>()];
+
+                reader.read_exact(&mut buf)?;
+
+                let raw = match endian {
+                    binrw::Endian::Big => <#repr>::from_be_bytes(buf),
+                    binrw::Endian::Little => <#repr>::from_le_bytes(buf),
+                };
+
+                Ok(Self::from_bits(raw))
+            }
+        }
+    }
+}