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Add support for custom inner types
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Signed-off-by: Martin Kröning <[email protected]>
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@mkroening
mkroening committed Jun 1, 2024
1 parent cc9aae2 commit 0ceac3d
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Showing 2 changed files with 78 additions and 11 deletions.
62 changes: 51 additions & 11 deletions src/lib.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,9 @@ fn bitfield_inner(args: TokenStream, input: TokenStream) -> syn::Result<TokenStr
let input = syn::parse2::<syn::ItemStruct>(input)?;
let Params {
ty,
inner,
into,
from,
bits,
debug,
default,
Expand All @@ -66,7 +69,15 @@ fn bitfield_inner(args: TokenStream, input: TokenStream) -> syn::Result<TokenStr
let mut offset = 0;
let mut members = Vec::with_capacity(fields.named.len());
for field in fields.named {
let f = Member::new(ty.clone(), bits, field, offset, order)?;
let f = Member::new(
ty.clone(),
bits,
into.clone(),
from.clone(),
field,
offset,
order,
)?;
offset += f.bits;
members.push(f);
}
Expand Down Expand Up @@ -122,11 +133,11 @@ fn bitfield_inner(args: TokenStream, input: TokenStream) -> syn::Result<TokenStr
let conversion = if conversion {
quote! {
/// Convert from bits.
#vis const fn from_bits(bits: #ty) -> Self {
#vis const fn from_bits(bits: #inner) -> Self {
Self(bits)
}
/// Convert into bits.
#vis const fn into_bits(self) -> #ty {
#vis const fn into_bits(self) -> #inner {
self.0
}
}
Expand All @@ -138,12 +149,12 @@ fn bitfield_inner(args: TokenStream, input: TokenStream) -> syn::Result<TokenStr
#attrs
#[derive(Copy, Clone)]
#[repr(transparent)]
#vis struct #name(#ty);
#vis struct #name(#inner);

impl #name {
/// Creates a new default initialized bitfield.
#vis const fn new() -> Self {
let mut this = Self(0);
let mut this = Self(#from(0));
#( #defaults )*
this
}
Expand All @@ -154,13 +165,13 @@ fn bitfield_inner(args: TokenStream, input: TokenStream) -> syn::Result<TokenStr

#default_impl

impl From<#ty> for #name {
fn from(v: #ty) -> Self {
impl From<#inner> for #name {
fn from(v: #inner) -> Self {
Self(v)
}
}
impl From<#name> for #ty {
fn from(v: #name) -> #ty {
impl From<#name> for #inner {
fn from(v: #name) -> #inner {
v.0
}
}
Expand All @@ -174,6 +185,8 @@ struct Member {
offset: usize,
bits: usize,
base_ty: syn::Type,
inner_into: Option<syn::Path>,
inner_from: Option<syn::Path>,
default: TokenStream,
inner: Option<MemberInner>,
}
Expand All @@ -191,6 +204,8 @@ impl Member {
fn new(
base_ty: syn::Type,
base_bits: usize,
inner_into: Option<syn::Path>,
inner_from: Option<syn::Path>,
f: syn::Field,
offset: usize,
order: Order,
Expand Down Expand Up @@ -259,6 +274,8 @@ impl Member {
offset,
bits,
base_ty,
inner_into,
inner_from,
default,
inner: Some(MemberInner {
ident,
Expand All @@ -278,6 +295,8 @@ impl Member {
offset,
bits,
base_ty,
inner_into,
inner_from,
default,
inner: None,
})
Expand Down Expand Up @@ -316,6 +335,8 @@ impl ToTokens for Member {
offset,
bits,
base_ty,
inner_into,
inner_from,
default: _,
inner:
Some(MemberInner {
Expand Down Expand Up @@ -361,7 +382,7 @@ impl ToTokens for Member {
#[doc = #location]
#vis const fn #ident(&self) -> #ty {
let mask = #base_ty::MAX >> (#base_ty::BITS - Self::#bits_ident as u32);
let this = (self.0 >> Self::#offset_ident) & mask;
let this = (#inner_into(self.0) >> Self::#offset_ident) & mask;
#from
}
});
Expand All @@ -378,7 +399,8 @@ impl ToTokens for Member {
let mask = #base_ty::MAX >> (#base_ty::BITS - Self::#bits_ident as u32);
#[allow(unused_comparisons)]
debug_assert!(value <= mask, "value out of bounds");
Self(self.0 & !(mask << Self::#offset_ident) | (value & mask) << Self::#offset_ident)
let bits = #inner_into(self.0) & !(mask << Self::#offset_ident) | (value & mask) << Self::#offset_ident;
Self(#inner_from(bits))
}

#doc
Expand Down Expand Up @@ -656,6 +678,9 @@ enum Order {
/// The bitfield macro parameters
struct Params {
ty: syn::Type,
inner: syn::Type,
into: Option<syn::Path>,
from: Option<syn::Path>,
bits: usize,
debug: bool,
default: bool,
Expand All @@ -673,6 +698,9 @@ impl Parse for Params {
return Err(s_err(input.span(), "unsupported type"));
}

let mut inner = ty.clone();
let mut from = None;
let mut into = None;
let mut debug = true;
let mut default = true;
let mut order = Order::Lsb;
Expand All @@ -683,6 +711,15 @@ impl Parse for Params {
let ident = Ident::parse(input)?;
<Token![=]>::parse(input)?;
match ident.to_string().as_str() {
"inner" => {
inner = input.parse()?;
}
"from" => {
from = Some(input.parse()?);
}
"into" => {
into = Some(input.parse()?);
}
"debug" => {
debug = syn::LitBool::parse(input)?.value;
}
Expand All @@ -705,6 +742,9 @@ impl Parse for Params {

Ok(Self {
ty,
inner,
from,
into,
bits,
debug,
default,
Expand Down
27 changes: 27 additions & 0 deletions tests/test.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -398,3 +398,30 @@ fn raw() {
assert_eq!(raw.r#type(), 0xff);
assert_eq!(raw.into_bits(), 0xff);
}

#[test]
fn custom_inner() {
#[bitfield(u32, inner = CustomInner, from = CustomInner::from_inner, into = CustomInner::to_inner)]
#[derive(PartialEq, Eq)]
struct MyBitfield {
data: u32,
}

#[derive(PartialEq, Eq, Clone, Copy, Debug)]
#[repr(transparent)]
struct CustomInner(u32);

impl CustomInner {
const fn to_inner(self) -> u32 {
self.0
}

const fn from_inner(inner: u32) -> Self {
Self(inner)
}
}

let my_bitfield = MyBitfield::new();
assert_eq!(my_bitfield, MyBitfield::from_bits(CustomInner(0)));
assert_eq!(my_bitfield.into_bits(), CustomInner(0));
}

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