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#![deny(warnings)]
extern crate proc_macro;
#[macro_use]
extern crate quote;
extern crate core;
extern crate proc_macro2;
#[macro_use]
extern crate syn;
use proc_macro2::Span;
use syn::{
parse::{self, Parse},
spanned::Spanned,
FnArg, ItemFn, LitInt, LitStr, PathArguments, ReturnType, Type, Visibility,
};
use proc_macro::TokenStream;
/// Attribute to declare the entry point of the program
///
/// **IMPORTANT**: This attribute must appear exactly *once* in the dependency graph. Also, if you
/// are using Rust 1.30 the attribute must be used on a reachable item (i.e. there must be no
/// private modules between the item and the root of the crate); if the item is in the root of the
/// crate you'll be fine. This reachability restriction doesn't apply to Rust 1.31 and newer releases.
///
/// The specified function will be called by the reset handler *after* RAM has been initialized.
/// If present, the FPU will also be enabled before the function is called.
///
/// The type of the specified function must be `[unsafe] fn() -> !` (never ending function)
///
/// # Properties
///
/// The entry point will be called by the reset handler. The program can't reference to the entry
/// point, much less invoke it.
///
/// # Examples
///
/// - Simple entry point
///
/// ``` no_run
/// # #![no_main]
/// # use riscv_rt_macros::entry;
/// #[entry]
/// fn main() -> ! {
/// loop {
/// /* .. */
/// }
/// }
/// ```
#[proc_macro_attribute]
pub fn entry(args: TokenStream, input: TokenStream) -> TokenStream {
let f = parse_macro_input!(input as ItemFn);
// check the function arguments
if f.sig.inputs.len() > 3 {
return parse::Error::new(
f.sig.inputs.last().unwrap().span(),
"`#[entry]` function has too many arguments",
)
.to_compile_error()
.into();
}
for arg in &f.sig.inputs {
match arg {
FnArg::Receiver(_) => {
return parse::Error::new(arg.span(), "invalid argument")
.to_compile_error()
.into();
}
FnArg::Typed(t) => {
if !is_simple_type(&t.ty, "usize") {
return parse::Error::new(t.ty.span(), "argument type must be usize")
.to_compile_error()
.into();
}
}
}
}
// check the function signature
let valid_signature = f.sig.constness.is_none()
&& f.sig.asyncness.is_none()
&& f.vis == Visibility::Inherited
&& f.sig.abi.is_none()
&& f.sig.generics.params.is_empty()
&& f.sig.generics.where_clause.is_none()
&& f.sig.variadic.is_none()
&& match f.sig.output {
ReturnType::Default => false,
ReturnType::Type(_, ref ty) => matches!(**ty, Type::Never(_)),
};
if !valid_signature {
return parse::Error::new(
f.span(),
"`#[entry]` function must have signature `[unsafe] fn([arg0: usize, ...]) -> !`",
)
.to_compile_error()
.into();
}
if !args.is_empty() {
return parse::Error::new(Span::call_site(), "This attribute accepts no arguments")
.to_compile_error()
.into();
}
// XXX should we blacklist other attributes?
let attrs = f.attrs;
let unsafety = f.sig.unsafety;
let args = f.sig.inputs;
let stmts = f.block.stmts;
quote!(
#[allow(non_snake_case)]
#[export_name = "main"]
#(#attrs)*
pub #unsafety fn __risc_v_rt__main(#args) -> ! {
#(#stmts)*
}
)
.into()
}
#[allow(unused)]
fn is_simple_type(ty: &Type, name: &str) -> bool {
if let Type::Path(p) = ty {
if p.qself.is_none() && p.path.leading_colon.is_none() && p.path.segments.len() == 1 {
let segment = p.path.segments.first().unwrap();
if segment.ident == name && segment.arguments == PathArguments::None {
return true;
}
}
}
false
}
/// Attribute to mark which function will be called at the beginning of the reset handler.
///
/// **IMPORTANT**: This attribute can appear at most *once* in the dependency graph. Also, if you
/// are using Rust 1.30 the attribute must be used on a reachable item (i.e. there must be no
/// private modules between the item and the root of the crate); if the item is in the root of the
/// crate you'll be fine. This reachability restriction doesn't apply to Rust 1.31 and newer
/// releases.
///
/// The function must have the signature of `unsafe fn()`.
///
/// The function passed will be called before static variables are initialized. Any access of static
/// variables will result in undefined behavior.
///
/// # Examples
///
/// ```
/// # use riscv_rt_macros::pre_init;
/// #[pre_init]
/// unsafe fn before_main() {
/// // do something here
/// }
///
/// # fn main() {}
/// ```
#[proc_macro_attribute]
pub fn pre_init(args: TokenStream, input: TokenStream) -> TokenStream {
let f = parse_macro_input!(input as ItemFn);
// check the function signature
let valid_signature = f.sig.constness.is_none()
&& f.sig.asyncness.is_none()
&& f.vis == Visibility::Inherited
&& f.sig.unsafety.is_some()
&& f.sig.abi.is_none()
&& f.sig.inputs.is_empty()
&& f.sig.generics.params.is_empty()
&& f.sig.generics.where_clause.is_none()
&& f.sig.variadic.is_none()
&& match f.sig.output {
ReturnType::Default => true,
ReturnType::Type(_, ref ty) => match **ty {
Type::Tuple(ref tuple) => tuple.elems.is_empty(),
_ => false,
},
};
if !valid_signature {
return parse::Error::new(
f.span(),
"`#[pre_init]` function must have signature `unsafe fn()`",
)
.to_compile_error()
.into();
}
if !args.is_empty() {
return parse::Error::new(Span::call_site(), "This attribute accepts no arguments")
.to_compile_error()
.into();
}
// XXX should we blacklist other attributes?
let attrs = f.attrs;
let ident = f.sig.ident;
let block = f.block;
quote!(
#[export_name = "__pre_init"]
#(#attrs)*
pub unsafe fn #ident() #block
)
.into()
}
struct AsmLoopArgs {
asm_template: String,
count: usize,
}
impl Parse for AsmLoopArgs {
fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
let template: LitStr = input.parse().unwrap();
_ = input.parse::<Token![,]>().unwrap();
let count: LitInt = input.parse().unwrap();
Ok(Self {
asm_template: template.value(),
count: count.base10_parse().unwrap(),
})
}
}
/// Loops an asm expression n times.
///
/// `loop_asm!` takes 2 arguments, the first is a string literal and the second is a number literal
/// See [the formatting syntax documentation in `std::fmt`](../std/fmt/index.html)
/// for details.
///
/// Argument 1 is an assembly expression, all "{}" in this assembly expression will be replaced with the
/// current loop index.
///
/// Argument 2 is the number of loops to do with the provided expression.
///
/// # Examples
///
/// ```
/// # use riscv_rt_macros::loop_asm;
/// unsafe {
/// loop_asm!("fmv.w.x f{}, x0", 32); // => core::arch::asm!("fmv.w.x f0, x0") ... core::arch::asm!("fmv.w.x f31, x0")
/// }
/// ```
#[proc_macro]
pub fn loop_asm(input: TokenStream) -> TokenStream {
let args = parse_macro_input!(input as AsmLoopArgs);
let tokens = (0..args.count)
.map(|i| {
let i = i.to_string();
let asm = args.asm_template.replace("{}", &i);
format!("core::arch::asm!(\"{}\");", asm)
})
.collect::<Vec<String>>()
.join("\n");
tokens.parse().unwrap()
}