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extern crate proc_macro;
extern crate rand;
#[macro_use]
extern crate quote;
extern crate core;
extern crate proc_macro2;
#[macro_use]
extern crate syn;
use proc_macro2::Span;
use rand::Rng;
use rand::SeedableRng;
use std::sync::atomic::{AtomicUsize, Ordering};
use std::time::{SystemTime, UNIX_EPOCH};
use syn::{parse, spanned::Spanned, Ident, ItemFn, ReturnType, Type, Visibility};
static CALL_COUNT: AtomicUsize = AtomicUsize::new(0);
use proc_macro::TokenStream;
#[proc_macro_attribute]
pub fn xous_main(args: TokenStream, input: TokenStream) -> TokenStream {
let f = parse_macro_input!(input as ItemFn);
let valid_signature = f.sig.constness.is_none()
&& f.sig.asyncness.is_none()
&& f.vis == Visibility::Inherited
&& 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 => false,
ReturnType::Type(_, ref ty) => matches!(**ty, Type::Never(_)),
};
if !valid_signature {
return parse::Error::new(
f.span(),
"`#[xous_main]` 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();
}
let attrs = f.attrs;
let unsafety = f.sig.unsafety;
let hash = random_ident();
let stmts = f.block.stmts;
let r = quote!(
#[export_name = "xous_entry"]
#(#attrs)*
pub #unsafety fn #hash() -> ! {
xous::init();
#(#stmts)*
}
xous::maybe_main!();
);
r.into()
}
fn random_ident() -> Ident {
let secs = SystemTime::now()
.duration_since(UNIX_EPOCH)
.unwrap()
.as_secs();
let count: u64 = CALL_COUNT.fetch_add(1, Ordering::SeqCst) as u64;
let mut seed: [u8; 16] = [0; 16];
for (i, v) in seed.iter_mut().take(8).enumerate() {
*v = ((secs >> (i * 8)) & 0xFF) as u8
}
for (i, v) in seed.iter_mut().skip(8).enumerate() {
*v = ((count >> (i * 8)) & 0xFF) as u8
}
let mut rng = rand::rngs::SmallRng::from_seed(seed);
Ident::new(
&(0..16)
.map(|i| {
if i == 0 || rng.gen() {
(b'a' + rng.gen::<u8>() % 25) as char
} else {
(b'0' + rng.gen::<u8>() % 10) as char
}
})
.collect::<String>(),
Span::call_site(),
)
}