irq commit: this large commit gets interrupts working

Signed-off-by: Sean Cross <sean@xobs.io>

xous-kernel-riscv-rt/macros/Cargo.toml

@@ -0,0 +1,28 @@
+[package]
+authors = [
+    "The RISC-V Team <risc-v@teams.rust-embedded.org>",
+    "Jorge Aparicio <jorge@japaric.io>",
+]
+categories = ["embedded", "no-std"]
+description = "Attributes re-exported in `riscv-rt`"
+documentation = "https://docs.rs/riscv-rt"
+keywords = ["riscv", "runtime", "startup"]
+license = "MIT OR Apache-2.0"
+name = "xous-kernel-riscv-rt-macros"
+repository = "https://github.com/rust-embedded/riscv-rt"
+version = "0.1.6"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+quote = "0.6.8"
+proc-macro2 = "0.4.20"
+
+[dependencies.syn]
+features = ["extra-traits", "full"]
+version = "0.15.13"
+
+[dependencies.rand]
+version = "0.5.5"
+default-features = false

xous-kernel-riscv-rt/macros/src/lib.rs

@@ -0,0 +1,210 @@
+#![deny(warnings)]
+
+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;
+
+/// 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.
+///
+/// # Examples
+///
+/// - Simple entry point
+///
+/// ``` no_run
+/// #![no_main]
+/// use xous_riscv_rt::entry;
+/// #[entry]
+/// fn main() -> ! {
+///     loop {
+///         /* .. */
+///     }
+/// }
+/// ```
+#[proc_macro_attribute]
+pub fn xous_kernel_entry(args: TokenStream, input: TokenStream) -> TokenStream {
+    let f = parse_macro_input!(input as ItemFn);
+
+    // check the function signature
+    let valid_signature = f.constness.is_none()
+        && f.vis == Visibility::Inherited
+        && f.abi.is_none()
+        && f.decl.inputs.is_empty()
+        && f.decl.generics.params.is_empty()
+        && f.decl.generics.where_clause.is_none()
+        && f.decl.variadic.is_none()
+        && match f.decl.output {
+            ReturnType::Default => false,
+            ReturnType::Type(_, ref ty) => match **ty {
+                Type::Never(_) => true,
+                _ => false,
+            },
+        };
+
+    if !valid_signature {
+        return parse::Error::new(
+            f.span(),
+            "`#[entry]` 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 unsafety = f.unsafety;
+    let hash = random_ident();
+    let stmts = f.block.stmts;
+
+    quote!(
+        #[export_name = "xous_kernel_main"]
+        #(#attrs)*
+        pub #unsafety fn #hash() -> ! {
+            #(#stmts)*
+        }
+    )
+    .into()
+}
+
+/// 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.constness.is_none()
+        && f.vis == Visibility::Inherited
+        && f.unsafety.is_some()
+        && f.abi.is_none()
+        && f.decl.inputs.is_empty()
+        && f.decl.generics.params.is_empty()
+        && f.decl.generics.where_clause.is_none()
+        && f.decl.variadic.is_none()
+        && match f.decl.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.ident;
+    let block = f.block;
+
+    quote!(
+        #[export_name = "__pre_init"]
+        #(#attrs)*
+        pub unsafe fn #ident() #block
+    )
+    .into()
+}
+
+// Creates a random identifier
+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() {
+                    ('a' as u8 + rng.gen::<u8>() % 25) as char
+                } else {
+                    ('0' as u8 + rng.gen::<u8>() % 10) as char
+                }
+            })
+            .collect::<String>(),
+        Span::call_site(),
+    )
+}