compile time verified ceilings

1 files changed, 100 insertions, 3 deletions

diff --git a/build.rs b/build.rs
index 46bdb71..19625e5 100644
--- a/build.rs
+++ b/build.rs
@@ -1,9 +1,106 @@
+#[macro_use]
+extern crate quote;
+extern crate syn;
+
 use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::PathBuf;
+
+use syn::{Ident, IntTy, Lit};
 
 fn main() {
-    let target = env::var("TARGET").unwrap();
+    let bits = if env::var_os("CARGO_FEATURE_P2").is_some() {
+        2
+    } else if env::var_os("CARGO_FEATURE_P3").is_some() {
+        3
+    } else if env::var_os("CARGO_FEATURE_P4").is_some() {
+        4
+    } else if env::var_os("CARGO_FEATURE_P5").is_some() {
+        5
+    } else {
+        panic!(
+            "Specify the number of priority bits through one of these Cargo \
+                features: P2, P3, P4 or P5"
+        );
+    };
+
+    let n = Lit::Int(bits, IntTy::Unsuffixed);
+    let mut tokens = vec![];
+    tokens.push(
+        quote! {
+            const PRIORITY_BITS: u8 = #n;
+        },
+    );
+
+    // Ceilings
+    for i in 1..(1 << bits) + 1 {
+        let c = Ident::new(format!("C{}", i));
+        let u = Ident::new(format!("U{}", i));
+
+        tokens.push(
+            quote! {
+                /// Ceiling
+                pub type #c = C<::typenum::#u>;
+
+                unsafe impl Ceiling for #c {}
+            },
+        );
+    }
+
+    // Priorities
+    for i in 1..(1 << bits) + 1 {
+        let p = Ident::new(format!("P{}", i));
+        let u = Ident::new(format!("U{}", i));
+
+        tokens.push(
+            quote! {
+                /// Priority
+                pub type #p = P<::typenum::#u>;
+
+                unsafe impl Priority for #p {}
 
-    if target == "thumbv6m-none-eabi" {
-        println!("cargo:rustc-cfg=thumbv6m");
+                unsafe impl Level for ::typenum::#u {
+                    fn hw() -> u8 {
+                        logical2hw(::typenum::#u::to_u8())
+                    }
+                }
+            },
+        );
     }
+
+    // GreaterThanOrEqual
+    for i in 1..(1 << bits) + 1 {
+        for j in 1..(i + 1) {
+            let i = Ident::new(format!("U{}", i));
+            let j = Ident::new(format!("U{}", j));
+
+            tokens.push(
+                quote! {
+                    unsafe impl GreaterThanOrEqual<::typenum::#j> for
+                        ::typenum::#i {}
+                },
+            );
+        }
+    }
+
+    let u = Ident::new(format!("U{}", (1 << bits)));
+    tokens.push(quote! {
+        #[doc(hidden)]
+        pub type CMAX = C<::typenum::#u>;
+
+        /// Maximum priority level
+        pub type UMAX = ::typenum::#u;
+    });
+
+    let tokens = quote! {
+        #(#tokens)*
+    };
+
+    let out_dir = env::var("OUT_DIR").unwrap();
+    let mut out = File::create(PathBuf::from(out_dir).join("prio.rs")).unwrap();
+
+    out.write_all(tokens.as_str().as_bytes()).unwrap();
+
+    println!("cargo:rerun-if-changed=build.rs");
 }