Merge #88

88: make compilable on stable r=japaric a=japaric

This PR makes this crate compilable on stable when the "inline-asm" and "singleton" Cargo features
are disabled (they are enabled by default to maintain backwards compatibility).

The main change has been replacing almost (\*) all inline `asm!` invocations with FFI calls into
external assembly files.

(\*) Stuff that has not been converted into external assembly file and thus is not available on
stable:

- Reading the (A)PSR register (I'm not sure if this will work with the extra function call overhead)

- Reading and writing the Link Register (LR)

- Reading and writing the Program Counter (PC)

I would appreciate if someone checked that all the stuff that's now using FFI calls has the same
semantics as the inline `asm!` version.


Co-authored-by: Jorge Aparicio <jorge@japaric.io>

1 files changed, 41 insertions, 1 deletions

diff --git a/build.rs b/build.rs
index 4d5a706..4866ed2 100644
--- a/build.rs
+++ b/build.rs
@@ -1,18 +1,58 @@
+extern crate cc;
+
 use std::env;
 
 fn main() {
     let target = env::var("TARGET").unwrap();
 
+    if target.starts_with("thumb") && env::var_os("CARGO_FEATURE_INLINE_ASM").is_none() {
+        // NOTE we need to place each routine in a separate assembly file or the linker won't be
+        // able to discard the unused routines
+        let mut build = cc::Build::new();
+        build
+            .file("asm/basepri_r.s")
+            .file("asm/bkpt.s")
+            .file("asm/control.s")
+            .file("asm/cpsid.s")
+            .file("asm/cpsie.s")
+            .file("asm/dmb.s")
+            .file("asm/dsb.s")
+            .file("asm/faultmask.s")
+            .file("asm/isb.s")
+            .file("asm/msp_r.s")
+            .file("asm/msp_w.s")
+            .file("asm/nop.s")
+            .file("asm/primask.s")
+            .file("asm/psp_r.s")
+            .file("asm/psp_w.s")
+            .file("asm/sev.s")
+            .file("asm/wfe.s")
+            .file("asm/wfi.s");
+
+        if env::var_os("CARGO_FEATURE_CM7_R0P1").is_some() {
+            build.file("asm/basepri_max-cm7-r0p1.s");
+            build.file("asm/basepri_w-cm7-r0p1.s");
+        } else {
+            build.file("asm/basepri_max.s");
+            build.file("asm/basepri_w.s");
+        }
+
+        build.compile("asm");
+    }
+
     if target.starts_with("thumbv6m-") {
+        println!("cargo:rustc-cfg=cortex_m");
         println!("cargo:rustc-cfg=armv6m");
     } else if target.starts_with("thumbv7m-") {
+        println!("cargo:rustc-cfg=cortex_m");
         println!("cargo:rustc-cfg=armv7m");
     } else if target.starts_with("thumbv7em-") {
+        println!("cargo:rustc-cfg=cortex_m");
         println!("cargo:rustc-cfg=armv7m");
         //println!("cargo:rustc-cfg=armv7em");
     }
 
-    if target.ends_with("eabihf") {
+    if target.ends_with("-eabihf") {
         println!("cargo:rustc-cfg=has_fpu");
     }
 }