Merge #262

262: Merge asm implementations r=therealprof a=jonas-schievink

This replaces the implementation of `inline-asm` with the file I wrote in #259 (and some fixes).

All functions that call assembly now do so via a `call_asm!` macro that either dispatches to a call to an `#[inline(always)]` function containing the inline `asm!`, or to the FFI shim. This makes all functions that call into asm significantly shorter.

The FFI shim is now also macro-generated, which makes it very small.

Co-authored-by: Jonas Schievink <jonasschievink@gmail.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/src/call_asm.rs b/src/call_asm.rs
new file mode 100644
index 0000000..295277f
--- /dev/null
+++ b/src/call_asm.rs
@@ -0,0 +1,24 @@
+/// An internal macro to invoke an assembly routine.
+///
+/// Depending on whether the unstable `inline-asm` feature is enabled, this will either call into
+/// the inline assembly implementation directly, or through the FFI shim (see `asm/lib.rs`).
+macro_rules! call_asm {
+    ( $func:ident ( $($args:ident: $tys:ty),* ) $(-> $ret:ty)? ) => {{
+        #[allow(unused_unsafe)]
+        unsafe {
+            match () {
+                #[cfg(feature = "inline-asm")]
+                () => crate::asm::inline::$func($($args),*),
+
+                #[cfg(not(feature = "inline-asm"))]
+                () => {
+                    extern "C" {
+                        fn $func($($args: $tys),*) $(-> $ret)?;
+                    }
+
+                    $func($($args),*)
+                },
+            }
+        }
+    }};
+}