Support aarch64

Add support for Aarch64.

src/impl-aarch64-elf.rs

+use std::{mem, ptr};
+use super::VaPrimitive;
+
+pub struct VaList(*mut VaListInner);
+
+#[repr(C)]
+#[derive(Debug)]
+#[doc(hidden)]
+pub struct VaListInner {
+    stack: *const (),
+    gr_top: *const (),
+    vr_top: *const (),
+    gr_offs: i32,
+    vr_offs: i32,
+}
+
+impl VaList {
+    fn inner(&mut self) -> &mut VaListInner {
+        // This pointer should be valid
+        unsafe { &mut *self.0 }
+    }
+}
+
+impl VaListInner {
+    pub unsafe fn get_gr<T>(&mut self) -> T {
+        assert!(!self.gr_top.is_null());
+        let rv = ptr::read((self.gr_top as usize - self.gr_offs.abs() as usize) as *const _);
+        self.gr_offs += 8;
+        rv
+    }
+
+    pub unsafe fn get_vr<T>(&mut self) -> T {
+        assert!(!self.vr_top.is_null());
+        let rv = ptr::read((self.vr_top as usize - self.vr_offs.abs() as usize) as *const _);
+        self.vr_offs += 16;
+        rv
+    }
+}
+
+impl<T: 'static> VaPrimitive for *const T {
+    unsafe fn get(list: &mut VaList) -> Self {
+        <usize>::get(list) as *const T
+    }
+}
+
+macro_rules! impl_va_prim_gr {
+    ($u: ty, $s: ty) => {
+        impl VaPrimitive for $u {
+            unsafe fn get(list: &mut VaList) -> Self {
+                list.inner().get_gr()
+            }
+        }
+        impl VaPrimitive for $s {
+            unsafe fn get(list: &mut VaList) -> Self {
+                mem::transmute(<$u>::get(list))
+            }
+        }
+    };
+}
+
+macro_rules! impl_va_prim_vr {
+    ($($t:ty),+) => {
+        $(
+            impl VaPrimitive for $t {
+                unsafe fn get(list: &mut VaList) -> Self {
+                    list.inner().get_vr()
+                }
+            }
+        )+
+    };
+}
+
+impl_va_prim_gr!{ usize, isize }
+impl_va_prim_gr!{ u64, i64 }
+impl_va_prim_gr!{ u32, i32 }
+impl_va_prim_vr!{ f64, f32 }

src/lib.rs

@@ -59,6 +59,11 @@ mod imp;
 #[path = "impl-x86-sysv.rs"]
 mod imp;
 
+// aarch64
+#[cfg(all(target_arch = "aarch64", any(target_family = "unix", target_os = "redox")))]
+#[path = "impl-aarch64-elf.rs"]
+mod imp;
+
 // arm+unix = cdecl
 #[cfg(all(target_arch = "arm", target_family = "unix"))]
 #[path = "impl-arm-sysv.rs"]