initial commit

1 files changed, 47 insertions, 0 deletions

diff --git a/src/interrupt.rs b/src/interrupt.rs
new file mode 100644
index 0000000..6fb8aeb
--- /dev/null
+++ b/src/interrupt.rs
@@ -0,0 +1,47 @@
+//! Interrupts
+
+/// Disable interrupts, globally
+#[inline(always)]
+pub unsafe fn disable() {
+    match () {
+        #[cfg(target_arch = "arm")]
+        () => {
+            asm!("cpsid i" :::: "volatile");
+        }
+        #[cfg(not(target_arch = "arm"))]
+        () => {}
+    }
+}
+
+/// Enable interrupts, globally
+#[inline(always)]
+pub unsafe fn enable() {
+    match () {
+        #[cfg(target_arch = "arm")]
+        () => {
+            asm!("cpsie i" :::: "volatile");
+        }
+        #[cfg(not(target_arch = "arm"))]
+        () => {}
+    }
+}
+
+/// Execute closure `f` in an interrupt-free context.
+/// This as also known as a "critical section".
+pub unsafe fn free<F>(f: F)
+    where F: FnOnce()
+{
+    let primask = ::register::primask::read();
+
+    disable();
+
+    f();
+
+    // If the interrupts were enabled before our `disable` call, then re-enable them
+    // Otherwise, keep them disabled
+    // PRIMASK & 1 = 1 indicates that the interrupts were disabled
+    // PRIMASK & 1 = 0 indicates that they were enabled
+    if primask & 1 == 0 {
+        enable();
+    }
+}