1 files changed, 31 insertions, 0 deletions
diff --git a/third_party/rust/redox_syscall/src/io/mmio.rs b/third_party/rust/redox_syscall/src/io/mmio.rs
new file mode 100644
index 0000000000..b8e7727d3c
--- /dev/null
+++ b/third_party/rust/redox_syscall/src/io/mmio.rs
@@ -0,0 +1,31 @@
+use core::ptr::{read_volatile, write_volatile};
+use core::mem::uninitialized;
+use core::ops::{BitAnd, BitOr, Not};
+
+use super::io::Io;
+
+#[repr(packed)]
+pub struct Mmio<T> {
+    value: T,
+}
+
+impl<T> Mmio<T> {
+    /// Create a new Mmio without initializing
+    pub fn new() -> Self {
+        Mmio {
+            value: unsafe { uninitialized() }
+        }
+    }
+}
+
+impl<T> Io for Mmio<T> where T: Copy + PartialEq + BitAnd<Output = T> + BitOr<Output = T> + Not<Output = T> {
+    type Value = T;
+
+    fn read(&self) -> T {
+        unsafe { read_volatile(&self.value) }
+    }
+
+    fn write(&mut self, value: T) {
+        unsafe { write_volatile(&mut self.value, value) };
+    }
+}