1 files changed, 45 insertions, 0 deletions
diff --git a/vendor/redox_syscall/src/io/mmio.rs b/vendor/redox_syscall/src/io/mmio.rs
new file mode 100644
index 000000000..3966ab454
--- /dev/null
+++ b/vendor/redox_syscall/src/io/mmio.rs
@@ -0,0 +1,45 @@
+use core::ptr::{read_volatile, write_volatile, addr_of, addr_of_mut};
+use core::mem::MaybeUninit;
+use core::ops::{BitAnd, BitOr, Not};
+
+use super::io::Io;
+
+#[repr(packed)]
+pub struct Mmio<T> {
+    value: MaybeUninit<T>,
+}
+
+impl<T> Mmio<T> {
+    /// Create a new Mmio without initializing
+    #[deprecated = "unsound because it's possible to read even though it's uninitialized"]
+    pub fn new() -> Self {
+        unsafe { Self::uninit() }
+    }
+    pub unsafe fn zeroed() -> Self {
+        Self {
+            value: MaybeUninit::zeroed(),
+        }
+    }
+    pub unsafe fn uninit() -> Self {
+        Self {
+            value: MaybeUninit::uninit(),
+        }
+    }
+    pub const fn from(value: T) -> Self {
+        Self {
+            value: MaybeUninit::new(value),
+        }
+    }
+}
+
+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(addr_of!(self.value).cast::<T>()) }
+    }
+
+    fn write(&mut self, value: T) {
+        unsafe { write_volatile(addr_of_mut!(self.value).cast::<T>(), value) };
+    }
+}