Vendor things

third-party/vendor/redox_syscall/src/io/mmio.rs

@@ -0,0 +1,168 @@
+use core::mem::MaybeUninit;
+use core::ptr;
+#[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
+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),
+        }
+    }
+}
+
+// Generic implementation (WARNING: requires aligned pointers!)
+#[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
+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 { ptr::read_volatile(ptr::addr_of!(self.value).cast::<T>()) }
+    }
+
+    fn write(&mut self, value: T) {
+        unsafe { ptr::write_volatile(ptr::addr_of_mut!(self.value).cast::<T>(), value) };
+    }
+}
+
+// x86 u8 implementation
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+impl Io for Mmio<u8> {
+    type Value = u8;
+
+    fn read(&self) -> Self::Value {
+        unsafe {
+            let value: Self::Value;
+            let ptr: *const Self::Value = ptr::addr_of!(self.value).cast::<Self::Value>();
+            core::arch::asm!(
+                "mov {}, [{}]",
+                out(reg_byte) value,
+                in(reg) ptr
+            );
+            value
+        }
+    }
+
+    fn write(&mut self, value: Self::Value) {
+        unsafe {
+            let ptr: *mut Self::Value = ptr::addr_of_mut!(self.value).cast::<Self::Value>();
+            core::arch::asm!(
+                "mov [{}], {}",
+                in(reg) ptr,
+                in(reg_byte) value,
+            );
+        }
+    }
+}
+
+// x86 u16 implementation
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+impl Io for Mmio<u16> {
+    type Value = u16;
+
+    fn read(&self) -> Self::Value {
+        unsafe {
+            let value: Self::Value;
+            let ptr: *const Self::Value = ptr::addr_of!(self.value).cast::<Self::Value>();
+            core::arch::asm!(
+                "mov {:x}, [{}]",
+                out(reg) value,
+                in(reg) ptr
+            );
+            value
+        }
+    }
+
+    fn write(&mut self, value: Self::Value) {
+        unsafe {
+            let ptr: *mut Self::Value = ptr::addr_of_mut!(self.value).cast::<Self::Value>();
+            core::arch::asm!(
+                "mov [{}], {:x}",
+                in(reg) ptr,
+                in(reg) value,
+            );
+        }
+    }
+}
+
+// x86 u32 implementation
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+impl Io for Mmio<u32> {
+    type Value = u32;
+
+    fn read(&self) -> Self::Value {
+        unsafe {
+            let value: Self::Value;
+            let ptr: *const Self::Value = ptr::addr_of!(self.value).cast::<Self::Value>();
+            core::arch::asm!(
+                "mov {:e}, [{}]",
+                out(reg) value,
+                in(reg) ptr
+            );
+            value
+        }
+    }
+
+    fn write(&mut self, value: Self::Value) {
+        unsafe {
+            let ptr: *mut Self::Value = ptr::addr_of_mut!(self.value).cast::<Self::Value>();
+            core::arch::asm!(
+                "mov [{}], {:e}",
+                in(reg) ptr,
+                in(reg) value,
+            );
+        }
+    }
+}
+
+// x86 u64 implementation (x86_64 only)
+#[cfg(target_arch = "x86_64")]
+impl Io for Mmio<u64> {
+    type Value = u64;
+
+    fn read(&self) -> Self::Value {
+        unsafe {
+            let value: Self::Value;
+            let ptr: *const Self::Value = ptr::addr_of!(self.value).cast::<Self::Value>();
+            core::arch::asm!(
+                "mov {:r}, [{}]",
+                out(reg) value,
+                in(reg) ptr
+            );
+            value
+        }
+    }
+
+    fn write(&mut self, value: Self::Value) {
+        unsafe {
+            let ptr: *mut Self::Value = ptr::addr_of_mut!(self.value).cast::<Self::Value>();
+            core::arch::asm!(
+                "mov [{}], {:r}",
+                in(reg) ptr,
+                in(reg) value,
+            );
+        }
+    }
+}