vendor/redox_syscall/src/io/mmio.rs

   1 use core::ptr::{read_volatile, write_volatile, addr_of, addr_of_mut};
   2 use core::mem::MaybeUninit;
   3 use core::ops::{BitAnd, BitOr, Not};
   4
   5 use super::io::Io;
   6
   7 #[repr(packed)]
   8 pub struct Mmio<T> {
   9     value: MaybeUninit<T>,
  10 }
  11
  12 impl<T> Mmio<T> {
  13     /// Create a new Mmio without initializing
  14     #[deprecated = "unsound because it's possible to read even though it's uninitialized"]
  15     pub fn new() -> Self {
  16         unsafe { Self::uninit() }
  17     }
  18     pub unsafe fn zeroed() -> Self {
  19         Self {
  20             value: MaybeUninit::zeroed(),
  21         }
  22     }
  23     pub unsafe fn uninit() -> Self {
  24         Self {
  25             value: MaybeUninit::uninit(),
  26         }
  27     }
  28     pub const fn from(value: T) -> Self {
  29         Self {
  30             value: MaybeUninit::new(value),
  31         }
  32     }
  33 }
  34
  35 impl<T> Io for Mmio<T> where T: Copy + PartialEq + BitAnd<Output = T> + BitOr<Output = T> + Not<Output = T> {
  36     type Value = T;
  37
  38     fn read(&self) -> T {
  39         unsafe { read_volatile(addr_of!(self.value).cast::<T>()) }
  40     }
  41
  42     fn write(&mut self, value: T) {
  43         unsafe { write_volatile(addr_of_mut!(self.value).cast::<T>(), value) };
  44     }
  45 }