Function revm::precompile::primitives::bitvec::ptr::read_volatile

source · 
pub unsafe fn read_volatile<T, O>(src: BitPtr<Const, T, O>) -> bool
where
    T: BitStore,
    O: BitOrder,
Expand description

§Single-Bit Volatile Read

This reads the bit out of src directly, using a volatile I/O intrinsic to prevent compiler reördering or removal.

You should not use bitvec to perform any volatile I/O operations. You should instead do volatile I/O work on integer values directly, or use a crate like voladdress to perform I/O transactions, and use bitvec only on stack locals that have no additional memory semantics.

§Original

ptr::read_volatile

§Safety

Because this performs a dereference of memory, it inherits the original ptr::read_volatile’s requirements:

  • src must be valid to read.
  • src must be properly aligned. This is an invariant of the BitPtr type as well as of the memory access.
  • src must point to an initialized value of T.

Remember that volatile accesses are ordinary loads that the compiler cannot remove or reörder! They are not an atomic synchronizer.

§Examples

use bitvec::prelude::*;
use bitvec::ptr as bv_ptr;

let data = 128u8;
let ptr = BitPtr::<_, _, Msb0>::from_ref(&data);
assert!(unsafe { bv_ptr::read_volatile(ptr) });