Function revm::interpreter::primitives::bitvec::ptr::write_unaligned

pub unsafe fn write_unaligned<T, O>(dst: BitPtr<Mut, T, O>, value: bool)
where
    T: BitStore,
    O: BitOrder,

👎Deprecated: BitPtr does not have unaligned addresses

Single-Bit Unaligned Write

This writes a bit into dst directly. It uses compiler intrinsics to tolerate an unaligned T address. However, because BitPtr has a type invariant that addresses are always well-aligned (and non-null), this has no benefit or purpose.

Original

`ptr::write_unaligned

Safety

• dst must be valid to write
• dst must be properly aligned. This is an invariant of the BitPtr type as well as of the memory access.

Additionally, dst must point to an initialized value of T. Integers cannot be initialized one bit at a time.

Behavior

This is required to perform a read/modify/write cycle on the memory location. LLVM may or may not emit a bit-write instruction on targets that have them in the ISA, but this is not specified in any way.

Examples

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

let mut data = 0u8;
let ptr = BitPtr::<_, _, Lsb0>::from_mut(&mut data);
unsafe { bv_ptr::write_unaligned(ptr.add(2), true); }
assert_eq!(data, 4);