Function write
pub unsafe fn write<T, O>(dst: BitPtr<Mut, T, O>, value: bool)
Available on non-
tarpaulin_include
only.Expand description
§Single-Bit Write
This writes a bit into dst
directly.
§Original
§Safety
Because this performs a dereference of memory, it inherits the original
ptr::write
’s requirements:
dst
must be valid to writedst
must be properly aligned. This is an invariant of theBitPtr
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(ptr.add(2), true); }
assert_eq!(data, 4);