Function copy_nonoverlapping
pub unsafe fn copy_nonoverlapping<T1, T2, O1, O2>(
src: BitPtr<Const, T1, O1>,
dst: BitPtr<Mut, T2, O2>,
count: usize,
)Expand description
§Bit-wise memcpy
This copies bits from a region beginning at src into a region beginning at
dst, each extending upwards in the address space for count bits.
The two regions may not overlap.
§Original
§Overlap Definition
The two regions may be in the same provenance as long as they have no common
bits. bitvec only defines the possibility of overlap when the O1 and O2
bit-ordering parameters are the same; if they are different, then it considers
the regions to not overlap, and does not attempt to detect real-memory
collisions.
§Safety
In addition to the bit-ordering constraints, this inherits the restrictions of
the original ptr::copy_nonoverlapping:
srcmust be valid to read the nextcountbits out of memory.dstmust be valid to write into the nextcountbits.- Both
srcanddstmust satisfyBitPtr’s non-null, well-aligned, requirements.
§Behavior
This reads and writes each bit individually. It is incapable of optimizing its behavior to perform batched memory accesses that have better awareness of the underlying memory.
The BitSlice::copy_from_bitslice method is able to perform this
optimization, and tolerates overlap. You should always prefer to use BitSlice
if you are sensitive to performance.
§Examples
use bitvec::prelude::*;
use bitvec::ptr as bv_ptr;
let start = 0b1011u8;
let mut end = 0u16;
let src = BitPtr::<_, _, Lsb0>::from_ref(&start);
let dst = BitPtr::<_, _, Msb0>::from_mut(&mut end);
unsafe {
bv_ptr::copy_nonoverlapping(src, dst, 4);
}
assert_eq!(end, 0b1101_0000_0000_0000);