arrays - Temporarily transmute [u8] to [u16]

Question

I have a [u8; 16384] and a u16. How would I "temporarily transmute" the array so I can set the two u8s at once, the first to the least significant byte and the second to the most significant byte?

Answer 1

The obvious, safe and portable way is to just use math.

fn set_u16_le(a: &mut [u8], v: u16) {
    a[0] = v as u8;
    a[1] = (v >> 8) as u8;
}

If you want a higher-level interface, there's the byteorder crate which is designed to do this.

You should definitely not use transmute to turn a [u8] into a [u16], because that doesn't guarantee anything about the byte order.