#[inline]
fn u16tou8ale(v: u16) -> [u8; 2] {
    [
        v as u8,
        (v >> 8) as u8,
    ]
}

// little endian
#[inline]
fn u32tou8ale(v: u32) -> [u8; 4] {
    [
        v as u8,
        (v >> 8) as u8,
        (v >> 16) as u8,
        (v >> 24) as u8,
    ]
}

// big endian
#[inline]
fn u32tou8abe(v: u32) -> [u8; 4] {
    [
        (v >> 24) as u8,
        (v >> 16) as u8,
        (v >> 8) as u8,
        v as u8,
    ]
}

fn main() {
    println!("{:?}", u32tou8ale(0x12345678));
    println!("{:?}", u32tou8abe(0x12345678));
}

fn main() {
    unsafe {
        let p: *const u32 = std::mem::transmute(main);
        println!("{:?}", u32tou8ale(*p));
    }
}