Code shared from the Rust Playground

playground.rs

#[no_mangle]
pub fn write(message: &str, color: u8, len: u8, slice: &mut [u8]) {
    let bytes = message.bytes().take(len as usize);
    let mut out = slice.iter_mut();
    
    bytes.for_each(|byte| {
        *out.next().unwrap() = byte;
        *out.next().unwrap() = color;
    })
}

fn main() {
    let mut slice = [0; 30];
    
    write("hello world", 0x02, 10, &mut slice[..]);
    
    println!("{:?}", slice)
}