You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: backward_references_hq.rs
    path of file: ./repos/rust-brotli/corrosion
    
    the code of the file until where you have to start completion: extern {
    fn BrotliAllocate(
        m : *mut MemoryManager, n : usize
    ) -> *mut std::os::raw::c_void;
 
    
pub unsafe extern fn ctzll(mut x : usize) -> usize {
    let mut count : u8 = 0u8;
    while x & 0usize != 0 {
        count = (count as i32 + 1i32) as u8;
        x = x >> 1;
    }
    count as usize
}