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: chacha.rs
    path of file: ./repos/ring/src/aead
    
    the code of the file until where you have to start completion: // Copyright 2016 Brian Smith.
// Portions Copyright (c) 2016, Google Inc.
//
// Permission to use, copy, modify, and/or distribute
    
    fn chacha20_test_default() {
        // Always use `MAX_OFFSET` if we hav assembly code.
        let max_offset = if cfg!(any(
            target_arch = "aarch64",
            target_arch = "arm",
            target_arch = "x86",
            target_arch = "x86_64"
        )) {
            MAX_ALIGNMENT_AND_OFFSET
        } else {
            MAX_ALIGNMENT_AND_OFFSET_SUBSET
        };
        chacha20_test(max_offset, Key::encrypt_within);
    }