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: mod.rs
    path of file: ./repos/icu4x/utils/zerotrie/src/byte_phf
    
    the code of the file until where you have to start completion: // This file is part of ICU4X. For terms of use, please see the file
// called LICENSE at the top level of the ICU4X source tree
// (online at: https://
    
pub fn f1(byte: u8, p: u8, n: usize) -> usize {
    let n = if n > 0 {
        n
    } else {
        debug_assert!(false, "unreachable by invariant");
        1
    };
    if p == 0 {
        byte as usize % n
    } else {
        let mut result = byte ^ p ^ byte.wrapping_shr(p as u32);
        // In almost all cases, the PHF works with the above constant-time operation.
        // However, to crack a few difficult cases, we fall back to the linear-time
        // operation shown below.
        for _ in P_FAST_MAX..p {
            result = result ^ (result << 1) ^ (result >> 1);
        }
        result as usize % n
    }
}