JenkHash 0.2.1

//! Implementation of the Lookup3 hash algorithm.
//!
//! Lookup3 is an improved version of Bob Jenkins' hash function, designed to be faster
//! and provide better avalanche properties than Lookup2. It processes input data and
//! produces a 32-bit hash value. Lookup3 is optimized for modern processors and is
//! widely used in various software systems.
//!
//! ## Algorithm Overview
//!
//! The Lookup3 algorithm uses an internal state of three 32-bit values that are mixed
//! and updated as data is processed. The algorithm features two main phases:
//!
//! 1. The mixing phase (`mix` function): Processes chunks of input data through a series
//!    of arithmetic and bitwise operations to achieve good avalanche properties.
//! 2. The finalization phase (`final` function): Combines the internal state to produce
//!    the final hash values.
//!
//! The algorithm can process both word-aligned data (using `hash_word`) and byte-oriented
//! data (using `hash_little` and `hash_big` for different endianness). It provides excellent
//! distribution properties and is suitable for use in hash table implementations and other
//! applications requiring fast, well-distributed hash values.

use crate::extensions::ext_slice_u8::ExtSliceU8;
use crate::utils::rot32;

/// A struct providing access to the Lookup3 hash algorithm functions.
///
/// Lookup3 is an improved version of Bob Jenkins' hash function, designed to be faster
/// and provide better avalanche properties than Lookup2. It processes input data and
/// produces 32-bit hash values with excellent distribution properties.
///
/// This struct provides access to different variants of the Lookup3 algorithm optimized
/// for different use cases and platform architectures.
///
/// # Examples
///
/// Basic usage with default seed:
///
/// ```
/// use JenkHash::Lookup3;
///
/// let data = b"hello world";
/// let (hash, _) = Lookup3::hash_little(data, 0, None);
/// println!("Hash: 0x{:08x}", hash);
/// ```
///
/// Using a custom seed:
///
/// ```
/// use JenkHash::Lookup3;
///
/// let data = b"hello world";
/// let (hash, _) = Lookup3::hash_little(data, 0x12345678, None);
/// println!("Hash with seed: 0x{:08x}", hash);
/// ```
///
/// Getting both primary and secondary hash values:
///
/// ```
/// use JenkHash::Lookup3;
///
/// let data = b"hello world";
/// let (primary_hash, secondary_hash) = Lookup3::hash_little(data, 0, Some(0x87654321));
/// println!("Primary hash: 0x{:08x}", primary_hash);
/// if let Some(secondary) = secondary_hash {
///     println!("Secondary hash: 0x{:08x}", secondary);
/// }
/// ```
pub struct Lookup3 {}

impl Lookup3 {
    /// Internal mixing function for the Lookup3 algorithm.
    ///
    /// This function performs the core mixing operations that provide the algorithm's
    /// avalanche properties. It takes three 32-bit state values and processes them
    /// through a series of arithmetic and bitwise rotation operations. The mixing
    /// function ensures that small changes in input lead to significant changes in
    /// the output hash value.
    ///
    /// # Parameters
    ///
    /// * `states` - An array of three 32-bit values representing the internal state
    ///
    /// # Returns
    ///
    /// An array of three 32-bit values representing the mixed internal state
    #[inline]
    #[rustfmt::skip]
    const fn mix(mut states: [u32; 3]) -> [u32; 3] {
        states[0] = states[0].wrapping_sub(states[2]); states[0] ^= rot32(states[2], 4); states[2] = states[2].wrapping_add(states[1]);
        states[1] = states[1].wrapping_sub(states[0]); states[1] ^= rot32(states[0], 6); states[0] = states[0].wrapping_add(states[2]);
        states[2] = states[2].wrapping_sub(states[1]); states[2] ^= rot32(states[1], 8); states[1] = states[1].wrapping_add(states[0]);
        states[0] = states[0].wrapping_sub(states[2]); states[0] ^= rot32(states[2],16); states[2] = states[2].wrapping_add(states[1]);
        states[1] = states[1].wrapping_sub(states[0]); states[1] ^= rot32(states[0],19); states[0] = states[0].wrapping_add(states[2]);
        states[2] = states[2].wrapping_sub(states[1]); states[2] ^= rot32(states[1], 4); states[1] = states[1].wrapping_add(states[0]);

        states
    }

    /// Internal finalization function for the Lookup3 algorithm.
    ///
    /// This function performs the final mixing operations to produce the output hash values.
    /// It combines the three internal state values through a series of arithmetic and
    /// bitwise rotation operations. The finalization function ensures proper mixing of
    /// all state values before producing the final hash result.
    ///
    /// # Parameters
    ///
    /// * `states` - An array of three 32-bit values representing the internal state
    ///
    /// # Returns
    ///
    /// An array of three 32-bit values with the final mixed state
    #[inline]
    #[rustfmt::skip]
    const fn r#final(mut states: [u32; 3]) -> [u32; 3] {
        states[2] ^= states[1]; states[2] = states[2].wrapping_sub(rot32(states[1],14));
        states[0] ^= states[2]; states[0] = states[0].wrapping_sub(rot32(states[2],11));
        states[1] ^= states[0]; states[1] = states[1].wrapping_sub(rot32(states[0],25));
        states[2] ^= states[1]; states[2] = states[2].wrapping_sub(rot32(states[1],16));
        states[0] ^= states[2]; states[0] = states[0].wrapping_sub(rot32(states[2],04));
        states[1] ^= states[0]; states[1] = states[1].wrapping_sub(rot32(states[0],14));
        states[2] ^= states[1]; states[2] = states[2].wrapping_sub(rot32(states[1],24));

        states
    }

    /// Computes the Lookup3 hash of an array of 32-bit words.
    ///
    /// This function processes word-aligned data for optimal performance. It implements
    /// a variant of the algorithm that works directly with 32-bit values rather than
    /// individual bytes. This approach can provide better performance when the input
    /// data is already aligned as 32-bit words.
    ///
    /// # Parameters
    ///
    /// * `data` - A slice of 32-bit words to hash
    /// * `seed1` - The primary seed value for the hash computation
    /// * `seed2` - An optional secondary seed value; if provided, a secondary hash value
    ///   is also returned
    ///
    /// # Returns
    ///
    /// A tuple containing:
    /// * The primary 32-bit hash value
    /// * An optional secondary 32-bit hash value (present if `seed2` was provided)
    pub fn hash_word(mut data: &[u32], seed1: u32, seed2: Option<u32>) -> (u32, Option<u32>) {
        let starting_length = data.len() as u32;
        let initial_state = 0xdeadbeef + ((starting_length) << 2) + seed1;
        let mut states = [initial_state, initial_state, initial_state];
        if let Some(seed) = seed2 {
            states[2] = states[2].wrapping_add(seed);
        }

        while data.len() > 3 {
            states[0] = states[0].wrapping_add(data[0]);
            states[1] = states[1].wrapping_add(data[1]);
            states[2] = states[2].wrapping_add(data[2]);
            states = Self::mix(states);
            data = &data[3..];
        }

        if data.len() == 3 {
            states[2] = states[2].wrapping_add(data[2])
        }
        if (2..=3).contains(&data.len()) {
            states[1] = states[1].wrapping_add(data[1])
        }
        if (1..=3).contains(&data.len()) {
            states[2] = states[2].wrapping_add(data[0]);
            states = Self::r#final(states);
        }

        (states[2], seed2.map(|_| states[1]))
    }

    /// Computes the Lookup3 hash of a byte slice using little-endian interpretation.
    ///
    /// This function implements the little-endian optimized variant of the Lookup3 algorithm.
    /// It processes byte-oriented input data and produces 32-bit hash values. The function
    /// interprets multi-byte values in little-endian format, making it optimal for
    /// little-endian architectures while maintaining deterministic results on all platforms.
    ///
    /// This variant is optimized for performance on little-endian architectures.
    ///
    /// # Parameters
    ///
    /// * `data` - A byte slice to hash
    /// * `seed1` - The primary seed value for the hash computation
    /// * `seed2` - An optional secondary seed value; if provided, a secondary hash value
    ///   is also returned
    ///
    /// # Returns
    ///
    /// A tuple containing:
    /// * The primary 32-bit hash value
    /// * An optional secondary 32-bit hash value (present if `seed2` was provided)
    ///
    /// # Examples
    ///
    /// ```
    /// use JenkHash::Lookup3;
    ///
    /// let data = b"hello world";
    /// let (hash, _) = Lookup3::hash_little(data, 0, None);
    /// println!("Hash: 0x{:08x}", hash);
    /// ```
    ///
    /// With a seed value:
    ///
    /// ```
    /// use JenkHash::Lookup3;
    ///
    /// let data = b"hello world";
    /// let (hash, _) = Lookup3::hash_little(data, 0x12345678, None);
    /// println!("Hash with seed: 0x{:08x}", hash);
    /// ```
    #[cfg(target_endian = "little")] #[rustfmt::skip]
    pub fn hash_little(mut data: &[u8], seed1: u32, seed2: Option<u32>) -> (u32, Option<u32>) {
        let initial_state = 0xdeadbeef + (data.len() as u32) + seed1;
        let mut states = [initial_state, initial_state, initial_state];
        if let Some(seed2) = seed2 {
            states[2] = states[2].wrapping_add(seed2)
        }

        while data.len() > 12 {
            states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_le());
            states[1] = states[1].wrapping_add(data[4 * 1..].read_u32_le());
            states[2] = states[2].wrapping_add(data[4 * 2..].read_u32_le());
            states = Self::mix(states);
            data = &data[4 * 3..];
        }

        match data.len() {
            12 => { states[2] = states[2].wrapping_add(data[4 * 2..].read_u32_le());                 states[1] = states[1].wrapping_add(data[4 * 1..].read_u32_le()); states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_le()); }
            11 => { states[2] = states[2].wrapping_add(data[4 * 2..].read_u32_le() & 0xffffff); states[1] = states[1].wrapping_add(data[4 * 1..].read_u32_le()); states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_le()); }
            10 => { states[2] = states[2].wrapping_add(data[4 * 2..].read_u32_le() & 0xffff);   states[1] = states[1].wrapping_add(data[4 * 1..].read_u32_le()); states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_le()); }
            09 => { states[2] = states[2].wrapping_add(data[4 * 2..].read_u32_le() & 0xff);     states[1] = states[1].wrapping_add(data[4 * 1..].read_u32_le()); states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_le()); }
            08 => { states[1] = states[1].wrapping_add(data[4 * 1..].read_u32_le());                 states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_le()); }
            07 => { states[1] = states[1].wrapping_add(data[4 * 1..].read_u32_le() & 0xffffff); states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_le()); }
            06 => { states[1] = states[1].wrapping_add(data[4 * 1..].read_u32_le() & 0xffff);   states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_le()); }
            05 => { states[1] = states[1].wrapping_add(data[4 * 1..].read_u32_le() & 0xff);     states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_le()); }
            04 => { states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_le());                 }
            03 => { states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_le() & 0xffffff); }
            02 => { states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_le() & 0xffff);   }
            01 => { states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_le() & 0xff);     }
            0 => return (states[2], seed2.map(|_| states[1])),
            _ => unreachable!(),
        }

        states = Self::r#final(states);

        (states[2], seed2.map(|_| states[1]))
    }
    
    /// Computes the Lookup3 hash of a byte slice using little-endian interpretation (fallback for non-little-endian platforms).
    ///
    /// This function implements the little-endian optimized variant of the Lookup3 algorithm
    /// for platforms that are not little-endian. It processes byte-oriented input data and
    /// produces 32-bit hash values, maintaining the same deterministic results as the
    /// little-endian version by explicitly handling byte order during processing.
    ///
    /// # Parameters
    ///
    /// * `data` - A byte slice to hash
    /// * `seed1` - The primary seed value for the hash computation
    /// * `seed2` - An optional secondary seed value; if provided, a secondary hash value
    ///   is also returned
    ///
    /// # Returns
    ///
    /// A tuple containing:
    /// * The primary 32-bit hash value
    /// * An optional secondary 32-bit hash value (present if `seed2` was provided)
    #[cfg(not(target_endian = "little"))] #[rustfmt::skip]
    pub fn hash_little(mut data: &[u8], seed1: u32, seed2: Option<u32>) -> (u32, Option<u32>) {
        let initial_state = 0xdeadbeef + (data.len() as u32) + seed1;
        let mut states = [initial_state, initial_state, initial_state];
        if let Some(seed2) = seed2 {
            states[2] = states[2].wrapping_add(seed2)
        }

        while data.len() > 12 {
            states[0] = states[0] .wrapping_add(data[0] as u32);
            states[0] = states[0] .wrapping_add((data[1] as u32) << 8);
            states[0] = states[0] .wrapping_add((data[2] as u32) << 16);
            states[0] = states[0] .wrapping_add((data[3] as u32) << 24);
            states[1] = states[1] .wrapping_add(data[4] as u32);
            states[1] = states[1] .wrapping_add((data[5] as u32) << 8);
            states[1] = states[1] .wrapping_add((data[6] as u32) << 16);
            states[1] = states[1] .wrapping_add((data[7] as u32) << 24);
            states[2] = states[2] .wrapping_add(data[8] as u32);
            states[2] = states[2] .wrapping_add((data[9] as u32) << 8);
            states[2] = states[2] .wrapping_add((data[10] as u32) << 16);
            states[2] = states[2] .wrapping_add((data[11] as u32) << 24);
            states = Self::mix(states);
            data = &data[4 * 3..];
        }

        if data.len() == 12  { states[2] = states[2].wrapping_add((data[11] as u32) << 24); }
        if (11..=12).contains(&data.len()) { states[2] = states[2].wrapping_add((data[10] as u32) << 16); }
        if (10..=12).contains(&data.len()) { states[2] = states[2].wrapping_add((data[9] as u32) << 8); }
        if (09..=12).contains(&data.len()) { states[2] = states[2].wrapping_add(data[8] as u32); }
        if (08..=12).contains(&data.len()) { states[1] = states[1].wrapping_add((data[7] as u32) << 24); }
        if (07..=12).contains(&data.len()) { states[1] = states[1].wrapping_add((data[6] as u32) << 16); }
        if (06..=12).contains(&data.len()) { states[1] = states[1].wrapping_add((data[5] as u32) << 8); }
        if (05..=12).contains(&data.len()) { states[1] = states[1].wrapping_add(data[4] as u32); }
        if (04..=12).contains(&data.len()) { states[0] = states[0].wrapping_add((data[3] as u32) << 24); }
        if (03..=12).contains(&data.len()) { states[0] = states[0].wrapping_add((data[2] as u32) << 16); }
        if (02..=12).contains(&data.len()) { states[0] = states[0].wrapping_add((data[1] as u32) << 8); }
        if (01..=12).contains(&data.len()) { states[0] = states[0].wrapping_add(data[0] as u32); }
        if data.len() == 00  { return (states[2], seed2.map(|_| states[1])); }

        states = Self::r#final(states);

        (states[2], seed2.map(|_| states[1]))
    }

    /// Computes the Lookup3 hash of a byte slice using big-endian interpretation.
    ///
    /// This function implements the big-endian variant of the Lookup3 algorithm.
    /// It processes byte-oriented input data and produces 32-bit hash values. The function
    /// interprets multi-byte values in big-endian format, making it optimal for
    /// big-endian architectures. This function is primarily for compatibility with
    /// big-endian platforms.
    ///
    /// The original C implementation did not include a `hashbig2` function, so this implementation assumes the same process as `hashlittle2`.
    ///
    /// **Note:** This function is provided for completeness and big-endian compatibility.
    /// However, it has limited testing on actual big-endian platforms.
    ///
    /// # Parameters
    ///
    /// * `data` - A byte slice to hash
    /// * `seed1` - The primary seed value for the hash computation
    /// * `seed2` - An optional secondary seed value; if provided, a secondary hash value
    ///   is also returned
    ///
    /// # Returns
    ///
    /// A tuple containing:
    /// * The primary 32-bit hash value
    /// * An optional secondary 32-bit hash value (present if `seed2` was provided)
    #[cfg(target_endian = "big")] #[rustfmt::skip]
    fn hash_big(mut data: &[u8], seed1: u32, seed2: Option<u32>) -> (u32, Option<u32>) {
        let initial_state = 0xdeadbeef + (data.len() as u32) + seed1;
        let mut states = [initial_state, initial_state, initial_state];
        if let Some(seed2) = seed2 {
            states[2] = states[2].wrapping_add(seed2)
        }

        while data.len() > 12 {
            states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_be());
            states[1] = states[1].wrapping_add(data[4 * 1..].read_u32_be());
            states[2] = states[2].wrapping_add(data[4 * 2..].read_u32_be());
            states = Self::mix(states);
            data = &data[4 * 3..];
        }

        match data.len() {
            12 => { states[2] = states[2].wrapping_add(data[4 * 2..].read_u32_be());              states[1] = states[1].wrapping_add(data[4 * 1..].read_u32_be()); states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_be()); }
            11 => { states[2] = states[2].wrapping_add(data[4 * 2..].read_u32_be() & 0xffffff00); states[1] = states[1].wrapping_add(data[4 * 1..].read_u32_be()); states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_be()); }
            10 => { states[2] = states[2].wrapping_add(data[4 * 2..].read_u32_be() & 0xffff0000); states[1] = states[1].wrapping_add(data[4 * 1..].read_u32_be()); states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_be()); }
            09 => { states[2] = states[2].wrapping_add(data[4 * 2..].read_u32_be() & 0xff000000); states[1] = states[1].wrapping_add(data[4 * 1..].read_u32_be()); states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_be()); }
            08 => { states[1] = states[1].wrapping_add(data[4 * 1..].read_u32_be());              states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_be()); }
            07 => { states[1] = states[1].wrapping_add(data[4 * 1..].read_u32_be() & 0xffffff00); states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_be()); }
            06 => { states[1] = states[1].wrapping_add(data[4 * 1..].read_u32_be() & 0xffff0000); states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_be()); }
            05 => { states[1] = states[1].wrapping_add(data[4 * 1..].read_u32_be() & 0xff000000); states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_be()); }
            04 => { states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_be());              }
            03 => { states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_be() & 0xffffff00); }
            02 => { states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_be() & 0xffff0000); }
            01 => { states[0] = states[0].wrapping_add(data[4 * 0..].read_u32_be() & 0xff000000); }
            00 => return (states[2], seed2.map(|_| states[1])),
            _ => unreachable!(),
        }

        states = Self::r#final(states);

        (states[2], seed2.map(|_| states[1]))
    }
    
    /// Computes the Lookup3 hash of a byte slice using big-endian interpretation (fallback for non-big-endian platforms).
    ///
    /// This function implements the big-endian variant of the Lookup3 algorithm
    /// for platforms that are not big-endian. It processes byte-oriented input data and
    /// produces 32-bit hash values, maintaining the same deterministic results as the
    /// big-endian version by explicitly handling byte order during processing.
    ///
    /// The original C implementation did not include a `hashbig2` function, so this implementation assumes the same process as `hashlittle2`.
    ///
    /// **Note:** This function is provided for completeness and big-endian compatibility.
    /// However, it has limited testing on actual big-endian platforms.
    ///
    /// # Parameters
    ///
    /// * `data` - A byte slice to hash
    /// * `seed1` - The primary seed value for the hash computation
    /// * `seed2` - An optional secondary seed value; if provided, a secondary hash value
    ///   is also returned
    ///
    /// # Returns
    ///
    /// A tuple containing:
    /// * The primary 32-bit hash value
    /// * An optional secondary 32-bit hash value (present if `seed2` was provided)
    #[cfg(not(target_endian = "big"))] #[rustfmt::skip]
    fn hash_big(mut data: &[u8], seed1: u32, seed2: Option<u32>) -> (u32, Option<u32>) {
        let initial_state = 0xdeadbeef + (data.len() as u32) + seed1;
        let mut states = [initial_state, initial_state, initial_state];
        if let Some(seed2) = seed2 {
            states[2] = states[2].wrapping_add(seed2)
        }

        while data.len() > 12 {
            states[0] = states[0].wrapping_add((data[00] as u32) << 24);
            states[0] = states[0].wrapping_add((data[01] as u32) << 16);
            states[0] = states[0].wrapping_add((data[02] as u32) << 08);
            states[0] = states[0].wrapping_add((data[03] as u32));
            states[1] = states[0].wrapping_add((data[04] as u32) << 24);
            states[1] = states[0].wrapping_add((data[05] as u32) << 16);
            states[1] = states[0].wrapping_add((data[06] as u32) << 08);
            states[1] = states[0].wrapping_add((data[07] as u32));
            states[2] = states[0].wrapping_add((data[08] as u32) << 24);
            states[2] = states[0].wrapping_add((data[09] as u32) << 16);
            states[2] = states[0].wrapping_add((data[10] as u32) << 08);
            states[2] = states[0].wrapping_add((data[11] as u32));
            states = Self::mix(states);
            data = &data[4 * 3..];
        }

        if data.len() == 12 { states[2] = states[2].wrapping_add((data[11] as u32)); }
        if (11..=12).contains(&data.len()) { states[2] = states[2].wrapping_add((data[10] as u32) << 08); }
        if (10..=12).contains(&data.len()) { states[2] = states[2].wrapping_add((data[09] as u32) << 16); }
        if (09..=12).contains(&data.len()) { states[2] = states[2].wrapping_add((data[08] as u32) << 24); }
        if (08..=12).contains(&data.len()) { states[1] = states[1].wrapping_add((data[07] as u32)); }
        if (07..=12).contains(&data.len()) { states[1] = states[1].wrapping_add((data[06] as u32) << 08); }
        if (06..=12).contains(&data.len()) { states[1] = states[1].wrapping_add((data[05] as u32) << 16); }
        if (05..=12).contains(&data.len()) { states[1] = states[1].wrapping_add((data[04] as u32) << 24); }
        if (04..=12).contains(&data.len()) { states[0] = states[0].wrapping_add((data[03] as u32)); }
        if (03..=12).contains(&data.len()) { states[0] = states[0].wrapping_add((data[02] as u32) << 08); }
        if (02..=12).contains(&data.len()) { states[0] = states[0].wrapping_add((data[01] as u32) << 16); }
        if (01..=12).contains(&data.len()) { states[0] = states[0].wrapping_add((data[00] as u32) << 24); }
        if data.len() == 00 { return (states[2], seed2.map(|_| states[1])); }

        states = Self::r#final(states);

        (states[2], seed2.map(|_| states[1]))
    }
}

#[cfg(test)]
mod tests {
    use crate::Lookup3;

    #[cfg(target_endian = "little")] #[test]
    fn test_hash_little() {
        let str = b"hello world";
        let (hash, _) = Lookup3::hash_little(str, 0, None);
        assert_eq!(hash, 0x4AA94E65)
    }
    #[cfg(not(target_endian = "little"))]#[test]
    fn test_hash_little() {
        let str = b"hello world";
        let (hash, _) = Lookup3::hash_little(str, 0, None);
        assert_eq!(hash, 0x4AA94E65)
    }
    #[test]
    #[ignore = "Don't have a way to properly test this hash method. Don't have any big-endian machines"]
    #[cfg(target_endian = "big")]#[test]
    fn test_hash_big() {
        let str = b"hello world";
        let (hash, _) = Lookup3::hash_big(str, 0, None);
        assert_eq!(hash, 0xF1DFDD63)
    }
    #[test]
    #[ignore = "Don't have a way to properly test this hash method. Don't have any big-endian machines"]
    #[cfg(not(target_endian = "big"))]#[test]
    fn test_hash_big() {
        let str = b"hello world";
        let (hash, _) = Lookup3::hash_big(str, 0, None);
        assert_eq!(hash, 0xC7CE1547)
    }
}