Node / public / precursor-lxmfchat.git / files / xous-core / loader / src / murmur3.rs

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// Copyright (c) 2020 Stu Small

//

// Licensed under the Apache License, Version 2.0

// <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0> or the MIT

// license <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your

// option. All files in the project carrying such notice may not be copied,

// modified, or distributed except according to those terms.

// This murmur3 code was vendored in on April 28, 2021. We choose to vendor the code for this simple

// non-cryptographic hash in to reduce the number of crate dependencies in the build system. See

// https://github.com/betrusted-io/xous-core/issues/54 for more details on why.

// It also allowed us to adapt the code for our specific no_std needs.

const C1: u32 = 0x85eb_ca6b;

const C2: u32 = 0xc2b2_ae35;

const R1: u32 = 16;

const R2: u32 = 13;

const M: u32 = 5;

const N: u32 = 0xe654_6b64;

pub fn murmur3_32(source: &[u32], seed: u32) -> u32 {

let mut processed = 0;

let mut state = seed;

for &k in source.iter() {

processed += 4;

state ^= calc_k(k);

state = state.rotate_left(R2);

state = (state.wrapping_mul(M)).wrapping_add(N);

}

finish(state, processed)

}

fn finish(state: u32, processed: u32) -> u32 {

let mut hash = state;

hash ^= processed as u32;

hash ^= hash.wrapping_shr(R1);

hash = hash.wrapping_mul(C1);

hash ^= hash.wrapping_shr(R2);

hash = hash.wrapping_mul(C2);

hash ^= hash.wrapping_shr(R1);

hash

}

fn calc_k(k: u32) -> u32 {

const C1: u32 = 0xcc9e_2d51;

const C2: u32 = 0x1b87_3593;

const R1: u32 = 15;

k.wrapping_mul(C1).rotate_left(R1).wrapping_mul(C2)

}

#[cfg(test)]

mod tests {

use super::*;

struct Result {

slice: &'static [u32],

hash_32: u32,

}

#[test]

fn test_static_slices() {

let tests = [

Result {

slice: &[0x34333231], //"1234",

hash_32: 0x721c5dc3,

},

Result {

slice: &[0x34333231, 0x38373635], // "12345678",

hash_32: 0x91b313ce,

},

Result { slice: &[], hash_32: 0 },

];

for test in &tests {

assert_eq!(murmur3_32(test.slice, 0), test.hash_32, "Failed on slice {:x?}", test.slice);

}

}

}