@woosh/meep-engine/src/core/math/hash/murmur3_32.js

Pure JavaScript game engine. Fully featured and production ready.

/**
 * NOTE: based on https://github.com/garycourt/murmurhash-js/blob/master/murmurhash3_gc.js
 * @param {Uint32Array} key
 * @param {number} seed
 * @returns {number}
 */
export function murmur3_32(key, seed) {
    let h1 = seed;
    let k1;
    let i = 0;

    const key_length = key.length;

    while (i < key_length) {
        k1 = key[i];
        ++i;

        k1 = ((((k1 & 0xffff) * 0xcc9e2d51) + ((((k1 >>> 16) * 0xcc9e2d51) & 0xffff) << 16)));
        k1 = (k1 << 15) | (k1 >>> 17);
        k1 = ((((k1 & 0xffff) * 0x1b873593) + ((((k1 >>> 16) * 0x1b873593) & 0xffff) << 16)));

        h1 ^= k1;
        h1 = (h1 << 13) | (h1 >>> 19);
        h1 = ((((h1 & 0xffff) * 5) + ((((h1 >>> 16) * 5) & 0xffff) << 16)));
        h1 = (((h1 & 0xffff) + 0x6b64) + ((((h1 >>> 16) + 0xe654) & 0xffff) << 16));
    }

    // mix in array length
    h1 ^= key_length;

    h1 ^= h1 >>> 16;
    h1 = (((h1 & 0xffff) * 0x85ebca6b) + ((((h1 >>> 16) * 0x85ebca6b) & 0xffff) << 16));
    h1 ^= h1 >>> 13;
    h1 = ((((h1 & 0xffff) * 0xc2b2ae35) + ((((h1 >>> 16) * 0xc2b2ae35) & 0xffff) << 16)));
    h1 ^= h1 >>> 16;

    // cast to uint32
    return h1 >>> 0;
}