webpack/lib/util/numberHash.js

Packs CommonJs/AMD modules for the browser. Allows to split your codebase into multiple bundles, which can be loaded on demand. Support loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/

"use strict";

const SAFE_LIMIT = 0x80000000;
const SAFE_PART = SAFE_LIMIT - 1;
const COUNT = 4;
const arr = [0, 0, 0, 0, 0];
const primes = [3, 7, 17, 19];

module.exports = (str, range) => {
	arr.fill(0);
	for (let i = 0; i < str.length; i++) {
		const c = str.charCodeAt(i);
		for (let j = 0; j < COUNT; j++) {
			const p = (j + COUNT - 1) % COUNT;
			arr[j] = (arr[j] + c * primes[j] + arr[p]) & SAFE_PART;
		}
		for (let j = 0; j < COUNT; j++) {
			const q = arr[j] % COUNT;
			arr[j] = arr[j] ^ (arr[q] >> 1);
		}
	}
	if (range <= SAFE_PART) {
		let sum = 0;
		for (let j = 0; j < COUNT; j++) {
			sum = (sum + arr[j]) % range;
		}
		return sum;
	} else {
		let sum1 = 0;
		let sum2 = 0;
		const rangeExt = Math.floor(range / SAFE_LIMIT);
		for (let j = 0; j < COUNT; j += 2) {
			sum1 = (sum1 + arr[j]) & SAFE_PART;
		}
		for (let j = 1; j < COUNT; j += 2) {
			sum2 = (sum2 + arr[j]) % rangeExt;
		}
		return (sum2 * SAFE_LIMIT + sum1) % range;
	}
};