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

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

"use strict";

/**
 * Threshold for switching from 32-bit to 64-bit hashing. This is selected to ensure that the bias towards lower modulo results when using 32-bit hashing is <0.5%.
 * @type {number}
 */
const FNV_64_THRESHOLD = 1 << 24;

/**
 * The FNV-1a offset basis for 32-bit hash values.
 * @type {number}
 */
const FNV_OFFSET_32 = 2166136261;
/**
 * The FNV-1a prime for 32-bit hash values.
 * @type {number}
 */
const FNV_PRIME_32 = 16777619;
/**
 * The mask for a positive 32-bit signed integer.
 * @type {number}
 */
const MASK_31 = 0x7fffffff;

/**
 * The FNV-1a offset basis for 64-bit hash values.
 * @type {bigint}
 */
const FNV_OFFSET_64 = BigInt("0xCBF29CE484222325");
/**
 * The FNV-1a prime for 64-bit hash values.
 * @type {bigint}
 */
const FNV_PRIME_64 = BigInt("0x100000001B3");

/**
 * Computes a 32-bit FNV-1a hash value for the given string.
 * See https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function
 * @param {string} str The input string to hash
 * @returns {number} - The computed hash value.
 */
function fnv1a32(str) {
	let hash = FNV_OFFSET_32;
	for (let i = 0, len = str.length; i < len; i++) {
		hash ^= str.charCodeAt(i);
		// Use Math.imul to do c-style 32-bit multiplication and keep only the 32 least significant bits
		hash = Math.imul(hash, FNV_PRIME_32);
	}
	// Force the result to be positive
	return hash & MASK_31;
}

/**
 * Computes a 64-bit FNV-1a hash value for the given string.
 * See https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function
 * @param {string} str The input string to hash
 * @returns {bigint} - The computed hash value.
 */
function fnv1a64(str) {
	let hash = FNV_OFFSET_64;
	for (let i = 0, len = str.length; i < len; i++) {
		hash ^= BigInt(str.charCodeAt(i));
		hash = BigInt.asUintN(64, hash * FNV_PRIME_64);
	}
	return hash;
}

/**
 * Computes a hash value for the given string and range. This hashing algorithm is a modified
 * version of the [FNV-1a algorithm](https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function).
 * It is optimized for speed and does **not** generate a cryptographic hash value.
 *
 * We use `numberHash` in `lib/ids/IdHelpers.js` to generate hash values for the module identifier. The generated
 * hash is used as a prefix for the module id's to avoid collisions with other modules.
 *
 * @param {string} str The input string to hash.
 * @param {number} range The range of the hash value (0 to range-1).
 * @returns {number} - The computed hash value.
 *
 * @example
 *
 * ```js
 * const numberHash = require("webpack/lib/util/numberHash");
 * numberHash("hello", 1000); // 73
 * numberHash("hello world"); // 72
 * ```
 *
 */
module.exports = (str, range) => {
	if (range < FNV_64_THRESHOLD) {
		return fnv1a32(str) % range;
	} else {
		return Number(fnv1a64(str) % BigInt(range));
	}
};