/**

 * Copyright (c) Meta Platforms, Inc. and affiliates.

 *

 * This source code is licensed under the MIT license found in the

 * LICENSE file in the root directory of this source tree.

 *

 * @flow

 */

// TODO: This is pretty well supported by browsers. Maybe we can drop it.

export const clz32: (x: number) => number = Math.clz32

  ? Math.clz32

  : clz32Fallback;

// Count leading zeros.

// Based on:

// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/clz32

const log = Math.log;

const LN2 = Math.LN2;

function clz32Fallback(x: number): number {

  const asUint = x >>> 0;

  if (asUint === 0) {

    return 32;

  }

  return (31 - ((log(asUint) / LN2) | 0)) | 0;

}