githubmirror/immutable-js

src/Math.js

26 строк854 B

Lee Byron

CHERRY-PICK: d3bce8d onto v3.8.1

03 окт 2017, 21:26

03 окт 2017, 21:2667a18dd

/**
 * Copyright (c) 2014-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

export var imul =
  typeof Math.imul === 'function' && Math.imul(0xffffffff, 2) === -2 ?
  Math.imul :
  function imul(a, b) {
    a = a | 0; // int
    b = b | 0; // int
    var c = a & 0xffff;
    var d = b & 0xffff;
    // Shift by 0 fixes the sign on the high part.
    return (c * d) + ((((a >>> 16) * d + c * (b >>> 16)) << 16) >>> 0) | 0; // int
  };

// v8 has an optimization for storing 31-bit signed numbers.
// Values which have either 00 or 11 as the high order bits qualify.
// This function drops the highest order bit in a signed number, maintaining
// the sign bit.
export function smi(i32) {
  return ((i32 >>> 1) & 0x40000000) | (i32 & 0xBFFFFFFF);
}