es6.math.imul.js 534 Bytes
// 20.2.2.18 Math.imul(x, y)
var $export = require('./$.export')
  , $imul   = Math.imul;

// some WebKit versions fails with big numbers, some has wrong arity
$export($export.S + $export.F * require('./$.fails')(function(){
  return $imul(0xffffffff, 5) != -5 || $imul.length != 2;
}), 'Math', {
  imul: function imul(x, y){
    var UINT16 = 0xffff
      , xn = +x
      , yn = +y
      , xl = UINT16 & xn
      , yl = UINT16 & yn;
    return 0 | xl * yl + ((UINT16 & xn >>> 16) * yl + xl * (UINT16 & yn >>> 16) << 16 >>> 0);
  }
});