public static function getRangeMem($start, $end, $dec = 2)
{
if (!isset(self::$mem['mem'][$end])) {
self::$mem['mem'][$end] = memory_get_usage();
}
$size = self::$mem['mem'][$end] - self::$mem['mem'][$start];
$a = ['B', 'KB', 'MB', 'GB', 'TB'];
$pos = 0;
while ($size >= 1024) {
$size /= 1024;
$pos++;
}
return round($size, $dec) . " " . $a[$pos];
}