php 文件大小 单位自动转换函数

//文件大小单位自动转换
    public static function autoShow($value = 0)
    {
        $kb = 1024;
        $mb = 1048576;
        $gb = 1073741824;
        $tb = $gb * 1024;
        $pb = $tb * 1024;
        if (abs($value) > $pb) {
            return round($value / $pb, 2) . "PB";
        } elseif (abs($value) > $tb) {
            return round($value / $tb, 2) . "TB";
        } elseif (abs($value) > $gb) {
            return round($value / $gb, 2) . "GB";
        } elseif (abs($value) > $mb) {
            return round($value / $mb, 2) . "MB";
        } elseif (abs($value) > $kb) {
            return round($value / $kb, 2) . "KB";
        } else {
            return round($value, 2) . "B";
        }
    }