function is_mobile() {
    var useragents = [
        'iPhone',
        'iPad',
        'iPod',
        'Android'
        ];
    var pattern = new RegExp(useragents.join('|'), 'i');
    return pattern.test(navigator.userAgent);
}

if (is_mobile()) {
	var protocol = location.protocol + '//';
    var host = location.host;
    var pathname = '/sp' + location.pathname;
    var search = location.search;
    var hash = location.hash;
    
    location.href = protocol + host + '/sp/';
}