function ss_timing_start ($name = default) {
　global $ss_timing_start_times;
　$ss_timing_start_times[$name] = explode( , microtime());
}
function ss_timing_stop ($name = default) {
　global $ss_timing_stop_times;
　$ss_timing_stop_times[$name] = explode(, microtime());
}
function ss_timing_current ($name = default) {
　global $ss_timing_start_times, $ss_timing_stop_times;
　if (!isset($ss_timing_start_times[$name])) {
　　return 0;
　}
　if (!isset($ss_timing_stop_times[$name])) {
　　$stop_time = explode(, microtime());
　}
　else {
　　$stop_time = $ss_timing_stop_times[$name];
　}
　$current = $stop_time[1] － $ss_timing_start_times[$name][1];
　$current ＋= $stop_time[0] － $ss_timing_start_times[$name][0];
　return $current;
}


在很多网站上都有这段代码，测试代码速度用的几个函数，可是我怎么看都不通