DllExport unsigned int
win32_alarm(unsigned int sec)
{
    /*
     * the 'obvious' implentation is SetTimer() with a callback
     * which does whatever receiving SIGALRM would do
     * we cannot use SIGALRM even via raise() as it is not
     * one of the supported codes in <signal.h>
     */
    dTHX;

    if (w32_message_hwnd == INVALID_HANDLE_VALUE)
        w32_message_hwnd = win32_create_message_window();

    if (sec) {
        if (w32_message_hwnd == NULL)
            w32_timerid = SetTimer(NULL, w32_timerid, sec*1000, NULL);
        else {
  	    w32_timerid = 1;
            SetTimer(w32_message_hwnd, w32_timerid, sec*1000, NULL);
        }
    }
    else {
    	if (w32_timerid) {
            KillTimer(w32_message_hwnd, w32_timerid);
  	    w32_timerid = 0;
    	}
    }
    return 0;
}