public static long read32bitLittleEndianUnsignedInt(RandomAccessFile f) throws IOException {
        Integer d0,d1,d2,d3;
        d0=0xff & read_sure(f);
        d1=0xff & read_sure(f);
        d2=0xff & read_sure(f);
        d3=0xff & read_sure(f);
        return (long)(d3<<24) + (d2<<16) + (d1<<8) + d0;
    }