public String readString() throws IOException {
   return AcDataUtils.readString(in);
 }
 public double readDouble() throws IOException {
   return Double.longBitsToDouble(AcDataUtils.readVLong(in));
 }
 public long readLong() throws IOException {
   return AcDataUtils.readVLong(in);
 }
 public float readFloat() throws IOException {
   return Float.intBitsToFloat(AcDataUtils.readVInt(in));
 }
 public int readInt() throws IOException {
   return AcDataUtils.readVInt(in);
 }