unsigned char *GamePacketSize(unsigned char *data, unsigned int *size,
               unsigned int *offset)
{
  unsigned int a;

  if (data[0] < 0xF0) {
    *size = data[0] - 1;
    *offset = 1;
    return &data[1];
  }

  a = (data[0] & 0xF) << 8;
  *size = a + data[1] - 2;
  *offset = 2;
  return &data[2];
}