/// <summary>
/// Decode the field into an object reference.
/// </summary>
/// <param name="typ">the type of data in the value array</param>
/// <param name="val">the binary representation of the data</param>
/// <returns>the object value of the data encoded in the value attribute.</returns>
private object GetObjectValue(byte typ, byte[] val)
{
if (val == null)
{
return(null);
}
else if (val.Length == 0)
{
if (typ == FRAME)
{
// empty value in a frame indicates an empty frame
return(new DataFrame());
}
else
{
// an empty value for any other type indicates a null object
return(null);
}
}
else
{
FieldType datatype = GetDataType(typ);
return(datatype.Decode(val));
}
}
public virtual object Decode(byte[] value)
{
object[] retval = EMPTY_ARRAY;
List <object> elements = new List <object>();
byte type = 0;
byte[] data = null;
FieldType datatype = null;
if (value != null)
{
try {
using (MemoryStream stream = new MemoryStream(value)) {
using (BinaryReader reader = new BinaryReader(stream)) {
while (reader.BaseStream.Position != reader.BaseStream.Length)
{
// the next field we read is the data type
type = reader.ReadByte();
// get the proper field type
try {
datatype = DataField.GetDataType(type);
} catch (System.Exception) {
throw new IOException("non supported type: '" + type + "'");
}
// if the file type is a variable length (i.e. size < 0), read in the length
if (datatype.Size < 0)
{
// Read the next 4 bytes
byte[] u32 = reader.ReadBytes(4);
// ...and convert it to a length using big-endian encoding
uint length = ByteUtil.RetrieveUnsignedInt(u32, 0);
if (length < 0)
{
throw new IOException("read length bad value: length = " + length + " type = " + type);
}
data = new byte[length];
if (length > 0)
{
reader.Read(data, 0, data.Length);
}
}
else
{
data = new byte[datatype.Size];
reader.Read(data, 0, data.Length);
}
// now get the object value of the data
elements.Add(datatype.Decode(data));
} // while there is data available to read
retval = elements.ToArray();
}
}
} catch (Exception e) {
throw new ArgumentException("Could not decode value", e);
}
}
return(retval);
}
