private DecoderMetadataBuilder ReadDecoder()
{
var decoder = new DecoderMetadataBuilder();
var mainByte = ReadByte();
if ((mainByte & 0x80) != 0)
{
throw new NotImplementedException();
}
var idLen = (mainByte & 0x0F);
if (idLen > 4)
{
throw new InvalidDataException(); // all known decoders use 4 bytes or less
}
int id = 0;
for (int i = idLen - 1; i >= 0; i--)
{
id |= ReadByte() << (i * 8);
}
decoder.Method = CompressionMethod.TryDecode(id);
if (decoder.Method.IsUndefined)
{
throw new InvalidDataException(); // unknown decoder
}
if ((mainByte & 0x10) != 0)
{
decoder.InputCount = ReadNumberAsInt32();
decoder.OutputCount = ReadNumberAsInt32();
}
else
{
decoder.InputCount = 1;
decoder.OutputCount = 1;
}
decoder.Method.CheckInputOutputCount(decoder.InputCount, decoder.OutputCount);
decoder.InputInfo = ImmutableArray.CreateBuilder <DecoderInputMetadata>(decoder.InputCount);
// We need to fill the array because it is not guaranteed that inputs will be connected in order.
// No valid decoder can have Int32.MaxValue inputs so we can use this as a placeholder value to detect bugs.
var placeholder = new DecoderInputMetadata(Int32.MaxValue, Int32.MaxValue);
for (int i = 0; i < decoder.InputCount; i++)
{
decoder.InputInfo.Add(placeholder);
}
if ((mainByte & 0x20) != 0)
{
var settingsLength = ReadNumberAsInt32();
var settingsBuilder = ImmutableArray.CreateBuilder <byte>(settingsLength);
for (int i = 0; i < settingsLength; i++)
{
settingsBuilder.Add(ReadByte());
}
decoder.Settings = settingsBuilder.MoveToImmutable();
}
else
{
decoder.Settings = ImmutableArray <byte> .Empty;
}
return(decoder);
}
