Hi Sebatian,
I just had a look at your mspec work … it seems in the AMSHeader type, you ran
into a problem which I would like to help you with.
The simple field:
[simple uint 32 '../data.lengthInBytes' ]
What should this field contain? I am asking as the mspec code doesn’t have a
parent relationship so this will not work. However you can pass in data via
type arguments.
But for me it feels like perhaps refactoring the structure could eliminate
problems.
The general problem is that we need the “data” object to produce the output. So
we would need this before parsing the header, which can’t happen as it hasn’t
been parsed yet.
One option would be to make this a normal property in the header and to
reference this, if needed in the data. The downside would be that this might
introduce double data.
I would suggest to merge the AMSPacket and the AMSHeader.
[type 'AMSPacket'
[reserved uint 16 '0x0000' ]
[implicit uint 32 'totalLength' 'lengthInBytes - 6']
[simple AMSNetId 'targetAmsNetId' ]
[simple uint 16 'targetAmsPort' ]
[simple AMSNetId 'sourceAmsNetId' ]
[simple uint 16 'sourceAmsPort' ]
[enum CommandId 'commandId' ]
[enum State 'state' ]
[implicit uint 32 'dataLength' 'data.lengthInBytes']
[simple uint 32 'errorCode' ]
[simple byte 32 'invokeId' ]
[simple ADSData 'data' ]
]
I know why you might want to model the header separately, but sometimes
adjusting the structure to avoid complexities like this is a good thing to do.
The other thing is your proposed “bitmask” … I can’t really see the difference
between an enum and your bitmask.
I think it shouldn’t be a problem to make the enum parser to understand the
bit-pattern you propose (Which I really like, by the way).
If you are worried that enums are in java not extendable, I would really like
to change the enum code-generation to make extendable enum structures instead
of pure java enums.
What do you think about this?
But I am happy that you seem to have generally grasped how to build mspecs
which makes me really happy as I think you are one of the first to do that :-)
