Packing from multiple classes

[frodus]

Hi All,

I'm currently trying to write a frame generator with support for multiple

protocols.

My current idea is to implement one class for each protocol which I have to

support and then one frame class which can instance the different protocols

as needed.

Currently I've some difficulties to figure out how to do the packing in such

an approach can be implemented.

In principal I do have a do_pack as described below for simple packet.

If I would like to add another level of protocol it would have been put right after

the type field and before the data.

The question is which approach I've to follow in order to change this position

from another protocol class. (Note: I have to support a lot of protocols so hard coding each

combination is not an option.)

function void do_pack(uvm_packer packer);

super.do_pack(packer);

packer.pack_field_int(dest,$bits(dest));

packer.pack_field_int(src,$bits(src));

packer.pack_field_int(type,$bits(type));

foreach(data)

packer.pack_field_int(data,8);

packer.pack_field_int(fcs,$bits(fcs);

endfunction

Thanks,

Frodus

[vishal.jain]

Hi Frodus,

One approach that I took in similar application was to flatten out all packets in singe class. Depending on class type (another field in class), I would do packing of required fields.

Pros: Simplified code for coverage / automation / generation

Cons : Debug might become a slight issue. Depending on protocols, flattening can results into the class being always huge

-Vishal

[frodus]

Hi Vishal,

thanks for the reply. Unfortionatly I'm looking into a lot of protocols, including

IEEE802, MPLS, OAM etc.

So I guess putting everything in one class is not an option.

Bye,

Frodus

[jadec]

For encapsulation protocols, you can use pack_field_object for the data. This will allow the sub-object type to determine the data and packing of its section.

For things that modify the fields themselves, you could have a virtual functions in your base class that are called from do_pack and pack certain groups of fields. Overriding those would allow you to insert, modify, delete those groups individually.