Packer on pack/unpack operation

[budisantoso]

Hi All,

I am developing a UVM bench right now, but got a little problem with the use of packer when I do pack/unpack operation. Let me explain my problem below:

For a scenario where there is subclass inside a class, during pack/unpack I notice that the packer of the parent class is shared with the subclass.

As a result the parent class packer information will be overwritten by subclass.

For example, see pseudo code below:

      parent.unpack_bytes begin (bytestream1, packer)

           subclass.unpack_bytes (bytestream2, packer) begin

                         ……….. 

           end

           ….....(continue with parent other operation which uses packer information i.e: m_packed_size)

      end

In this case, I notice the value of m_packed_size of parent packer is overwritten by subclass m_packed_size. Is there any way not to change the value of m_packed_size? so that I can use the original value of m_packed_size (before it is edited by subclass.unpacked_bytes) at the end of parent class?

Really appreciate your helps.

Thanks,

Budi

Edited June 26, 2012 by budisantoso

[janick]

Are you writing your own do_unpack?

[budisantoso]

Yes, you are correct. I am writing my do_unpack.

[janick]

Do not call obj.unpack_bytes(packer) but packer.unpack_object(obj).

[budisantoso]

Hi Janick,

Thanks for you reply. Using the method that you recommended, the packer properties will not be modified. However, if i use that method, I can not pass the bytestream to be unpack.

So in my case, I am still using obj.unpack_bytes(bytestream, packer) but before i call that function, I keep the old properties of packer (ex:m_packed_size) as temp and set it back at the end.

Thanks

[janick]

The packed stream is a variable inside the uvm_packer instance. You need not pass it.