why is,what is, and how is tlm used ?

[shubham_v]

Hi,

I was having few basic doubts regarding tlm,I am using system c again after few months.

I wanted to know ,how exactly tlm is being used.I know the basics of system c and was approaching to start with tlm.

I had googled to see few of tlm uses,but i was not able to catch up those points.

I want to know under this scenario,like if i had modelled a system in system c and was having 5 files,design.cpp,producer.cpp,consumer.cpp,top.cpp,main.cpp .I would have used threads as function and called at particular time and would do the communicvation between modules.But what about tlm,as i had read in tlm we are having initiator and target and there are different types of interface connections which can be used for communication.

But my question here would be,how and where would i put those 5 files when commuication mode being used is tlm.Do i need to model producer as initiator & vice versa & use any of the interface method of tlm or what !?

Any help would be appreciated a lot.

Thank you.

 

Regards,

Shubham 

 

 

[Eyck]

Hi,

TLM2.0 is used to model bus-like transactions as you have in APB, AHB, AXI or alike. It abstracts those transactions in to e.g. read and write with some attribites (liek protection and alike). This saves some from dealing with bit wiggling and, as you have less events, improves simulation performance.

If you use in your scenarion fifo between your producer and consumer you are already using TLM as you abstract the transmission of more or less complex data as a write into the fifo. If you keep this style in your design you do transaction level modeling (TLM).

If you are asking if it makes sense to use the TLM2.0 standard is a different question and depends on what aspects of your design do you need to represent in your model. If you have some kind bus structure (e.g. some micro processor or controller) then it is highly advisable to use TLM2.0. In that case your producer calls the transfer functions of the initiator socket and your consumer needs to react on the callbacks of the target socket.

Actually this does not relate to your file structure but as a starting poitn I would suggest to study the lt example comign with the SysetmC distribution. You will find it under examples/tlm/lt, it contains 2 initiator_top mdouels, a bus and 2 lt_target modules. if you reduce the thing to just one initiator_top and one lt_target being directly connected you have your producer/consumer scenario.

HTH

[shubham_v]

Hi eyck,

 

Thank you for the answer.

Bu with respect to point 2 of your answer i.e producer ,consumer and fifo example.If i am using read or write operation then its a higher abstraction level and i am aware about it .But where does this concept of initiator ,target and socket comes?

Though i am feeling like both are same,but exactly i dont know why should i use them .

I had read it that system c and tlm combinedly will be helpful in architecture exploration and performance modelling.

Ok ,so acc. to my understanding now, i can relate prod,cons,and fifo to a tlm standard.In tlm , we will be using packet as generic transaction,we are having initiator which will use any of the interface methods like blocking,non blocking and what about the function which we need to implement ?,where will i put that function ?

Thanks for the example suggestion, i will look into it.

 

Regards,

Shubham 

 

 

   

 

[Eyck]

Well, in TLM1.0 there is even a tlm::tlm_fifo channel which provides something similar what you use. The sockets defined in TLM2.0 are more geared towards memory-mapped busses and provide facilities to model for speed (DMI, loosly-timed blocking interfaces) or accurracy (approximately-timed non-blocking interfaces). To achive this with pure SystemC provided classes takes some effort and it ends to be proprietary...

BR

-Eyck

[shubham_v]

Hi ,

 

Yes i am getting things slowly.Its all with respect to speed ,accuracy and complexity.

Ok eyck,thanks a lot for the answers.

 

Regards,

shubham