e Templates: A Nifty Way To Create Reusable Code

Hi All,

An e template (known as a parameterized type in other programming languages) is a feature that has been around for several releases and can be a great way of creating re-usable code.  Templates can be used anywhere a user would like to create a single re-useable object that might operate on different data types.  An example would be to create a scoreboard (if you were not already using the ovm_scbd package) that can be instantiated to perform checking on packets, transactions, or any other type of data structure of interest. 

Below is a short example of a simple FIFO scoreboard implemented using a template:

 

File: scoreboard.e
<'
template unit scoreboard of (<T'type>) {

    // Instantiate the TLM analysis ports to receive items for adding items to the scoreboard and checking
    add_pkt: in interface_port of tlm_analysis of <T'type> using prefix=add_pkt_ is instance;
    check_pkt: in interface_port of tlm_analysis of <T'type> using prefix=check_pkt_ is instance;

    // The actual scoreboard list
   !sblist: list of <T'type>;  

   // Implement the _write() method of the TLM analysis port
   add_pkt_write(p: <T'type>) is {
      message(NONE, "scoreboard added item: ", p);
      sblist.push(p);
   };

   // Implement the _write() method of the TLM analysis port
   check_pkt_write(p: <T'type>) is { 
      if (deep_compare_physical(p, sblist[0], 10).is_empty()) then {sblist.delete(0);};
      message(NONE, "scoreboard checked item: ", p);
   };           
};
‘>  

Using the above code, a user can instantiate the same scoreboard code to handle any type of data structure.

 

File: env.e

<'
unit env_u {
   packet_sb: scoreboard of (packet_s) is instance;  // Scoreboard to handle packets
   transaction_sb: scoreboard of (transaction_s) is instance;  // Scoreboard to handle transactions
   ...
};
‘>
 

Hope this little technical tidbit helps.

Happy verifying!

Corey