Stats

  • Locked Locked
  • Replies 1
  • Subscribers 65
  • Views 15821
  • Members are here 0
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Using interface signals as coverpoint bins

RajeshCM

Hi,

 I have my functional coverage like this:

class mem_cov_grp;

virtual SysRegIntf;

covergroup walks();

level:      coverpoint SysRegIntf.Addr {

                 bins MAX = {31- SysRegIntf.Tag};

                 bins MAX_PLUS_ONE = {31 - SysRegIntf.Tag + 1}; 

              }  

endgroup 

function new (Virtual SysRegIntf);

    this.SysRegIntf = SysRegIntf;

    walks = new(); 

endfunction 

function void sample ();

    walks.sample(); 

endfunction   

endclass 

In this case, bin values are not static and vary depending on Tag bits in the interface. Is this allowed in system verilog?. It compiles well but the bin values are fozen to 31 - 0 = 30 for MAX and 31 - 0 + 1 to 32 to MAX_PLUS_ONE.  

 

  • The ranges in a bin declaration need to be compile-time constants. Since SysRegIntf is a virtual interface, it can be assigned during run time. So I'm really surprised that this code even compiled. I think it should have been rejected. Here's one way to accomplish your goal.

    class mem_cov_grp;
      virtual SysRegIntf vintf;
     
      logic max_addr, max_addr_1;
      covergroup walks;
        level: coverpoint {max_addr_1,max_addr} {
                   bins MAX = {2'b01};
                   bins MAX_PLUS_ONE = {2'b10};
               } 
      endgroup

      function new (virtual SysRegIntf vintf);
        this.vintf = vintf;
        walks = new();
      endfunction

      function void sample ();
        max_addr   = (vintf.Addr==(31-vintf.Tag));
        max_addr_1 = (vintf.Addr==(31-vintf.Tag+1));
        walks.sample();
      endfunction  

    endclass

    Using this, Tag does not have to be a compile-time constant but different interfaces can have different tags and the bins will be selected appropriately.

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.