How to define cross coverage for the selected range

SystemVerilog
1

hi,
i have the following reqirement

int A,B;
coverpoint A { a ={[0:27]};}
coverpoint B { b = {[0:27]};}
cross_A_B cross a,b;

here cross_A_B gives all combinations but i need selected range cross between A,B

like i need cross between a[2]…a[5] & b[3]…b[6] ==> a[2],b[3];a[2],b[4];a[2],b[5];a[2],b[6];
a[3],b[3]…
can please tell me the procedure to do this

thank you,
murali

2

You can ignore the ranges you do not want to cross

cross_A_B : cross A,B
{
   ignore_bins of_a = binsof(a) intersect { [$:1],[6:$] } ;
   ignore_bins of_b = binsof(b) intersect { [$:2],[7:$] } ;
}

Dave

3

In reply to murali_yalamanchi:

thank you dave,
i need some more, i forgot to mention

coverpoint A { a ={[0:27]};}
coverpoint B { b = {[0:27]};}
cross_A_B cross a,b;

here cross_A_B gives all combinations but i need selected range cross between A,B

like i need cross between a[2]…a[5] & b[3]…b[6],
a[6]…a[8] & b[7]…b[10],
a[9]…a[15] & b[11]…b[15],
a[16]…a[27] & b[16]…b[27];

like this i want to create cross coverage can u please help me.

thank you
Murali

4

In reply to murali_yalamanchi:

You can either do

cross A_B a,b {
  bins r1 = binsof(a) intersect {[2:5]} && binsof(b) intersect {[3:6]};
  bins r2 = binsof(a) intersect {[6:8]} && binsof(b) intersect {[7:10]};
  bins r3 = binsof(a) intersect {[9:15]} && binsof(b) intersect {[11:15]};
  bins r4 = binsof(a) intersect {[16:27]} && binsof(b) intersect {[16:27]};
}

or change the bins for the coverpoints A and B

coverpoint A { 
  bins a1 = {[2:5]};
  bins a2 = {[2:8]};
  bins a3 = {[9:15]};
  bins a4 = {[16:27]};
}
coverpoint B { 
  bins b1 = {[3:6]};
  bins b2 = {[7:10]};
  bins b3 = {[11:15]};
  bins b4 = {[16:27]};
}

and cross the specific bins you want.

5

In reply to dave_59:

i have tried first method,

but what i observed from the results, for r1 it is creating single bin instead of 16 bins.
same for r2,r3,r4 and i am getting remaining combinations which are not covered in r1,r2,r3,r4 but i dont want those…

when i am trying second method, iam getting compilation error

i gave like this
cross_A_B : cross A.a1,B.b1;

its giving hierarchical name not found, please correct me.

thnak you,
murali

6

In reply to dave_59:

OK, this is the most compact way to get the exact bins you are looking for with the information you have provided.

covergroup cg;
      a: coverpoint v_a { bins a[] = {[2:27]}; }
      b: coverpoint v_a { bins b[] = {[2:27]}; }
      c1: cross a,b
	{ignore_bins ib = ! binsof(a) intersect {[2:5]} || ! binsof(b) intersect {[3:6]};}
      c2: cross a,b
	{ignore_bins ib = ! binsof(a) intersect {[6:8]} || ! binsof(b) intersect {[7:10]};}
      c3: cross a,b
	{ignore_bins ib = ! binsof(a) intersect {[9:15]} || ! binsof(b) intersect {[11:15]};}
      c4: cross a,b
	{ignore_bins ib = ! binsof(a) intersect {[16:27]} || ! binsof(b) intersect {[16:27]};}
   endgroup // cg
7

In reply to dave_59:

thank you for response dave.

8

In reply to murali_yalamanchi:

Hi Dave,
What if I want to ignore all the bins of coverpoint a(except a1),the following code is not working. a2,a3…ax bins are not ignored,but scalar bins aa and aaa are ignored. Any reason.


     covergroup cg;
      a: coverpoint v_a { bins aa = {[1:10]}; bins aaa = {[12:20]};
                          bins a1[] = {[2:27]}; bins a2[] = {[28:37]}; bins a3[] = {[38:47]}; .... bins ax[] = {[1:20]};}

      b: coverpoint v_a { bins b1[] = {[2:27]}; bins b2[] = {[28:37]};}
      c1: cross a,b
	{ignore_bins ib = ! binsof(a.a1) || ! binsof(b) intersect {[3:6]};}
     
   endgroup // cg
9

In reply to muralikrishna.makkena:

how can i cross coverpoints that belongs to diffrent covergroups ??

10

In reply to rtawade:
SystemVerilog does not allow this. you have to replicate the coverpoints you want to cross in a single covergroup.

BTW, please use a new topic to ask a new question.

11

In reply to dave_59:

Hello Dave,

Could you please let me know the difference between these two lines?

c1: cross a,b
	{ignore_bins ib = ! binsof(a) intersect {[2:5]} || ! binsof(b) intersect {[3:6]}; //1

        ignore_bins ib =  binsof(a) intersect {[2:5]} &&  binsof(b) intersect {[3:6]};} //2

I am a bit confused about the !binsof and binsof in ignore bins. Thanks

12

In reply to the_ceylonese:
By De Morgan’s law, the two lines are complements of each other.

Assuming the cross refers to the coverpoints in the first post with bins a = {[0:27]}, then the first ignore_bins says
Remove all the crosses where the A has one of the values: 0,1,6-27, or B has one of the values 0-2,7-27

and the second ignore_bins says
Remove all the crosses where the A has one of the values 2-7 and B has the value 3-6

13

In reply to dave_59:

Cheers Dave, appreciate it.