Array locator method usage with a bin

UVM
1

I have a 32b unsigned field, which I want to sample in a covergroup. In a particular test, I want to cover that any value was hit, except for one.

E.g. bins invalid_code = {[0:4294967295]} with (item!=VALID_CODE);

This doesn’t work, because array locator methods return a queue of int, whose max value is 2147483647;

[0:2147483647] works.
[0:2147483648] errors on right bound.

I need the array [0:4294967295], minus VALID_CODE.
thoughts?

EDIT:
this does the job, but eager to see alternate solutions

bins invcode1 = {[0:VALID_CODE-1]};
      bins valid_code = {VALID_CODE};
      bins invcode2 = {[VALID_CODE+1:$]};
2

In reply to bmorris:

Array locator methods return a queue of the type you are calling them on. In your case, [0:4294967295] is probably being interpreted as a set of int values. You can force the compiler to treat them as unsigned by declaring the array outside of the coverpoint:


// not sure about the initialization syntax, but it doesn't really matter
// - this is probably illegal
// - could also initialize over loop
int unsigned vals = '{ [0:4294967295] };

int unsigned illegal_vals[$] = vals with (item!=VALID_CODE);

bins invalid_code = illegal_vals;

Some tools might have issues with this syntax, though. You could also try putting ‘illegal_vals’ between curly brackets.

Also, are you sure that your coverpoint knows that you are sampling an unsigned value? You probably have something like:


coverpoint some_expr {
  // ...
}

If some_expr is computed out of more variables, casting rules might make it be intepreted as int. Try forcing the compiler with a static cast:


coverpoint (int unsigned)'some_expr {
  // ...
}
3

In reply to Tudor Timi:

Not sure if the second point applies, though, with the coverpoint being treated as int instead of int unsigned, since then the example code you showed wouldn’t work either.

4

In reply to Tudor Timi:

I wasn’t able to get any of this working. could be tool, or not allowed in SV.

int unsigned vals = '{ [0:4294967295] }; // error
int unsigned illegal_vals[$] = vals with (item!=VALID_CODE); // error. no array locator method used, and as far as I know, only allowed as-is in the bin definition context
coverpoint (int unsigned)'some_expr // error

Ill stick with my solution for now; alternative is a lot of language hoop jumping

5

In reply to bmorris:

I mean to write:


int unsigned illegal_vals[$] = vals.find() with (item!=VALID_CODE);