How to write functions that handle in-line constraints

SystemVerilog
,
5

In reply to dave_59:

Hi Dave,

I need to implement a function in db_manager something like below


function myClass db_manager::getRandomItem (
  input expression_type find_clause,  // Operates only on const fields of myClass
  input expression_type constraints   // Operates only on random fields of myClass
);

myClass obj;
int matching_idxs[$];

matching_idxs = q.find_index () with (find_clause);
noMatchingElements: assert (matching_idxs.size() > 0) else $fatal ("No matching elements found");

// Take a copy of matching item
obj = q[matching_idxs[$urandom_range(matching_idxs.size() - 1)]].copy()

constraintFaulire:  assert (obj.randomize() with constraints) else $fatal (
"Randomizing failed at line", `__LINE__
);

return obj;

endfunction : getRandomItem

and call it from somewhere as below


initial begin
  myClass obj;
  db_manager db;

  obj = db.getRandomItem (
    // find_clause
    (
      (item.a inside {A0, A1, A2}) &&
      (item.b inside {B0, B1, B2})
    ),
    // constraints
    (
      ar inside {['d0:'d20]};
      br inside {['d0:'d20]};
    )
  );
end

Sample output (3 iterations)…


a   b   c   ar    br    cr
A0  B1  C5  'd10  'd13  'd89
A1  B1  C9  'd19  'd13  'd48
A2  B2  C2  'd11  'd10  'd20