How to initialize a union in Systemverilog?

[boardlanguage]

I've tried to initialize a union (in Modelsim 6.2f SE) , but it's not working.
I want the union to initialize to '0' (instead of 'X'.) I can't use a 2-state base-type (bit), because the union must be capable of capturing 4-state ('X') values.

typedef union packed {
  logic blah7;
  logic blah6;
  logic blah5;
  logic blah4;
} t_myunion;

t_myunion foo = { default:0 };

/*
COMPILER ERROR: Illegal assignment of structural literals to union
*/

Is there a way to initialize a union?[/code]

 

[sumit_techkgp]

Ya. Create it and initialize it in a procedural statement
Sumit

 

[modelsim62c]

Yes, you have two choices:
(a) initialize in procedural code (task/subprogram or other program block)
(b) since you declared the struct/union 'packed', you can simply assign it directly to a 4-state literal value -- no need for the braces {}.

typedef union packed {
  logic blah7;
  logic blah6;
  logic blah5;
  logic blah4;
} t_myunion;

t_myunion foo = 'h42;// single value, only works for packed union/struct

...so you almost had it right the first time