How to test the current instance name?

Question

I need to use the current instance name (full hierarchical name) in a generate if condition:

generate
   if (current_instance_name() == "a.b.c.foo")
   ...

Is there any way to do that in Verilog or SystemVerilog? I know %m, but it only allows to print the instance name.

Thanks.

I'm pretty sure you can't do that. If you want a certain instance to contain different generated blocks, you'll have to use parameters and parameterize the instance accordingly. — Tudor Timi, Sep 30 '14 at 11:39
Also, relying on full hierarchical paths inside a module is a very bad practice, because this breaks encapsulation. — Tudor Timi, Sep 30 '14 at 11:40
The generate if condition requires a constant expression which can be evaluated during elaboration phase. — jclin, Oct 01 '14 at 04:07

score 3 · Accepted Answer · edited May 16 '20 at 17:26

3

The way to do this is

localparam string current_path = $sformatf("%m");

generate
if (current_path == "a.b.c.foo") begin ...

edited May 16 '20 at 17:26

toolic

answered Oct 01 '14 at 18:42

dave_59

score 0 · Answer 2 · answered Sep 30 '14 at 08:33

0

You can still use %m by passing it to $psprintf which will return a string. The following function should solve your problem:

function string current_instance_name();
return $psprintf("%m");
endfunction

answered Sep 30 '14 at 08:33

AldoT

1

While this does return the full path, I'm pretty sure he can't use it in a generate statement, because it doesn't resolve to an elaborate time constant. – Tudor Timi Sep 30 '14 at 11:41
1

Although the major simulator support `$psprintf` it is not part of the IEEE1364(Verilog) or IEEE1800(SystemVerilog) standards. To be complaint with the standard(s), use `$sformatf` – Greg Sep 30 '14 at 15:55
"%m" returns the current path where the format string locates, not the instance name. If you place the function in a package, and call the function inside your module/instance, the format string results in "package_name::current_instance_name" – jclin Oct 01 '14 at 03:03
@jclin, ha, ok that's also so true. It will return function location and function name. – AldoT Oct 01 '14 at 07:36
2

Instead of "%m", in VCS there is "%i" that will return string indicating from which instance/block the function was called. – AldoT Oct 01 '14 at 07:53

2 Answers2