Usage of "virtual interface" and "virtual"

UVM
,
1

Dear All,

I came across usage of vitial interface and interface, But I’m confused it.

For example,

-agent.sv

class sys_agent extends uvm_agent;
....
virtual interface sys_if_vif;
...
virtual function void build_phase(uvm...)
...
dirver.vif = vif;
monitor.vif = vif;
endfunction
endclass

-driver.sv

class sys_monitor extends uvm_monitor;
...
virtual sys_if vif; <--Is this correct usage?
...
endclass

from 2 files, we can see the usage of virtual interface declared.
But I’m confused that why “vitual interface sys_if vif” instead vitual sys_if vif in driver.sv?

2

In reply to UVM_LOVE:

This is not legal syntax.

virtual interface sys_if_vif;
3

In reply to dave_59:

Sorry my typo,

What is the difference usage between
type1.

virtual interface sys_if_vif vif;

and
type2.

virtual sys_if_vif vif;

I came across some examples such as type1 or type2.

I’m confused it. So I checked it from

But they are working as the same.

4

In reply to UVM_LOVE:

The syntax for declaring a virtual interface variable is

virtual [ interface ] interface_identifier [ parameter_value_assignment ] [ . modport_identifier ]

That means the presence of the
interface interface keyword is optional. Don’t ask me why Verilog/SystemVerilog has so many ways to do the same thing.

5

In reply to dave_59:

Don’t ask me why Verilog/SystemVerilog has so many ways to do the same thing.

Trust me, if Dave doesn’t know why something is the way it is in Verilog/SystemVerilog, it is unknowable.