What is a ref and const Ref argument in SystemVerilog functions?

What is a ref and const Ref argument in SystemVerilog functions?

A class variable is already a reference. Passing a class variable by ref means that you can update the handle the class variable has from within the function. Making the argument a const ref means you will not be able to update the class variable, but you can still update members of the class the variable references.

What are functions in SystemVerilog?

In SystemVerilog, a function is a subprogram which takes one or more input values, performs some calculation and returns an output value. We use functions to implement small portions of code which we want to use in multiple places in our design.

What is the use of automatic keyword in SystemVerilog?

automatic (called auto in software world) storage class variables are mapped on the stack. When a function is called, all the local (non-static) variables declared in the function are mapped to individual locations in the stack.

Can we call task inside function in SystemVerilog?

Solution. You can only do it indirectly from within a process spawned by a fork/join_none. In reply to manavshah33: I am not sure if there is a separate method in System Verilog.

Why do we need cast in SystemVerilog?

Importance of Casting In SystemVerilog, a data type is essential to mention while declaring a variable and it can hold values of the same data type. For example, the int data type can not hold real data type values. If we try doing so, it will lead to a compilation error. Casting helps to resolve this problem.

What is the difference between task and function in SystemVerilog?

A function is meant to do some processing on the input and return a single value, whereas a task is more general and can calculate multiple result values and return them using output and inout type arguments. Tasks can contain simulation time consuming elements such as @, posedge and others.

What is static variable in SystemVerilog?

The use of a static SystemVerilog variable implies that only one copy exists. A static method is subject to all the class scoping and access rules, but behaves like a regular subroutine that can be called outside the class, even with no class instantiation.

Can SV task return a value?

SystemVerilog allows functions to be declared as type void, which do not have a return value. For nonvoid functions, a value can be returned by assigning the function name to a value, as in Verilog, or by using return with a value. The return statement shall override any value assigned to the function name.

What is the use of $cast in UVM?

When $cast is called as a function, it will attempt to assign the source expression to the target variable and return 1 if it succeeds. It does not make the assignment if it fails and returns 0.

What is difference between reg and wire in Verilog?

The wire is used for a continuous assignment whereas reg is used in a procedural assignment.

What is virtual in SystemVerilog?

Virtual method functionality is set at run‐time, which allows extended class handles to be assigned to base class handles and run‐time method calls using the base class handle will execute the extended class method functionality. This is a powerful feature that is called polymorphism.

What are advantages of passing arguments by reference?

The advantage of passing an argument ByRef is that the procedure can return a value to the calling code through that argument. The advantage of passing an argument ByVal is that it protects a variable from being changed by the procedure.

How does pass by reference work?

Pass by reference (also called pass by address) means to pass the reference of an argument in the calling function to the corresponding formal parameter of the called function so that a copy of the address of the actual parameter is made in memory, i.e. the caller and the callee use the same variable for the parameter.

What is the use of extern in SystemVerilog?

Using extern qualifier in method declaration indicates that the implementation is done outside the body of this class.

What is ref In System Verilog?

System Verilog “ref” is a nice reference instead of “value”, Isn’t it? Pass by reference is an interesting and very useful feature in system verilog. Very useful and importatn topic to understand and you might hit this as interview question in your next verification interview. This one is one of the very commonly asked interview question.

What is SystemVerilog package?

SystemVerilog Package. Packages provide a mechanism for storing and sharing data, methods, property, parameters that can be re-used in multiple other modules, interfaces or programs. They have explicitly named scopes that exist at the same level as the top-level module. So, all parameters and enumerations can be referenced via this scope.

What is pass by reference in System Verilog?

In system verilog, methods can also have “pass by reference”. In this case, arguments passed by reference are not copied into subroutine area instead, a reference to the original arguments are passed to subroutine.

What is Verilog hierarchical reference scope?

Verilog Hierarchical Reference Scope Most programming languages have a characteristic feature called scope which defines the visibility of certain sections of code to variables and methods. The scope defines a namespace to avoid collision between different object names within the same namespace.