UVM Object

The uvm_object class is the base class for all uvm hierarchical classes such as uvm_report_object, uvm_component, uvm_transaction, uvm_sequence_item, uvm_sequence etc. It serves an important role to define a set of methods such as create, copy, print, clone, compare, record, etc.

UVM Utility Macros and field macros

We have seen how the ‘create’ method works in the UVM factory section that the ‘create’ method allocates memory for the object and returns a handle of the same type.

The `uvm_object_utils or `uvm_object_utils_begin..`uvm_object_utils_end macros are used to register an uvm_object and other derived types like uvm_transaction, uvm_sequece_items in the UVM factory.

UVM field macros provide an implementation for methods like create, copy, print, clone, compare, record, etc. There are different `uvm_field_* macros available for various data type variables for registration in the factory. The `uvm_field_* macro accepts at least two arguments as arg (instance name of the variable that is compatible with `uvm_field_* macro) and flag (act as a control mechanism to add corresponding data methods).

The new() method is important to define with the corresponding class name as an augment.

Note: During compilation time, these UVM automation macros expand the complete code available for the corresponding macros.

Syntax without field macros

`uvm_object_utils(<class Type>)

Syntax with field macros

`uvm_object_utils_begin(<class_type>)
  `uvm_field_*(<arg>, <flag>)
`uvm_object_utils_end

Below field macros are commonly used for data methods (copy, compare, pack, unpack, print, clone, etc) for scalar/dynamic class properties. The complete list can be studied from the UVM reference document.

`uvm_field_* macros

The `uvm_field_* macros implement data methods for scalar properties.

*`uvm_field_ macros**	Description
`uvm_field_int	Implements data methods for any packed integral property.
`uvm_field_string	Implements data methods for a string property.
`uvm_field_real	Implements data methods for any real property.
`uvm_field_enum	Implements data methods for an enumerated property.
`uvm_field_event	Implements data methods for an event property.
`uvm_field_object	Implements data methods for an uvm_object based property.

`uvm_field_sarray_* macros

The `uvm_field_sarray* macros implement data methods for one-dimensional static array properties.

*`uvm_field_sarray_ macros**	Description
`uvm_field_sarray_int	Implements data methods for 1D static integral array.
`uvm_field_sarray_string	Implements data methods for 1D static string array.
`uvm_field_sarray_enum	Implements data methods for 1D static enum array.
`uvm_field_sarray_object	Implements data methods for 1D static uvm_object based object array.

`uvm_field_array_* macros

The `uvm_field_array* macros implement data methods for one-dimensional dynamic array properties.

*`uvm_field_array_ macros**	Description
`uvm_field_array_int	Implements data methods for 1D dynamic integral array.
`uvm_field_array_string	Implements data methods for 1D dynamic string array.
`uvm_field_array_enum	Implements data methods for 1D dynamic enum array.
`uvm_field_array_object	Implements data methods for 1D dynamic uvm_object based object array.

`uvm_field_* macro flag

flag	Description
UVM_DEFAULT	Use default flag settings
UVM_ALL_ON	Set all operations/method on
UVM_NO_COPY	Do not copy this field
UVM_NOCOMPARE	Do not compare this field
UVM_NOPRINT	Do not print this field
UVM_NOPACK	Do not pack or unpack this field
UVM_ABSTRACT	Use the abstract setting in the policy class for this abstract field.
UVM_REFERENCE	For object types, operate only on the handle (e.g. no deep copy)
UVM_PHYSICAL	Use a physical setting in policy class for this field.
UVM_READONLY	Do not allow setting of this field from the set_*_local methods or during <apply_config_settings> operation.

A radix can be specified for printing and recording by OR’ing one of the following constants in the <flag> argument. Hex is the default radix for integral types if it is not specified.

flag	Description
UVM_BIN	Print/record the field in binary (base-2).
UVM_HEX	Print/record the field in hexadecimal (base-16).
UVM_DEC	Print/record the field in decimal (base-10).
UVM_OCT	Print/record the field in octal (base-8).
UVM_TIME	Print/record the field in time format
UVM_STRING	Print/record the field in string format
UVM_UNSIGNED	Print/record the field in unsigned decimal (base-10)

Code with `uvm_object_utils

typedef enum{RED, GREEN, BLUE} color_type;
class my_object extends uvm_object;
  int        o_var;
  string     o_name;
  color_type colors;
  byte       data[4];
  bit [7:0]  addr;
  
  `uvm_object_utils(my_object)
  
  function new(string name = "my_object");
    super.new(name);
  endfunction
endclass

Code with `uvm_object_utils_begin and `uvm_object_utils_end

typedef enum{RED, GREEN, BLUE} color_type;
class my_object extends uvm_object;
  rand int        value;
       string     names;
  rand color_type colors;
  rand byte       data[4];
  rand bit [7:0]  addr;
  
  `uvm_object_utils_begin(my_object)
    `uvm_field_int(value, UVM_ALL_ON)
    `uvm_field_string(names, UVM_ALL_ON)
    `uvm_field_enum(color_type, colors, UVM_ALL_ON)
    `uvm_field_sarray_int(data, UVM_ALL_ON)
    `uvm_field_int(addr, UVM_ALL_ON)
  `uvm_object_utils_end
  
  function new(string name = "my_object");
    super.new(name);
  endfunction
endclass

UVM Tutorials