uvm_reg_cbs

UVM (Universal Verification Methodology) provides a set of classes and macros to facilitate verification of hardware designs. One of the key components in UVM is the register model, which represents the registers and memories in the design.

UVM provides a callback mechanism called UVM Callbacks (uvm_callbacks) to handle events and actions during the register access process. UVM register callbacks (uvm_reg_cbs) are a specific type of callback used for registering certain events related to register accesses.

UVM register callbacks allow users to customize and extend the behavior of UVM register operations. These callbacks can be used to perform additional tasks before or after register read/write operations, such as logging, synchronization, or checking certain conditions.

To use UVM register callbacks, you need to define a class derived from uvm_reg_callback and implement the desired callback methods. These methods will be called by UVM framework when corresponding events occur during register access.

Here's an example of using UVM register callbacks:

class my_reg_callback extends uvm_reg_cbs;
  function new(string name = "my_reg_callback");
    super.new(name);
  endfunction

  virtual function void pre_read(uvm_reg rg);
    // Perform pre-read tasks
  endfunction

  virtual function void post_read(uvm_reg rg);
    // Perform post-read tasks
  endfunction

  virtual function void pre_write(uvm_reg rg);
    // Perform pre-write tasks
  endfunction

  virtual function void post_write(uvm_reg rg);
    // Perform post-write tasks
  endfunction
endclass

// Register the callback with the desired register block
my_reg_callback reg_cb = new();
my_register_block.my_register.add_callback(reg_cb);

In this example, `my_reg_callback` is a user-defined class derived from `uvm_reg_cbs`. It defines the callback methods `pre_read`, `post_read`, `pre_write`, and `post_write` which will be called by UVM framework at corresponding events.

The callback object `reg_cb` is created and added to the desired register block using the `add_callback` method. This will enable the callback functionality for the specific register block.

Please note that this is just a basic example, and there are more advanced features and options available for UVM register callbacks. The UVM User Guide provides detailed information on using and customizing register callbacks.