UVM——Callback

step

1、 take UVM Callback Method is embedded in the component .
2、 Create a basic UVM Callback Class for extension .
3、 Extend the required... From the class created in the previous step Callback class .
4、 Instantiate and register at the top level Callback object .

Code example

step 1, First , stay driver Association implementation in Callback Class of method （ The most basic UVM Callback class ）.

class my_driver extends uvm_driver #(my_transaction);

    `uvm_component_utils(my_driver)
    `uvm_register_cb(my_driver, driver_base_callback);

    virtual dut_interface m_vif;
    int unsigned pad_cycles;
    
    //  Parameters 1 Specify which type will be used Callback
    //  Parameters 2 Appoint Callback Method will be implemented in which class 
    `uvm_register_cb(my_driver, driver_base_callback)

    function new(string name = "my_driver", uvm_component parent);
        super.new(name, parent);
    endfunction

    ...

    virtual task run_phase(uvm_phase phase);
        logic [7:0] temp;
        repeat(15) @(m_vif.driver_cb);
        forever begin
            seq_item_port.get_next_item(req);
            `uvm_info("DRV_RUN_PHASE", {
    "\n", "Driver now send the transaction \n", req.sprint() }, UVM_MEDIUM)
            
			//  Use `uvm_do_callbacks Macro to call callback Method 
            `uvm_do_callbacks(my_driver, driver_base_callback, pre_send(this))

            '''

            `uvm_do_callbacks(my_driver, driver_base_callback, post_send())

            seq_item_port.item_done();

        end
    endtask

endclass

next , Create a basic UVM Callback Class for extension .

typedef class my_driver;

class driver_base_callback extends uvm_callback;

    function new(string name = "driver_base_callback");
        super.new(name);
    endfunction

    virtual task pre_send(my_driver drv);
        
    endtask

    virtual task post_send();

    endtask

endclass

then , Expand what you need Callback class .

class driver_error_callbacks extends driver_base_callback;

    function new(string name = "driver_error_callbacks");
        super.new(name);
    endfunction

    virtual task pre_send(my_driver drv);
        drv.req.payload.push_back(5'b10101);
    endtask

endclass

class driver_info_callbacks extends driver_base_callback;

    function new(string name = "driver_info_callbacks");
        super.new(name);
    endfunction

    virtual task post_send();
        `uvm_info("DRIVER_CALLBACK", "This information is for UVM Callback test !!!", UVM_MEDIUM)
    endtask

endclass

Last , Instantiate and register in the top level Callback object .

class my_test_driver_error extends my_test;
    
    `uvm_component_utils(my_test_driver_error)

	//  Statement Callback Class handle 
    driver_error_callbacks drv_err_cb;

    function new(string name = "", uvm_component parent);
        super.new(name, parent);
    endfunction

    virtual function void connect_phase(uvm_phase phase);
        drv_err_cb = new();
		
		//  towards driver Register new in callback object 
		// uvm_callbacks#(my_driver, driver_base_callback) Provide component lookup 
		// add(m_env.m_agent.m_driv, drv_err_cb) Call for callback Method specifies an implementation callback Class of method .
        uvm_callbacks#(my_driver, driver_base_callback)::add(m_env.m_agent.m_driv, drv_err_cb);

    endfunction

endclass

When running the simulation ,driver Two of them callback Methods all execute , In this case post_send() No function .