[CU]uvm base test

资料来源

(1) https://github.com/Practical-UVM-Step-By-Step/Practical-UVM-Step-By-Step

(2) 《Practical UVM step by step with IEEE》

1. 测试用例的作用

base_test所做的事情因公司而异,常见的使用如下：

(1) 实例化top-level env;

(2) 通过config_db设置验证平台中某些参数的值,或使用factory override机制配置环境;

(3) 通过调用UVM sequences施加激励;

(4) 在report_phase根据UVM_ERROR的数量打印不同信息;

注1:注意uvm_report_server的使用;

(5) 设置整个验证平台的超时退出时间;

通常,只有一个uvm_base_test,在其中实现env以及其他组件的例化; 其他tests均派生于base_test;

class base_test extends uvm_test;
    my_env env;

    function new(string name="base_test", uvm_component parent=null);
        super.new(name,parent);
    endfunction
    
    extern virtual function void build_phase(uvm_phase phase);
    extern virtual function void report_phase(uvm_phase phase);

endclass

function void base_test::build_phase(uvm_phase phase);
    super.build_phase(phase);
    env=my_env::type_id::create("env",this);
    uvm_config_db#(uvm_object_wrapper)::set(this,"env.i_agt.sqr.main_phase","default_sequence",my_sequence::type_id::get());
endfunction

function void base_test::report_phase(uvm_phase phase);
    uvm_report_server server;
    int err_num;
    super.report_phase(phase);

    server=get_report_server(); //uvm_report_server srvr; srvr=uvm_report_server::get_server();
    err_num=server.get_severity_count(UVM_ERROR);

    if(err_num!=0) begin       //通常不这么使用,而是使用UVM_MAX_QUIT_COUNT,一旦由多少个错误,就退出仿真;
        $display("TEST CASE FAILED!");
    end
    else begin
        $display("TEST CASE PASSED!");
    end

endfunction

class wb_env_base_test extends uvm_test;

   wb_config wb_master_config;
   wb_config wb_slave_config;

   `uvm_component_utils(wb_env_base_test)

   wb_env env;

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

   virtual function void build_phase(uvm_phase phase);
      super.build_phase(phase);
      env = wb_env::type_id::create("env", this);
      wb_master_config = new("wb_master_config");
      wb_slave_config = new("wb_slave_config");

      wb_master_config.max_n_wss = 10;
      wb_master_config.min_addr = 0;
      wb_master_config.max_addr = 10000000;

      wb_slave_config.max_n_wss = 10;
      wb_slave_config.min_addr = 0;
      wb_slave_config.max_addr = 10000000;

      begin: configure
          uvm_config_db #(uvm_object_wrapper)::set(this, "env.rst_agent.mast_sqr.reset_phase", "default_sequence", reset_sequence::get_type()); 
          uvm_config_db #(uvm_object_wrapper)::set(this, "env.master_agent.mast_sqr.main_phase", "default_sequence", sequence_1::get_type()); 
          uvm_config_db #(uvm_object_wrapper)::set(this, "env.slave_agent.slv_seqr.run_phase", "default_sequence", ram_sequence::get_type()); 

          uvm_config_db #(wb_config)::set(this, "env.master_agent", "config", wb_master_config); 
          uvm_config_db #(wb_config)::set(this, "env.slave_agent", "config", wb_slave_config); 
      end 
   endfunction

endclass : wb_env_base_test

2. 测试用例的启动

(1) 在top_tb中更改run_test的参数,跑不同的测试用例;

//top_tb.sv
initial begin
    run_test("my_case0");
end

initial begin
    run_test("my_case1");
end

(2) UVM提供对不加参数的run_test_的支持; 在这种情况下, UVM会利用UVM_TESTNAME从命令行中寻找测试用例的名字,创建它的实例并运行.

注1:在同一仿真中,如果及指定了run_test的参数,又在命令行传递了UVM_TESTNAME,后者的优先级更高;

//top_tb.sv
initial begin
    run_test();
end

//<sim command>
... +UVM_TESTNAME=my_case0

//<sim command>
... +UVM_TESTNAME=my_case1

3. 测试用例的执行流程

              启动验证平台
                  |
                  v
     根据UVM_TESTNAME产生my_case的实例
                  |
                  v
    依次执行build_phase,形成完整的UVM树
                  |
                  v
顺序执行UVM树各节点的connect_phase,main_phase等
                  |
                  v
        所有phase执行完毕,结束仿真