UVMC学习笔记三：在SystemC/C++作用域实现UVM factory操作

前言

UVMC 提供了一组API可用于在SystemC layer对UVM的组件factory进行访问操作，用于层次打印，组件重载，调试，以及打印重载类型等等

1. 组件打印：
   uvmc_print_factory(),
   传入参数当all_types为0时，只显示类型和实例覆盖。当all_types为1(默认值)时，所有注册的用户定义类型也会被打印出来，前提是它们具有与之关联的类型名称。(参数化类型通常不需要。)当all_types为2时，所有UVM类型(前缀为uvm_)都包含在注册类型列表中。
2. 组件重载
   uvmc_set_factory_type_override(request_type，override_type, context ） 设置类型覆盖
   uvmc_set_factory_inst_override(request_type，override_type, context) 设置指定类型实例覆盖
   所有被覆盖的类型必须要首先被工厂模式所注册

参数说明：
request_type : 需要替换的原始类型
override_type: 将要替换的目标类型， override_type 必须继承自request_type
context: 用于实例替换，指明实例在仿真空间的层次

3. 组件重载信息调试
   uvmc_debug_factory_create(requset_type, context)
   显示关于UVM factory将创建的对象类型的详细信息(给定请求的类型和上下文)，列出指定context的应用的所有重载情况
   参数说明与上文一致
   显示调试信息如下

   Given a request for an object of type 'producer' with an instance
   path of 'e.prod' the factory encountered
   
   the following relevant overrides. An 'x' next to a match indicates a
   match that was ignored.
   
   Original Type  Instance Path  Override Type
     -------------  -------------  -------------
     producer     
     *              producer_ext   <type override>
   Result:
   
     The factory will produce an object of type 'producer_ext'
   
   (*) Types with no associated type name will be printed as <unknown>
   
   ####
   
   
   UVM_INFO /home/shawntan/EDA/snps/vcs_2018.09/vcs-mx/O-2018.09/etc/uvm/src/base/uvm_factory.svh(1786) @ 0: reporter [UVM/FACTORY/DUMP] 
   #### Factory Override Information (*)
   
   Given a request for an object of type 'scoreboard' with an instance
   path of 'e.sb' the factory encountered
   
   the following relevant overrides. An 'x' next to a match indicates a
   match that was ignored.
   
   Original Type  Instance Path  Override Type 
     -------------  -------------  --------------
     scoreboard   
     e.*            scoreboard_ext
   
   Result:
   
     The factory will produce an object of type 'scoreboard_ext'
   
   (*) Types with no associated type name will be printed as <unknown>

4. 获得当前对象的实际重载类型
   string uvmc_find_factory_override（requeset_type, context)
   返回类型为context指明组件重载类型的字符串名字
   参数：
   request_type:为要创建的假设调用请求的类型名
   context: 发出请求的组件的层次结构路径。不允许通配符或正则表达式。上下文必须与现有组件的层次结构名称完全匹配，或者可以是指定全局上下文的空字符串
   实际的操作效果如下：
   uvmc_set_type_override("B","C");
uvmc_set_type_override("A","B");
uvmc_set_inst_override("D", "C", "top.env.agent1.*");

   • $display(uvmc_find_factory_override("A"));显示类型为“C”,说明重载的链式关系
     * $display(uvmc_find_factory_override("A", "top.env.agent1.driver")); , 显示类型为“D”, 因为假设创建driver的类型与A不一致，所以显示driver的类型为“D”

返回的字符串可用于随后对uvmc_set_factory_type_override和uvmc_set_factory_inst_override的调用

5. 实例说明

   class producer_ext extends producer;
   
   `uvm_component_utils(producer_ext)
   
   function new(string name, uvm_component parent=null);
      super.new(name,parent);
      `uvm_info("PRODUCER_EXTENSION","Derived producer created!",UVM_NONE);
   endfunction
   
   endclass
   
   class scoreboard_ext extends scoreboard;
   
   `uvm_component_utils(scoreboard_ext)
   
   function new(string name, uvm_component parent=null);
      super.new(name,parent);
      `uvm_info("SCOREBOARD_EXTENSION","Derived scoreboard created!",UVM_NONE);
   endfunction
   
   endclass

   以上producer_ext和scoreboard_ext 均派生自工厂方法注册的producer_ext/scoreboard基本类
   在systemC侧的factory方法如下

void top::show_uvm_factory()
{
  string override;

  // print the factory before we do anything
  uvmc_print_factory();

  // what type would the factory give if we asked for a producer?
  override = uvmc_find_factory_override("producer","e.prod");

  UVMC_INFO("SHOW_FACTORY",
    (string("Factory override for type 'producer' ") +
     + "in context 'e.prod' is " + override).c_str(),
     UVM_NONE,"");

  // show how factory chooses what type it creates
  uvmc_debug_factory_create("producer","e.prod");

  // set a type and instance override
  uvmc_set_factory_type_override("producer","producer_ext","e.*");
  uvmc_set_factory_inst_override("scoreboard","scoreboard_ext","e.*");

  // print the factory after setting overrides
  uvmc_print_factory();

  uvmc_debug_factory_create("producer","e.prod");
  uvmc_debug_factory_create("scoreboard","e.sb");

  // NOW what type would the factory give if we asked for a producer?
  override = uvmc_find_factory_override("producer","e.prod");

  UVMC_INFO("SHOW_FACTORY",
    (string("Factory override for type 'producer' ") +
     + "with context 'e.prod' is " + override).c_str(),
     UVM_NONE,"");

  // What type would the factory give if we asked for a scoreboard?
  override = uvmc_find_factory_override("scoreboard","e.*");

  UVMC_INFO("SHOW_FACTORY",
    (string("Factory override for type 'scoreboard' ") +
     + "given a context 'e.*' is " + override).c_str(),
     UVM_NONE,"");
}