uvm environment

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本篇主要介绍uvm_env

uvm environment实际上是验证环境的可重用的单元。 其中可以包含多个uvm_agent, 不同的interface，

coverage collector和checker等。

如下图所示是一个uvm_env的示例图：

下面说明创建uvm_env的过程：

  1. 从uvm_env派生出一个自定义的env， 比如说是my_env, 用factory 机制注册， 并且创建new函数：
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class my_env extends uvm_env;
    // [Recommended] Makes this driver more re-usable
    `uvm_component_utils (my_env)
    // This is standard code for all components
    function new (string name = "my_env", uvm_component parent = null);
      super.new (name, parent);
    endfunction
    // Code for rest of the steps come here
endclass
  1. 申明这个env中的一些component：
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// apb_agnt and other components are assumed to be user-defined classes that already exist in TB
apb_agnt  m_apb_agnt;
func_cov   m_func_cov;
scbd     m_scbd;
env_cfg   m_env_cfg;
 
// Build components within the "build_phase"
virtual function void build_phase (uvm_phase phase);
  super.build_phase (phase);
  m_apb_agnt = apb_agnt::type_id::create ("m_apb_agnt", this);
  m_func_cov = func_cov::type_id::create ("m_func_cov", this);
  m_scbd     = scbd::type_id::create ("m_scbd", this);
 
  // [Optional] Collect configuration objects from the test class if applicable
  if (uvm_config_db #(env_cfg)::get(this, "", "env_cfg", m_env_cfg))
    `uvm_fatal ("build_phase", "Did not get a configuration object for env")
 
  // [Optional] Pass other configuration objects to sub-components via uvm_config_db
endfunction
  1. 在connec_phase连接各个uvm_component

如下图所示是一个定义env的例子：

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class my_env extends uvm_env ;
 
   `uvm_component_utils (my_env)
 
   my_agent             m_agnt0;
   my_scoreboard        m_scbd0;
 
   function new (string name, uvm_component parent);
      super.new (name, parent);
   endfunction : new
 
   virtual function void build_phase (uvm_phase phase);
      super.build_phase (phase);
      m_agnt0 = my_agent::type_id::create ("my_agent", this);
      m_scbd0 = my_scoreboard::type_id::create ("my_scoreboard", this);
   endfunction : build_phase
 
   virtual function void connect_phase (uvm_phase phase);
      // Connect the scoreboard with the agent
      m_agnt0.m_mon0.item_collected_port.connect (m_scbd0.data_export); 
   endfunction
 
endclass