uvm中的monitor

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uvm中的monitor的作用主要是捕捉interface上面的信号， 转换成transaction， 然后发送给其他的component。因此需要下面2个要素：

  • 要观测的virtual interface
  • 申明tlm_analysis_port， 然后广播要传输的数据。

monitor的作用

monitor由[uvm_monitor]这个class派生出来， 基本的作用如下：

  • 通过virtual interface收集总线信号；
  • 收集用于cheker和coverage分析的数据；
  • 通过analysis_port传输数据

如下图所示：

创建monitor

  1. 由[uvm_monitor]创建一个自定义的class， 注册， 然后创建new函数：
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// my_monitor is user-given name for this class that has been derived from "uvm_monitor"
class my_monitor extends uvm_monitor;
 
  // [Recommended] Makes this monitor more re-usable
  `uvm_component_utils (my_monitor)
 
  // This is standard code for all components
  function new (string name = "my_monitor", uvm_component parent = null);
    super.new (name, parent);
  endfunction
 
  // Rest of the steps come here
endclass
  1. 申明analysisport和virtual interface
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// Actual interface object is later obtained by doing a get() call on uvm_config_db
virtual if_name vif;
 
// my_data is a custom class object used to encapsulate signal information
// and can be sent to other components
uvm_analysis_port  #(my_data) mon_analysis_port;
  1. 在build_phase中实例化analysis_port并且配置virtual interface。
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virtual function void build_phase (uvm_phase phase);
   super.build_phase (phase);
 
   // Create an instance of the declared analysis port
   mon_analysis_port = new ("mon_analysis_port", this);
 
   // Get virtual interface handle from the configuration DB
   if (! uvm_config_db #(virtual if_name) :: get (this, "", "vif", vif)) begin
      `uvm_error (get_type_name (), "DUT interface not found")
   end
endfunction
  1. 编写run_phase
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// This is the main piece of monitor code which decides how it has to decode 
 // signal information. For example, AXI monitors need to follow AXI protocol
 virtual task run_phase (uvm_phase phase);
   // Fork off multiple threads "if" required to monitor the interface,  for example:
   fork
     // Thread 1: Monitor address channel
     // Thread 2: Monitor data channel, populate "obj" data object
     // Thread 3: Monitor control channel, decide if transaction is over
     // Thread 4: When data transfer is complete, send captured information 
      // through the declared analysis port
     mon_analysis_port.write(obj);
   join_none
 endtask

参考

本文图片和code来源于网站： http://www.chipverify.com/uvm/monitor