uvm_subscriber——告诉她我们来过

　　Subscribers are basically listeners of an analysis port. They subscribe to a broadcaster and receive objects whenever an item is broadcasted via the connected analysis port. A uvm_component class does not have an in-built analysis port, while a uvm_subscriber is an extended version with an analysis port named analysis_export。uvm_subsriber的功能就是收集整个平台的function coverage, 它的派生类必须重写write 函数。

//------------------------------------------------------------------------------
//
// CLASS: uvm_subscriber
//
// This class provides an analysis export for receiving transactions from a
// connected analysis export. Making such a connection "subscribes" this
// component to any transactions emitted by the connected analysis port.
//
// Subtypes of this class must define the write method to process the incoming
// transactions. This class is particularly useful when designing a coverage
// collector that attaches to a monitor. 
//------------------------------------------------------------------------------

virtual class uvm_subscriber #(type T=int) extends uvm_component;

  typedef uvm_subscriber #(T) this_type;

  // Port: analysis_export
  //
  // This export provides access to the write method, which derived subscribers
  // must implement.

  uvm_analysis_imp #(T, this_type) analysis_export;
  
  // Function: new
  //
  // Creates and initializes an instance of this class using the normal
  // constructor arguments for <uvm_component>: ~name~ is the name of the
  // instance, and ~parent~ is the handle to the hierarchical parent, if any.

  function new (string name, uvm_component parent);
    super.new(name, parent);
    analysis_export = new("analysis_imp", this);
  endfunction
  
  // Function: write
  //
  // A pure virtual method that must be defined in each subclass. Access
  // to this method by outside components should be done via the
  // analysis_export.

  pure virtual function void write(T t);
    
endclass

参考文献：

1 uvm_subscriber. http://www.chipverify.com/uvm/uvm-subscriber