uvm_analysis_port——TLM1事务级建模方法（二）

　　UVM中的TLM1端口，第一类是用于uvm_driver 和uvm_sequencer连接端口，第二类是用于其他component之间连接的端口，如uvm_monitor和uvm_scoreboard。首先让我们看第二类。首先来看uvm_analysis_port。

//------------------------------------------------------------------------------

// Title: Analysis Ports

//------------------------------------------------------------------------------

//

// This section defines the port, export, and imp classes used for transaction

// analysis.

//

//------------------------------------------------------------------------------

//------------------------------------------------------------------------------

// Class: uvm_analysis_port

//

// Broadcasts a value to all subscribers implementing a <uvm_analysis_imp>.

//

//| class mon extends uvm_component;

//|   uvm_analysis_port#(trans) ap;

//|

//|   function new(string name = "sb", uvm_component parent = null);

//|      super.new(name, parent);

//|      ap = new("ap", this);

//|   endfunction

//|

//|   task run_phase(uvm_phase phase);

//|       trans t;

//|       ...

//|       ap.write(t);

//|       ...

//|   endfunction

//| endclass

//------------------------------------------------------------------------------

class uvm_analysis_port # (type T = int)

  extends uvm_port_base # (uvm_tlm_if_base #(T,T));

  function new (string name, uvm_component parent);

    super.new (name, parent, UVM_PORT, , UVM_UNBOUNDED_CONNECTIONS);

    m_if_mask = `UVM_TLM_ANALYSIS_MASK;

  endfunction

  virtual function string get_type_name();

    return "uvm_analysis_port";

  endfunction

  // Method: write

  // Send specified value to all connected interface

  function void write (input T t);

    uvm_tlm_if_base # (T, T) tif;

    for (int i = ; i < this.size(); i++) begin

      tif = this.get_if (i);

      if ( tif == null )

        uvm_report_fatal ("NTCONN", {"No uvm_tlm interface is connected to ", get_full_name(), " for executing write()"}, UVM_NONE);

      tif.write (t);

    end

  endfunction

endclass

//------------------------------------------------------------------------------

// Class: uvm_analysis_imp

//

// Receives all transactions broadcasted by a <uvm_analysis_port>. It serves as

// the termination point of an analysis port/export/imp connection. The component

// attached to the ~imp~ class--called a ~subscriber~-- implements the analysis

// interface.

//

// Will invoke the ~write(T)~ method in the parent component.

// The implementation of the ~write(T)~ method must not modify

// the value passed to it.

//

//| class sb extends uvm_component;

//|   uvm_analysis_imp#(trans, sb) ap;

//|

//|   function new(string name = "sb", uvm_component parent = null);

//|      super.new(name, parent);

//|      ap = new("ap", this);

//|   endfunction

//|

//|   function void write(trans t);

//|       ...

//|   endfunction

//| endclass

//------------------------------------------------------------------------------

class uvm_analysis_imp #(type T=int, type IMP=int)

  extends uvm_port_base #(uvm_tlm_if_base #(T,T));

  `UVM_IMP_COMMON(`UVM_TLM_ANALYSIS_MASK,"uvm_analysis_imp",IMP)

  function void write (input T t);

    m_imp.write (t);

  endfunction

endclass

//------------------------------------------------------------------------------

// Class: uvm_analysis_export

//

// Exports a lower-level <uvm_analysis_imp> to its parent.

//------------------------------------------------------------------------------

class uvm_analysis_export #(type T=int)

  extends uvm_port_base #(uvm_tlm_if_base #(T,T));

  // Function: new

  // Instantiate the export.

  function new (string name, uvm_component parent = null);

    super.new (name, parent, UVM_EXPORT, , UVM_UNBOUNDED_CONNECTIONS);

    m_if_mask = `UVM_TLM_ANALYSIS_MASK;

  endfunction

  virtual function string get_type_name();

    return "uvm_analysis_export";

  endfunction

  // analysis port differs from other ports in that it broadcasts

  // to all connected interfaces. Ports only send to the interface

  // at the index specified in a call to set_if (0 by default).

  function void write (input T t);

    uvm_tlm_if_base #(T, T) tif;

    for (int i = ; i < this.size(); i++) begin

      tif = this.get_if (i);

      if (tif == null)

         uvm_report_fatal ("NTCONN", {"No uvm_tlm interface is connected to ", get_full_name(), " for executing write()"}, UVM_NONE);

      tif.write (t);

    end

  endfunction

endclass

我们可以看到所有的类都是继承自uvm_port_base #(uvm_tlm_if_base #(T,T))。uvm_analysis_imp其实更像一个普通的imp,它不具备有任何analysis的性质，即不具备任何广播的性质。对于uvm_analysis_port 和uvm_analysis_export 只能是analysis_imp.