uvm_subscriber

subscriber是消费，用户的意思

uvm_subscriber主要作为coverage的收集方式之一

uvm_subscriber的代码非常简单，继承于uvm_component，再加上一个analysis export而已。

其代码如下：

virtual class uvm_subscriber #(type T=int) extends uvm_component;
  typedef uvm_subscriber #(T) this_type;
 
  uvm_analysis_imp #(T, this_type) analysis_export;
 
  function new (string name, uvm_component parent);
    super.new (name, parent);
    analysis_export = new ("analysis_imp", this);
  endfunction
 
  pure virtual function void write (T, t);
endclass

他的用法一般是，将monitor的analysis port连接到subscriber，将transaction传递过来，做function coverage。

class my_coverage extends uvm_subscriber #(bus_pkt);
 
  covergroup cg_bus;
    ...
  endgroup
 
  virtual function void write (bus_pkt pkt);
    cg_bus.sample ();
  endfunction
endclass
 
class my_env extends uvm_env;
  ...
  virtual function void connect_phase (uvm_phase phase);
    super.connect_phase (phase);
    my_agent.custom_ap.connect (my_cov.analysis_export);
  endfunction
endclass

example:

class uvm_ip_subscriber extends uvm_subscriber;
  //這裡使用FIFO通信而不是IMP，大大降低了工作量
  uvm_tlm_analysis_fiof#(dma_trans)            dma_monitor_to_sub_fifo[1];
 
  extern function new(string name, uvm_component parent);
  extern virtual function write(T t);
  extern virtual task get_dma_trans();
 
  extern virtual task run_phase(uvm_phase phase);
 
  //coverage group
  covergroup ostd_cfg_group;
    option.per_instance = 1;
    ostd: coverpoint(reg_cfg_trans.reg_wr_ostd[7:0]){
            bins udb_0    =    {0};
            bins udb_1    =    {[1:8]};
            bins udb_2    =    {[9:16]};
            bins udb_3    =    {[17:254]};
            bins udb_4    =    {255};
    }
  endgroup
 
endclass: uvm_ip_subscriber
function uvm_ip_subscriber::new(string name, uvm_component parent);
  super.new();
  dma_monitor_to_sub_fifo[0] = new("dma_monitor_to_sub_fifo_0", this);
  //創建covergroup
  ostd_cfg_group = new();
endfunction: new
 
//必須得重寫write這個純虛函數
function uvm_ip_subscriber::write(T t);  
endfunction: write
task uvm_ip_subscriber::get_dma_trans();
  dma_monitor_to_sub_fifo[0].get(tr);
  $cast(tr_clone, tr);
  reg_cfg_tr_q[0].push_back(tr_clone);
 
  if(reg_cfg_tr_q[0].size() > 0) begin
    reg_cfg_trans = reg_cfg_tr_q[0].pop_front();
    //採樣
    ostd_cfg_group.sample();
  end
endtask: get_dma_trans