用uvm搭建一个异步fifo的验证环境

以下是一个简单的异步FIFO验证环境，使用UVM中的sequence、driver、monitor、agent和scoreboard组件。

1. 首先，在UVM中定义一个sequence，用于产生随机数据并将其推入FIFO中。

class fifo_seq extends uvm_sequence #(fifo_transaction);
  `uvm_object_utils(fifo_seq)
  
  fifo_driver drv;
  rand bit [7:0] data;
  bit [1:0] op;
  
  function new(string name="fifo_seq");
    super.new(name);
  endfunction
  
  virtual task body();
    repeat(10) begin
      data = $random;
      op = $random % 2;
      if(op == 0) begin
        // write operation
        `uvm_info(get_full_name(), $sformatf("Writing data: %h", data), UVM_MEDIUM)
        fifo_transaction tx = fifo_transaction::type_id::create("tx");
        tx.op = FIFO_WRITE;
        tx.data = data;
        start_item(tx);
        drv.item_done();
      end else begin
        // read operation
        `uvm_info(get_full_name(), "Reading data", UVM_MEDIUM)
        fifo_transaction tx = fifo_transaction::type_id::create("tx");
        tx.op = FIFO_READ;
        start_item(tx);
        fifo_transaction resp;
        finish_item(resp);
        drv.item_done();
      end
    end
  endtask
endclass

2. 然后，定义一个monitor来监视FIFO中的数据，以确保它们被正确地读取和写入。

class fifo_monitor extends uvm_monitor;
  `uvm_component_utils(fifo_monitor)
  
  fifo_agent agent;
  int unsigned data_items[$];
  
  function new(string name="fifo_monitor", uvm_component parent=null);
    super.new(name, parent);
  endfunction
  
  virtual task run_phase(uvm_phase phase);
    fork
      read_data();
    join
  endtask
  
  virtual task read_data();
    fifo_transaction trans;
    forever begin
      agent.fifo_if.get(trans);
      if(trans.op == FIFO_WRITE) begin
        `uvm_info(get_full_name(), $sformatf("Writing data: %h", trans.data), UVM_MEDIUM)
        data_items.push_back(trans.data);
      end else begin
        `uvm_info(get_full_name(), "Reading data", UVM_MEDIUM)
        if(data_items.size() == 0) begin
          `uvm_error(get_full_name(), "No data available to read from FIFO!")
        end else begin
          int unsigned index = $random % data_items.size();
          fifo_transaction resp = fifo_transaction::type_id::create("resp");
          resp.op = FIFO_READ;
          resp.data = data_items[index];
          agent.fifo_if.put(resp);
          `uvm_info(get_full_name(), $sformatf("Read data: %h", resp.data), UVM_MEDIUM)
          data_items.delete(index);
        end
      end
    end
  endtask
endclass

3. 接下来，定义一个driver来将transaction推入FIFO中

class fifo_driver extends uvm_driver #(fifo_transaction);
  `uvm_component_utils(fifo_driver)
  
  fifo_if fifo_if;
  
  function new(string name="fifo_driver", uvm_component parent=null);
    super.new(name, parent);
  endfunction
  
  virtual task run_phase(uvm_phase phase);
    fifo_if = fifo_if::type_id::create("fifo_if", this);
  endtask
  
  virtual task put(fifo_transaction tx);
    fifo_if.put(tx);
  endtask
  
  virtual task get(fifo_transaction tx);
    fifo_if.get(tx);
  endtask
  
  virtual function void item_done();
    fifo_if.item_done();
  endfunction
endclass

4. 然后，定义一个scoreboard来比较读取的数据是否与写入的数据相同。

class fifo_scoreboard extends uvm_scoreboard;
  `uvm_component_utils(fifo_scoreboard)
  
  fifo_monitor mon;
  int unsigned data_items[$];
  
  function new(string name="fifo_scoreboard", uvm_component parent=null);
    super.new(name, parent);
  endfunction
  
  virtual function void compare(fifo_transaction ref_tr, fifo_transaction tr);
    if(ref_tr.op == FIFO_WRITE) begin
      `uvm_info(get_full_name(), $sformatf("Expecting data: %h", ref_tr.data), UVM_MEDIUM)
      data_items.push_back(ref_tr.data);
    end else begin
      `uvm_info(get_full_name(), $sformatf("Comparing data: %h", tr.data), UVM_MEDIUM)
      if(data_items.size() == 0) begin
        `uvm_error(get_full_name(), "No data available to compare!")
      end else begin
        int unsigned index = $random % data_items.size();
        if(tr.data != data_items[index]) begin
          `uvm_error(get_full_name(), $sformatf("Read data (%h) does not match expected data (%h)", tr.data, data_items[index]))
        end
        data_items.delete(index);
      end
    end
  endfunction
endclass

5. 最后，在UVM中定义一个agent，将它们组合在一起。

class fifo_agent extends uvm_agent;
  `uvm_component_utils(fifo_agent)
  
  fifo_seq seq;
  fifo_driver drv;
  fifo_monitor mon;
  fifo_scoreboard sb;
  
  function new(string name="fifo_agent", uvm_component parent=null);
    super.new(name, parent);
  endfunction
  
  virtual function void build_phase(uvm_phase phase);
    seq = fifo_seq::type_id::create("seq", this);
    drv = fifo_driver::type_id::create("drv", this);
    mon = fifo_monitor::type_id::create("mon", this);
    sb = fifo_scoreboard::type_id::create("sb", this);
  endfunction
  
  virtual function void connect_phase(uvm_phase phase);
    drv.fifo_if.connect(mon.fifo_if);
  endfunction
endclass

6. 最后，在UVM测试中使用这些组件来验证异步FIFO。

class fifo_test extends uvm_test;
  `uvm_component_utils(fifo_test)
  
  fifo_agent agent;
  
  function new(string name="fifo_test", uvm_component parent=null);
    super.new(name, parent);
  endfunction
  
  virtual function void build_phase(uvm_phase phase);
    agent = fifo_agent::type_id::create("agent", this);
  endfunction
  
  virtual task run_phase(uvm_phase phase);
    uvm_config_db#(virtual fifo_if)#(null, "agent.*", "fifo_if").set(agent.drv.fifo_if);
    fifo_seq seq = fifo_seq::type_id::create("seq");
    seq.drv = agent.drv;
    seq.start(agent.sequencer);
    seq.wait_for_sequences();
  endtask
endclass

这就是一个简单的异步FIFO验证环境，通过UVM中的sequence、driver、monitor、agent和scoreboard组件，对FIFO进行验证。