How to generate response for AHB Slave VIP

 

You can create a “ahbSlaveResponser.sv” that extends from vmm_xactor, and the responses are “transfer” level based, that is, if a burst read/write have 4 transfers, the Slave VIP will send 4 objects to its output channel, and you need to response 4 times.

 

 

In this xactor, do following:

 

1.       Create function new with input/ouput channels that are connected to AHB Slave VIP, also pass the slave VIP handle to this class, this is because you will have to use this handle to access the internal memory in Slave VIP.

 

  AhbSlave                      oSlave_mem; //handle for internal slave memory in slave VIP

  dw_vip_ahb_slave_rvm          slave_vip;      //handle for slave VIP

  dw_vip_ahb_slave_transfer     resp_trans;

  dw_vip_ahb_slave_transfer_channel o_output_chan;

  dw_vip_ahb_slave_transfer_channel o_input_chan;   
 

function ahbSlaveResponser::new( 

                dw_vip_ahb_slave_rvm              slave_vip, 

                dw_vip_ahb_slave_transfer_channel o_output_chan =null, 

                dw_vip_ahb_slave_transfer_channel o_input_chan=null);

                super.new("ahbSlaveResponser", "class"); 

    this.o_output_chan = o_output_chan ;

    this.o_input_chan  = o_input_chan  ;

    this.slave_vip=slave_vip;

endfunction

 

2.       Create a task main that always tries to pop object from the output channel from Slave VIP, and then decide whether it is a “READ” or “WRITE” operation:

 

  task ahbSlaveResponser::main();

      super.main();

      oSlave_mem = slave_vip.getAhbSlave();

      //Slave VIP response 

      while(1) begin  

              wait_if_stopped_or_empty(o_output_chan);  

              o_output_chan.peek(resp_trans);

              case(resp_trans.m_bHwrite)

                 0: recv_read();

                1: recv_write();

              endcase 

              o_output_chan.get(resp_trans);

      end

 endtask

 

3.       Implement the response for READ/WRITE operations,

 

//for WRITE, receives data from the object from Slave VIP output channel ; 

task ahbSlaveResponser::recv_write();

   bit[31:0]    wdata;

   dw_vip_ahb_slave_transfer     cpy_trans;

   $cast(cpy_trans,resp_trans.copy());

   o_input_chan.put(cpy_trans);                  //response status first

   cpy_trans.notify.wait_for(vmm_data::ENDED);   //wait data transfer complete

   cpy_trans.display("SLAVE RECV ::\t");         //debug, display content

   wdata=cpy_trans.m_bvHdata;                    // store the transfer data from slave VIP to user-defined variable

endtask

 
// for READ, provide the rdata by  “set_mem” to VIP internal slave memory, then slave VIP will use this data to generate response to Master

task ahbSlaveResponser::recv_read();

  logic[7:0]                                            rdata;  

    rdata=$random();

    for(int i=0;i<=4;i++) begin
        oSlave_mem.set_mem(0,resp_trans.m_bvHaddr+i, 8, rdata); //provide read data, 4 bytes for 32bit data bus
        $display($time,,"set_mem[%0h]=%0h",resp_trans.m_bvHaddr+i,rdata);
        rdata++;
    end

    o_input_chan.put(resp_trans);                         //response status

    resp_trans.notify.wait_for(vmm_data::ENDED);          //wait read transfer complete

    resp_trans.display("SLAVE RESP ::\t");

endtask