What is m_sequencer and p_sequencer ?

m_sequencer  is default sequencer and p_sequncer is typecast to m_sequencer in other words

m_sequencer is a handle of type uvm_sequencer_base which is available by default in a sequence.

p_sequencer :The real sequencer on which a sequence is running would normally be derived from the uvm_sequencer_base class.Hence to access the real sequencer on which sequence is running , you would need to typecast the m_sequencer to the physical sequencer which is generally called p_sequencer

 

Lets see by example : A sequence wants to access a  component (clock monitor)which is available with its sequencer.

class test_sequencer_c extends uvm_sequencer;

  clock_monitor_c clk_monitor;

endclass

class test_sequence_c extends uvm_sequence

test_sequencer_c p_sequencer

clock_monitor_c my_clock_monitor

task pre_body();

  //Typecast the m_sequencer base type to p_sequencer

  if(!$cast(p_sequencer, m_sequencer)) begin

    `uvm_fatal(“Sequencer Type Mismatch:”, ” Wrong Sequencer”)

en

  //get access to clock monitor  

   my_clock_monitor = p_sequencer.clk_monitor;

  endtas

endclass

use of m_sequencer

accessing cfg file

class seq_plb_base extends uvm_sequence #(plb_transaction);
`uvm_object_utils(seq_plb_base);
const string report_id=”SEQ”;

plb_agent_configuration cfg;

function new(string name=””);
super.new(name);
endfunction

virtual task body();
if( !uvm_config_db #( plb_agent_configuration )::get( m_sequencer, “”, “AGENT_CONFIG”, cfg ))
`uvm_fatal(report_id, “cannot find resource AGENT_CONFIG” )
// .. do stuff

endtask

endclass