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TLM connections: sequencer to component and component to driver

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hello all,

this is a real "how to" question as i have very little experience at UVM

in my environment i have a need of having a uvm_component between the sequencer and driver, i can elaborate later what is the reason to do that.

i didn't find a reasonable explanation of how to implement that.

i need to use nonblocking pull mode ports (driver "try_get" from component, component "try_get" from sequencer).

i would appreciate a good explanation about that issue,


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To put it simply, your component will need to be a driver and a sequencer (generally you would use "sequencer layering" for this instead).

class adapter_comp#(type REQ=int, type RSP=REQ);

`uvm_component_param_utils(adapter_comp#(type REQ=int, type RSP=REQ))

typedef adapter_comp#(REQ,RSP) this_type;

uvm_seq_item_pull_imp #(REQ, RSP, this_type) out_seq_item_export;

uvm_seq_item_pull_port#(REQ, RSP) in_seq_item_port;

// implement the seq_item_export tasks

virtual task try_next_item (output REQ t);

in_seq_item_port.try_next_item( t );


// etc.


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thank you very much

it's very helpful, and it solves half of my problems

the component is connected to a sequencer in one side, and two drivers in the other (that's why i need a component in the middle, to be like a splitter)

the question is: how do i implement 2 "try_next_item" functions for both exports?


try_next_item is a function and not a task, right?

thanks again

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There's no imp macro for this tlm port type so you'll have to extend it yourself. You can either have your extension call a different task (like the uvm imp macros do) or have it add an argument to the called task to identify the port.

While try_next_item is non-blocking when no transaction is available, it awakens the sequence body task for next transaction (which also shouldn't consume time, but does involve a delta cycle) thus it needs to be a task.

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Here's an example using multiple analysis ports:

class my_scoreboard extends uvm_component;
  class my_imp extends uvm_analysis_export#(my_obj);
  my_scoreboard parent;
  int ndx;
  function new( string name, my_scoreboard parent, int ndx );
    super.new( name, parent );
    this.parent = parent;
    this.ndx = ndx;
  function void write( my_obj t );
    parent.write( ndx, t );

  my_imp in_port[];
  int num_ports = 3;

    `uvm_field_int(num_ports, UVM_DEFAULT)

  function new( string name, uvm_component parent );
    super.new( name, parent );

  function void build();
    in_port = new[num_ports];
    for( int i = 0; i < num_ports; i++ ) begin
      in_port[i] = new( $psprintf( "in_port[%0d]", i ), this, i );

  function void write( int ndx, my_obj t );
    // do whatever


But I do agree with Dave, this is not standard UVM way of doing things.

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This is a great way to deal with muli-channel type items, though (like 256 for a mixer on a sound card). Also when you have programmable vip you can use a dynamic array to set the #channels for the vif and this code would appropriately deal with a multi-channel situation in the scoreboard. I think I'll re-write our yapp_router example for dealing with the channels this way.

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