Byte_array_mfb environment

This environment has two high-level agents. The first one is a byte array agent and it works with data. The second one is a logic vector agent which works with metadata. This package contains two environments. Environment RX generates data and metadata and sends them to the DUT. Environment TX generates the DST_RDY signal and observes the TX interface.

The environment is configured by these four parameters: mfb documentation.

REGIONS
REGIONS_SIZE
BLOCK_SIZE
META_WIDTH

Top sequencers and sequences

In the RX direction, there are two sequencers: the first is a Byte Array sequencer that handles MFB_DATA. The second is a Logic Vector sequencer that handles MFB_METADATA. Both sequencers pull the data from sequences together.

In the TX direction, there is one sequencer of type mfb::sequencer #(), which generates the DST_RDY signal.

Both directions have two analysis_exports. One export is for the Byte Array transactions, and the second is for the Logic Vector (metadata) transactions.

Configuration

The config class has three variables.

Variable	Description
active	Set to UVM_ACTIVE if the agent is active, otherwise set to UVM_PASSIVE.
interface_name	The name of the interface under which you can find it in the UVM config database.
meta_behave	The moment when the metadata are being generated and valid: config_item::META_SOF => valid with the SOF, config_item::META_EOF => valid with the EOF.
seq_cfg	Configure a low-level sequence that converts byte_array to MFB words.

The top level the environment contains the reset_sync class, which is required for reset synchronization. The example shows how to connect the reset to the byte_array_mfb environment and basic configuration.

class test extends uvm_test
    `uvm_componet_utils(test::base)
    reset::agent                m_resets;
    byte_array_mfb::env_rx#(...) m_env;

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

    function void build_phase(uvm_phase phase);
         byte_array_mfb::config_item m_cfg;

         m_resets = reset::agent::type_id::create("m_reset", this);

         m_cfg = new();
         m_cfg.active = UVM_ACTIVE;
         m_cfg.interface_name = "MFB_IF";
         m_cfg.meta_behav     = config_item::META_SOF;
         m_cfg.cfg = new();
         m_cfg.cfg.space_size_set(128, 1024);
         uvm_config_db#(byte_array_mfb_env::config_item)::set(this, "m_eth", "m_config", m_cfg);
         m_env = byte_arra_mfb::env_rx#(...)::type_id::create("m_env", this);
    endfunction

     function void connect_phase(uvm_phase phase);
        m_reset.sync_connect(m_env.reset_sync);
     endfunction
endclass

Low sequence configuration

configuration object config_sequence contain two function.

Function	Type	Description
probability_set(min, max)	[percentige]	set probability of no inframe gap. probability_set(100,100) => no inframe gap
space_size_set(min, max)	[bytes]	set min and max space between two packets.

RX Inner sequences

For the RX direction exists one base sequence class “sequence_simple_rx_base” which simplifies creating others sequences. It processes the reset signal and exports virtual function create_sequence_item. In this function can child create mfb::sequence_item what they like. Other important function in “sequence_simple_rx_base” class is try_get() which downloads required data from base array agent. It is also important to note that the base class is state oriented. Following table describes internal states.

State	Description
state_packet_none	No data for packet
state_packet_new	new packet has been read by function try_get
state_packet_data	process is somewhere in middle of packet
state_pakcet_space	Process send all data and generate space before new packet
state_packet_space_new	Randomize new space size before new packet

The environment has three sequences. The table below describes them. In the default, the RX env runs sequence_lib_rx.

Sequence	Description
sequence_simple_rx	A basic random sequence. This sequence behaves very variably.
sequence_full_speed_rx	The sequence gets data and then sends them as quickly as possible.
sequence_stop_rx	This sequence doesn’t send any data. There are no data on the interface.
sequence_lib_rx	Repetitively randomly choose one of the sequences above and run it.

The example below shows how to change the inner sequence to test the maximum throughput. The environment runs the sequence_full_speed_rx instead of the sequence_lib_rx.

class mfb_rx_speed#(...) extends byte_array_mfb_env::sequence_lib_rx#(...);

    function new(string name = "mfb_rx_speed");
        super.new(name);
        init_sequence_library();
    endfunction

    virtual function void init_sequence(config_sequence param_cfg = null);
        if (param_cfg == null) begin
            this.cfg = new();
        end else begin
            this.cfg = param_cfg;
        end
        this.add_sequence(byte_array_mfb_env::sequence_full_speed_rx #(REGIONS, REGION_SIZE, BLOCK_SIZE, ITEM_WIDTH, META_WIDTH)::get_type());
    endfunction
endclass


class test extends uvm_test
    `uvm_componet_utils(test::base)
    byte_arra_mfb::env_rx#(...) m_env;

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

    function void build_phase(uvm_phase phase);
        ...
         byte_array_mfb_env::sequence_lib_rx#(...)::type_id::set_inst_override(mfb_rx_speed#(...)::get_type(),
         {this.get_full_name(), ".m_env.*"});
         m_env = byte_arra_mfb::env_rx#(...)::type_id::create("m_env", this);
    endfunction
endclass