uvm_sequencer_base

Creates and initializes an instance of this class using the normal constructor arguments for uvm_component: name is the name of the instance, and parent is the handle to the hierarchical parent.

Returns 1 if the child sequence is a child of the parent sequence, 0 otherwise.

When the sequencer arbitration mode is set to UVM_SEQ_ARB_USER (via the set_arbitration method), the sequencer will call this function each time that it needs to arbitrate among sequences.

Derived sequencers may override this method to perform a custom arbitration policy.  The override must return one of the entries from the avail_sequences queue, which are indexes into an internal queue, arb_sequence_q.

The default implementation behaves like UVM_SEQ_ARB_FIFO, which returns the entry at avail_sequences[0].

Executes the given transaction item directly on this sequencer.  A temporary parent sequence is automatically created for the item.  There is no capability to retrieve responses.  If the driver returns responses, they will accumulate in the sequencer, eventually causing response overflow unless uvm_sequence_base::set_response_queue_error_report_disabled is called.

Start the default sequence for this phase, if any.  The default sequence is configured via resources using either a sequence instance or sequence type (object wrapper).  If both are used, the sequence instance takes precedence.  When attempting to override a previous default sequence setting, you must override both the instance and type (wrapper) resources, else your override may not take effect.

When setting the resource using set, the 1st argument specifies the context pointer, usually this for components or null when executed from outside the component hierarchy (i.e. in module).  The 2nd argument is the instance string, which is a path name to the target sequencer, relative to the context pointer.  The path must include the name of the phase with a “_phase” suffix.  The 3rd argument is the resource name, which is “default_sequence”.  The 4th argument is either an object wrapper for the sequence type, or an instance of a sequence.

Configuration by instances allows pre-initialization, setting rand_mode, use of inline constraints, etc.

myseq_t myseq = new("myseq");
myseq.randomize() with { ... };
uvm_config_db #(uvm_sequence_base)::set(null, "top.agent.myseqr.main_phase",
                                        "default_sequence",
                                        myseq);

Configuration by type is shorter and can be substituted via the factory.

uvm_config_db #(uvm_object_wrapper)::set(null, "top.agent.myseqr.main_phase",
                                         "default_sequence",
                                         myseq_type::type_id::get());

The uvm_resource_db can similarly be used.

myseq_t myseq = new("myseq");
myseq.randomize() with { ... };
uvm_resource_db #(uvm_sequence_base)::set({get_full_name(), ".myseqr.main_phase",
                                          "default_sequence",
                                          myseq, this);

uvm_resource_db #(uvm_object_wrapper)::set({get_full_name(), ".myseqr.main_phase",
                                           "default_sequence",
                                           myseq_t::type_id::get(),
                                           this );

Stop the default sequence for this phase, if any exists, and it is still executing.

This task issues a request for the specified sequence.  If item_priority is not specified, then the current sequence priority will be used by the arbiter.  If a lock_request is made, then the sequencer will issue a lock immediately before granting the sequence.  (Note that the lock may be granted without the sequence being granted if is_relevant is not asserted).

When this method returns, the sequencer has granted the sequence, and the sequence must call send_request without inserting any simulation delay other than delta cycles.  The driver is currently waiting for the next item to be sent via the send_request call.

A sequence may optionally call wait_for_item_done.  This task will block until the driver calls item_done() or put() on a transaction issued by the specified sequence.  If no transaction_id parameter is specified, then the call will return the next time that the driver calls item_done() or put().  If a specific transaction_id is specified, then the call will only return when the driver indicates that it has completed that specific item.

Note that if a specific transaction_id has been specified, and the driver has already issued an item_done or put for that transaction, then the call will hang waiting for that specific transaction_id.

Returns 1 if the sequence referred to by sequence_ptr is currently locked out of the sequencer.  It will return 0 if the sequence is currently allowed to issue operations.

Note that even when a sequence is not blocked, it is possible for another sequence to issue a lock before this sequence is able to issue a request or lock.

Returns 1 if the sequence referred to in the parameter currently has a lock on this sequencer, 0 otherwise.

Note that even if this sequence has a lock, a child sequence may also have a lock, in which case the sequence is still blocked from issuing operations on the sequencer

Requests a lock for the sequence specified by sequence_ptr.

A lock request will be arbitrated the same as any other request.  A lock is granted after all earlier requests are completed and no other locks or grabs are blocking this sequence.

The lock call will return when the lock has been granted.

Requests a lock for the sequence specified by sequence_ptr.

A grab request is put in front of the arbitration queue.  It will be arbitrated before any other requests.  A grab is granted when no other grabs or locks are blocking this sequence.

The grab call will return when the grab has been granted.

Removes any locks and grabs obtained by the specified sequence_ptr.

Removes any locks and grabs obtained by the specified sequence_ptr.

Tells the sequencer to kill all sequences and child sequences currently operating on the sequencer, and remove all requests, locks and responses that are currently queued.  This essentially resets the sequencer to an idle state.

Returns 1 if any sequence currently has a lock or grab on this sequencer, 0 otherwise.

Returns a reference to the sequence that currently has a lock or grab on the sequence.  If multiple hierarchical sequences have a lock, it returns the child that is currently allowed to perform operations on the sequencer.

Returns 1 if any sequence running on this sequencer is ready to supply a transaction, 0 otherwise.  A sequence is ready if it is not blocked (via grab or lock and is_relevant returns 1.

Specifies the arbitration mode for the sequencer.  It is one of

The default user function specifies FIFO order.

Return the current arbitration mode set for this sequencer.  See set_arbitration for a list of possible modes.

Waits for a sequence to have a new item available.  Uses uvm_wait_for_nba_region to give a sequence as much time as possible to deliver an item before advancing time.

Derived classes implement this function to send a request item to the sequencer, which will forward it to the driver.  If the rerandomize bit is set, the item will be randomized before being sent to the driver.

This function may only be called after a wait_for_grant call.

Can be called at any time to change the maximum number of times wait_for_relevant() can be called by the sequencer in zero time before an error is declared.  The default maximum is 10.