sqr_if_base #(REQ,RSP)

This class defines an interface for sequence drivers to communicate with sequencers. The driver requires the interface via a port, and the sequencer implements it and provides it via an export.

Summary

This class defines an interface for sequence drivers to communicate with sequencers.

Class Declaration

virtual class sqr_if_base #( type T1 = ovm_object,
T2 = T1 )

Methods

get_next_item

Retrieves the next available item from a sequence.

try_next_item

Retrieves the next available item from a sequence if one is available.

item_done

Indicates that the request is completed to the sequencer.

wait_for_sequences

Waits for a sequence to have a new item available.

has_do_available

Indicates whether a sequence item is available for immediate processing.

get

Retrieves the next available item from a sequence.

peek

Returns the current request item if one is in the sequencer fifo.

put

Sends a response back to the sequence that issued the request.

get_next_item

virtual task get_next_item( output T1 t )

Retrieves the next available item from a sequence. The call will block until an item is available. The following steps occur on this call:

1	Arbitrate among requesting, unlocked, relevant sequences - choose the highest priority sequence based on the current sequencer arbitration mode. If no sequence is available, wait for a requesting unlocked relevant sequence, then re-arbitrate.
2	The chosen sequence will return from wait_for_grant
3	The chosen sequence pre_do is called
4	The chosen sequence item is randomized
5	The chosen sequence post_do is called
6	Return with a reference to the item

Once get_next_item is called, item_done must be called to indicate the completion of the request to the sequencer. This will remove the request item from the sequencer fifo.

try_next_item

virtual task try_next_item( output T1 t )

Retrieves the next available item from a sequence if one is available. Otherwise, the function returns immediately with request set to null. The following steps occur on this call:

1	Arbitrate among requesting, unlocked, relevant sequences - choose the highest priority sequence based on the current sequencer arbitration mode. If no sequence is available, return null.
2	The chosen sequence will return from wait_for_grant
3	The chosen sequence pre_do is called
4	The chosen sequence item is randomized
5	The chosen sequence post_do is called
6	Return with a reference to the item

Once try_next_item is called, item_done must be called to indicate the completion of the request to the sequencer. This will remove the request item from the sequencer fifo.

item_done

virtual function void item_done( input T2 t = null )

Indicates that the request is completed to the sequencer. Any wait_for_item_done calls made by a sequence for this item will return.

The current item is removed from the sequencer fifo.

If a response item is provided, then it will be sent back to the requesting sequence. The response item must have it’s sequence ID and transaction ID set correctly, using the set_id_info method:

rsp.set_id_info(req);

Before item_done is called, any calls to peek will retrieve the current item that was obtained by get_next_item. After item_done is called, peek will cause the sequencer to arbitrate for a new item.

Waits for a sequence to have a new item available. The default implementation in the sequencer delays pound_zero_count delta cycles. (This variable is defined in ovm_sequencer_base.) User-derived sequencers may override its wait_for_sequences implementation to perform some other application-specific implementation.

has_do_available

virtual function bit has_do_available()

Indicates whether a sequence item is available for immediate processing. Implementations should return 1 if an item is available, 0 otherwise.

get

virtual task get( output T1 t )

Retrieves the next available item from a sequence. The call blocks until an item is available. The following steps occur on this call:

1	Arbitrate among requesting, unlocked, relevant sequences - choose the highest priority sequence based on the current sequencer arbitration mode. If no sequence is available, wait for a requesting unlocked relevant sequence, then re-arbitrate.
2	The chosen sequence will return from wait_for_grant
3	The chosen sequence <pre_do> is called
4	The chosen sequence item is randomized
5	The chosen sequence post_do is called
6	Indicate item_done to the sequencer
7	Return with a reference to the item

When get is called, item_done may not be called. A new item can be obtained by calling get again, or a response may be sent using either put, or rsp_port.write.

peek

virtual task peek( output T1 t )

Returns the current request item if one is in the sequencer fifo. If no item is in the fifo, then the call will block until the sequencer has a new request. The following steps will occur if the sequencer fifo is empty:

1	Arbitrate among requesting, unlocked, relevant sequences - choose the highest priority sequence based on the current sequencer arbitration mode. If no sequence is available, wait for a requesting unlocked relevant sequence, then re-arbitrate.
2	The chosen sequence will return from wait_for_grant
3	The chosen sequence pre_do is called
4	The chosen sequence item is randomized
5	The chosen sequence post_do is called

Once a request item has been retrieved and is in the sequencer fifo, subsequent calls to peek will return the same item. The item will stay in the fifo until either get or item_done is called.

put

virtual task put( input T2 t )

Sends a response back to the sequence that issued the request. Before the response is put, it must have it’s sequence ID and transaction ID set to match the request. This can be done using the set_id_info call:

rsp.set_id_info(req);

This task will not block. The response will be put into the sequence response_queue or it will be sent to the sequence response handler.