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.
| uvm_sqr_if_base #(REQ,RSP) | |||||||||||||
| This class defines an interface for sequence drivers to communicate with sequencers. | |||||||||||||
| Class Declaration | |||||||||||||
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| 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. | ||||||||||||
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 uvm_sequence_base::pre_do is called |
| 4 | The chosen sequence item is randomized |
| 5 | The chosen sequence uvm_sequence_base::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.
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 uvm_sequence_base::pre_do is called |
| 4 | The chosen sequence item is randomized |
| 5 | The chosen sequence uvm_sequence_base::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.
virtual function void item_done( input T2 t = null )
Indicates that the request is completed to the sequencer. Any uvm_sequence_base::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 uvm_sequence_item::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.
virtual task wait_for_sequences()
Waits for a sequence to have a new item available. The default implementation in the sequencer delays <uvm_sequencer_base::pound_zero_count> delta cycles. User-derived sequencers may override its wait_for_sequences implementation to perform some other application-specific implementation.
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.
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 uvm_sequence_base::wait_for_grant |
| 3 | The chosen sequence uvm_sequence_base::pre_do is called |
| 4 | The chosen sequence item is randomized |
| 5 | The chosen sequence uvm_sequence_base::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 uvm_driver::rsp_port.write().
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 uvm_sequence_base::wait_for_grant |
| 3 | The chosen sequence uvm_sequence_base::pre_do is called |
| 4 | The chosen sequence item is randomized |
| 5 | The chosen sequence uvm_sequence_base::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.
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 uvm_sequence_item::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.
This class defines an interface for sequence drivers to communicate with sequencers.
virtual class uvm_sqr_if_base #( type T1 = uvm_object, T2 = T1 )
Retrieves the next available item from a sequence.
virtual task get_next_item( output T1 t )
Retrieves the next available item from a sequence if one is available.
virtual task try_next_item( output T1 t )
Indicates that the request is completed to the sequencer.
virtual function void item_done( input T2 t = null )
Waits for a sequence to have a new item available.
virtual task wait_for_sequences()
Indicates whether a sequence item is available for immediate processing.
virtual function bit has_do_available()
Retrieves the next available item from a sequence.
virtual task get( output T1 t )
Returns the current request item if one is in the sequencer fifo.
virtual task peek( output T1 t )
Sends a response back to the sequence that issued the request.
virtual task put( input T2 t )
This task is a user-definable callback task that is called on the parent sequence, if any.the sequence has issued a wait_for_grant() call and after the sequencer has selected this sequence, and before the item is randomized.
virtual task pre_do( bit is_item )
This function is a user-definable callback function that is called after the driver has indicated that it has completed the item, using either this item_done or put methods.
virtual function void post_do( uvm_sequence_item this_item )
A sequence may optionally call wait_for_item_done.
virtual task wait_for_item_done( int transaction_id = -1 )
Copies the sequence_id and transaction_id from the referenced item into the calling item.
function void set_id_info( uvm_sequence_item item )
This task issues a request to the current sequencer.
virtual task wait_for_grant( int item_priority = -1, bit lock_request = 0 )