UVM Virtual Sequence: Getting Response from Child Sequence
Greetings, Readers!
Welcome to this comprehensive guide on retrieving responses from child sequences using UVM virtual sequences. In the realm of verification, UVM (Universal Verification Methodology) is an industry-leading framework that simplifies the creation of robust test environments. Virtual sequences, a fundamental component of UVM, enable the modeling of complex test scenarios and communication with lower-level sequences.
Grasping the Concept of Child Sequences
Virtual sequences can often be hierarchically organized, with parent sequences initiating and monitoring the execution of child sequences. Acquiring the response from a child sequence is crucial for verifying the overall behavior of the system under test. The get_response() method in UVM provides a straightforward mechanism to retrieve the response from a child sequence.
Executing Child Sequences and Retrieving Responses
1. Sequence Initiation and Execution
To initiate a child sequence, the parent sequence employs the start() method. This method accepts an instance of the child sequence as its argument and returns a uvm_sequence_item object. The start() method triggers the execution of the child sequence within the UVM execution tree.
my_child_seq = uvm_sequence #(my_child_seq_type);
resp = parent_seq.start(my_child_seq);
2. Waiting for Child Sequence Completion
After initiating the child sequence, the parent sequence needs to wait for its completion. The wait() method provides a convenient way to achieve this. It blocks the execution of the parent sequence until the child sequence finishes or times out.
resp = resp.wait();
3. Retrieving the Response
Once the child sequence has completed, the response can be retrieved from the resp object. The response typically contains the results of the child sequence’s execution, including any errors or data collected.
assert(resp.get_status() == UVM_FINISHED);
my_data = resp.get_data();
Breaking Down the get_response() Method
| Parameter | Description |
|---|---|
resp |
The handle to the child sequence response |
timeout |
Timeout value in seconds |
agent |
Agent for error reporting |
Conclusion
Retrieving responses from child sequences is a fundamental aspect of UVM virtual sequence programming. By utilizing the get_response() method and following the steps outlined in this guide, readers can effectively communicate with and verify the behavior of their child sequences.
We encourage readers to explore other articles on our platform for further insights into UVM virtual sequences and advanced verification techniques. Stay tuned for more informative content!
FAQs about UVM Virtual Sequence Get Response from Child Sequence
Q: How do I get the response from a child sequence in a UVM virtual sequence?
A: Use the get_response() method to retrieve the response from the child sequence.
Q: What parameters does the get_response() method take?
A: The get_response() method takes two parameters:
response_id: The unique ID of the response you want to retrieve.timeout: The maximum amount of time to wait for the response.
Q: What type of object does the get_response() method return?
A: The get_response() method returns a uvm_response object.
Q: What happens if the response is not available within the timeout period?
A: If the response is not available within the timeout period, the get_response() method will return null.
Q: Can I get the response from multiple child sequences at the same time?
A: Yes, you can use the get_responses() method to get the responses from multiple child sequences at once.
Q: How do I set the timeout for the get_response() method?
A: You can set the timeout for the get_response() method using the set_timeout() method.
Q: Can I interrupt the get_response() method if the response is not available?
A: Yes, you can interrupt the get_response() method using the interrupt() method.
Q: What happens if the child sequence is terminated before the response is available?
A: If the child sequence is terminated before the response is available, the get_response() method will return null.
Q: How can I handle errors when getting the response?
A: You can handle errors when getting the response by using the try/catch statement.
Q: Can I get the response from a child sequence that is running on a different thread?
A: Yes, you can use the uvm_channel mechanism to get the response from a child sequence that is running on a different thread.
