what is callback in systemverilog
We may have to create a verification environment that can be used for all the tests. Test program should be able to inject new code without modifying original classes. Any change in the transaction(like injecting errors, inserting delays, synchronizing this transaction with others, put the transaction in scoreboard, gather functional coverage data) can be achieved by “callback” routine without changing the original classes.
The callback task is created in the top level test and called from the driver, lowest level of environment.