Question

Tasks and functions can be defined within an interface, or they can be defined within one or more of the modules connected. This allows a more abstract level of modeling. For example “read” and “write” can be defined as tasks, without reference to any wires, and the master module can merely call these tasks. In a modport these tasks are declared as import tasks.

If a module is connected to a modport containing an exported task or function, and the module does not define that task or function, then an elaboration error shall occur. Similarly if the modport contains an exported task or function prototype, and the task or function defined in the module does not exactly match that prototype, then an elaboration error shall occur.

If the tasks or functions are defined in a module, using a hierarchical name, they must also be declared as extern in the interface, or as export in a modport.

Tasks (not functions) can be defined in a module that is instantiated twice, e.g. two memories driven from the same CPU. Such multiple task definitions are allowed by a forkjoin extern declaration in the interface.