ANN: Python as a test and modeling language for Verilog

[tom.sheffler at sbcglobal.net]

Oroboro is an approach to integrating Python and Verilog. With it, Python generator functions are used to model simulation threads in a cooperative multitasking style. An Oroboro task can suspend its execution with a yield statement that lists the reasons the task should be resumed. Typical reasons map directly to VPI callback reasons. Oroboro does not implement a scheduler of its own, rather, it relies on Verilog for all event scheduling through the use of callback functions. 
A short example illustrates some basic capabilities for interacting with a Verilog simulation. 

  from oroboro import *

  def watcher(sig):
    print "Watching signal %s" % sig
    while 1:

      yield sigchange(sig), timeout(10)

      if isinstance(currentreason(), sigchange):
        print "New value for signal %s is %s" % (sig, sig.get())

      if isinstance(currentreason(), timeout):
        print "Timeout has elapsed.  Wait again."


  def main(systf):

    s = signal("top.mysignal")
    t = task(watcher, s)

    yield timeout(0)
    returnThe example above illustrates a simple task that watches a Verilog signal. The task 'watcher' loops indefinitely, suspending its execution with a yield statement that lists the reasons it should be resumed. Here, the task waits until either the signal value changes, or a 10 simulation tick timeout occurs ... whichever comes first. When the task resumes, it uses the 'currentreason' function to determine whether the first or second reason in the yield statement was triggered. The task prints an informative message and then loops. 

Source downloads and documentation can be found at:

  http://apvm.sourceforge.net


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