[ANN] Python as a Verilog test and modeling language

tom.sheffler at sbcglobal.net tom.sheffler at sbcglobal.net
Fri Jul 16 07:41:28 CEST 2004


Oroboro is an approach to using Python as a test and
modeling language for Verilog.  With it, Python generator
functions are used to model simulation threads in a
cooperative multitasking style.  A simulation task in Python
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)


The 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.

A longer paper discussing Oroboro, source downloads and
examples can be found at:

  http://apvm.sourceforge.net









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