[myhdl-list] Setting "sig.next" before starting the simulation

[Nick P. <np...@in...>]

On Mon, Sep 29, 2003 at 09:23:42PM +0200, Jan Decaluwe wrote:
[[[ refers to an off-list discussion ]]]
> 
> Very nice work! I would gladly add it as an example to future
> MyHDL distributions.
> 
> Some upfront comments:
>

Sorry for taking so long to answer, but I was engaged in other
activities that kept me away for several days. As I was trying to
address your comments, and write a test-framework for mu0 (which is
turning out very nicely), I came upon this strange behavior:

  from myhdl import *

  def gen_tst (db):
      while 1:
          yield delay(10)
          if db.val: print "now = %d" % (now())

  def mktst():
      db=Signal(bool(0))
      g = gen_tst(db)
      return g, db

  g, db = mktst()
  db.next = 1
  sim = Simulation(g)
  print "db.val=%d, db.next=%d" % (db.val, db.next)
  sim.run(50)

When I run this, I get:

  $ python2.3 tst.py
  db.val=0, db.next=1
  now = 10
  now = 20
  now = 30
  now = 40
  now = 50
  SuspendSimulation: Simulated for duration 50

Which is fine. Now, if I comment-out the "print" line like this:

  from myhdl import *

  def gen_tst (db):
      while 1:
          yield delay(10)
          if db.val: print "now = %d" % (now())

  def mktst():
      db=Signal(bool(0))
      g = gen_tst(db)
      return g, db

  g, db = mktst()
  db.next = 1
  sim = Simulation(g)
  # print "db.val=%d, db.next=%d" % (db.val, db.next)
  sim.run(50)

Then I strangely get:

  $ python2.3 tst.py
  SuspendSimulation: Simulated for duration 50

Is this supposed to happen?

/npat

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