Re: [myhdl-list] difficulty using itertools with MyHDL

[George P. <ge...@ga...>]

I agree, I think I could have done a better job explaining what I wanted 
to do.

I want to run multi-stage simulations for automated unit testing.

For example, I have a ring buffer that I want to unit test.

For some tests I want to check the border case where its full and read 
or writes are done to it.
The first stage of the test involves filling it to capacity. The second 
stage involves driving signals and checking outputs.
There could be multiple tests that start off by filling it up, so in 
practice I'd want to reuse the filler function.

Stage 1:
   Fill ring buffer.

Stage 2:
   Simultaneously drive signals and check outputs


If I just return instances() then all the generators will be run 
together by the Simulation class, which is not what I want.
Thus, I use chain() to impose an ordering. For Stage 2 I use izip() to 
ensure that the driver and monitor are run in lockstep.

It goes something like this:

stage1 = filler()

stage2 = izip(driver, monitor)

complete_sequence = chain(stage1, stage2)


Right now I just copied and pasted the itertools functions from the 
Python docs into my code.
In this way they are generators, and not itertools objects. Perhaps this 
is because in the Python library they inherit from a superclass and I don't?

I've left out the definition of the Driver and Monitor, but they are 
ordinary
generators like the ones found in the test benches in your cookbooks.

    def bench():
      
        # I've deliberately glossed over the dut setup
        dut = RingBuffer(clk, rst, dat_i, we)
        clk = Signal(bool(0))
        clkgen = ClkGen(clk)

        def filler():
           
            # Fill up the Ring Buffer
            for i in range(depth):
               
                # Set up a write
                dat_i.next = i+10
                we.next = True
               
                yield clk.posedge
                yield clk.negedge
           
            # De-assert the write enable
            we.next = False
            yield clk.posedge
            yield clk.negedge
           
        # Itertools can't directly be used.
        # Seems that the _Simulation.py checks for GeneratorType, but 
itertools object are not of that
        # type. See one idea for a solution here:
        # http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/439359
       
        # duplicate of Python's built-in izip(), except this one is of 
type 'generator'
        def izip(*iterables):
            iterables = map(iter, iterables)
            while iterables:
                result = [it.next() for it in iterables]
                yield tuple(result)
       
        # Same goes for chain:
        def chain(*iterables):
            for it in iterables:
                for element in it:
                    yield element
       
      
        # Stage 1 - Fill the ring buffer
        stage1 = filler()
       
        # Stage 2 - Perform border-case testing
        # Simultaneously drive signals and monitor them 
        stage2 = izip(driver, monitor)
       
        # Make this look like a generator
        def stopsim():
            raise StopSimulation()
            yield None
           
        # Chain the generators so they run sequentially
        ordered_tests = chain(stage1, stage2, stopsim())
              
        return clkgen, dut, ordered_tests

# For py.test
def test_1():
    tb = traceSignals(bench())
    sim = Simulation(tb)
    sim.run()
 

Sorry for the confusion earlier. Does this help you understand what I 
want to accomplish? This is already working for me, except that I have 
to redefine izip() and ichain() myself. Perhaps you know of a better way 
to do this?

Thanks,
George