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

[Jan D. <ja...@ja...>]

George Pantazopoulos wrote:

> 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?

George:

Yes, I understand now. I think this qualifies as Truly Advanced Usage :-)
What happens is that you do want to use itertools to describe
behavior, not structure, in MyHDL terminology. You use the fact
that you can have a generator yield other generators, something
which I originally included to support bus-functional procedures.
With all this low-level RTL stuff that I'm doing these days, I
had all but forgotten about it :-)

I understand why you want to use itertools - not for performance,
but as a clear and concise way to manipulate iterators.

The missing part is how to make sure that the MyHDL simulator
handles your final iterator properly. There are 2 options:
either it should support that object directly, or it should be
converted to a generator first.

I have briefly looked at the first option - but this whole
typing system related to iterators seems complex. It's not
clear how to do it robustly. Moreover, it may not be wise:
perhaps someday somebody would want to use a similar object for
structure instead of behavior.

So at this point I would look for a workaround and convert
iterator objects to the "officially" supported types
(for behavior or structure) as desired. The advantage is
of course that no change to MyHDL would be required.

A workaround for your case could be the following. Just use
itertools to set up your iterator as desired. Then convert
it to a generator using a one-liner generator expression, e.g.:

ordered_tests = (t for t in chain(stage1, stage2, stopsim()))

This should work for any iterator you can imagine.

Regards,

Jan

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