Re: [myhdl-list] MEP 107 assessment

[Christopher F. <chr...@gm...>]

On 6/5/2012 3:52 PM, Jan Decaluwe wrote:
> I have read and thought about MEP 107. Here is my initial
> assessment.
>
> This MEP is strictly about conversion. This is explained in
> the first paragraph, but I think it should be mentioned in
> the title also, because this has proven to be an eternal source
> of confusion. It should be made clear that all modeling
> aspects being discussed are supported by MyHDL as it is today.

All aspects being discussed are almost supported for modeling today.  It 
has been reported that the @always_comb decorator fails to extract the 
sensitivity list if a signal is buried in a structure.  I have 4 
examples below that demonstrate the issue (a control and 3 fails). 
There is the limitation that the structures cannot be used on the right 
hand side currently (at lest for the version of 0.8dev I tested this with).


In [76]: x = Signal(False)
     ...: y = Signal(False)
     ...: con1 = {'x':Signal(False)}
     ...: con2 = [Signal(False),
                  'gibberish',
                  Signal(intbv(0, min=-234, max=19987))]
     ...: class Container(object): x = Signal(False)
     ...: con3 = Container()
     ...:

In [77]: @always_comb
     ...: def sim_sig():
     ...:     x.next = y
     ...:

In [78]: @always_comb
     ...: def sim_con1():
     ...:     x.next = con1['x']
     ...:
---------------------------------------------------------------------------
AlwaysCombError                           Traceback (most recent call last)
...
AlwaysCombError: sensitivity list is empty

In [79]: @always_comb
     ...: def con2():
     ...:     x.next = con2[0]
     ...:
---------------------------------------------------------------------------
AlwaysCombError                           Traceback (most recent call last)
..
AlwaysCombError: sensitivity list is empty

In [80]: @always_comb
     ...: def sim_con3():
     ...:     x.next = con3.x
     ...:
---------------------------------------------------------------------------
AlwaysCombError                           Traceback (most recent call last)
...
AlwaysCombError: sensitivity list is empty


Regards,
Chris F.