Re: [myhdl-list] Conversion error: Type mismatch with earlier assignment

[Guy E. <guy...@gm...>]

Hi Josy,

I believe this has something to do with how name assignment works in
Python. There's a section about this in the manual at
http://docs.myhdl.org/en/stable/manual/conversion.html#intbv-objects

My only criticism is that if you do it wrong (e.g. forget the "[:]"), you
get an error message that is of little help to debug the issue.

Regards,
Guy.


On Mon, Sep 7, 2015 at 9:36 PM, Josy Boelen <jos...@gm...> wrote:

> Hi Guy,
>
> I studied this a bit deeper and went looking for some 'variable'
> examples in the MyHDL doc and found this one:
> def bin2gray(B, G, width):
>
>     """ Gray encoder.
>
>     B -- input intbv signal, binary encoded
>     G -- output intbv signal, gray encoded
>     width -- bit width
>
>     """
>
>     @always_comb
>     def logic():
>         Bext = intbv(0)[width+1:]
>         Bext[:] = B
>         for i in range(width):
>             G.next[i] = Bext[i+1] ^ Bext[i]
>
>     return logic
>
> And to my surprise it uses the [:] ...
> So it may not be a bug, as it is actually _documented_ behaviour ...
> But I maintain that it is inconsistent because e.g.:  if I change
>         count_v = count_v + 1
> into:
>         count_v += 1
> the conversion will pass without errors.
>
> Regards,
>
> Josy
>
>
>
>
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