Re: [myhdl-list] Wrap-around support in MyHDL

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

On 5/29/2011 4:55 PM, Jan Decaluwe wrote:
> On 05/20/2011 05:25 PM, Jan Decaluwe wrote:
>> As you like the proposal after putting the feature
>> back on the map, and I hear no objections, I'd like
>> to make some progress.
>>
>> This is definitely a 0.8 feature, so I will open
>> a 0.8-dev branch for development. I will also turn
>> the proposal into a MEP.
>
> http://myhdl.org/doku.php/meps:mep-106
>

I didn't notice this in the previous draft but there is an error in the 
code examples; handling wrap using modulus (Wrap-around type proposals).

"""
   if count == N:
         count.next = 0
         some_decode_action()
     else:
         count.next = count + 1
...

     if count == N:
         some_decode action()

     count.next = (count + 1) % N
"""

The code snippets should be count == 0 or count = N-1, count will never 
actually equal N in the "%" case.  The first case will not act like a mod.

To double check my sanity, here is a small capture from a python session:
   In [176]: N = 2**3
   In [179]: count = intbv(0, min=0, max=N)
   In [180]: for ii in range(2*N):
      .....:     if count == N:
      .....:         print "Do some action"
      .....:     count[:] = (count + 1) % N
      .....:     print count
   1
   2
   3
   4
   5
   6
   7
   0
   1
   2
   3
   4
   5
   6
   7
   0
   In [181]: N
   Out[181]: 8


Chris