Re: [myhdl-list] intbv improvement?

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

Neal Becker wrote:
> Jan Decaluwe wrote:
> 
>> Neal Becker wrote:
>>> I would find this addition to the intbv constructor helpful:
>>>
>>> class intbv(object):
>>>     __slots__ = ('_val', '_min', '_max', '_nrbits')
>>>     
>>>     def __init__(self, val=None, min=None, max=None, _nrbits=0,
>>> is_signed=False):
>>>         if _nrbits:
>>>             if (is_signed):
>>>                self._min = -1 << (_nrbits-1)
>>>                self._max = ~(-1 << (_nrbits-1))
>>>             else:
>>>               self._min = 0
>>>               self._max = 2**_nrbits
>> I infer that you want to use _nrbits as an end user also?
>> This is not how the type is set up. _nrbits is intended
>> to be a private parameter of the constructor for internal
>> use.
>>
>> One of the goals of intbv is to get rid of unsigned/signed
>> thinking as much as possible, and push the use of fine-grained
>> range control as high-level alternative.
>> (I'm actually writing a paper about this, almost finished.)
>>
>> Jan
>>
> 
> I want to make sure my value is converted to verilog signed.  AFAICT, the 
> only way I have now to do this is with intbv specifying min and max, rather 
> than nrbits?

Yes.

> That's OK, but a little inconvenient.

Here I disagree, I actually believe the opposite is true though
I understand it goes against current conventional wisdom.

Note that by using min and max, you never have to think
or worry about the difference between signed/unsigned.
The convertor should solve the issues for you.

My upcoming essay deals exactly with these issues
in detail, please stay tuned! (in one week or so)

Jan

-- 
Jan Decaluwe - Resources bvba - http://www.jandecaluwe.com
    Python as a hardware description language:
    http://www.myhdl.org