Re: [myhdl-list] Slicing an unsigned intbv to a signed one

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

Christopher L. Felton wrote:
> Ok, below was my quick test to double check if it could be done.  A  
> real implementation probably need more thought (if feasible at all).
> 
> With that said, I do think this approach will work.  Even if you have  
> a non power of 2 limit you still need N bits to represent the max and  
> min values.  If the msb of the "bit container" is modified it will  
> change the sign.   

I meant non-power of 2 values, not the limits, and I don't
think it works:

---
 >>> x = intbv(7, min=-8, max=8)
 >>> bin(x)
'111'
 >>> x[3] = 1
1 1 15 -8 8 4
Traceback (most recent call last):
   File "<stdin>", line 1, in <module>
   File "/home/jand/dev/myhdl/myhdl/_intbv.py", line 173, in __setitem__
     self._checkBounds()
   File "/home/jand/dev/myhdl/myhdl/_intbv.py", line 89, in _checkBounds
     (self._val, self._min))
ValueError: intbv value -15 < minimum -8
---

Should give -1, right?

Jan

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