verilog like class w/ bitslicing & int/long classtype

[Stef Mientki]

mark.seagoe at gmail.com wrote:
> I'm trying to make a script environment with datatypes (or classes)
> for accessing hardware registers.  At the top level, I would like the
> ability to bitwise ops if bit slice brackets are used, but if no
> brackets are used, I would like it to write/read the whole value.
>
> For example, if I have something like:
>
>   
>>>> shadow_register = MyRegClass(0xAA)
>>>> shadow_register
>>>>         
> 170
>   
>>>> shadow_register[7:4] = 3  # <== changes value to 0x3A
>>>> shadow_register
>>>>         
> 58
>   
>>>> shadow_register = 0x89
>>>> shadow_register
>>>>         
> 137
>   
>>>> shadow_register[4:1]
>>>>         
> 4
>
> I have the bitslice part working.  But of course as expected, if I
> type
>   
>>>> shadow_register
>>>>         
> <__main__.boo object at 0x00A130D0>
>
> I wanted to avoid having something like shadow_register.value just
> because it's clumsier.  I read about the __new__() class for
> overriding the classtype, like:
>
> print 'foo'
> class foo(object):
>     def __new__(*args): return 0
>
> but if I stick in a __init__(self, val): method, then it chokes saying
> val is a global name that's not defined.
>
> Now I know that I have to live with the fact that I can't have
>   
>>>> shadow_register = 0x89
>>>>         
> Because it will get reassigned from my class value to a newly
> intialized memory location (int object).  But can I have it read the
> value without the .value extension?  Is this even possible?  Maybe
> there's a way to override the = operator?  (Go easy on me - I'm a
> hardware guy).
>
>   
Interesting what you're doing. I've struggled with the same issues, 
simulating a pic,
never really solved them.
Maybe this is what you're looking for:

class MyRegClass ( object ) :
  def __init__ ( self, value ) :
    self.Value = value
  def __repr__ ( self ) :
    line = hex ( self.Value )
    line = line [:2] + line [2:].upper()
    return line

btw, I'm a hardware guy too, and therefor I've never understood why the 
hex function returns lowercase ;-)

cheers,
Stef