[myhdl-list] Re: VCD viewer ?

[Jean D. <jea...@un...>]

Jan Decaluwe a écrit :
> Jean Demartini wrote:
> 
>> Jean DEMARTINI a écrit :
>>
>>> Hi all,
>>>
>>> For many reasons I've to use MyHDL on a Windows platform (XP SP2). 
>>> Python and MyHDL works perfectly. But has anyone knowledge of a 
>>> working free VCD viewer onto Windows. Despite many effort, I've not 
>>> succeded to use GTKwave and Wavevcd from ISS (beta downloadable at 
>>> www.iss-us.com) does not recognize the VCD format generated by MyHDL 
>>> (its is a drawback of the ISS viewer as the VCD format generated by 
>>> MyDHL is quite correct) .
>>>
>>> Jean
>>>
>>>
>>
>> ISS has just release a new version of its free Wave VCD viewer 
>> (http://www.iss-us.com/wavevcd/). This viewer functions quite properly 
>> but is only conformant with IEEE VCD std. To generate such VCD files, 
>> it is necessary to modifie:
>> _Signal.py
>> _traceSignals.py
>>
>> Enclosed are a modified version of these files. Testing is in progress 
>> and these files are given as it.
> 
> 
> In _traceSignal.py, I had expected a type check to differentiate
> between the various types - instead this is done by checking the
> bit width. Doesn't this mean that a reg of width 32 or 64 would
> be declared as an int or a float ??
> 
> Jan

Yes.

It is in memory of the (not so) old ineger size (32 bits) and the IEEE 
float size (64 bits).
It could be now probably better to introduce a "true" type checking. But 
as it was the 1st time I was "intruding" in your code, I prefered not to 
modify its structure. Then the trick.

A more deep modification has been done in _Signal.py code to track enum 
variables. The default _printVcd() method is no more for strings but for 
an integer which is the _index attribute of the val of an (potentially) 
enum variable. It seems that this default case is invocated only in this 
case.

I'm a little newbie in Python and some Python idiom's are a little 
puzzling. Then my question:

Why an enum variable is not a true class testable by isinstance(..,Enum) 
? this will simplify the catching of enum variables in _Signal.py.

Jean