[Cryptech Tech] Pascal indexing?

[Joachim Strömbergson]

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Aloha!

Paul Selkirk wrote:
> On 05/04/2015 08:49 AM, Joachim Strömbergson wrote:
>> One thing I noted in the cryptech.h is that bits seems to be 
>> counted from 1 and onwards, not 0 and onwards as I'm used to in C. 
>> Since the cores define bits as in C it becomes slightly confusing.
> 
> Those are bit masks rather than bit positions, i.e. bit position 0
> is value 1, bit position 1 is value 2. If we had more than 2 control
> or status bits defined, it would be more obvious that bit position 2
> is value 4, etc.
> 
> If you think it would be clearer to express bits positionally, or to 
> express them in terms of shifts (e.g. INIT=1<<0, NEXT=1<<1), I can 
> make that change.

To me it makes more sence to have someting called _BIT be the index
number of the bit. But hey, I'm the HW guy and also know the context. If
the team thinks it would be easier to grokk for users (esp SW
developers) to have _BIT mean the bitmask then I'm all for it.


> You also define things like AES_CTRL_INIT_BIT equal to
> CTRL_INIT_BIT, which I think is unnecessary; if we want all cores to
> use the same values for INIT and NEXT, READY and VALID, then we
> should use the base names, rather than cluttering the namespace with
> redundant names.

My though was that when a SW-developer wants to do stuff with AES and by
looking at AES_-something, you get all defines you need to operate the
core. But I can also understand the namespace issue.

- -- 
Med vänlig hälsning, Yours

Joachim Strömbergson - Alltid i harmonisk svängning.
========================================================================
 Joachim Strömbergson          Secworks AB          joachim at secworks.se
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