Re: [netmod] bit positions

On Wed, 2018-12-19 at 13:16 +0100, Juergen Schoenwaelder wrote:
> Lada,
> 
> RFC 7950 says:
> 
>    The "position" statement, which is optional, takes as an argument a
>    non-negative integer value that specifies the bit's position within a
>    hypothetical bit field.  The position value MUST be in the range 0 to
>    4294967295, and it MUST be unique within the bits type.
> 
> Neither the XML nor the JSON encoding rulse uses the position
> property.  I believe the interpretation of the position field is going
> to be protocol specific. DNS may do things in its own way, a CBOR
> encoding of bits may do a different thing.

So do you suggest to keep the position equal to the number in the IANA registry?

Lada

> 
> /js
> 
> On Wed, Dec 19, 2018 at 12:58:48PM +0100, Ladislav Lhotka wrote:
> > Hi,
> > 
> > I ran into a problem when trying to translate IANA registry "DNSKEY Flags"
> > [1]
> > into a YANG "bits" type. Each bit is the registry has an assigned number (0-
> > 15), 
> > so it seems natural to specify this number as the position of each bit in
> > YANG.
> > 
> > However, it turns out that each bit contributes to the numeric value of the
> > entire bit field with a value of 2^(15-n) where n is the bit number. For
> > example, if bits ZONE (number 7) and SEP (15) are set, then the value of the
> > flags field, which also appears in the DNSKEY resource record, is
> > 
> >   257 = 2^8 + 2^0
> > 
> > My question is: Although it is not specified in RFC 7950, was the intention
> > that
> > bit of position n contributes with 2^n?
> > 
> > Thanks, Lada
> > 
> > [1] https://www.iana.org/assignments/dnskey-flags/dnskey-flags.xhtml
> > 
> > -- 
> > Ladislav Lhotka
> > Head, CZ.NIC Labs
> > PGP Key ID: 0xB8F92B08A9F76C67
> > 
> > _______________________________________________
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> > netmod@ietf.org
> > https://www.ietf.org/mailman/listinfo/netmod
-- 
Ladislav Lhotka
Head, CZ.NIC Labs
PGP Key ID: 0xB8F92B08A9F76C67