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Re: [Cbor] Benjamin Kaduk's No Objection on draft-ietf-cbor-network-addresses-09: (with COMMENT)

Carsten Bormann <cabo@tzi.org> Fri, 08 October 2021 10:03 UTC

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From: Carsten Bormann <cabo@tzi.org>
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Date: Fri, 08 Oct 2021 12:03:43 +0200
Cc: Benjamin Kaduk <kaduk@mit.edu>, draft-ietf-cbor-network-addresses@ietf.org, Barry Leiba <barryleiba@computer.org>, cbor@ietf.org, The IESG <iesg@ietf.org>, cbor-chairs@ietf.org
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Subject: Re: [Cbor] Benjamin Kaduk's No Objection on draft-ietf-cbor-network-addresses-09: (with COMMENT)
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Strike that; I forgot that C doesn’t actually have a modulo operator (that’s why I’m used to & 7).
Duuh.

Maybe 

unused_bits = (128 - prefix_length_in_bits) % 8;

But that arbitrary 128 causes cognitive dissonance.

Grüße, Carsten


On 2021-10-08, at 09:31, Carsten Bormann <cabo@tzi.org> wrote:
> 
> On 7. Oct 2021, at 20:55, Michael Richardson <mcr+ietf@sandelman.ca> wrote:
>> 
>> unused_bits = (8 - (prefix_length_in_bits % 8) % 8;
> 
> Yes.  If you want to make this simpler, take note that adding 8 to a modulo doesn’t change anything, and use
> 
> unused_bits = (- prefix_length_in_bits) % 8;
> 
> Oh, that’s the current text with & 7 (which is representation specific) replaced by % 8.
> 
> WFM.
> 
> Grüße, Carsten
> 
>

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