Wireshark-dev: Re: [Wireshark-dev] Calculating CRC5 of 11-bit data
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From: Guy Harris <guy@xxxxxxxxxxxx>
Date: Fri, 19 Jul 2019 17:34:22 -0700
On Jul 19, 2019, at 9:26 AM, Tomasz Moń <desowin@xxxxxxxxx> wrote:

> The CRC-5/USB is not so straightforward as it does not operate on the
> byte boundary. The CRC-5/USB is calculated on 11 bits of data. I think
> there are two possible approaches to check the CRC-5/USB in Wireshark:
> 1. Compute the CRC5 bitwise on the 11 bits of data, or
> 2. Compute the CRC5 with table-based algorithm on 2 bytes (11 bits
> data + 5 bits CRC) and relying on the CRC properties expect fixed
> output.

Meaning that if you run the CRC on the entire Link Control Word, including the 5-bit CRC and the remaining 11 bits, the result should be a fixed value?  (Is that what "The residual of CRC-5 shall be 01100b." is referring to?)

If the goal is just to check the CRC, approach 2) seems as if it's as good as approach 1), and may involve a simpler implementation.