Wireshark mailing list archives
Re: Calculating CRC5 of 11-bit data
From: Guy Harris <guy () alum mit edu>
Date: Fri, 19 Jul 2019 17:34:22 -0700
On Jul 19, 2019, at 9:26 AM, Tomasz Moń <desowin () gmail com> 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. ___________________________________________________________________________ Sent via: Wireshark-dev mailing list <wireshark-dev () wireshark org> Archives: https://www.wireshark.org/lists/wireshark-dev Unsubscribe: https://www.wireshark.org/mailman/options/wireshark-dev mailto:wireshark-dev-request () wireshark org?subject=unsubscribe
Current thread:
- Calculating CRC5 of 11-bit data Tomasz Moń (Jul 19)
- Re: Calculating CRC5 of 11-bit data Ross Jacobs (Jul 19)
- Re: Calculating CRC5 of 11-bit data Tomasz Moń (Jul 19)
- Re: Calculating CRC5 of 11-bit data Guy Harris (Jul 19)
- Re: Calculating CRC5 of 11-bit data Tomasz Moń (Jul 19)
- Re: Calculating CRC5 of 11-bit data Tomasz Moń (Jul 20)
- Re: Calculating CRC5 of 11-bit data John Sullivan (Jul 20)
- Re: Calculating CRC5 of 11-bit data Tomasz Moń (Jul 20)
- Re: Calculating CRC5 of 11-bit data John Sullivan (Jul 21)
- Re: Calculating CRC5 of 11-bit data Tomasz Moń (Jul 25)
- Re: Calculating CRC5 of 11-bit data Tomasz Moń (Jul 19)
- Re: Calculating CRC5 of 11-bit data Ross Jacobs (Jul 19)