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Author Topic: HASH: CRC-16  (Read 6220 times)

Thaddy

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Re: HASH: CRC-16
« Reply #15 on: September 17, 2017, 09:43:57 pm »
Marco, I can add it, but are you sure that is OK? It only uses 15 bits.. that's wrong.. (Basically all other CRC16's are actually 17 bits, yup, within a word ;) , through the shift-out shift-in ) But if it is a common one and you can test it, I will include it.
See https://en.wikipedia.org/wiki/Cyclic_redundancy_check

Sure it is not a CRC15? Can you identify it for me in that wiki table? Appreciated.
« Last Edit: September 17, 2017, 09:48:42 pm by Thaddy »
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marcov

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Re: HASH: CRC-16
« Reply #16 on: September 17, 2017, 09:47:58 pm »
No, leave it out. It was a long time ago.

As it happens that customer recently got live again, so maybe I'll pick it up in the near future.

Thaddy

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Re: HASH: CRC-16
« Reply #17 on: September 17, 2017, 09:50:29 pm »
Posts crossed: can you identify it? I am curious and will test $BEEF ;)
'123456789'
Ada's daddy wrote this:"Fools are my theme, let satire be my song."

Thaddy

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Re: HASH: CRC-16
« Reply #18 on: September 24, 2017, 09:26:06 am »
I delved in my sources, and it seems that microchip uses a different algo, I added a CCIT implementation in the same vein for reference.

I have the references for your implementation now and will include it.
It is called a CLASSB_CRC16 (without reflection) a.k.a. RF69 as used in e.g. radio communications and sensors. See ATMEL, Microchip, ISO/IEC CD 14443-3.3  appendix B.
It is NOT CCITT compliant, although it uses the same start value of zero, $1021 it uses a different polynomial using only 15 bit, but a very common implementation in hardware, so it should be in.
« Last Edit: September 24, 2017, 09:43:19 am by Thaddy »
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