Hi Everyone,=20

Yes that was fun.. At some stage when I get some time, I was going to add
all the optimised version to my page as well so people could get the enti=
re
story (and fry their brains trying to workout the optimisations) :)

I've been pretty busy lately so I haven't had the chance..=20

Cheers,
Ash.

---
Ashley Roll
Digital Nemesis Pty Ltd
www.digitalnemesis.com
Mobile: +61 (0)417 705 718




> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Tony K=FCbek
> Sent: Tuesday, 6 August 2002 6:12 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [PIC]: Charles Ader, CRC-16

[ snip ]

> Well, it is a bit 'tricky' to just read the outcome :) anyway=20
> it started
> out
> with this:
> http://www.digitalnemesis.com/ash/projects/EmbeddedCRC16/default.htm
>=20
> When Ashley Roll made a nice initiative for sharing some easy to
> read/use
> crc code. What can be concluded out of this simple routine is breifly
> the following:
>=20
> -update crc16 for first nibble=20
> -calculate nibble indexes to crc tables.
> -shift left 4 times
> -update crc16 for second nibble=20
> -calculate nibble indexes to crc tables.
>=20
> Then Scott Dattalo realised some possible optimisations:
> http://www.infosite.com/~jkeyzer/piclist/2002/May/0823.html
>=20
>=20
> Then I realised that for this poly ( might differ for others )
> it was quite easy to just skip the tables and calculate the output
> directly:
> http://www.infosite.com/~jkeyzer/piclist/2002/May/0919.html
>=20
> Scott followed by introducing the optimised screamer:
> http://www.infosite.com/~jkeyzer/piclist/2002/May/0966.html
>=20
> To use another poly one probably would have to start from the=20
> beginning
> by making an new table. I'm not certain that all poly would=20
> be suitable
> for this optimisation, but it wouldn't stop me from trying :)
>=20
> Fun stuff,

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