| Title: | Mathematics at DEC |
| Moderator: | RUSURE::EDP |
| Created: | Mon Feb 03 1986 |
| Last Modified: | Fri Jun 06 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 2083 |
| Total number of notes: | 14613 |
Could someone shed some light on the procedure to create the generator
polynomial from the CRC polynomial.
ie CRC-16 CRC polynomial x^16 + x^15 + x^2 + 1 has the generator polynomial
120001 (octal)
This has been bugging me for quite a while - and I'm sure the answer is
staring me in the face, but I just can't see it.
Any takers???
Andy
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 1163.1 | ALLVAX::ROTH | If you plant ice you'll harvest wind | Fri Dec 15 1989 16:15 | 16 | |
The octal code is the polynomial in reverse, representing the shift
register that can implement division by the polynomial by shifts
and xors (it does not include the implied highest power coefficient, so
there will be n-1 bits set in the polynomial word...)
For example:
X^16 + X^15 + X^2 + 1
1 2 0 0 0 1 octal
1, 0 1 0, 0 0 0, 0 0 0, 0 0 0, 0 0 1 binary
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 reverse powers
This is shown in the Vax architecture handbook.
- Jim
| |||||
| 1163.2 | Is that all there is to it ??? | SIEVAX::MUMFORD | Don't try to outweird ME!!!!!!! | Mon Dec 18 1989 15:57 | 6 |
Thanks Jim, three guesses for who feels like the winner of the idiot of the year award - and the first two guesses don't count :-) Cheers, Andy | |||||
| 1163.3 | IMHO, | VMSDEV::HALLYB | The Smart Money was on Goliath | Mon Dec 18 1989 19:26 | 1 |
The real idiot was the guy who didn't ask in the first place... | |||||