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author | Roger Knecht <roger@norberthealth.com> | 2022-05-21 15:47:45 +0300 |
---|---|---|
committer | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-06-07 11:27:38 +0300 |
commit | 77991645952c21962a095910c51fe0f73d35bf91 (patch) | |
tree | 390109e8afbf963abde0928317275fefb85c58db | |
parent | e71e60cd74df9386c3f684c54888f2367050b831 (diff) | |
download | linux-77991645952c21962a095910c51fe0f73d35bf91.tar.xz |
crc-itu-t: fix typo in CRC ITU-T polynomial comment
The code comment says that the polynomial is x^16 + x^12 + x^15 + 1, but
the correct polynomial is x^16 + x^12 + x^5 + 1. Quoting from page 2 in
the ITU-T V.41 specification [1]:
2 Encoding and checking process
The service bits and information bits, taken in conjunction,
correspond to the coefficients of a message polynomial having terms
from x^(n-1) (n = total number of bits in a block or sequence) down to
x^16. This polynomial is divided, modulo 2, by the generating
polynomial x^16 + x^12 + x^5 + 1.
The hex (truncated) polynomial 0x1021 and CRC code implementation are
correct, however.
[1] https://www.itu.int/rec/T-REC-V.41-198811-I/en
Signed-off-by: Roger Knecht <roger@norberthealth.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
-rw-r--r-- | include/linux/crc-itu-t.h | 2 | ||||
-rw-r--r-- | lib/crc-itu-t.c | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/crc-itu-t.h b/include/linux/crc-itu-t.h index a4367051e192..2f991a427ade 100644 --- a/include/linux/crc-itu-t.h +++ b/include/linux/crc-itu-t.h @@ -4,7 +4,7 @@ * * Implements the standard CRC ITU-T V.41: * Width 16 - * Poly 0x1021 (x^16 + x^12 + x^15 + 1) + * Poly 0x1021 (x^16 + x^12 + x^5 + 1) * Init 0 */ diff --git a/lib/crc-itu-t.c b/lib/crc-itu-t.c index 1974b355c148..1d26a1647da5 100644 --- a/lib/crc-itu-t.c +++ b/lib/crc-itu-t.c @@ -7,7 +7,7 @@ #include <linux/module.h> #include <linux/crc-itu-t.h> -/** CRC table for the CRC ITU-T V.41 0x1021 (x^16 + x^12 + x^15 + 1) */ +/* CRC table for the CRC ITU-T V.41 0x1021 (x^16 + x^12 + x^5 + 1) */ const u16 crc_itu_t_table[256] = { 0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7, 0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef, |