As described in #42403, there was an issue with the existing crc16_ansi()
implementation, since it was not calculating the CRC-16-ANSI (aka
CRC-16-MODBUS). This is because the existing crc16() function only
supported non-reflected input and output (and the CRC-16-ANSI requires
reflection on both) and also it did not seem to support correctly inial
seeds different from 0x0000 (and, again, the CRC-16-ANSI requires 0xffff
as an initial seed).
This commit replaces the existing crc16() with a functional pair,
crc16() and crc16_reflect(), that also work with any poly, any initial seed
and allow to select whether reflection is performed.
It also adapts crc16_ansi() so that it actually returns the correct CRC.
Fixes#42403.
Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
The crc16_ccitt and crc16_itu_t functions' documentation could lead to
slight misunderstandings because of the fact that, although they bear
those names, those functions are actually able to compute CRCs that bear
other names, depending on the inital seed provided and an optional XOR
on the result.
In order to avoid confusion, document thoroughly with links to the
standard reveng page that lists all existing CRCs.
Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
This introduces the support for CRC32C (Castagnoli) algorithm.
The generator polynomial used is 0x1EDC6F41UL.
Signed-off-by: Rajavardhan Gundi <rajavardhan.gundi@intel.com>
move crc.h to sys/crc.h and
create a shim for backward-compatibility.
No functional changes to the headers.
A warning in the shim can be controlled with CONFIG_COMPAT_INCLUDES.
Related to #16539
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
