Add two new functions: crc4 for generic calculations
of CRC4, and crc4_ti which use look-up table for
faster calculations of CRC4 algortihms that base
on 0x03 polynomial.
Signed-off-by: Michal Morsisko <morsisko@gmail.com>
lib/ was starting to get messy and inconsitent. Files being either
dumped in the root or in sub-directories without a clear plan.
Move all library components into one single folder and call it 'os'.
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
Used as a checksum on command messages when talking with MMC cards.
Implemented using the unwound bytewise implementation from
https://en.wikipedia.org/wiki/Computation_of_cyclic_redundancy_checks
which is a good mix of size and speed.
The API and naming matches lib/crc7.c in Linux.
Signed-off-by: Michael Hope <mlhx@google.com>
This is a minor change that makes the data pointer const and shifts
the length to a size_t to match the other CRC functions.
Signed-off-by: Michael Hope <mlhx@google.com>
The existing version of crc16_ccitt() is actually CRC-16/AUG-CCITT and
gives different results to Linux, Contiki, and the CRC unit in the
SAM0 SOC. This version matches Linux.
Note that this is an incompatible API change.
Signed-off-by: Michael Hope <mlhx@google.com>
Michal Morsisko