Updated version of CrC calculations by Mecanix #933
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crc files from Mecanix
Part of the crc alternative suggested by Mecanix
Wrong cut& paste, sorry
File in wrong directory
mutatrum
approved these changes
May 21, 2025
Initialize variables so the code can be compiled with -O2 option.
eandersson
approved these changes
May 22, 2025
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Updated crc files from Mecanix
[quote from Mecanix]
Had a pretty severe sense of humour failure today after finding out that my ISR was choking on sending & receiving asic packets. Turned out to be that dead-slow array shuffling madness (a.k.a.crcin[]/crcout[]) from that 1968 style CRC5().
See attached for a reworked ver of that. Some more on the crc16. Benchmark below:
GCC, Optimization level: -Ofast (production/release)
Cycles (Optimized): 529
Cycles (Slow crc5): 1114
Cycles (Optimized): 452
Cycles (Slow crc5): 1103
Verdict: 2.44X FASTER
GCC, Optimization level: -Og (dev/debug)
Cycles (Optimized): 3266
Cycles (Slow crc5): 3938
Cycles (Optimized): 3227
Cycles (Slow crc5): 3931
Verdict: 1.22X FASTER
When protocol timing and latency matters...