Update of bug #37901 (project avr-libc):
Open/Closed: Closed => Open
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Follow-up Comment #3:
> The standard CCITT CRC should produce an endian
> and bit-order independent result that is compatible
> with other implementations.
It's simply impossible to implement a bit-order independent CRC. The
existing _crc_ccitt_update() is known to work with any kind of
communication protocol that transfers the low-order bit first (not
only IrDA but many others; probably any communication protocol except
USB works this way).
If anyone wants the opposite-bit-order CRC function that is compatible
with the Xmega CRC, they ought to use _crc_xmodem_update().
Yes, renaming anything is sheer impossible, as it would break
backwards compatibility for all those people who use the current
functions.
I reopen the bug report so you can append a patch that you think would
make the documentation clearer on this. Perhaps mention that
_crc_xmodem_update() is the one that is compatible with the Xmega CRC?
Insert a paragraph describing the bit-order problem?
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