Yes, I figured that I could and probably will lift the CRC code for standalone use.
Some versions of my code will also use the SDfat library tho, which means that in those versions I'll have two copies of essentially the same CRC code and table loaded in memory, right? (my own lifted copy, and the copy built into SDfat).
What I was wondering was whether SDfat could be refactored so that the CRC code was separate, but used by SDfat, like SPI.
Case 1: using standalone CRC library only, no SDFat loaded
Case 2: using standalone CRC library and SDfat, latter of which also (potentially) uses the same standalone CRC library code & table
Case 3: using SDfat only without CRC support - no CRC code & table loaded (maybe)