Yes blibble's procedure has nothing to do with the actual calculation. The protocol says to treat the 256-bit hash as a little-endian integer, and then check if

Yes blibble's procedure has nothing to do with the actual calculation. The protocol says to treat the 256-bit hash as a little-endian integer, and then check if that is less than the target value. The target value is an integer value that is stored as a custom-format floating point value in the block header and adjusted every 2016 blocks. "Difficulty" per se doesn't actually exist at the protocol level, it's a purely human-interface concern.