This a little utility to calculate the CRC64 checksum, using the ECMA polynom. The original code is by Roman Nikitchenko (roman@nikitchenko.dp.ua), posted on StackOverflow.
The nifty trick here is that it is using a nested lookup table design invented by Mark Adler for increased performance, with performance tuned bitwise-ops to keep the amount of instructions per byte as low as possible.
So how fast is it you ask?
On my 2,3 GHz i7 MBP, I got 1150 MB/s using Java 8. The non-optimized version peaked at 375 MB/s, so thats about 3x faster.
The Jar is available via Maven Central: net.boeckling:crc-64:1.0.0