Awesome
countbench
Benchmark for histograms of byte frequencies.
Faster versions of functions based on Yann Collet's https://github.com/Cyan4973/FiniteStateEntropy/blob/master/test/fullbench.c
Description and some sample timings on Yann's blog: http://fastcompression.blogspot.com/2014/09/counting-bytes-fast-little-trick-from.html
Includes tests from https://github.com/powturbo/turbohist