https://www.jagregory.com/abrash-black-book/#lessons-learned...
You can gloss over the asm if you wish, the tricks that are explained around it are worth it imho.
[0] https://git.savannah.gnu.org/cgit/coreutils.git/tree/src/wc_...
And then the actual code explicitly filters out and ignores every character larger than 0x7F. Just why.
http://en.wikipedia.org/wiki/Plan_9_from_Bell_Labs follows the Unix philosophy. A lot of legacy has been shed. I can count 13 options to ls, 11 options to sed and just 5 to sed.
The standard Plan 9 shell, Rc, is described in mere ~500 lines of manpage, while Bash takes whooping ~5400 lines.
Oh, and there is no `dll hell' in P9 :-)