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A fun read on word count optimization can be found in Abrash's Black Book:

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.

I wonder if large lookup tables/table-driven state machines are still as good as they used to be. After all, even with all the on-chip caches, the additional memory accesses today seem to be slower than doing some multi-instruction SIMD voodoo.

At least the GNU version of wc [0] uses AVX2 for line counting, if available. Though it falls back to a simple character-by-character loop if you ask for a character count [not to be confused with a byte count!] or a word count.

[0] https://git.savannah.gnu.org/cgit/coreutils.git/tree/src/wc_...

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