Another (stupid) question: "find first set" (or "find first zero")

Hi

I am wasti.... devoting some time to recreational hacking and I bumped into an interesting bit fiddling operation.

I pored over the CLHS, but, while I may have missed something obvious, I am not sure what would be the best way to implement such a function using the standard operations.

Any ideas?

Note that it appears that most HW does have an instruction to do that directly. Find first set - Wikipedia https://en.wikipedia.org/wiki/Find_first_set

Thanks Marco