[libcxx-commits] [PATCH] D70640: Optimize std::midpoint for signed integers

[Andrej Korman via Phabricator via libcxx-commits]

Aj0SK added a comment.

Maybe I would add explanation why the term

  (__a & __b) + ((__a ^ __b) >> 1)

calculates the floored average. Adding a and b can be rewritten as a + b = (a ^ b) + ((a & b) << 1) . After this we have to divide a+b by 2. This can be done also using shifting to right by 1. After this we get (a + b)/2 = ((a ^ b) >>1) + (a & b).


Repository:
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  https://reviews.llvm.org/D70640/new/

https://reviews.llvm.org/D70640