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IMHO it's a bit cheeky to use exp2 from the standard library. It's likely got all the same math exp does. Fortunately, if you know that your exponent is an integer, there's a constant time version. It's 5 instructions: add, and, shift, mov, ret.

https://godbolt.org/z/KNyoVd




Excellent, thank you! I agree, I had the use of `exp2(x)` on my list of implementation nits to revisit. I'm going to revise to use your method and credit the comment.


I think you can spare the "and", because if you overflow the exponent field, the result will be wrong either way.




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