[ros-dev] ping Alex regarding log2() for scheduler

[Royce Mitchell III]

Rick Parrish wrote:

> Couldn't you just take the binary log and round down? Okay ... just 
> kidding.
>
> Seriously, I think Mark had the right idea ... if you use a smaller 
> table. This is similar to some ECC code I use for counting the number 
> of 1's in a word. Removing the while() loop is left "as an exercise 
> for the reader" ...
>
> static const unsigned char list[16] = {0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 
> 4, 4, 4, 4, 4, 4};
>
I have experimented with both 16 and 256 entry tables. 16 = somewhat 
slower than no tables, 256 = somewhat faster than no tables, but both of 
those results are based on the code and tables getting cached. I don't 
anticipate our particular target benefiting from cache coherency... it 
runs very frequently, but not in a tight loop.