[U-Boot-Users] [PATCH] ppc: Add u64 versions of fls64 and __ilog bitops

[Wolfgang Denk]

Dear Kumar,

in message <3F2661BD-8C86-410F-984D-B887242A8AA2 at kernel.crashing.org> you wrote:
> 
> > Comments and code do not match; you'r actually adding much more code.
> 
> I was just needing the u64 versions and the other stuff came along to  
> make it work :)

Please make the comment match the code.

> > Also: is fls() vs. __fls() a good way to differentiate between int and
> > ulong?
> 
> I took this from the kernel source tree and didn't really pay much  
> attention to it.

Maybe we can do better?

> >> + * fls64(value) returns 0 if value is 0 or the position of the last
> >> + * set bit if value is nonzero. The last (most significant) bit is
> >
> > Sorry, I can't parse this.
> 
> again taken from kernel land.

No reason not to fix it.

> >> +#elif BITS_PER_LONG == 64
> >> +static inline int fls64(__u64 x)
> >> +{
> >> +	if (x == 0)
> >> +		return 0;
> >> +	return __fls(x) + 1;
> >
> > Do I  have to understand where the "+1" is coming from?
> 
> Nope, you can just accept it.  I can drop this for now since I don't  
> believe we support any ppc64 machines.

I guess we might see support for the PA6T soon. SO please leave it
here.

And I'd appreciate if somebody could explain the code to me...

> >> +static inline int ffs64(u64 x)
> >> +{
> >> +	return __ilog2_u64(x & -x) + 1ull;
> >
> > Isn't there an easier way to do this?
> 
> Not aware of one.
> 
> So, I've stolen this from the kernel and am not sure what you'd like  
> for me to change at this point.

Please clean it up and fix at least the obvious issues.

Best regards,

Wolfgang Denk

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