Re: [musl] [C23 new stdlib 2/4] C23: add the memalignment function

["Jₑₙₛ Gustedt" <jens.gustedt@inria.fr>]

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Alexander,

on Thu, 1 Jun 2023 16:35:04 +0300 (MSK) you (Alexander Monakov
<amonakov@ispras.ru>) wrote:

> On Thu, 25 May 2023, Jₑₙₛ Gustedt wrote:
> 
> > Rich,
> > 
> > on Wed, 24 May 2023 17:28:35 -0400 you (Rich Felker
> > <dalias@libc.org>) wrote:
> >   
> > > There's a more efficient implementation of this function which
> > > does not depend on __builtin_ctzll (which we don't): p^(p-1)&p  
> > 
> > yes, nice
> > 
> > If you have other such nice formulas for some of the interfaces in
> > <stdbit.h>, please let me know. They are hard to find in search
> > engines.  
> 
> It seems this was unanswered. Hacker's Delight by Henry Warren offers
> a lot of material on such topics. For this particular question it also
> gives the efficient implementation: 'p & -p'.

right, even better

> I looked over the recently posted stdbit.h patch and I don't have
> anything to suggest in terms of formulas. The things that would worry
> me are of a different nature anyway.

Could you share those that concern this particular new header
<stdbit.h> ? (Perhaps in the thread with the patches?)

Thanks
Jₑₙₛ

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