Re: [PATCH 10/31] Add sparc-specific parity functions

[Zeng Zhaoxiu]

å 2016å03æ28æ 10:43, David Miller åé:
> From: "zhaoxiu.zeng" <zhaoxiu.zeng@xxxxxxxxx>
> Date: Sun, 27 Mar 2016 14:43:10 +0800
>
> > +
> > +/*
> > + * parityN: returns the parity of a N-bit word,
> > + * i.e. the number of 1-bits in x modulo 2.
> > + */
> > +
> > +#define __arch_parity4(w)	(__arch_hweight8((w) & 0xf) & 1)
> > +#define __arch_parity8(w)	(__arch_hweight8(w) & 1)
> > +#define __arch_parity16(w)	(__arch_hweight16(w) & 1)
> > +#define __arch_parity32(w)	(__arch_hweight32(w) & 1)
> > +#define __arch_parity64(w)	((unsigned int)__arch_hweight64(w) & 1)
> This looks like asm-generic/ material to me.

This is generic for the architectures which have popcount instruction,
but more higher costs than asm-generic/ for others.