Messages in this thread | | | Subject | Re: [PATCH 10/31] Add sparc-specific parity functions | From | Zeng Zhaoxiu <> | Date | Mon, 28 Mar 2016 13:44:03 +0800 |
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在 2016年03月28日 10:43, David Miller 写道: > From: "zhaoxiu.zeng" <zhaoxiu.zeng@gmail.com> > 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.
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