From: Sam Ravnborg <sam@ravnborg.org>
To: David Miller <davem@davemloft.net>
Cc: zhaoxiu.zeng@gmail.com, linux-kernel@vger.kernel.org,
sparclinux@vger.kernel.org
Subject: Re: [PATCH 10/31] Add sparc-specific parity functions
Date: Mon, 28 Mar 2016 17:37:43 +0200 [thread overview]
Message-ID: <20160328153743.GA13061@ravnborg.org> (raw)
In-Reply-To: <20160328.112915.1286498398436148099.davem@davemloft.net>
On Mon, Mar 28, 2016 at 11:29:15AM -0400, David Miller wrote:
> From: Zeng Zhaoxiu <zhaoxiu.zeng@gmail.com>
> Date: Mon, 28 Mar 2016 13:44:03 +0800
>
> > 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.
>
> Which is why said stanza's in the asm-generic header should be triggered
> by a CPP define or similar.
For sparc we would need to do a run-time patch as far as I see.
If popc is availble then use of hweight* should be fine.
But without popc then I think the generic implementation that
uses the stanford algorithm would be most efficient,
rather than the base this on the generic hweight functions.
Sam
next prev parent reply other threads:[~2016-03-28 15:37 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-24 3:03 [PATCH 01/31] bitops: add parity functions Zhaoxiu Zeng
2016-03-24 8:38 ` Denys Vlasenko
2016-03-24 22:28 ` Andrew Morton
2016-03-26 22:08 ` Martin Kepplinger
2016-03-27 7:51 ` zhaoxiu.zeng
2016-03-27 3:33 ` zhaoxiu.zeng
2016-03-27 12:44 ` Sam Ravnborg
2016-03-27 13:38 ` zhaoxiu.zeng
2016-03-27 17:56 ` Sam Ravnborg
2016-03-28 2:44 ` Zeng Zhaoxiu
2016-03-28 2:15 ` Zeng Zhaoxiu
2016-03-28 6:51 ` Sam Ravnborg
2016-03-29 2:27 ` Zeng Zhaoxiu
2016-03-29 2:56 ` Joe Perches
2016-03-27 4:02 ` [PATCH 02/31] Include generic parity.h in some architectures' bitops.h zhaoxiu.zeng
2016-03-27 5:43 ` [PATCH 03/31] Add alpha-specific parity functions zhaoxiu.zeng
2016-03-28 18:33 ` Richard Henderson
2016-03-27 5:47 ` [PATCH 04/31] Add avr32-specific " zhaoxiu.zeng
2016-03-28 20:00 ` Hans-Christian Noren Egtvedt
2016-03-27 5:53 ` [PATCH 05/31] Add blackfin-specific " zhaoxiu.zeng
2016-03-27 6:00 ` [PATCH 06/31] Add ia64-specific " zhaoxiu.zeng
2016-03-27 6:06 ` [PATCH 07/31] Add mips-specific " zhaoxiu.zeng
2016-03-28 17:25 ` David Daney
2016-03-29 2:15 ` Zeng Zhaoxiu
2016-03-27 6:10 ` [PATCH 08/31] Add tile-specific " zhaoxiu.zeng
2016-03-27 6:37 ` [PATCH 09/31] Add powerpc-specific " zhaoxiu.zeng
2016-03-27 6:43 ` [PATCH 10/31] Add sparc-specific " zhaoxiu.zeng
2016-03-28 2:43 ` David Miller
2016-03-28 5:44 ` Zeng Zhaoxiu
2016-03-28 15:29 ` David Miller
2016-03-28 15:37 ` Sam Ravnborg [this message]
2016-03-28 15:46 ` David Miller
2016-03-27 6:45 ` [PATCH 11/31] Add x86-specific " zhaoxiu.zeng
2016-03-29 12:11 ` One Thousand Gnomes
2016-03-27 6:51 ` [PATCH 12/31] sunrpc: auth_gss: use parity8 zhaoxiu.zeng
2016-03-27 6:55 ` [PATCH 13/31] mips: use parity functions in cerr-sb1.c zhaoxiu.zeng
2016-03-27 7:01 ` [PATCH 14/31] lib: bch: use parity32 zhaoxiu.zeng
2016-03-27 7:06 ` [PATCH 15/31] media: use parity8 in vivid-vbi-gen.c zhaoxiu.zeng
2016-03-27 7:10 ` [PATCH 16/31] media: saa7115: use parity functions zhaoxiu.zeng
2016-03-27 7:13 ` [PATCH 17/31] input: joystick: use parity32 in grip_mp.c zhaoxiu.zeng
2016-03-27 7:15 ` [PATCH 18/31] input: joystick: use parity64 in sidewinder.c zhaoxiu.zeng
2016-03-27 7:18 ` [PATCH 19/31] input: serio: use parity16 in ams_delta_serio.c zhaoxiu.zeng
2016-03-27 7:20 ` [PATCH 20/31] scsi: use parity32 in isci/phy.c zhaoxiu.zeng
2016-03-27 7:24 ` [PATCH 21/31] mtd: use parity16 in ssfdc.c zhaoxiu.zeng
2016-04-01 23:48 ` Brian Norris
2016-03-27 7:27 ` [PATCH 22/31] mtd: use parity functions in inftlcore.c zhaoxiu.zeng
2016-03-27 7:30 ` [PATCH 23/31] crypto: qat: use parity functions in qat_hal.c zhaoxiu.zeng
2016-03-27 7:33 ` [PATCH 24/31] mtd: use parity16 in sm_ftl.c zhaoxiu.zeng
2016-03-27 7:36 ` [PATCH 25/31] ethernet: use parity8 in sun/niu.c zhaoxiu.zeng
2016-03-28 14:33 ` Michal Nazarewicz
2016-03-27 7:38 ` [PATCH 26/31] input: serio: use parity8 in pcips2.c zhaoxiu.zeng
2016-03-27 7:40 ` [PATCH 27/31] input: serio: use parity8 in sa1111ps2.c zhaoxiu.zeng
2016-03-27 7:42 ` [PATCH 28/31] iio: gyro: use parity32 in adxrs450.c zhaoxiu.zeng
2016-03-28 8:35 ` Jonathan Cameron
2016-03-28 8:50 ` Lars-Peter Clausen
2016-03-27 7:44 ` [PATCH 29/31] serial: use parity32 in max3100.c zhaoxiu.zeng
2016-03-27 7:48 ` [PATCH 30/31] input: mouse: use parity8 in elantech zhaoxiu.zeng
2016-03-27 7:50 ` [PATCH 31/31] ethernet: broadcom: use parity8 in tg3.c zhaoxiu.zeng
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