From: Yury Norov <yury.norov@gmail.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jacob Keller <jacob.e.keller@intel.com>,
David Laight <david.laight.linux@gmail.com>,
Jiri Slaby <jirislaby@kernel.org>, Ingo Molnar <mingo@kernel.org>,
Kuan-Wei Chiu <visitorckw@gmail.com>,
tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, x86@kernel.org, jk@ozlabs.org,
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linux-serial@vger.kernel.org, bpf@vger.kernel.org,
jserv@ccns.ncku.edu.tw, Yu-Chun Lin <eleanor15x@gmail.com>
Subject: Re: [PATCH v3 01/16] bitops: Change parity8() return type to bool
Date: Thu, 13 Mar 2025 12:24:38 -0400 [thread overview]
Message-ID: <Z9MGxknjluvbX19w@thinkpad> (raw)
In-Reply-To: <0F794C6F-32A9-4F34-9516-CEE24EA4BC49@zytor.com>
On Wed, Mar 12, 2025 at 05:09:16PM -0700, H. Peter Anvin wrote:
> On March 12, 2025 4:56:31 PM PDT, Jacob Keller <jacob.e.keller@intel.com> wrote:
[...]
> >This is really a question of whether you expect odd or even parity as
> >the "true" value. I think that would depend on context, and we may not
> >reach a good consensus.
> >
> >I do agree that my brain would jump to "true is even, false is odd".
> >However, I also agree returning the value as 0 for even and 1 for odd
> >kind of made sense before, and updating this to be a bool and then
> >requiring to switch all the callers is a bit obnoxious...
>
> Odd = 1 = true is the only same definition. It is a bitwise XOR, or sum mod 1.
The x86 implementation will be "popcnt(val) & 1", right? So if we
choose to go with odd == false, we'll have to add an extra negation.
So because it's a purely conventional thing, let's just pick a simpler
one?
Compiler's builtin parity() returns 1 for odd.
Thanks,
Yury
next prev parent reply other threads:[~2025-03-13 16:24 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-06 16:25 [PATCH v3 00/16] Introduce and use generic parity16/32/64 helper Kuan-Wei Chiu
2025-03-06 16:25 ` [PATCH v3 01/16] bitops: Change parity8() return type to bool Kuan-Wei Chiu
2025-03-06 20:45 ` David Laight
2025-03-07 6:48 ` Jiri Slaby
2025-03-07 11:38 ` Ingo Molnar
2025-03-07 11:42 ` Jiri Slaby
2025-03-07 12:13 ` Ingo Molnar
2025-03-07 12:14 ` H. Peter Anvin
2025-03-07 19:30 ` Yury Norov
2025-03-07 19:33 ` H. Peter Anvin
2025-03-13 16:26 ` Yury Norov
2025-03-07 19:36 ` David Laight
2025-03-07 19:39 ` H. Peter Anvin
2025-03-12 23:56 ` Jacob Keller
2025-03-13 0:09 ` H. Peter Anvin
2025-03-13 16:24 ` Yury Norov [this message]
2025-03-13 16:36 ` H. Peter Anvin
2025-03-13 21:09 ` Jacob Keller
2025-03-14 19:06 ` David Laight
2025-03-15 0:14 ` H. Peter Anvin
2025-03-06 16:25 ` [PATCH v3 02/16] bitops: Add parity16(), parity32(), and parity64() helpers Kuan-Wei Chiu
2025-03-06 16:25 ` [PATCH v3 03/16] media: media/test_drivers: Replace open-coded parity calculation with parity8() Kuan-Wei Chiu
2025-03-06 16:25 ` [PATCH v3 04/16] media: pci: cx18-av-vbi: " Kuan-Wei Chiu
2025-03-06 16:25 ` [PATCH v3 05/16] media: saa7115: " Kuan-Wei Chiu
2025-03-06 16:25 ` [PATCH v3 06/16] serial: max3100: " Kuan-Wei Chiu
2025-03-06 16:25 ` [PATCH v3 07/16] lib/bch: Replace open-coded parity calculation with parity32() Kuan-Wei Chiu
2025-03-06 16:25 ` [PATCH v3 08/16] Input: joystick - " Kuan-Wei Chiu
2025-03-06 16:25 ` [PATCH v3 09/16] net: ethernet: oa_tc6: " Kuan-Wei Chiu
2025-03-06 16:25 ` [PATCH v3 10/16] wifi: brcm80211: " Kuan-Wei Chiu
2025-03-06 16:25 ` [PATCH v3 11/16] drm/bridge: dw-hdmi: " Kuan-Wei Chiu
2025-03-06 16:25 ` [PATCH v3 12/16] mtd: ssfdc: " Kuan-Wei Chiu
2025-03-06 16:25 ` [PATCH v3 13/16] fsi: i2cr: " Kuan-Wei Chiu
2025-03-06 16:25 ` [PATCH v3 14/16] fsi: i2cr: Replace open-coded parity calculation with parity64() Kuan-Wei Chiu
2025-03-06 16:25 ` [PATCH v3 15/16] Input: joystick - " Kuan-Wei Chiu
2025-03-06 16:25 ` [PATCH v3 16/16] nfp: bpf: " Kuan-Wei Chiu
2025-03-07 3:08 ` [PATCH v3 00/16] Introduce and use generic parity16/32/64 helper H. Peter Anvin
2025-03-07 18:49 ` Andrew Cooper
2025-03-07 19:30 ` H. Peter Anvin
2025-03-07 19:53 ` David Laight
2025-03-07 20:07 ` H. Peter Anvin
2025-03-09 15:48 ` Kuan-Wei Chiu
2025-03-09 16:00 ` H. Peter Anvin
2025-03-09 17:42 ` Jiri Slaby
2025-03-11 22:01 ` Yury Norov
2025-03-11 22:24 ` H. Peter Anvin
2025-03-12 15:51 ` Yury Norov
2025-03-12 16:29 ` Kuan-Wei Chiu
2025-03-13 7:41 ` Kuan-Wei Chiu
2025-03-23 15:16 ` Kuan-Wei Chiu
2025-03-23 22:40 ` H. Peter Anvin
2025-03-24 15:53 ` Yury Norov
2025-03-29 16:00 ` Kuan-Wei Chiu
2025-03-25 19:43 ` H. Peter Anvin
2025-04-03 14:39 ` Kuan-Wei Chiu
2025-04-03 16:14 ` Yury Norov
2025-04-03 16:54 ` Kuan-Wei Chiu
2025-04-04 2:51 ` Jeremy Kerr
2025-04-04 8:46 ` Kuan-Wei Chiu
2025-04-04 9:01 ` Jeremy Kerr
2025-04-04 8:47 ` Kuan-Wei Chiu
2025-03-07 3:14 ` H. Peter Anvin
2025-03-07 9:19 ` Kuan-Wei Chiu
2025-03-07 10:52 ` Jiri Slaby
2025-03-07 6:57 ` Jiri Slaby
2025-03-07 9:22 ` Kuan-Wei Chiu
2025-03-07 15:55 ` Yury Norov
2025-03-07 18:30 ` Kuan-Wei Chiu
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