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From: "H. Peter Anvin" <hpa@zytor.com>
To: Andrea Mazzoleni <amadvance@gmail.com>
Cc: David Brown <david.brown@hesbynett.no>,
	Linux RAID Mailing List <linux-raid@vger.kernel.org>,
	Btrfs BTRFS <linux-btrfs@vger.kernel.org>,
	David Smith <creamyfish@gmail.com>
Subject: Re: Triple parity and beyond
Date: Wed, 20 Nov 2013 11:00:12 -0800	[thread overview]
Message-ID: <528D06BC.3070504@zytor.com> (raw)
In-Reply-To: <CAGKKSfV-jie=6X+DuJJB6L7AdW4f83bQofYHBHwuuZvV+6mUxg@mail.gmail.com>

On 11/20/2013 10:56 AM, Andrea Mazzoleni wrote:
> Hi,
> 
> Yep. At present to multiply for 2^-1 I'm using in C:
> 
> static inline uint64_t d2_64(uint64_t v)
> {
>         uint64_t mask = v & 0x0101010101010101U;
>         mask = (mask << 8) - mask;

(mask << 7) I assume...


  parent reply	other threads:[~2013-11-20 19:00 UTC|newest]

Thread overview: 113+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-11-18 22:08 Triple parity and beyond Andrea Mazzoleni
2013-11-18 22:12 ` H. Peter Anvin
2013-11-18 22:35   ` Andrea Mazzoleni
2013-11-18 23:25     ` H. Peter Anvin
2013-11-19 10:16       ` David Brown
2013-11-19 17:36         ` Andrea Mazzoleni
2013-11-19 22:51           ` Drew
2013-11-20  0:54             ` Chris Murphy
2013-11-20  1:23               ` John Williams
2013-11-20 10:35                 ` David Brown
2013-11-20 10:31           ` David Brown
2013-11-20 18:09             ` John Williams
2013-11-20 18:44               ` Andrea Mazzoleni
2013-11-21  6:15                 ` Stan Hoeppner
2013-11-21  8:32               ` David Brown
2013-11-20 18:34             ` Andrea Mazzoleni
2013-11-20 18:43               ` H. Peter Anvin
2013-11-20 18:56                 ` Andrea Mazzoleni
2013-11-20 18:59                   ` H. Peter Anvin
2013-11-20 21:21                     ` Andrea Mazzoleni
2013-11-20 19:00                   ` H. Peter Anvin [this message]
2013-11-20 21:04                     ` Andrea Mazzoleni
2013-11-20 21:06                       ` H. Peter Anvin
2013-11-21  8:36               ` David Brown
2013-11-19 17:28       ` Andrea Mazzoleni
2013-11-19 20:29         ` Ric Wheeler
2013-11-20 16:16           ` James Plank
2013-11-20 19:05             ` Andrea Mazzoleni
2013-11-20 19:10               ` H. Peter Anvin
2013-11-20 20:30                 ` James Plank
2013-11-20 21:23                   ` Andrea Mazzoleni
2013-11-27  2:50                     ` ronnie sahlberg
2013-11-20 21:28                   ` H. Peter Anvin
2013-11-21  1:28             ` Stan Hoeppner
2013-11-21  2:46               ` John Williams
2013-11-21  6:52                 ` Stan Hoeppner
2013-11-21  7:05                   ` John Williams
2013-11-21 22:57                     ` Stan Hoeppner
2013-11-21 23:38                       ` John Williams
2013-11-22  9:35                         ` Stan Hoeppner
2013-11-22 11:24                           ` joystick
2013-11-22 15:01                           ` John Williams
2013-11-22 22:28                             ` Stan Hoeppner
2013-11-22 23:07                       ` NeilBrown
2013-11-23  3:46                         ` Stan Hoeppner
2013-11-23  5:04                           ` NeilBrown
2013-11-23  5:34                             ` John Williams
2013-11-23  7:12                               ` NeilBrown
2013-11-24  4:03                                 ` Stan Hoeppner
2013-11-24  4:03                                   ` Stan Hoeppner
2013-11-24  5:14                                   ` John Williams
2013-11-24 21:13                                     ` Stan Hoeppner
2013-11-24 21:13                                       ` Stan Hoeppner
2013-11-24 23:28                                       ` Rudy Zijlstra
2013-11-24 23:28                                         ` Rudy Zijlstra
2013-11-24 23:53                                       ` Alex Elsayed
2013-11-25  2:04                                         ` Stan Hoeppner
2013-11-25  2:04                                           ` Stan Hoeppner
2013-11-25  4:48                                           ` Alex Elsayed
2013-11-25  9:15                                       ` David Brown
2013-11-25  9:15                                         ` David Brown
2013-11-24  5:19                                   ` Russell Coker
2013-11-24 21:44                                     ` Stan Hoeppner
2013-11-24 22:31                                       ` Mark Knecht
2013-11-25  2:14                                       ` Russell Coker
2013-11-25  9:20                                         ` David Brown
2013-11-21  8:08               ` joystick
2013-11-22  0:30                 ` Stan Hoeppner
2013-11-22  0:33                   ` H. Peter Anvin
2013-11-22  0:45                   ` David Brown
2013-11-21  9:07               ` David Brown
2013-11-21  9:54                 ` Adam Goryachev
2013-11-21 10:32                   ` David Brown
2013-11-22  8:12                   ` Russell Coker
2013-11-25 18:23                     ` Pasi Kärkkäinen
2013-11-22  8:13                 ` Stan Hoeppner
2013-11-22 13:15                   ` David Brown
2013-11-22 16:07                   ` Stan Hoeppner
2013-11-22 22:59                     ` NeilBrown
2013-11-23 17:39                       ` David Brown
2013-11-22 16:50                   ` Mark Knecht
2013-11-22 19:51                     ` Duncan
2013-11-22 19:51                       ` Duncan
2013-11-22  8:38                 ` Stan Hoeppner
2013-11-22 13:24                   ` David Brown
2013-11-28  7:16                     ` Stan Hoeppner
2013-11-28  7:36                       ` Russell Coker
2013-11-28  9:56                       ` David Brown
2013-11-30  7:32                       ` Alex Elsayed
2013-12-01 15:37                         ` Stan Hoeppner
2013-11-22 14:19                   ` David Taylor
2013-11-21 19:56               ` Piergiorgio Sartor
2013-11-19 18:12 ` Piergiorgio Sartor
2013-11-20 10:44   ` David Brown
2013-11-20 21:59     ` Piergiorgio Sartor
2013-11-20 21:59       ` Piergiorgio Sartor
2013-11-21 10:13       ` David Brown
2013-11-21 10:13         ` David Brown
2013-11-21 17:37         ` Goffredo Baroncelli
2013-11-21 17:37           ` Goffredo Baroncelli
2013-11-21 20:05         ` Piergiorgio Sartor
2013-11-21 20:31           ` David Brown
2013-11-21 20:52             ` Piergiorgio Sartor
2013-11-22  0:32               ` David Brown
2013-11-22 20:32                 ` Piergiorgio Sartor
2013-11-26 18:10             ` joystick
2013-11-20 21:38   ` Andrea Mazzoleni
2013-11-20 22:29 ` Piergiorgio Sartor
2013-11-23  7:55   ` Andrea Mazzoleni
2013-11-23 22:10     ` Piergiorgio Sartor
2013-11-24  9:39       ` Andrea Mazzoleni
  -- strict thread matches above, loose matches on Subject: below --
2013-12-01 17:53 Richard Scobie
2013-12-02  4:30 ` Stan Hoeppner

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