From: Grant Grundler <iod00d@hp.com>
To: linux@horizon.com
Cc: linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org,
mita@miraclelinux.com
Subject: Re: [PATCH 8/12] generic hweight{32,16,8}()
Date: Tue, 31 Jan 2006 18:14:01 +0000 [thread overview]
Message-ID: <20060131181401.GB10640@esmail.cup.hp.com> (raw)
In-Reply-To: <20060131164949.3365.qmail@science.horizon.com>
On Tue, Jan 31, 2006 at 11:49:49AM -0500, linux@horizon.com wrote:
> This is an extremely well-known technique. You can see a similar version
> that uses a multiply for the last few steps at
> http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
> whch refers to
> "Software Optimization Guide for AMD Athlon 64 and Opteron Processors"
> http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/25112.PDF
...
> The next step consists of breaking up b (made of 16 2-bir fields) into
> even and odd halves and adding them into 4-bit fields. Since the largest
> possible sum is 2+2 = 4, which will not fit into a 4-bit field, the 2-bit
> fields have to be masked before they are added.
Up to here, things were clear.
My guess is you meant "which will not fit into a 2-bit field".
thanks,
grant
next prev parent reply other threads:[~2006-01-31 18:14 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-25 11:26 [PATCH 0/6] RFC: use include/asm-generic/bitops.h Akinobu Mita
2006-01-25 11:28 ` [PATCH 1/6] {set,clear,test}_bit() related cleanup Akinobu Mita
2006-01-25 11:46 ` Andi Kleen
2006-01-26 16:14 ` Pavel Machek
2006-01-26 16:47 ` Russell King
2006-01-26 19:14 ` Paul Jackson
2006-01-25 11:30 ` [PATCH 2/6] use non atomic operations for minix_*_bit() and ext2_*_bit() Akinobu Mita
2006-01-25 11:32 ` [PATCH 3/6] C-language equivalents of include/asm-*/bitops.h Akinobu Mita
2006-01-25 11:54 ` Keith Owens
2006-01-26 2:13 ` Akinobu Mita
2006-01-25 20:02 ` Russell King
2006-01-25 20:59 ` Grant Grundler
2006-01-26 3:27 ` Akinobu Mita
2006-01-26 3:29 ` [PATCH 1/12] generic *_bit() Akinobu Mita
2006-02-01 15:11 ` Chen, Kenneth W
2006-02-01 18:02 ` Christoph Hellwig
2006-02-01 18:07 ` Chen, Kenneth W
2006-02-01 19:19 ` Russell King
2006-02-03 10:24 ` Geert Uytterhoeven
2006-02-03 10:27 ` Russell King
2006-02-01 19:39 ` Grant Grundler
2006-02-02 22:43 ` Paul Mackerras
2006-02-01 19:25 ` Chen, Kenneth W
2006-02-01 19:35 ` Russell King
2006-02-01 21:41 ` Chen, Kenneth W
2006-02-01 22:09 ` Grant Grundler
2006-02-01 22:49 ` Anton Altaparmakov
2006-02-02 0:08 ` Grant Grundler
2006-02-02 8:52 ` Anton Altaparmakov
2006-02-02 10:13 ` Andreas Schwab
2006-02-03 17:07 ` Luck, Tony
2006-01-26 3:30 ` [PATCH 2/12] generic __ffs() Akinobu Mita
2006-01-26 3:31 ` [PATCH 3/12] generic ffz() Akinobu Mita
2006-01-26 8:21 ` Michael Tokarev
2006-01-27 6:39 ` [PATCH] parisc: add ()-pair in __ffs() Akinobu Mita
2006-01-26 3:32 ` [PATCH 4/12] generic fls() and fls64() Akinobu Mita
2006-01-26 3:33 ` [PATCH 5/12] generic find_{next,first}{,_zero}_bit() Akinobu Mita
2006-01-26 3:34 ` [PATCH 6/12] generic sched_find_first_bit() Akinobu Mita
2006-01-26 3:35 ` [PATCH 7/12] generic ffs() Akinobu Mita
2006-01-26 3:36 ` [PATCH 8/12] generic hweight{32,16,8}() Akinobu Mita
2006-01-26 7:24 ` Balbir Singh
2006-01-26 10:04 ` Rutger Nijlunsing
2006-01-27 4:55 ` Akinobu Mita
2006-01-27 5:52 ` Balbir Singh
2006-01-27 6:40 ` Akinobu Mita
2006-01-31 11:26 ` Balbir Singh
2006-01-26 18:57 ` Bryan O'Sullivan
2006-01-27 4:43 ` Akinobu Mita
2006-01-27 5:23 ` Bryan O'Sullivan
2006-01-31 16:49 ` linux
2006-01-31 18:14 ` Grant Grundler [this message]
2006-02-02 9:46 ` Balbir Singh
2006-01-26 3:36 ` [PATCH 9/12] generic hweight64() Akinobu Mita
2006-01-26 7:17 ` Balbir Singh
2006-01-26 3:38 ` [PATCH 10/12] generic ext2_{set,clear,test,find_first_zero,find_next_zero}_bit() Akinobu Mita
2006-01-26 3:38 ` [PATCH 11/12] generic ext2_{set,clear}_bit_atomic() Akinobu Mita
2006-01-26 3:39 ` [PATCH 12/12] generic minix_{test,set,test_and_clear,test,find_first_zero}_bit() Akinobu Mita
2006-01-25 23:25 ` [PATCH 3/6] C-language equivalents of include/asm-*/bitops.h Ian Molton
2006-01-26 0:06 ` Richard Henderson
2006-01-26 4:34 ` Edgar Toernig
2006-01-26 17:30 ` Richard Henderson
2006-01-26 8:55 ` Russell King
2006-01-26 16:18 ` [parisc-linux] " Grant Grundler
2006-01-26 16:30 ` [parisc-linux] Re: [PATCH 3/6] C-language equivalents of Nicolas Pitre
2006-01-27 0:28 ` John David Anglin
2006-01-26 16:40 ` [parisc-linux] Re: [PATCH 3/6] C-language equivalents of include/asm-*/bitops.h Russell King
2006-01-26 22:55 ` Grant Grundler
2006-01-26 23:03 ` Russell King
2006-01-29 7:12 ` Stuart Brady
2006-01-30 4:03 ` [parisc-linux] Re: [PATCH 3/6] C-language equivalents of David S. Miller
2006-01-30 17:06 ` [parisc-linux] Re: [PATCH 3/6] C-language equivalents of include/asm-*/bitops.h Ralf Baechle
2006-01-30 19:50 ` Stuart Brady
2006-01-30 23:02 ` [parisc-linux] Re: [PATCH 3/6] C-language equivalents of David S. Miller
2006-01-27 12:51 ` [PATCH 3/6] C-language equivalents of include/asm-*/bitops.h Hirokazu Takata
2006-01-30 3:29 ` Akinobu Mita
2006-01-25 11:34 ` [PATCH 5/6] fix warning on test_ti_thread_flag() Akinobu Mita
2006-01-25 12:28 ` Geert Uytterhoeven
2006-01-25 17:08 ` Chen, Kenneth W
2006-01-25 17:19 ` Geert Uytterhoeven
2006-01-25 20:02 ` Chen, Kenneth W
2006-01-26 3:50 ` Akinobu Mita
2006-01-26 4:12 ` Paul Mackerras
2006-01-25 22:28 ` Paul Mackerras
2006-01-26 0:04 ` David S. Miller
2006-01-25 11:35 ` [PATCH 6/6] remove unused generic bitops in include/linux/bitops.h Akinobu Mita
[not found] ` <20060125113336.GE18584@miraclelinux.com>
2006-01-26 1:49 ` [PATCH 4/6] use include/asm-generic/bitops for each architecture Akinobu Mita
2006-01-27 13:04 ` [PATCH 4/6] use include/asm-generic/bitops for each Hirokazu Takata
2006-01-30 3:15 ` [PATCH 4/6] use include/asm-generic/bitops for each architecture Akinobu Mita
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