From: Richard Henderson <rth@twiddle.net>
To: Akinobu Mita <mita@miraclelinux.com>,
linux-kernel@vger.kernel.org,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
Ian Molton <spyro@f2s.com>,
dev-etrax@axis.com, David Howells <dhowells@redhat.com>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Linus Torvalds <torvalds@osdl.org>,
linux-ia64@vger.kernel.org,
Hirokazu Takata <takata@linux-m32r.org>,
linux-m68k@vger.kernel.org, Greg Ungerer <gerg@uclinux.org>,
linux-mips@linux-mips.org, parisc-linux@parisc-linux.org,
linuxppc-dev@ozlabs.org, linux390@de.ibm.com,
linuxsh-dev@lists.sourceforge.net,
linuxsh-shmedia-dev@lists.sourceforge.net,
sparclinux@vger.kernel.org, ultralinux@vger.kernel.org,
Miles Bader <uclinux-v850@lsi.nec.co.jp>, Andi Kleen <ak@suse.de>,
Chris Zankel <chris@zankel.net>
Subject: Re: [PATCH 3/6] C-language equivalents of include/asm-*/bitops.h
Date: Wed, 25 Jan 2006 16:06:18 -0800 [thread overview]
Message-ID: <20060126000618.GA5592@twiddle.net> (raw)
In-Reply-To: <20060125200250.GA26443@flint.arm.linux.org.uk>
On Wed, Jan 25, 2006 at 08:02:50PM +0000, Russell King wrote:
> > + s = 16; if (word << 16 != 0) s = 0; b += s; word >>= s;
> > + s = 8; if (word << 24 != 0) s = 0; b += s; word >>= s;
> > + s = 4; if (word << 28 != 0) s = 0; b += s; word >>= s;
...
> Basically, shifts which depend on a variable are more expensive than
> constant-based shifts.
Actually, they're all constant shifts. Just written stupidly.
r~
next prev parent reply other threads:[~2006-01-26 0:59 UTC|newest]
Thread overview: 36+ 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
2006-01-26 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 23:25 ` Ian Molton
2006-01-26 0:06 ` Richard Henderson [this message]
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 ` Nicolas Pitre
2006-01-26 16:40 ` Russell King
2006-01-26 23:04 ` Grant Grundler
2006-01-26 23:03 ` Russell King
2006-01-29 7:12 ` Stuart Brady
2006-01-30 4:03 ` David S. Miller
2006-01-30 17:06 ` Ralf Baechle
2006-01-30 19:50 ` Stuart Brady
2006-01-30 23:02 ` David S. Miller
2006-01-27 0:28 ` [parisc-linux] Re: [PATCH 3/6] C-language equivalents of John David Anglin
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 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 ` Hirokazu Takata
2006-01-30 3:15 ` Akinobu Mita
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