From: Akinobu Mita <mita@miraclelinux.com>
To: linux-kernel@vger.kernel.org
Cc: Greg Ungerer <gerg@uclinux.org>,
linux-mips@linux-mips.org, sparclinux@vger.kernel.org,
ultralinux@vger.kernel.org, Akinobu Mita <mita@miraclelinux.com>
Subject: [patch 13/44] generic ffs()
Date: Wed, 01 Feb 2006 18:02:37 +0900 [thread overview]
Message-ID: <20060201090325.696670000@localhost.localdomain> (raw)
In-Reply-To: 20060201090224.536581000@localhost.localdomain
[-- Attachment #1: ffs-bitops.patch --]
[-- Type: text/plain, Size: 1195 bytes --]
This patch introduces the C-language equivalent of the function:
int ffs(int x);
In include/asm-generic/bitops/ffs.h
This code largely copied from:
include/linux/bitops.h
Signed-off-by: Akinobu Mita <mita@miraclelinux.com>
include/asm-generic/bitops/ffs.h | 41 +++++++++++++++++++++++++++++++++++++++
1 files changed, 41 insertions(+)
Index: 2.6-git/include/asm-generic/bitops/ffs.h
===================================================================
--- /dev/null
+++ 2.6-git/include/asm-generic/bitops/ffs.h
@@ -0,0 +1,41 @@
+#ifndef _ASM_GENERIC_BITOPS_FFS_H_
+#define _ASM_GENERIC_BITOPS_FFS_H_
+
+/**
+ * ffs - find first bit set
+ * @x: the word to search
+ *
+ * This is defined the same way as
+ * the libc and compiler builtin ffs routines, therefore
+ * differs in spirit from the above ffz (man ffs).
+ */
+static inline int ffs(int x)
+{
+ int r = 1;
+
+ if (!x)
+ return 0;
+ if (!(x & 0xffff)) {
+ x >>= 16;
+ r += 16;
+ }
+ if (!(x & 0xff)) {
+ x >>= 8;
+ r += 8;
+ }
+ if (!(x & 0xf)) {
+ x >>= 4;
+ r += 4;
+ }
+ if (!(x & 3)) {
+ x >>= 2;
+ r += 2;
+ }
+ if (!(x & 1)) {
+ x >>= 1;
+ r += 1;
+ }
+ return r;
+}
+
+#endif /* _ASM_GENERIC_BITOPS_FFS_H_ */
--
next prev parent reply other threads:[~2006-02-01 9:19 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-01 9:02 [patch 00/44] generic bitops Akinobu Mita
2006-02-01 9:02 ` [patch 01/44] ia64: use cpu_set() instead of __set_bit() Akinobu Mita
2006-02-01 9:02 ` [patch 02/44] parisc: add ()-pair in __ffz() macro Akinobu Mita
2006-02-01 9:02 ` [patch 03/44] cris: remove unnecessary local_irq_restore() Akinobu Mita
2006-02-01 9:02 ` [patch 04/44] use non atomic operations for minix_*_bit() and ext2_*_bit() Akinobu Mita
2006-02-01 9:02 ` [patch 05/44] generic {,test_and_}{set,clear,change}_bit() Akinobu Mita
2006-02-03 9:55 ` Martin Waitz
2006-02-06 23:07 ` Russell King
2006-02-01 9:02 ` [patch 06/44] generic __{,test_and_}{set,clear,change}_bit() and test_bit() Akinobu Mita
2006-02-01 9:02 ` [patch 07/44] generic __ffs() Akinobu Mita
2006-02-01 9:02 ` [patch 08/44] generic ffz() Akinobu Mita
2006-02-01 9:02 ` [patch 09/44] generic fls() Akinobu Mita
2006-02-01 9:02 ` [patch 10/44] generic fls64() Akinobu Mita
2006-02-01 9:02 ` [patch 11/44] generic find_{next,first}{,_zero}_bit() Akinobu Mita
2006-02-01 9:02 ` [patch 12/44] generic sched_find_first_bit() Akinobu Mita
2006-02-03 3:58 ` [parisc-linux] " Grant Grundler
2006-02-01 9:02 ` Akinobu Mita [this message]
2006-02-01 9:02 ` [patch 14/44] generic hweight{64,32,16,8}() Akinobu Mita
2006-02-01 9:06 ` Andi Kleen
2006-02-01 9:26 ` Michael Tokarev
2006-02-01 10:24 ` Andi Kleen
2006-02-02 12:50 ` Akinobu Mita
2006-02-09 5:55 ` [PATCH] alpha: remove __alpha_cix__ and __alpha_fix__ Akinobu Mita
2006-02-09 19:12 ` Richard Henderson
2006-02-10 5:40 ` Akinobu Mita
2006-02-02 1:26 ` [patch 14/44] generic hweight{64,32,16,8}() Gabriel Paubert
2006-02-06 11:52 ` Akinobu Mita
2006-02-03 8:31 ` Ulrich Eckhardt
2006-02-01 9:02 ` [patch 15/44] generic ext2_{set,clear,test,find_first_zero,find_next_zero}_bit() Akinobu Mita
2006-02-01 11:27 ` Roman Zippel
2006-02-06 11:47 ` Akinobu Mita
2006-02-08 10:41 ` Akinobu Mita
2006-02-01 9:02 ` [patch 16/44] generic ext2_{set,clear}_bit_atomic() Akinobu Mita
2006-02-01 9:02 ` [patch 17/44] generic minix_{test,set,test_and_clear,test,find_first_zero}_bit() Akinobu Mita
2006-02-01 9:02 ` [patch 18/44] alpha: use generic bitops Akinobu Mita
2006-02-01 9:02 ` [patch 19/44] arm: " Akinobu Mita
2006-02-01 9:02 ` [patch 20/44] arm26: " Akinobu Mita
2006-02-01 9:02 ` [patch 21/44] cris: " Akinobu Mita
2006-02-01 9:02 ` [patch 22/44] frv: " Akinobu Mita
2006-02-01 9:02 ` [patch 23/44] h8300: " Akinobu Mita
2006-02-01 9:02 ` [patch 24/44] i386: " Akinobu Mita
2006-02-01 9:02 ` [patch 25/44] ia64: " Akinobu Mita
2006-02-01 9:02 ` [patch 26/44] m32r: " Akinobu Mita
2006-02-01 9:02 ` [patch 27/44] m68k: " Akinobu Mita
2006-02-01 9:02 ` [patch 28/44] m68knommu: " Akinobu Mita
2006-02-01 9:02 ` [patch 29/44] mips: " Akinobu Mita
2006-02-01 9:02 ` [patch 30/44] parisc: " Akinobu Mita
2006-02-01 9:02 ` [patch 31/44] powerpc: " Akinobu Mita
2006-02-01 9:02 ` [patch 32/44] s390: " Akinobu Mita
2006-02-01 9:02 ` [patch 33/44] sh: " Akinobu Mita
2006-02-01 9:02 ` [patch 34/44] sh64: " Akinobu Mita
2006-02-01 9:02 ` [patch 35/44] sparc: " Akinobu Mita
2006-02-01 9:03 ` [patch 36/44] sparc64: " Akinobu Mita
2006-02-01 9:03 ` [patch 37/44] v850: " Akinobu Mita
2006-02-01 9:03 ` [patch 38/44] x86_64: " Akinobu Mita
2006-02-01 9:03 ` [patch 39/44] xtensa: " Akinobu Mita
2006-02-01 9:03 ` [patch 40/44] update include/asm-generic/bitops.h Akinobu Mita
2006-02-01 9:03 ` [patch 41/44] make thread_info.flags an unsigned long Akinobu Mita
2006-02-01 9:03 ` [patch 42/44] ia64: make partial_page.bitmap " Akinobu Mita
2006-02-01 9:03 ` [patch 43/44] ntfs: remove generic_ffs() Akinobu Mita
2006-02-01 9:03 ` [patch 44/44] remove unused generic bitops in include/linux/bitops.h Akinobu Mita
2006-02-06 10:26 ` [patch 11/44] generic find_{next,first}{,_zero}_bit() David Howells
2006-02-07 2:02 ` Akinobu Mita
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20060201090325.696670000@localhost.localdomain \
--to=mita@miraclelinux.com \
--cc=gerg@uclinux.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mips@linux-mips.org \
--cc=sparclinux@vger.kernel.org \
--cc=ultralinux@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).