linux-mips
[Top] [All Lists]

[patch 13/47] generic sched_find_first_bit()

To: linux-kernel@vger.kernel.org
Subject: [patch 13/47] generic sched_find_first_bit()
From: Akinobu Mita <mita@miraclelinux.com>
Date: Tue, 14 Feb 2006 14:04:04 +0900
Cc: akpm@osdl.org, Russell King <rmk@arm.linux.org.uk>, 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@lists.linux-m68k.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>, Akinobu Mita <mita@miraclelinux.com>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20060214050351.252615000@localhost.localdomain>
Sender: linux-mips-bounce@linux-mips.org
This patch introduces the C-language equivalent of the function:
int sched_find_first_bit(const unsigned long *b);

In include/asm-generic/bitops/sched.h

This code largely copied from:
include/asm-powerpc/bitops.h

Signed-off-by: Akinobu Mita <mita@miraclelinux.com>
 include/asm-generic/bitops/sched.h |   36 ++++++++++++++++++++++++++++++++++++
 1 files changed, 36 insertions(+)

Index: 2.6-rc/include/asm-generic/bitops/sched.h
===================================================================
--- /dev/null
+++ 2.6-rc/include/asm-generic/bitops/sched.h
@@ -0,0 +1,36 @@
+#ifndef _ASM_GENERIC_BITOPS_SCHED_H_
+#define _ASM_GENERIC_BITOPS_SCHED_H_
+
+#include <linux/compiler.h>    /* unlikely() */
+#include <asm/types.h>
+
+/*
+ * Every architecture must define this function. It's the fastest
+ * way of searching a 140-bit bitmap where the first 100 bits are
+ * unlikely to be set. It's guaranteed that at least one of the 140
+ * bits is cleared.
+ */
+static inline int sched_find_first_bit(const unsigned long *b)
+{
+#if BITS_PER_LONG == 64
+       if (unlikely(b[0]))
+               return __ffs(b[0]);
+       if (unlikely(b[1]))
+               return __ffs(b[1]) + 64;
+       return __ffs(b[2]) + 128;
+#elif BITS_PER_LONG == 32
+       if (unlikely(b[0]))
+               return __ffs(b[0]);
+       if (unlikely(b[1]))
+               return __ffs(b[1]) + 32;
+       if (unlikely(b[2]))
+               return __ffs(b[2]) + 64;
+       if (b[3])
+               return __ffs(b[3]) + 96;
+       return __ffs(b[4]) + 128;
+#else
+#error BITS_PER_LONG not defined
+#endif
+}
+
+#endif /* _ASM_GENERIC_BITOPS_SCHED_H_ */

--

<Prev in Thread] Current Thread [Next in Thread>
  • [patch 13/47] generic sched_find_first_bit(), Akinobu Mita <=