aboutsummaryrefslogtreecommitdiffstats
path: root/lib/find_last_bit.c
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2009-01-03 15:04:39 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-03 15:04:39 -0500
commit7d3b56ba37a95f1f370f50258ed3954c304c524b (patch)
tree86102527b92f02450aa245f084ffb491c18d2e0a /lib/find_last_bit.c
parent269b012321f2f1f8e4648c43a93bf432b42c6668 (diff)
parentab14398abd195af91a744c320a52a1bce814dd1e (diff)
Merge branch 'cpus4096-for-linus-3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'cpus4096-for-linus-3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (77 commits) x86: setup_per_cpu_areas() cleanup cpumask: fix compile error when CONFIG_NR_CPUS is not defined cpumask: use alloc_cpumask_var_node where appropriate cpumask: convert shared_cpu_map in acpi_processor* structs to cpumask_var_t x86: use cpumask_var_t in acpi/boot.c x86: cleanup some remaining usages of NR_CPUS where s/b nr_cpu_ids sched: put back some stack hog changes that were undone in kernel/sched.c x86: enable cpus display of kernel_max and offlined cpus ia64: cpumask fix for is_affinity_mask_valid() cpumask: convert RCU implementations, fix xtensa: define __fls mn10300: define __fls m32r: define __fls h8300: define __fls frv: define __fls cris: define __fls cpumask: CONFIG_DISABLE_OBSOLETE_CPUMASK_FUNCTIONS cpumask: zero extra bits in alloc_cpumask_var_node cpumask: replace for_each_cpu_mask_nr with for_each_cpu in kernel/time/ cpumask: convert mm/ ...
Diffstat (limited to 'lib/find_last_bit.c')
-rw-r--r--lib/find_last_bit.c45
1 files changed, 45 insertions, 0 deletions
diff --git a/lib/find_last_bit.c b/lib/find_last_bit.c
new file mode 100644
index 000000000000..5d202e36bdd8
--- /dev/null
+++ b/lib/find_last_bit.c
@@ -0,0 +1,45 @@
1/* find_last_bit.c: fallback find next bit implementation
2 *
3 * Copyright (C) 2008 IBM Corporation
4 * Written by Rusty Russell <rusty@rustcorp.com.au>
5 * (Inspired by David Howell's find_next_bit implementation)
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
11 */
12
13#include <linux/bitops.h>
14#include <linux/module.h>
15#include <asm/types.h>
16#include <asm/byteorder.h>
17
18unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
19{
20 unsigned long words;
21 unsigned long tmp;
22
23 /* Start at final word. */
24 words = size / BITS_PER_LONG;
25
26 /* Partial final word? */
27 if (size & (BITS_PER_LONG-1)) {
28 tmp = (addr[words] & (~0UL >> (BITS_PER_LONG
29 - (size & (BITS_PER_LONG-1)))));
30 if (tmp)
31 goto found;
32 }
33
34 while (words) {
35 tmp = addr[--words];
36 if (tmp) {
37found:
38 return words * BITS_PER_LONG + __fls(tmp);
39 }
40 }
41
42 /* Not found */
43 return size;
44}
45EXPORT_SYMBOL(find_last_bit);