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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-04-09 01:08:02 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-04-09 01:08:02 +0200
commit4b42fafc1cdc4aba38d4f147cb2f3f1a32cd4a15 (patch)
tree7f162d0612f7048dc52a3ba320a6685593100729 /tools/testing/radix-tree/find_next_bit.c
parentb318556479cc923970a79d6c2311138581c0db83 (diff)
parent6c9d9c81924b4b63c7a487e90fddb3b2d0f7d458 (diff)
Merge branch 'pm-cpufreq-sched' into pm-cpufreq
Diffstat (limited to 'tools/testing/radix-tree/find_next_bit.c')
-rw-r--r--tools/testing/radix-tree/find_next_bit.c57
1 files changed, 57 insertions, 0 deletions
diff --git a/tools/testing/radix-tree/find_next_bit.c b/tools/testing/radix-tree/find_next_bit.c
new file mode 100644
index 000000000000..d1c2178bb2d4
--- /dev/null
+++ b/tools/testing/radix-tree/find_next_bit.c
@@ -0,0 +1,57 @@
+/* find_next_bit.c: fallback find next bit implementation
+ *
+ * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/types.h>
+#include <linux/bitops.h>
+
+#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
+
+/*
+ * Find the next set bit in a memory region.
+ */
+unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
+ unsigned long offset)
+{
+ const unsigned long *p = addr + BITOP_WORD(offset);
+ unsigned long result = offset & ~(BITS_PER_LONG-1);
+ unsigned long tmp;
+
+ if (offset >= size)
+ return size;
+ size -= result;
+ offset %= BITS_PER_LONG;
+ if (offset) {
+ tmp = *(p++);
+ tmp &= (~0UL << offset);
+ if (size < BITS_PER_LONG)
+ goto found_first;
+ if (tmp)
+ goto found_middle;
+ size -= BITS_PER_LONG;
+ result += BITS_PER_LONG;
+ }
+ while (size & ~(BITS_PER_LONG-1)) {
+ if ((tmp = *(p++)))
+ goto found_middle;
+ result += BITS_PER_LONG;
+ size -= BITS_PER_LONG;
+ }
+ if (!size)
+ return result;
+ tmp = *p;
+
+found_first:
+ tmp &= (~0UL >> (BITS_PER_LONG - size));
+ if (tmp == 0UL) /* Are any bits set? */
+ return result + size; /* Nope. */
+found_middle:
+ return result + __ffs(tmp);
+}