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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /lib/find_next_bit.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'lib/find_next_bit.c')
-rw-r--r--lib/find_next_bit.c55
1 files changed, 55 insertions, 0 deletions
diff --git a/lib/find_next_bit.c b/lib/find_next_bit.c
new file mode 100644
index 000000000000..d08302d2a42c
--- /dev/null
+++ b/lib/find_next_bit.c
@@ -0,0 +1,55 @@
1/* find_next_bit.c: fallback find next bit implementation
2 *
3 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/bitops.h>
13
14int find_next_bit(const unsigned long *addr, int size, int offset)
15{
16 const unsigned long *base;
17 const int NBITS = sizeof(*addr) * 8;
18 unsigned long tmp;
19
20 base = addr;
21 if (offset) {
22 int suboffset;
23
24 addr += offset / NBITS;
25
26 suboffset = offset % NBITS;
27 if (suboffset) {
28 tmp = *addr;
29 tmp >>= suboffset;
30 if (tmp)
31 goto finish;
32 }
33
34 addr++;
35 }
36
37 while ((tmp = *addr) == 0)
38 addr++;
39
40 offset = (addr - base) * NBITS;
41
42 finish:
43 /* count the remaining bits without using __ffs() since that takes a 32-bit arg */
44 while (!(tmp & 0xff)) {
45 offset += 8;
46 tmp >>= 8;
47 }
48
49 while (!(tmp & 1)) {
50 offset++;
51 tmp >>= 1;
52 }
53
54 return offset;
55}