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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}