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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 | |
18 | #ifndef find_last_bit |
19 | |
20 | unsigned long find_last_bit(const unsigned long *addr, unsigned long size) |
21 | { |
22 | unsigned long words; |
23 | unsigned long tmp; |
24 | |
25 | /* Start at final word. */ |
26 | words = size / BITS_PER_LONG; |
27 | |
28 | /* Partial final word? */ |
29 | if (size & (BITS_PER_LONG-1)) { |
30 | tmp = (addr[words] & (~0UL >> (BITS_PER_LONG |
31 | - (size & (BITS_PER_LONG-1))))); |
32 | if (tmp) |
33 | goto found; |
34 | } |
35 | |
36 | while (words) { |
37 | tmp = addr[--words]; |
38 | if (tmp) { |
39 | found: |
40 | return words * BITS_PER_LONG + __fls(tmp); |
41 | } |
42 | } |
43 | |
44 | /* Not found */ |
45 | return size; |
46 | } |
47 | EXPORT_SYMBOL(find_last_bit); |
48 | |
49 | #endif |
50 |
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