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23e1a358 ACM |
1 | /* find_next_bit.c: fallback find next bit implementation |
2 | * | |
3 | * Copied from lib/find_next_bit.c to tools/lib/next_bit.c | |
4 | * | |
5 | * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved. | |
6 | * Written by David Howells (dhowells@redhat.com) | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU General Public License | |
10 | * as published by the Free Software Foundation; either version | |
11 | * 2 of the License, or (at your option) any later version. | |
12 | */ | |
13 | ||
14 | #include <linux/bitops.h> | |
15 | #include <asm/types.h> | |
16 | #include <asm/byteorder.h> | |
17 | ||
18 | #define BITOP_WORD(nr) ((nr) / BITS_PER_LONG) | |
19 | ||
20 | #ifndef find_next_bit | |
21 | /* | |
22 | * Find the next set bit in a memory region. | |
23 | */ | |
24 | unsigned long find_next_bit(const unsigned long *addr, unsigned long size, | |
25 | unsigned long offset) | |
26 | { | |
27 | const unsigned long *p = addr + BITOP_WORD(offset); | |
28 | unsigned long result = offset & ~(BITS_PER_LONG-1); | |
29 | unsigned long tmp; | |
30 | ||
31 | if (offset >= size) | |
32 | return size; | |
33 | size -= result; | |
34 | offset %= BITS_PER_LONG; | |
35 | if (offset) { | |
36 | tmp = *(p++); | |
37 | tmp &= (~0UL << offset); | |
38 | if (size < BITS_PER_LONG) | |
39 | goto found_first; | |
40 | if (tmp) | |
41 | goto found_middle; | |
42 | size -= BITS_PER_LONG; | |
43 | result += BITS_PER_LONG; | |
44 | } | |
45 | while (size & ~(BITS_PER_LONG-1)) { | |
46 | if ((tmp = *(p++))) | |
47 | goto found_middle; | |
48 | result += BITS_PER_LONG; | |
49 | size -= BITS_PER_LONG; | |
50 | } | |
51 | if (!size) | |
52 | return result; | |
53 | tmp = *p; | |
54 | ||
55 | found_first: | |
56 | tmp &= (~0UL >> (BITS_PER_LONG - size)); | |
57 | if (tmp == 0UL) /* Are any bits set? */ | |
58 | return result + size; /* Nope. */ | |
59 | found_middle: | |
60 | return result + __ffs(tmp); | |
61 | } | |
62 | #endif | |
63 | ||
64 | #ifndef find_first_bit | |
65 | /* | |
66 | * Find the first set bit in a memory region. | |
67 | */ | |
68 | unsigned long find_first_bit(const unsigned long *addr, unsigned long size) | |
69 | { | |
70 | const unsigned long *p = addr; | |
71 | unsigned long result = 0; | |
72 | unsigned long tmp; | |
73 | ||
74 | while (size & ~(BITS_PER_LONG-1)) { | |
75 | if ((tmp = *(p++))) | |
76 | goto found; | |
77 | result += BITS_PER_LONG; | |
78 | size -= BITS_PER_LONG; | |
79 | } | |
80 | if (!size) | |
81 | return result; | |
82 | ||
83 | tmp = (*p) & (~0UL >> (BITS_PER_LONG - size)); | |
84 | if (tmp == 0UL) /* Are any bits set? */ | |
85 | return result + size; /* Nope. */ | |
86 | found: | |
87 | return result + __ffs(tmp); | |
88 | } | |
89 | #endif |