summaryrefslogtreecommitdiffstats
path: root/kernel/arch/s390/lib/find.c
blob: 922003c1b90d388c96b26c33a19947dc1c8d95d0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
/*
 * MSB0 numbered special bitops handling.
 *
 * On s390x the bits are numbered:
 *   |0..............63|64............127|128...........191|192...........255|
 * and on s390:
 *   |0.....31|32....63|64....95|96...127|128..159|160..191|192..223|224..255|
 *
 * The reason for this bit numbering is the fact that the hardware sets bits
 * in a bitmap starting at bit 0 (MSB) and we don't want to scan the bitmap
 * from the 'wrong end'.
 */

#include <linux/compiler.h>
#include <linux/bitops.h>
#include <linux/export.h>

unsigned long find_first_bit_inv(const unsigned long *addr, unsigned long size)
{
	const unsigned long *p = addr;
	unsigned long result = 0;
	unsigned long tmp;

	while (size & ~(BITS_PER_LONG - 1)) {
		if ((tmp = *(p++)))
			goto found;
		result += BITS_PER_LONG;
		size -= BITS_PER_LONG;
	}
	if (!size)
		return result;
	tmp = (*p) & (~0UL << (BITS_PER_LONG - size));
	if (!tmp)		/* Are any bits set? */
		return result + size;	/* Nope. */
found:
	return result + (__fls(tmp) ^ (BITS_PER_LONG - 1));
}
EXPORT_SYMBOL(find_first_bit_inv);

unsigned long find_next_bit_inv(const unsigned long *addr, unsigned long size,
				unsigned long offset)
{
	const unsigned long *p = addr + (offset / BITS_PER_LONG);
	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)		/* Are any bits set? */
		return result + size;	/* Nope. */
found_middle:
	return result + (__fls(tmp) ^ (BITS_PER_LONG - 1));
}
EXPORT_SYMBOL(find_next_bit_inv);