1 /* find_next_bit.c: fallback find next bit implementation
3 * Copied from lib/find_next_bit.c to tools/lib/next_bit.c
5 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
6 * Written by David Howells (dhowells@redhat.com)
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.
14 #include <linux/bitops.h>
15 #include <asm/types.h>
16 #include <asm/byteorder.h>
18 #define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
22 * Find the next set bit in a memory region.
24 unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
27 const unsigned long *p = addr + BITOP_WORD(offset);
28 unsigned long result = offset & ~(BITS_PER_LONG-1);
34 offset %= BITS_PER_LONG;
37 tmp &= (~0UL << offset);
38 if (size < BITS_PER_LONG)
42 size -= BITS_PER_LONG;
43 result += BITS_PER_LONG;
45 while (size & ~(BITS_PER_LONG-1)) {
48 result += BITS_PER_LONG;
49 size -= BITS_PER_LONG;
56 tmp &= (~0UL >> (BITS_PER_LONG - size));
57 if (tmp == 0UL) /* Are any bits set? */
58 return result + size; /* Nope. */
60 return result + __ffs(tmp);
64 #ifndef find_first_bit
66 * Find the first set bit in a memory region.
68 unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
70 const unsigned long *p = addr;
71 unsigned long result = 0;
74 while (size & ~(BITS_PER_LONG-1)) {
77 result += BITS_PER_LONG;
78 size -= BITS_PER_LONG;
83 tmp = (*p) & (~0UL >> (BITS_PER_LONG - size));
84 if (tmp == 0UL) /* Are any bits set? */
85 return result + size; /* Nope. */
87 return result + __ffs(tmp);