1 /* find_next_bit.c: fallback find next bit implementation
3 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
12 #include <linux/bitops.h>
13 #include <linux/module.h>
14 #include <asm/types.h>
15 #include <asm/byteorder.h>
17 #define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
19 #undef find_next_zero_bit
22 * find_next_bit - find the next set bit in a memory region
23 * @addr: The address to base the search on
24 * @offset: The bitnumber to start searching at
25 * @size: The maximum size to search
27 unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
30 const unsigned long *p = addr + BITOP_WORD(offset);
31 unsigned long result = offset & ~(BITS_PER_LONG-1);
37 offset %= BITS_PER_LONG;
40 tmp &= (~0UL << offset);
41 if (size < BITS_PER_LONG)
45 size -= BITS_PER_LONG;
46 result += BITS_PER_LONG;
48 while (size & ~(BITS_PER_LONG-1)) {
51 result += BITS_PER_LONG;
52 size -= BITS_PER_LONG;
59 tmp &= (~0UL >> (BITS_PER_LONG - size));
60 if (tmp == 0UL) /* Are any bits set? */
61 return result + size; /* Nope. */
63 return result + __ffs(tmp);
66 EXPORT_SYMBOL(find_next_bit);
69 * This implementation of find_{first,next}_zero_bit was stolen from
70 * Linus' asm-alpha/bitops.h.
72 unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
75 const unsigned long *p = addr + BITOP_WORD(offset);
76 unsigned long result = offset & ~(BITS_PER_LONG-1);
82 offset %= BITS_PER_LONG;
85 tmp |= ~0UL >> (BITS_PER_LONG - offset);
86 if (size < BITS_PER_LONG)
90 size -= BITS_PER_LONG;
91 result += BITS_PER_LONG;
93 while (size & ~(BITS_PER_LONG-1)) {
96 result += BITS_PER_LONG;
97 size -= BITS_PER_LONG;
105 if (tmp == ~0UL) /* Are any bits zero? */
106 return result + size; /* Nope. */
108 return result + ffz(tmp);
111 EXPORT_SYMBOL(find_next_zero_bit);
115 /* include/linux/byteorder does not support "unsigned long" type */
116 static inline unsigned long ext2_swabp(const unsigned long * x)
118 #if BITS_PER_LONG == 64
119 return (unsigned long) __swab64p((u64 *) x);
120 #elif BITS_PER_LONG == 32
121 return (unsigned long) __swab32p((u32 *) x);
123 #error BITS_PER_LONG not defined
127 /* include/linux/byteorder doesn't support "unsigned long" type */
128 static inline unsigned long ext2_swab(const unsigned long y)
130 #if BITS_PER_LONG == 64
131 return (unsigned long) __swab64((u64) y);
132 #elif BITS_PER_LONG == 32
133 return (unsigned long) __swab32((u32) y);
135 #error BITS_PER_LONG not defined
139 unsigned long generic_find_next_zero_le_bit(const unsigned long *addr, unsigned
140 long size, unsigned long offset)
142 const unsigned long *p = addr + BITOP_WORD(offset);
143 unsigned long result = offset & ~(BITS_PER_LONG - 1);
149 offset &= (BITS_PER_LONG - 1UL);
151 tmp = ext2_swabp(p++);
152 tmp |= (~0UL >> (BITS_PER_LONG - offset));
153 if (size < BITS_PER_LONG)
157 size -= BITS_PER_LONG;
158 result += BITS_PER_LONG;
161 while (size & ~(BITS_PER_LONG - 1)) {
163 goto found_middle_swap;
164 result += BITS_PER_LONG;
165 size -= BITS_PER_LONG;
172 if (tmp == ~0UL) /* Are any bits zero? */
173 return result + size; /* Nope. Skip ffz */
175 return result + ffz(tmp);
178 return result + ffz(ext2_swab(tmp));
181 EXPORT_SYMBOL(generic_find_next_zero_le_bit);
183 unsigned long generic_find_next_le_bit(const unsigned long *addr, unsigned
184 long size, unsigned long offset)
186 const unsigned long *p = addr + BITOP_WORD(offset);
187 unsigned long result = offset & ~(BITS_PER_LONG - 1);
193 offset &= (BITS_PER_LONG - 1UL);
195 tmp = ext2_swabp(p++);
196 tmp &= (~0UL << offset);
197 if (size < BITS_PER_LONG)
201 size -= BITS_PER_LONG;
202 result += BITS_PER_LONG;
205 while (size & ~(BITS_PER_LONG - 1)) {
208 goto found_middle_swap;
209 result += BITS_PER_LONG;
210 size -= BITS_PER_LONG;
216 tmp &= (~0UL >> (BITS_PER_LONG - size));
217 if (tmp == 0UL) /* Are any bits set? */
218 return result + size; /* Nope. */
220 return result + __ffs(tmp);
223 return result + __ffs(ext2_swab(tmp));
225 EXPORT_SYMBOL(generic_find_next_le_bit);
226 #endif /* __BIG_ENDIAN */