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authorLinus Torvalds <torvalds@linux-foundation.org>2008-04-26 16:46:11 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-26 16:46:11 -0400
commit9b79ed952bd7344d40152f8a560ad8a0d93f3886 (patch)
tree0cdf72321a9eeb2a766b7b98d5a87ad3d46ad620 /lib/find_next_bit.c
parenta52b0d25a722e84da999005b75f972aa4824253c (diff)
parent19870def587554c4055df3e74a21508e3647fb7e (diff)
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-generic-bitops-v3
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-generic-bitops-v3: x86, bitops: select the generic bitmap search functions x86: include/asm-x86/pgalloc.h/bitops.h: checkpatch cleanups - formatting only x86: finalize bitops unification x86, UML: remove x86-specific implementations of find_first_bit x86: optimize find_first_bit for small bitmaps x86: switch 64-bit to generic find_first_bit x86: generic versions of find_first_(zero_)bit, convert i386 bitops: use __fls for fls64 on 64-bit archs generic: implement __fls on all 64-bit archs generic: introduce a generic __fls implementation x86: merge the simple bitops and move them to bitops.h x86, generic: optimize find_next_(zero_)bit for small constant-size bitmaps x86, uml: fix uml with generic find_next_bit for x86 x86: change x86 to use generic find_next_bit uml: Kconfig cleanup uml: fix build error
Diffstat (limited to 'lib/find_next_bit.c')
-rw-r--r--lib/find_next_bit.c77
1 files changed, 65 insertions, 12 deletions
diff --git a/lib/find_next_bit.c b/lib/find_next_bit.c
index 78ccd73a8841..d3f5784807b4 100644
--- a/lib/find_next_bit.c
+++ b/lib/find_next_bit.c
@@ -16,14 +16,12 @@
16 16
17#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG) 17#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
18 18
19/** 19#ifdef CONFIG_GENERIC_FIND_NEXT_BIT
20 * find_next_bit - find the next set bit in a memory region 20/*
21 * @addr: The address to base the search on 21 * Find the next set bit in a memory region.
22 * @offset: The bitnumber to start searching at
23 * @size: The maximum size to search
24 */ 22 */
25unsigned long find_next_bit(const unsigned long *addr, unsigned long size, 23unsigned long __find_next_bit(const unsigned long *addr,
26 unsigned long offset) 24 unsigned long size, unsigned long offset)
27{ 25{
28 const unsigned long *p = addr + BITOP_WORD(offset); 26 const unsigned long *p = addr + BITOP_WORD(offset);
29 unsigned long result = offset & ~(BITS_PER_LONG-1); 27 unsigned long result = offset & ~(BITS_PER_LONG-1);
@@ -60,15 +58,14 @@ found_first:
60found_middle: 58found_middle:
61 return result + __ffs(tmp); 59 return result + __ffs(tmp);
62} 60}
63 61EXPORT_SYMBOL(__find_next_bit);
64EXPORT_SYMBOL(find_next_bit);
65 62
66/* 63/*
67 * This implementation of find_{first,next}_zero_bit was stolen from 64 * This implementation of find_{first,next}_zero_bit was stolen from
68 * Linus' asm-alpha/bitops.h. 65 * Linus' asm-alpha/bitops.h.
69 */ 66 */
70unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size, 67unsigned long __find_next_zero_bit(const unsigned long *addr,
71 unsigned long offset) 68 unsigned long size, unsigned long offset)
72{ 69{
73 const unsigned long *p = addr + BITOP_WORD(offset); 70 const unsigned long *p = addr + BITOP_WORD(offset);
74 unsigned long result = offset & ~(BITS_PER_LONG-1); 71 unsigned long result = offset & ~(BITS_PER_LONG-1);
@@ -105,8 +102,64 @@ found_first:
105found_middle: 102found_middle:
106 return result + ffz(tmp); 103 return result + ffz(tmp);
107} 104}
105EXPORT_SYMBOL(__find_next_zero_bit);
106#endif /* CONFIG_GENERIC_FIND_NEXT_BIT */
107
108#ifdef CONFIG_GENERIC_FIND_FIRST_BIT
109/*
110 * Find the first set bit in a memory region.
111 */
112unsigned long __find_first_bit(const unsigned long *addr,
113 unsigned long size)
114{
115 const unsigned long *p = addr;
116 unsigned long result = 0;
117 unsigned long tmp;
108 118
109EXPORT_SYMBOL(find_next_zero_bit); 119 while (size & ~(BITS_PER_LONG-1)) {
120 if ((tmp = *(p++)))
121 goto found;
122 result += BITS_PER_LONG;
123 size -= BITS_PER_LONG;
124 }
125 if (!size)
126 return result;
127
128 tmp = (*p) & (~0UL >> (BITS_PER_LONG - size));
129 if (tmp == 0UL) /* Are any bits set? */
130 return result + size; /* Nope. */
131found:
132 return result + __ffs(tmp);
133}
134EXPORT_SYMBOL(__find_first_bit);
135
136/*
137 * Find the first cleared bit in a memory region.
138 */
139unsigned long __find_first_zero_bit(const unsigned long *addr,
140 unsigned long size)
141{
142 const unsigned long *p = addr;
143 unsigned long result = 0;
144 unsigned long tmp;
145
146 while (size & ~(BITS_PER_LONG-1)) {
147 if (~(tmp = *(p++)))
148 goto found;
149 result += BITS_PER_LONG;
150 size -= BITS_PER_LONG;
151 }
152 if (!size)
153 return result;
154
155 tmp = (*p) | (~0UL << size);
156 if (tmp == ~0UL) /* Are any bits zero? */
157 return result + size; /* Nope. */
158found:
159 return result + ffz(tmp);
160}
161EXPORT_SYMBOL(__find_first_zero_bit);
162#endif /* CONFIG_GENERIC_FIND_FIRST_BIT */
110 163
111#ifdef __BIG_ENDIAN 164#ifdef __BIG_ENDIAN
112 165