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1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* bit search implementation
4 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
7 * Copyright (C) 2008 IBM Corporation
8 * 'find_last_bit' is written by Rusty Russell <rusty@rustcorp.com.au>
9 * (Inspired by David Howell's find_next_bit implementation)
11 * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
12 * size and improve performance, 2015.
15 #include <linux/bitops.h>
16 #include <linux/bitmap.h>
17 #include <linux/export.h>
18 #include <linux/kernel.h>
20 #if !defined(find_next_bit) || !defined(find_next_zero_bit) || \
21 !defined(find_next_and_bit)
24 * This is a common helper function for find_next_bit, find_next_zero_bit, and
25 * find_next_and_bit. The differences are:
26 * - The "invert" argument, which is XORed with each fetched word before
27 * searching it for one bits.
28 * - The optional "addr2", which is anded with "addr1" if present.
30 static inline unsigned long _find_next_bit(const unsigned long *addr1
,
31 const unsigned long *addr2
, unsigned long nbits
,
32 unsigned long start
, unsigned long invert
)
36 if (unlikely(start
>= nbits
))
39 tmp
= addr1
[start
/ BITS_PER_LONG
];
41 tmp
&= addr2
[start
/ BITS_PER_LONG
];
44 /* Handle 1st word. */
45 tmp
&= BITMAP_FIRST_WORD_MASK(start
);
46 start
= round_down(start
, BITS_PER_LONG
);
49 start
+= BITS_PER_LONG
;
53 tmp
= addr1
[start
/ BITS_PER_LONG
];
55 tmp
&= addr2
[start
/ BITS_PER_LONG
];
59 return min(start
+ __ffs(tmp
), nbits
);
65 * Find the next set bit in a memory region.
67 unsigned long find_next_bit(const unsigned long *addr
, unsigned long size
,
70 return _find_next_bit(addr
, NULL
, size
, offset
, 0UL);
72 EXPORT_SYMBOL(find_next_bit
);
75 #ifndef find_next_zero_bit
76 unsigned long find_next_zero_bit(const unsigned long *addr
, unsigned long size
,
79 return _find_next_bit(addr
, NULL
, size
, offset
, ~0UL);
81 EXPORT_SYMBOL(find_next_zero_bit
);
84 #if !defined(find_next_and_bit)
85 unsigned long find_next_and_bit(const unsigned long *addr1
,
86 const unsigned long *addr2
, unsigned long size
,
89 return _find_next_bit(addr1
, addr2
, size
, offset
, 0UL);
91 EXPORT_SYMBOL(find_next_and_bit
);
94 #ifndef find_first_bit
96 * Find the first set bit in a memory region.
98 unsigned long find_first_bit(const unsigned long *addr
, unsigned long size
)
102 for (idx
= 0; idx
* BITS_PER_LONG
< size
; idx
++) {
104 return min(idx
* BITS_PER_LONG
+ __ffs(addr
[idx
]), size
);
109 EXPORT_SYMBOL(find_first_bit
);
112 #ifndef find_first_zero_bit
114 * Find the first cleared bit in a memory region.
116 unsigned long find_first_zero_bit(const unsigned long *addr
, unsigned long size
)
120 for (idx
= 0; idx
* BITS_PER_LONG
< size
; idx
++) {
121 if (addr
[idx
] != ~0UL)
122 return min(idx
* BITS_PER_LONG
+ ffz(addr
[idx
]), size
);
127 EXPORT_SYMBOL(find_first_zero_bit
);
130 #ifndef find_last_bit
131 unsigned long find_last_bit(const unsigned long *addr
, unsigned long size
)
134 unsigned long val
= BITMAP_LAST_WORD_MASK(size
);
135 unsigned long idx
= (size
-1) / BITS_PER_LONG
;
140 return idx
* BITS_PER_LONG
+ __fls(val
);
147 EXPORT_SYMBOL(find_last_bit
);
152 /* include/linux/byteorder does not support "unsigned long" type */
153 static inline unsigned long ext2_swab(const unsigned long y
)
155 #if BITS_PER_LONG == 64
156 return (unsigned long) __swab64((u64
) y
);
157 #elif BITS_PER_LONG == 32
158 return (unsigned long) __swab32((u32
) y
);
160 #error BITS_PER_LONG not defined
164 #if !defined(find_next_bit_le) || !defined(find_next_zero_bit_le)
165 static inline unsigned long _find_next_bit_le(const unsigned long *addr1
,
166 const unsigned long *addr2
, unsigned long nbits
,
167 unsigned long start
, unsigned long invert
)
171 if (unlikely(start
>= nbits
))
174 tmp
= addr1
[start
/ BITS_PER_LONG
];
176 tmp
&= addr2
[start
/ BITS_PER_LONG
];
179 /* Handle 1st word. */
180 tmp
&= ext2_swab(BITMAP_FIRST_WORD_MASK(start
));
181 start
= round_down(start
, BITS_PER_LONG
);
184 start
+= BITS_PER_LONG
;
188 tmp
= addr1
[start
/ BITS_PER_LONG
];
190 tmp
&= addr2
[start
/ BITS_PER_LONG
];
194 return min(start
+ __ffs(ext2_swab(tmp
)), nbits
);
198 #ifndef find_next_zero_bit_le
199 unsigned long find_next_zero_bit_le(const void *addr
, unsigned
200 long size
, unsigned long offset
)
202 return _find_next_bit_le(addr
, NULL
, size
, offset
, ~0UL);
204 EXPORT_SYMBOL(find_next_zero_bit_le
);
207 #ifndef find_next_bit_le
208 unsigned long find_next_bit_le(const void *addr
, unsigned
209 long size
, unsigned long offset
)
211 return _find_next_bit_le(addr
, NULL
, size
, offset
, 0UL);
213 EXPORT_SYMBOL(find_next_bit_le
);
216 #endif /* __BIG_ENDIAN */
218 unsigned long find_next_clump8(unsigned long *clump
, const unsigned long *addr
,
219 unsigned long size
, unsigned long offset
)
221 offset
= find_next_bit(addr
, size
, offset
);
225 offset
= round_down(offset
, 8);
226 *clump
= bitmap_get_value8(addr
, offset
);
230 EXPORT_SYMBOL(find_next_clump8
);