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2874c5fd 1// SPDX-License-Identifier: GPL-2.0-or-later
8f6f19dd 2/* bit search implementation
1da177e4
LT
3 *
4 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 *
8f6f19dd
YN
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)
10 *
2c57a0e2
YN
11 * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
12 * size and improve performance, 2015.
1da177e4
LT
13 */
14
15#include <linux/bitops.h>
8f6f19dd 16#include <linux/bitmap.h>
8bc3bcc9 17#include <linux/export.h>
2c57a0e2 18#include <linux/kernel.h>
1da177e4 19
b78c5713
YN
20#if !defined(find_next_bit) || !defined(find_next_zero_bit) || \
21 !defined(find_next_bit_le) || !defined(find_next_zero_bit_le) || \
22 !defined(find_next_and_bit)
64970b68 23/*
0ade34c3
CC
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.
c7f612cd 29 */
7dfaa98f 30static unsigned long _find_next_bit(const unsigned long *addr1,
0ade34c3 31 const unsigned long *addr2, unsigned long nbits,
b78c5713 32 unsigned long start, unsigned long invert, unsigned long le)
1da177e4 33{
b78c5713 34 unsigned long tmp, mask;
1da177e4 35
e4afd2e5 36 if (unlikely(start >= nbits))
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37 return nbits;
38
0ade34c3
CC
39 tmp = addr1[start / BITS_PER_LONG];
40 if (addr2)
41 tmp &= addr2[start / BITS_PER_LONG];
42 tmp ^= invert;
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43
44 /* Handle 1st word. */
b78c5713
YN
45 mask = BITMAP_FIRST_WORD_MASK(start);
46 if (le)
47 mask = swab(mask);
48
49 tmp &= mask;
50
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51 start = round_down(start, BITS_PER_LONG);
52
53 while (!tmp) {
54 start += BITS_PER_LONG;
55 if (start >= nbits)
56 return nbits;
57
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CC
58 tmp = addr1[start / BITS_PER_LONG];
59 if (addr2)
60 tmp &= addr2[start / BITS_PER_LONG];
61 tmp ^= invert;
1da177e4
LT
62 }
63
b78c5713
YN
64 if (le)
65 tmp = swab(tmp);
66
2c57a0e2 67 return min(start + __ffs(tmp), nbits);
c7f612cd 68}
19de85ef 69#endif
1da177e4 70
2c57a0e2 71#ifndef find_next_bit
c7f612cd 72/*
2c57a0e2 73 * Find the next set bit in a memory region.
c7f612cd 74 */
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YN
75unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
76 unsigned long offset)
77{
b78c5713 78 return _find_next_bit(addr, NULL, size, offset, 0UL, 0);
2c57a0e2
YN
79}
80EXPORT_SYMBOL(find_next_bit);
81#endif
82
83#ifndef find_next_zero_bit
fee4b19f
TG
84unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
85 unsigned long offset)
c7f612cd 86{
b78c5713 87 return _find_next_bit(addr, NULL, size, offset, ~0UL, 0);
1da177e4 88}
fee4b19f 89EXPORT_SYMBOL(find_next_zero_bit);
19de85ef 90#endif
77b9bd9c 91
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CC
92#if !defined(find_next_and_bit)
93unsigned long find_next_and_bit(const unsigned long *addr1,
94 const unsigned long *addr2, unsigned long size,
95 unsigned long offset)
96{
b78c5713 97 return _find_next_bit(addr1, addr2, size, offset, 0UL, 0);
0ade34c3
CC
98}
99EXPORT_SYMBOL(find_next_and_bit);
100#endif
101
19de85ef 102#ifndef find_first_bit
77b9bd9c
AH
103/*
104 * Find the first set bit in a memory region.
105 */
fee4b19f 106unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
77b9bd9c 107{
2c57a0e2 108 unsigned long idx;
77b9bd9c 109
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YN
110 for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
111 if (addr[idx])
112 return min(idx * BITS_PER_LONG + __ffs(addr[idx]), size);
77b9bd9c 113 }
77b9bd9c 114
2c57a0e2 115 return size;
77b9bd9c 116}
fee4b19f 117EXPORT_SYMBOL(find_first_bit);
19de85ef 118#endif
77b9bd9c 119
19de85ef 120#ifndef find_first_zero_bit
77b9bd9c
AH
121/*
122 * Find the first cleared bit in a memory region.
123 */
fee4b19f 124unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
77b9bd9c 125{
2c57a0e2 126 unsigned long idx;
77b9bd9c 127
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YN
128 for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
129 if (addr[idx] != ~0UL)
130 return min(idx * BITS_PER_LONG + ffz(addr[idx]), size);
77b9bd9c 131 }
77b9bd9c 132
2c57a0e2 133 return size;
77b9bd9c 134}
fee4b19f 135EXPORT_SYMBOL(find_first_zero_bit);
19de85ef 136#endif
930ae745 137
8f6f19dd
YN
138#ifndef find_last_bit
139unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
140{
141 if (size) {
142 unsigned long val = BITMAP_LAST_WORD_MASK(size);
143 unsigned long idx = (size-1) / BITS_PER_LONG;
144
145 do {
146 val &= addr[idx];
147 if (val)
148 return idx * BITS_PER_LONG + __fls(val);
149
150 val = ~0ul;
151 } while (idx--);
152 }
153 return size;
154}
155EXPORT_SYMBOL(find_last_bit);
156#endif
157
930ae745
AM
158#ifdef __BIG_ENDIAN
159
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160#ifndef find_next_zero_bit_le
161unsigned long find_next_zero_bit_le(const void *addr, unsigned
162 long size, unsigned long offset)
163{
b78c5713 164 return _find_next_bit(addr, NULL, size, offset, ~0UL, 1);
930ae745 165}
c4945b9e 166EXPORT_SYMBOL(find_next_zero_bit_le);
19de85ef 167#endif
930ae745 168
19de85ef 169#ifndef find_next_bit_le
a56560b3 170unsigned long find_next_bit_le(const void *addr, unsigned
aa02ad67
AK
171 long size, unsigned long offset)
172{
b78c5713 173 return _find_next_bit(addr, NULL, size, offset, 0UL, 1);
aa02ad67 174}
c4945b9e 175EXPORT_SYMBOL(find_next_bit_le);
19de85ef 176#endif
0664996b 177
930ae745 178#endif /* __BIG_ENDIAN */
169c474f
WBG
179
180unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr,
181 unsigned long size, unsigned long offset)
182{
183 offset = find_next_bit(addr, size, offset);
184 if (offset == size)
185 return size;
186
187 offset = round_down(offset, 8);
188 *clump = bitmap_get_value8(addr, offset);
189
190 return offset;
191}
192EXPORT_SYMBOL(find_next_clump8);