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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* bit search implementation
3 *
4 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 *
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 *
11 * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
12 * size and improve performance, 2015.
13 */
14
15#include <linux/bitops.h>
16#include <linux/bitmap.h>
17#include <linux/export.h>
18#include <linux/math.h>
19#include <linux/minmax.h>
20#include <linux/swab.h>
21
22#if !defined(find_next_bit) || !defined(find_next_zero_bit) || \
23 !defined(find_next_bit_le) || !defined(find_next_zero_bit_le) || \
24 !defined(find_next_and_bit)
25/*
26 * This is a common helper function for find_next_bit, find_next_zero_bit, and
27 * find_next_and_bit. The differences are:
28 * - The "invert" argument, which is XORed with each fetched word before
29 * searching it for one bits.
30 * - The optional "addr2", which is anded with "addr1" if present.
31 */
32unsigned long _find_next_bit(const unsigned long *addr1,
33 const unsigned long *addr2, unsigned long nbits,
34 unsigned long start, unsigned long invert, unsigned long le)
35{
36 unsigned long tmp, mask;
37
38 if (unlikely(start >= nbits))
39 return nbits;
40
41 tmp = addr1[start / BITS_PER_LONG];
42 if (addr2)
43 tmp &= addr2[start / BITS_PER_LONG];
44 tmp ^= invert;
45
46 /* Handle 1st word. */
47 mask = BITMAP_FIRST_WORD_MASK(start);
48 if (le)
49 mask = swab(mask);
50
51 tmp &= mask;
52
53 start = round_down(start, BITS_PER_LONG);
54
55 while (!tmp) {
56 start += BITS_PER_LONG;
57 if (start >= nbits)
58 return nbits;
59
60 tmp = addr1[start / BITS_PER_LONG];
61 if (addr2)
62 tmp &= addr2[start / BITS_PER_LONG];
63 tmp ^= invert;
64 }
65
66 if (le)
67 tmp = swab(tmp);
68
69 return min(start + __ffs(tmp), nbits);
70}
71EXPORT_SYMBOL(_find_next_bit);
72#endif
73
74#ifndef find_first_bit
75/*
76 * Find the first set bit in a memory region.
77 */
78unsigned long _find_first_bit(const unsigned long *addr, unsigned long size)
79{
80 unsigned long idx;
81
82 for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
83 if (addr[idx])
84 return min(idx * BITS_PER_LONG + __ffs(addr[idx]), size);
85 }
86
87 return size;
88}
89EXPORT_SYMBOL(_find_first_bit);
90#endif
91
92#ifndef find_first_zero_bit
93/*
94 * Find the first cleared bit in a memory region.
95 */
96unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size)
97{
98 unsigned long idx;
99
100 for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
101 if (addr[idx] != ~0UL)
102 return min(idx * BITS_PER_LONG + ffz(addr[idx]), size);
103 }
104
105 return size;
106}
107EXPORT_SYMBOL(_find_first_zero_bit);
108#endif
109
110#ifndef find_last_bit
111unsigned long _find_last_bit(const unsigned long *addr, unsigned long size)
112{
113 if (size) {
114 unsigned long val = BITMAP_LAST_WORD_MASK(size);
115 unsigned long idx = (size-1) / BITS_PER_LONG;
116
117 do {
118 val &= addr[idx];
119 if (val)
120 return idx * BITS_PER_LONG + __fls(val);
121
122 val = ~0ul;
123 } while (idx--);
124 }
125 return size;
126}
127EXPORT_SYMBOL(_find_last_bit);
128#endif
129
130unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr,
131 unsigned long size, unsigned long offset)
132{
133 offset = find_next_bit(addr, size, offset);
134 if (offset == size)
135 return size;
136
137 offset = round_down(offset, 8);
138 *clump = bitmap_get_value8(addr, offset);
139
140 return offset;
141}
142EXPORT_SYMBOL(find_next_clump8);
1/* bit search implementation
2 *
3 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * Copyright (C) 2008 IBM Corporation
7 * 'find_last_bit' is written by Rusty Russell <rusty@rustcorp.com.au>
8 * (Inspired by David Howell's find_next_bit implementation)
9 *
10 * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
11 * size and improve performance, 2015.
12 *
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License
15 * as published by the Free Software Foundation; either version
16 * 2 of the License, or (at your option) any later version.
17 */
18
19#include <linux/bitops.h>
20#include <linux/bitmap.h>
21#include <linux/export.h>
22#include <linux/kernel.h>
23
24#if !defined(find_next_bit) || !defined(find_next_zero_bit)
25
26/*
27 * This is a common helper function for find_next_bit and
28 * find_next_zero_bit. The difference is the "invert" argument, which
29 * is XORed with each fetched word before searching it for one bits.
30 */
31static unsigned long _find_next_bit(const unsigned long *addr,
32 unsigned long nbits, unsigned long start, unsigned long invert)
33{
34 unsigned long tmp;
35
36 if (!nbits || start >= nbits)
37 return nbits;
38
39 tmp = addr[start / BITS_PER_LONG] ^ invert;
40
41 /* Handle 1st word. */
42 tmp &= BITMAP_FIRST_WORD_MASK(start);
43 start = round_down(start, BITS_PER_LONG);
44
45 while (!tmp) {
46 start += BITS_PER_LONG;
47 if (start >= nbits)
48 return nbits;
49
50 tmp = addr[start / BITS_PER_LONG] ^ invert;
51 }
52
53 return min(start + __ffs(tmp), nbits);
54}
55#endif
56
57#ifndef find_next_bit
58/*
59 * Find the next set bit in a memory region.
60 */
61unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
62 unsigned long offset)
63{
64 return _find_next_bit(addr, size, offset, 0UL);
65}
66EXPORT_SYMBOL(find_next_bit);
67#endif
68
69#ifndef find_next_zero_bit
70unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
71 unsigned long offset)
72{
73 return _find_next_bit(addr, size, offset, ~0UL);
74}
75EXPORT_SYMBOL(find_next_zero_bit);
76#endif
77
78#ifndef find_first_bit
79/*
80 * Find the first set bit in a memory region.
81 */
82unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
83{
84 unsigned long idx;
85
86 for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
87 if (addr[idx])
88 return min(idx * BITS_PER_LONG + __ffs(addr[idx]), size);
89 }
90
91 return size;
92}
93EXPORT_SYMBOL(find_first_bit);
94#endif
95
96#ifndef find_first_zero_bit
97/*
98 * Find the first cleared bit in a memory region.
99 */
100unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
101{
102 unsigned long idx;
103
104 for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
105 if (addr[idx] != ~0UL)
106 return min(idx * BITS_PER_LONG + ffz(addr[idx]), size);
107 }
108
109 return size;
110}
111EXPORT_SYMBOL(find_first_zero_bit);
112#endif
113
114#ifndef find_last_bit
115unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
116{
117 if (size) {
118 unsigned long val = BITMAP_LAST_WORD_MASK(size);
119 unsigned long idx = (size-1) / BITS_PER_LONG;
120
121 do {
122 val &= addr[idx];
123 if (val)
124 return idx * BITS_PER_LONG + __fls(val);
125
126 val = ~0ul;
127 } while (idx--);
128 }
129 return size;
130}
131EXPORT_SYMBOL(find_last_bit);
132#endif
133
134#ifdef __BIG_ENDIAN
135
136/* include/linux/byteorder does not support "unsigned long" type */
137static inline unsigned long ext2_swab(const unsigned long y)
138{
139#if BITS_PER_LONG == 64
140 return (unsigned long) __swab64((u64) y);
141#elif BITS_PER_LONG == 32
142 return (unsigned long) __swab32((u32) y);
143#else
144#error BITS_PER_LONG not defined
145#endif
146}
147
148#if !defined(find_next_bit_le) || !defined(find_next_zero_bit_le)
149static unsigned long _find_next_bit_le(const unsigned long *addr,
150 unsigned long nbits, unsigned long start, unsigned long invert)
151{
152 unsigned long tmp;
153
154 if (!nbits || start >= nbits)
155 return nbits;
156
157 tmp = addr[start / BITS_PER_LONG] ^ invert;
158
159 /* Handle 1st word. */
160 tmp &= ext2_swab(BITMAP_FIRST_WORD_MASK(start));
161 start = round_down(start, BITS_PER_LONG);
162
163 while (!tmp) {
164 start += BITS_PER_LONG;
165 if (start >= nbits)
166 return nbits;
167
168 tmp = addr[start / BITS_PER_LONG] ^ invert;
169 }
170
171 return min(start + __ffs(ext2_swab(tmp)), nbits);
172}
173#endif
174
175#ifndef find_next_zero_bit_le
176unsigned long find_next_zero_bit_le(const void *addr, unsigned
177 long size, unsigned long offset)
178{
179 return _find_next_bit_le(addr, size, offset, ~0UL);
180}
181EXPORT_SYMBOL(find_next_zero_bit_le);
182#endif
183
184#ifndef find_next_bit_le
185unsigned long find_next_bit_le(const void *addr, unsigned
186 long size, unsigned long offset)
187{
188 return _find_next_bit_le(addr, size, offset, 0UL);
189}
190EXPORT_SYMBOL(find_next_bit_le);
191#endif
192
193#endif /* __BIG_ENDIAN */