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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 */
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/kernel.h>
19
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)
23/*
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.
29 */
30static unsigned long _find_next_bit(const unsigned long *addr1,
31 const unsigned long *addr2, unsigned long nbits,
32 unsigned long start, unsigned long invert, unsigned long le)
33{
34 unsigned long tmp, mask;
35
36 if (unlikely(start >= nbits))
37 return nbits;
38
39 tmp = addr1[start / BITS_PER_LONG];
40 if (addr2)
41 tmp &= addr2[start / BITS_PER_LONG];
42 tmp ^= invert;
43
44 /* Handle 1st word. */
45 mask = BITMAP_FIRST_WORD_MASK(start);
46 if (le)
47 mask = swab(mask);
48
49 tmp &= mask;
50
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
58 tmp = addr1[start / BITS_PER_LONG];
59 if (addr2)
60 tmp &= addr2[start / BITS_PER_LONG];
61 tmp ^= invert;
62 }
63
64 if (le)
65 tmp = swab(tmp);
66
67 return min(start + __ffs(tmp), nbits);
68}
69#endif
70
71#ifndef find_next_bit
72/*
73 * Find the next set bit in a memory region.
74 */
75unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
76 unsigned long offset)
77{
78 return _find_next_bit(addr, NULL, size, offset, 0UL, 0);
79}
80EXPORT_SYMBOL(find_next_bit);
81#endif
82
83#ifndef find_next_zero_bit
84unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
85 unsigned long offset)
86{
87 return _find_next_bit(addr, NULL, size, offset, ~0UL, 0);
88}
89EXPORT_SYMBOL(find_next_zero_bit);
90#endif
91
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{
97 return _find_next_bit(addr1, addr2, size, offset, 0UL, 0);
98}
99EXPORT_SYMBOL(find_next_and_bit);
100#endif
101
102#ifndef find_first_bit
103/*
104 * Find the first set bit in a memory region.
105 */
106unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
107{
108 unsigned long idx;
109
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);
113 }
114
115 return size;
116}
117EXPORT_SYMBOL(find_first_bit);
118#endif
119
120#ifndef find_first_zero_bit
121/*
122 * Find the first cleared bit in a memory region.
123 */
124unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
125{
126 unsigned long idx;
127
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);
131 }
132
133 return size;
134}
135EXPORT_SYMBOL(find_first_zero_bit);
136#endif
137
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
158#ifdef __BIG_ENDIAN
159
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{
164 return _find_next_bit(addr, NULL, size, offset, ~0UL, 1);
165}
166EXPORT_SYMBOL(find_next_zero_bit_le);
167#endif
168
169#ifndef find_next_bit_le
170unsigned long find_next_bit_le(const void *addr, unsigned
171 long size, unsigned long offset)
172{
173 return _find_next_bit(addr, NULL, size, offset, 0UL, 1);
174}
175EXPORT_SYMBOL(find_next_bit_le);
176#endif
177
178#endif /* __BIG_ENDIAN */
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);