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1/* bit search implementation
2 *
3 * Copied from lib/find_bit.c to tools/lib/find_bit.c
4 *
5 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
6 * Written by David Howells (dhowells@redhat.com)
7 *
8 * Copyright (C) 2008 IBM Corporation
9 * 'find_last_bit' is written by Rusty Russell <rusty@rustcorp.com.au>
10 * (Inspired by David Howell's find_next_bit implementation)
11 *
12 * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
13 * size and improve performance, 2015.
14 *
15 * This program is free software; you can redistribute it and/or
16 * modify it under the terms of the GNU General Public License
17 * as published by the Free Software Foundation; either version
18 * 2 of the License, or (at your option) any later version.
19 */
20
21#include <linux/bitops.h>
22#include <linux/bitmap.h>
23#include <linux/kernel.h>
24
25#if !defined(find_next_bit)
26
27/*
28 * This is a common helper function for find_next_bit and
29 * find_next_zero_bit. The difference is the "invert" argument, which
30 * is XORed with each fetched word before searching it for one bits.
31 */
32static unsigned long _find_next_bit(const unsigned long *addr,
33 unsigned long nbits, unsigned long start, unsigned long invert)
34{
35 unsigned long tmp;
36
37 if (!nbits || start >= nbits)
38 return nbits;
39
40 tmp = addr[start / BITS_PER_LONG] ^ invert;
41
42 /* Handle 1st word. */
43 tmp &= BITMAP_FIRST_WORD_MASK(start);
44 start = round_down(start, BITS_PER_LONG);
45
46 while (!tmp) {
47 start += BITS_PER_LONG;
48 if (start >= nbits)
49 return nbits;
50
51 tmp = addr[start / BITS_PER_LONG] ^ invert;
52 }
53
54 return min(start + __ffs(tmp), nbits);
55}
56#endif
57
58#ifndef find_next_bit
59/*
60 * Find the next set bit in a memory region.
61 */
62unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
63 unsigned long offset)
64{
65 return _find_next_bit(addr, size, offset, 0UL);
66}
67#endif
68
69#ifndef find_first_bit
70/*
71 * Find the first set bit in a memory region.
72 */
73unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
74{
75 unsigned long idx;
76
77 for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
78 if (addr[idx])
79 return min(idx * BITS_PER_LONG + __ffs(addr[idx]), size);
80 }
81
82 return size;
83}
84#endif
85
86#ifndef find_first_zero_bit
87/*
88 * Find the first cleared bit in a memory region.
89 */
90unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
91{
92 unsigned long idx;
93
94 for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
95 if (addr[idx] != ~0UL)
96 return min(idx * BITS_PER_LONG + ffz(addr[idx]), size);
97 }
98
99 return size;
100}
101#endif
102
103#ifndef find_next_zero_bit
104unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
105 unsigned long offset)
106{
107 return _find_next_bit(addr, size, offset, ~0UL);
108}
109#endif
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* bit search implementation
3 *
4 * Copied from lib/find_bit.c to tools/lib/find_bit.c
5 *
6 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
7 * Written by David Howells (dhowells@redhat.com)
8 *
9 * Copyright (C) 2008 IBM Corporation
10 * 'find_last_bit' is written by Rusty Russell <rusty@rustcorp.com.au>
11 * (Inspired by David Howell's find_next_bit implementation)
12 *
13 * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
14 * size and improve performance, 2015.
15 */
16
17#include <linux/bitops.h>
18#include <linux/bitmap.h>
19#include <linux/kernel.h>
20
21#if !defined(find_next_bit) || !defined(find_next_zero_bit) || \
22 !defined(find_next_and_bit)
23
24/*
25 * This is a common helper function for find_next_bit, find_next_zero_bit, and
26 * find_next_and_bit. The differences are:
27 * - The "invert" argument, which is XORed with each fetched word before
28 * searching it for one bits.
29 * - The optional "addr2", which is anded with "addr1" if present.
30 */
31unsigned long _find_next_bit(const unsigned long *addr1,
32 const unsigned long *addr2, unsigned long nbits,
33 unsigned long start, unsigned long invert, unsigned long le)
34{
35 unsigned long tmp, mask;
36 (void) le;
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
49 /*
50 * Due to the lack of swab() in tools, and the fact that it doesn't
51 * need little-endian support, just comment it out
52 */
53#if (0)
54 if (le)
55 mask = swab(mask);
56#endif
57
58 tmp &= mask;
59
60 start = round_down(start, BITS_PER_LONG);
61
62 while (!tmp) {
63 start += BITS_PER_LONG;
64 if (start >= nbits)
65 return nbits;
66
67 tmp = addr1[start / BITS_PER_LONG];
68 if (addr2)
69 tmp &= addr2[start / BITS_PER_LONG];
70 tmp ^= invert;
71 }
72
73#if (0)
74 if (le)
75 tmp = swab(tmp);
76#endif
77
78 return min(start + __ffs(tmp), nbits);
79}
80#endif
81
82#ifndef find_first_bit
83/*
84 * Find the first set bit in a memory region.
85 */
86unsigned long _find_first_bit(const unsigned long *addr, unsigned long size)
87{
88 unsigned long idx;
89
90 for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
91 if (addr[idx])
92 return min(idx * BITS_PER_LONG + __ffs(addr[idx]), size);
93 }
94
95 return size;
96}
97#endif
98
99#ifndef find_first_zero_bit
100/*
101 * Find the first cleared bit in a memory region.
102 */
103unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size)
104{
105 unsigned long idx;
106
107 for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
108 if (addr[idx] != ~0UL)
109 return min(idx * BITS_PER_LONG + ffz(addr[idx]), size);
110 }
111
112 return size;
113}
114#endif