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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) || !defined(find_next_zero_bit) || \
26 !defined(find_next_and_bit)
27
28/*
29 * This is a common helper function for find_next_bit, find_next_zero_bit, and
30 * find_next_and_bit. The differences are:
31 * - The "invert" argument, which is XORed with each fetched word before
32 * searching it for one bits.
33 * - The optional "addr2", which is anded with "addr1" if present.
34 */
35static inline unsigned long _find_next_bit(const unsigned long *addr1,
36 const unsigned long *addr2, unsigned long nbits,
37 unsigned long start, unsigned long invert)
38{
39 unsigned long tmp;
40
41 if (unlikely(start >= nbits))
42 return nbits;
43
44 tmp = addr1[start / BITS_PER_LONG];
45 if (addr2)
46 tmp &= addr2[start / BITS_PER_LONG];
47 tmp ^= invert;
48
49 /* Handle 1st word. */
50 tmp &= BITMAP_FIRST_WORD_MASK(start);
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 return min(start + __ffs(tmp), nbits);
65}
66#endif
67
68#ifndef find_next_bit
69/*
70 * Find the next set bit in a memory region.
71 */
72unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
73 unsigned long offset)
74{
75 return _find_next_bit(addr, NULL, size, offset, 0UL);
76}
77#endif
78
79#ifndef find_first_bit
80/*
81 * Find the first set bit in a memory region.
82 */
83unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
84{
85 unsigned long idx;
86
87 for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
88 if (addr[idx])
89 return min(idx * BITS_PER_LONG + __ffs(addr[idx]), size);
90 }
91
92 return size;
93}
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}
111#endif
112
113#ifndef find_next_zero_bit
114unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
115 unsigned long offset)
116{
117 return _find_next_bit(addr, NULL, size, offset, ~0UL);
118}
119#endif
120
121#ifndef find_next_and_bit
122unsigned long find_next_and_bit(const unsigned long *addr1,
123 const unsigned long *addr2, unsigned long size,
124 unsigned long offset)
125{
126 return _find_next_bit(addr1, addr2, size, offset, 0UL);
127}
128#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