1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* bit search implementation
4 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
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)
11 * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
12 * size and improve performance, 2015.
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>
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)
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.
32 unsigned 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)
36 unsigned long tmp, mask;
38 if (unlikely(start >= nbits))
41 tmp = addr1[start / BITS_PER_LONG];
43 tmp &= addr2[start / BITS_PER_LONG];
46 /* Handle 1st word. */
47 mask = BITMAP_FIRST_WORD_MASK(start);
53 start = round_down(start, BITS_PER_LONG);
56 start += BITS_PER_LONG;
60 tmp = addr1[start / BITS_PER_LONG];
62 tmp &= addr2[start / BITS_PER_LONG];
69 return min(start + __ffs(tmp), nbits);
71 EXPORT_SYMBOL(_find_next_bit);
74 #ifndef find_first_bit
76 * Find the first set bit in a memory region.
78 unsigned long _find_first_bit(const unsigned long *addr, unsigned long size)
82 for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
84 return min(idx * BITS_PER_LONG + __ffs(addr[idx]), size);
89 EXPORT_SYMBOL(_find_first_bit);
92 #ifndef find_first_and_bit
94 * Find the first set bit in two memory regions.
96 unsigned long _find_first_and_bit(const unsigned long *addr1,
97 const unsigned long *addr2,
100 unsigned long idx, val;
102 for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
103 val = addr1[idx] & addr2[idx];
105 return min(idx * BITS_PER_LONG + __ffs(val), size);
110 EXPORT_SYMBOL(_find_first_and_bit);
113 #ifndef find_first_zero_bit
115 * Find the first cleared bit in a memory region.
117 unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size)
121 for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
122 if (addr[idx] != ~0UL)
123 return min(idx * BITS_PER_LONG + ffz(addr[idx]), size);
128 EXPORT_SYMBOL(_find_first_zero_bit);
131 #ifndef find_last_bit
132 unsigned long _find_last_bit(const unsigned long *addr, unsigned long size)
135 unsigned long val = BITMAP_LAST_WORD_MASK(size);
136 unsigned long idx = (size-1) / BITS_PER_LONG;
141 return idx * BITS_PER_LONG + __fls(val);
148 EXPORT_SYMBOL(_find_last_bit);
151 unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr,
152 unsigned long size, unsigned long offset)
154 offset = find_next_bit(addr, size, offset);
158 offset = round_down(offset, 8);
159 *clump = bitmap_get_value8(addr, offset);
163 EXPORT_SYMBOL(find_next_clump8);