Commit | Line | Data |
---|---|---|
2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
8f6f19dd | 2 | /* bit search implementation |
1da177e4 LT |
3 | * |
4 | * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved. | |
5 | * Written by David Howells (dhowells@redhat.com) | |
6 | * | |
8f6f19dd YN |
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 | * | |
2c57a0e2 YN |
11 | * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease |
12 | * size and improve performance, 2015. | |
1da177e4 LT |
13 | */ |
14 | ||
15 | #include <linux/bitops.h> | |
8f6f19dd | 16 | #include <linux/bitmap.h> |
8bc3bcc9 | 17 | #include <linux/export.h> |
aa6159ab | 18 | #include <linux/math.h> |
b296a6d5 | 19 | #include <linux/minmax.h> |
aa6159ab | 20 | #include <linux/swab.h> |
1da177e4 | 21 | |
b78c5713 YN |
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) | |
64970b68 | 25 | /* |
0ade34c3 CC |
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. | |
c7f612cd | 31 | */ |
5c88af59 | 32 | unsigned long _find_next_bit(const unsigned long *addr1, |
0ade34c3 | 33 | const unsigned long *addr2, unsigned long nbits, |
b78c5713 | 34 | unsigned long start, unsigned long invert, unsigned long le) |
1da177e4 | 35 | { |
b78c5713 | 36 | unsigned long tmp, mask; |
1da177e4 | 37 | |
e4afd2e5 | 38 | if (unlikely(start >= nbits)) |
2c57a0e2 YN |
39 | return nbits; |
40 | ||
0ade34c3 CC |
41 | tmp = addr1[start / BITS_PER_LONG]; |
42 | if (addr2) | |
43 | tmp &= addr2[start / BITS_PER_LONG]; | |
44 | tmp ^= invert; | |
2c57a0e2 YN |
45 | |
46 | /* Handle 1st word. */ | |
b78c5713 YN |
47 | mask = BITMAP_FIRST_WORD_MASK(start); |
48 | if (le) | |
49 | mask = swab(mask); | |
50 | ||
51 | tmp &= mask; | |
52 | ||
2c57a0e2 YN |
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 | ||
0ade34c3 CC |
60 | tmp = addr1[start / BITS_PER_LONG]; |
61 | if (addr2) | |
62 | tmp &= addr2[start / BITS_PER_LONG]; | |
63 | tmp ^= invert; | |
1da177e4 LT |
64 | } |
65 | ||
b78c5713 YN |
66 | if (le) |
67 | tmp = swab(tmp); | |
68 | ||
2c57a0e2 | 69 | return min(start + __ffs(tmp), nbits); |
c7f612cd | 70 | } |
5c88af59 | 71 | EXPORT_SYMBOL(_find_next_bit); |
0ade34c3 CC |
72 | #endif |
73 | ||
19de85ef | 74 | #ifndef find_first_bit |
77b9bd9c AH |
75 | /* |
76 | * Find the first set bit in a memory region. | |
77 | */ | |
2cc7b6a4 | 78 | unsigned long _find_first_bit(const unsigned long *addr, unsigned long size) |
77b9bd9c | 79 | { |
2c57a0e2 | 80 | unsigned long idx; |
77b9bd9c | 81 | |
2c57a0e2 YN |
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); | |
77b9bd9c | 85 | } |
77b9bd9c | 86 | |
2c57a0e2 | 87 | return size; |
77b9bd9c | 88 | } |
2cc7b6a4 | 89 | EXPORT_SYMBOL(_find_first_bit); |
19de85ef | 90 | #endif |
77b9bd9c | 91 | |
19de85ef | 92 | #ifndef find_first_zero_bit |
77b9bd9c AH |
93 | /* |
94 | * Find the first cleared bit in a memory region. | |
95 | */ | |
2cc7b6a4 | 96 | unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size) |
77b9bd9c | 97 | { |
2c57a0e2 | 98 | unsigned long idx; |
77b9bd9c | 99 | |
2c57a0e2 YN |
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); | |
77b9bd9c | 103 | } |
77b9bd9c | 104 | |
2c57a0e2 | 105 | return size; |
77b9bd9c | 106 | } |
2cc7b6a4 | 107 | EXPORT_SYMBOL(_find_first_zero_bit); |
19de85ef | 108 | #endif |
930ae745 | 109 | |
8f6f19dd | 110 | #ifndef find_last_bit |
2cc7b6a4 | 111 | unsigned long _find_last_bit(const unsigned long *addr, unsigned long size) |
8f6f19dd YN |
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 | } | |
2cc7b6a4 | 127 | EXPORT_SYMBOL(_find_last_bit); |
8f6f19dd YN |
128 | #endif |
129 | ||
169c474f WBG |
130 | unsigned 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 | } | |
142 | EXPORT_SYMBOL(find_next_clump8); |