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git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/blob - tools/lib/find_bit.c
1 /* bit search implementation
3 * Copied from lib/find_bit.c to tools/lib/find_bit.c
5 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
6 * Written by David Howells (dhowells@redhat.com)
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)
12 * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
13 * size and improve performance, 2015.
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.
21 #include <linux/bitops.h>
22 #include <linux/bitmap.h>
23 #include <linux/kernel.h>
25 #if !defined(find_next_bit) || !defined(find_next_zero_bit) || \
26 !defined(find_next_and_bit)
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.
35 static 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
)
41 if (unlikely(start
>= nbits
))
44 tmp
= addr1
[start
/ BITS_PER_LONG
];
46 tmp
&= addr2
[start
/ BITS_PER_LONG
];
49 /* Handle 1st word. */
50 tmp
&= BITMAP_FIRST_WORD_MASK(start
);
51 start
= round_down(start
, BITS_PER_LONG
);
54 start
+= BITS_PER_LONG
;
58 tmp
= addr1
[start
/ BITS_PER_LONG
];
60 tmp
&= addr2
[start
/ BITS_PER_LONG
];
64 return min(start
+ __ffs(tmp
), nbits
);
70 * Find the next set bit in a memory region.
72 unsigned long find_next_bit(const unsigned long *addr
, unsigned long size
,
75 return _find_next_bit(addr
, NULL
, size
, offset
, 0UL);
79 #ifndef find_first_bit
81 * Find the first set bit in a memory region.
83 unsigned long find_first_bit(const unsigned long *addr
, unsigned long size
)
87 for (idx
= 0; idx
* BITS_PER_LONG
< size
; idx
++) {
89 return min(idx
* BITS_PER_LONG
+ __ffs(addr
[idx
]), size
);
96 #ifndef find_first_zero_bit
98 * Find the first cleared bit in a memory region.
100 unsigned long find_first_zero_bit(const unsigned long *addr
, unsigned long size
)
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
);
113 #ifndef find_next_zero_bit
114 unsigned long find_next_zero_bit(const unsigned long *addr
, unsigned long size
,
115 unsigned long offset
)
117 return _find_next_bit(addr
, NULL
, size
, offset
, ~0UL);
121 #ifndef find_next_and_bit
122 unsigned long find_next_and_bit(const unsigned long *addr1
,
123 const unsigned long *addr2
, unsigned long size
,
124 unsigned long offset
)
126 return _find_next_bit(addr1
, addr2
, size
, offset
, 0UL);