projects / linux-2.6-block.git / blame
| Commit | Line | Data |
|---|---|---|
| ab53d472 RR |
1 | /* find_last_bit.c: fallback find next bit implementation |
| 2 | * | |
| 3 | * Copyright (C) 2008 IBM Corporation | |
| 4 | * Written by Rusty Russell <rusty@rustcorp.com.au> | |
| 5 | * (Inspired by David Howell's find_next_bit implementation) | |
| 6 | * | |
| 2c57a0e2 YN |
7 | * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease |
| 8 | * size and improve performance, 2015. | |
| 9 | * | |
| ab53d472 RR |
10 | * This program is free software; you can redistribute it and/or |
| 11 | * modify it under the terms of the GNU General Public License | |
| 12 | * as published by the Free Software Foundation; either version | |
| 13 | * 2 of the License, or (at your option) any later version. | |
| 14 | */ | |
| 15 | ||
| 16 | #include <linux/bitops.h> | |
| 2c57a0e2 | 17 | #include <linux/bitmap.h> |
| 8bc3bcc9 | 18 | #include <linux/export.h> |
| 2c57a0e2 | 19 | #include <linux/kernel.h> |
| ab53d472 | 20 | |
| 19de85ef AM |
21 | #ifndef find_last_bit |
| 22 | ||
| ab53d472 RR |
23 | unsigned long find_last_bit(const unsigned long *addr, unsigned long size) |
| 24 | { | |
| 2c57a0e2 YN |
25 | if (size) { |
| 26 | unsigned long val = BITMAP_LAST_WORD_MASK(size); | |
| 27 | unsigned long idx = (size-1) / BITS_PER_LONG; | |
| ab53d472 | 28 | |
| 2c57a0e2 YN |
29 | do { |
| 30 | val &= addr[idx]; | |
| 31 | if (val) | |
| 32 | return idx * BITS_PER_LONG + __fls(val); | |
| ab53d472 | 33 | |
| 2c57a0e2 YN |
34 | val = ~0ul; |
| 35 | } while (idx--); | |
| ab53d472 | 36 | } |
| ab53d472 RR |
37 | return size; |
| 38 | } | |
| 39 | EXPORT_SYMBOL(find_last_bit); | |
| 19de85ef AM |
40 | |
| 41 | #endif |