mirror of https://gitee.com/openkylin/linux.git
42 lines
1.0 KiB
C
42 lines
1.0 KiB
C
/* find_last_bit.c: fallback find next bit implementation
|
|
*
|
|
* Copyright (C) 2008 IBM Corporation
|
|
* Written by Rusty Russell <rusty@rustcorp.com.au>
|
|
* (Inspired by David Howell's find_next_bit implementation)
|
|
*
|
|
* Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
|
|
* size and improve performance, 2015.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation; either version
|
|
* 2 of the License, or (at your option) any later version.
|
|
*/
|
|
|
|
#include <linux/bitops.h>
|
|
#include <linux/bitmap.h>
|
|
#include <linux/export.h>
|
|
#include <linux/kernel.h>
|
|
|
|
#ifndef find_last_bit
|
|
|
|
unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
|
|
{
|
|
if (size) {
|
|
unsigned long val = BITMAP_LAST_WORD_MASK(size);
|
|
unsigned long idx = (size-1) / BITS_PER_LONG;
|
|
|
|
do {
|
|
val &= addr[idx];
|
|
if (val)
|
|
return idx * BITS_PER_LONG + __fls(val);
|
|
|
|
val = ~0ul;
|
|
} while (idx--);
|
|
}
|
|
return size;
|
|
}
|
|
EXPORT_SYMBOL(find_last_bit);
|
|
|
|
#endif
|