diff options
Diffstat (limited to 'lib/find_next_bit.c')
| -rw-r--r-- | lib/find_next_bit.c | 27 |
1 files changed, 26 insertions, 1 deletions
diff --git a/lib/find_next_bit.c b/lib/find_next_bit.c index cbea5ef843aa..18072ea9c20e 100644 --- a/lib/find_next_bit.c +++ b/lib/find_next_bit.c @@ -1,8 +1,12 @@ -/* find_next_bit.c: fallback find next bit implementation +/* bit search implementation * * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) * + * Copyright (C) 2008 IBM Corporation + * 'find_last_bit' is 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. * @@ -13,6 +17,7 @@ */ #include <linux/bitops.h> +#include <linux/bitmap.h> #include <linux/export.h> #include <linux/kernel.h> @@ -106,6 +111,26 @@ unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size) EXPORT_SYMBOL(find_first_zero_bit); #endif +#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 + #ifdef __BIG_ENDIAN /* include/linux/byteorder does not support "unsigned long" type */ |