diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Makefile | 2 | ||||
| -rw-r--r-- | lib/find_next_bit.c | 27 |
2 files changed, 27 insertions, 2 deletions
diff --git a/lib/Makefile b/lib/Makefile index 58f74d2dd396..05f8fa56a1bc 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -25,7 +25,7 @@ obj-y += lockref.o obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \ bust_spinlocks.o kasprintf.o bitmap.o scatterlist.o \ gcd.o lcm.o list_sort.o uuid.o flex_array.o iov_iter.o clz_ctz.o \ - bsearch.o find_last_bit.o find_next_bit.o llist.o memweight.o kfifo.o \ + bsearch.o find_next_bit.o llist.o memweight.o kfifo.o \ percpu-refcount.o percpu_ida.o rhashtable.o reciprocal_div.o obj-y += string_helpers.o obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o 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 */ |