diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Makefile | 1 | ||||
| -rw-r--r-- | lib/find_next_bit.c | 55 |
2 files changed, 56 insertions, 0 deletions
diff --git a/lib/Makefile b/lib/Makefile index 6696c8ff22c6..aa25b683ea82 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -14,6 +14,7 @@ endif lib-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o +lib-$(CONFIG_GENERIC_FIND_NEXT_BIT) += find_next_bit.o obj-$(CONFIG_LOCK_KERNEL) += kernel_lock.o ifneq ($(CONFIG_HAVE_DEC_LOCK),y) diff --git a/lib/find_next_bit.c b/lib/find_next_bit.c new file mode 100644 index 000000000000..d08302d2a42c --- /dev/null +++ b/lib/find_next_bit.c @@ -0,0 +1,55 @@ +/* find_next_bit.c: fallback find next bit implementation + * + * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * 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> + +int find_next_bit(const unsigned long *addr, int size, int offset) +{ + const unsigned long *base; + const int NBITS = sizeof(*addr) * 8; + unsigned long tmp; + + base = addr; + if (offset) { + int suboffset; + + addr += offset / NBITS; + + suboffset = offset % NBITS; + if (suboffset) { + tmp = *addr; + tmp >>= suboffset; + if (tmp) + goto finish; + } + + addr++; + } + + while ((tmp = *addr) == 0) + addr++; + + offset = (addr - base) * NBITS; + + finish: + /* count the remaining bits without using __ffs() since that takes a 32-bit arg */ + while (!(tmp & 0xff)) { + offset += 8; + tmp >>= 8; + } + + while (!(tmp & 1)) { + offset++; + tmp >>= 1; + } + + return offset; +} |