diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /lib/find_next_bit.c |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'lib/find_next_bit.c')
-rw-r--r-- | lib/find_next_bit.c | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/lib/find_next_bit.c b/lib/find_next_bit.c new file mode 100644 index 00000000000..d08302d2a42 --- /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; +} |