diff options
author | Mauro Carvalho Chehab <mchehab@redhat.com> | 2012-10-17 09:32:49 -0300 |
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committer | Mauro Carvalho Chehab <mchehab@redhat.com> | 2012-10-17 09:32:49 -0300 |
commit | 214e2ca2b82d335935a861c253fe94c61ad77aad (patch) | |
tree | eee42ff74d10470789d919b8499737ad0e919360 /include/asm-generic/bitops/count_zeros.h | |
parent | 1fdead8ad31d3aa833bc37739273fcde89ace93c (diff) | |
parent | ddffeb8c4d0331609ef2581d84de4d763607bd37 (diff) |
Merge tag 'v3.7-rc1' into staging/for_v3.8
Linux 3.7-rc1
* tag 'v3.7-rc1': (9579 commits)
Linux 3.7-rc1
x86, boot: Explicitly include autoconf.h for hostprogs
perf: Fix UAPI fallout
ARM: config: make sure that platforms are ordered by option string
ARM: config: sort select statements alphanumerically
UAPI: (Scripted) Disintegrate include/linux/byteorder
UAPI: (Scripted) Disintegrate include/linux
UAPI: Unexport linux/blk_types.h
UAPI: Unexport part of linux/ppp-comp.h
perf: Handle new rbtree implementation
procfs: don't need a PATH_MAX allocation to hold a string representation of an int
vfs: embed struct filename inside of names_cache allocation if possible
audit: make audit_inode take struct filename
vfs: make path_openat take a struct filename pointer
vfs: turn do_path_lookup into wrapper around struct filename variant
audit: allow audit code to satisfy getname requests from its names_list
vfs: define struct filename and have getname() return it
btrfs: Fix compilation with user namespace support enabled
userns: Fix posix_acl_file_xattr_userns gid conversion
userns: Properly print bluetooth socket uids
...
Diffstat (limited to 'include/asm-generic/bitops/count_zeros.h')
-rw-r--r-- | include/asm-generic/bitops/count_zeros.h | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/include/asm-generic/bitops/count_zeros.h b/include/asm-generic/bitops/count_zeros.h new file mode 100644 index 00000000000..97520d21fe6 --- /dev/null +++ b/include/asm-generic/bitops/count_zeros.h @@ -0,0 +1,57 @@ +/* Count leading and trailing zeros functions + * + * Copyright (C) 2012 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 Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ + +#ifndef _ASM_GENERIC_BITOPS_COUNT_ZEROS_H_ +#define _ASM_GENERIC_BITOPS_COUNT_ZEROS_H_ + +#include <asm/bitops.h> + +/** + * count_leading_zeros - Count the number of zeros from the MSB back + * @x: The value + * + * Count the number of leading zeros from the MSB going towards the LSB in @x. + * + * If the MSB of @x is set, the result is 0. + * If only the LSB of @x is set, then the result is BITS_PER_LONG-1. + * If @x is 0 then the result is COUNT_LEADING_ZEROS_0. + */ +static inline int count_leading_zeros(unsigned long x) +{ + if (sizeof(x) == 4) + return BITS_PER_LONG - fls(x); + else + return BITS_PER_LONG - fls64(x); +} + +#define COUNT_LEADING_ZEROS_0 BITS_PER_LONG + +/** + * count_trailing_zeros - Count the number of zeros from the LSB forwards + * @x: The value + * + * Count the number of trailing zeros from the LSB going towards the MSB in @x. + * + * If the LSB of @x is set, the result is 0. + * If only the MSB of @x is set, then the result is BITS_PER_LONG-1. + * If @x is 0 then the result is COUNT_TRAILING_ZEROS_0. + */ +static inline int count_trailing_zeros(unsigned long x) +{ +#define COUNT_TRAILING_ZEROS_0 (-1) + + if (sizeof(x) == 4) + return ffs(x); + else + return (x != 0) ? __ffs(x) : COUNT_TRAILING_ZEROS_0; +} + +#endif /* _ASM_GENERIC_BITOPS_COUNT_ZEROS_H_ */ |