David Howells f0d1b0b30d [PATCH] LOG2: Implement a general integer log2 facility in the kernel ...

This facility provides three entry points:

	ilog2()		Log base 2 of unsigned long
	ilog2_u32()	Log base 2 of u32
	ilog2_u64()	Log base 2 of u64

These facilities can either be used inside functions on dynamic data:

	int do_something(long q)
	{
		...;
		y = ilog2(x)
		...;
	}

Or can be used to statically initialise global variables with constant values:

	unsigned n = ilog2(27);

When performing static initialisation, the compiler will report "error:
initializer element is not constant" if asked to take a log of zero or of
something not reducible to a constant.  They treat negative numbers as
unsigned.

When not dealing with a constant, they fall back to using fls() which permits
them to use arch-specific log calculation instructions - such as BSR on
x86/x86_64 or SCAN on FRV - if available.

[akpm@osdl.org: MMC fix]
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: David Howells <dhowells@redhat.com>
Cc: Wojtek Kaniewski <wojtekka@toxygen.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2006-12-08 08:28:51 -08:00

..

9p

[PATCH] 9p: change uses of f_{dentry,vfsmnt} to use f_path

2006-12-08 08:28:43 -08:00

adfs

[PATCH] struct path: convert adfs

2006-12-08 08:28:43 -08:00

affs

[PATCH] affs: change uses of f_{dentry, vfsmnt} to use f_path

2006-12-08 08:28:43 -08:00

afs

[PATCH] struct path: convert afs

2006-12-08 08:28:43 -08:00

autofs

[PATCH] autofs: change uses of f_{dentry, vfsmnt} to use f_path

2006-12-08 08:28:43 -08:00

autofs4

[PATCH] autofs4: change uses of f_{dentry, vfsmnt} to use f_path

2006-12-08 08:28:43 -08:00

befs

[PATCH] struct path: convert befs

2006-12-08 08:28:44 -08:00

bfs

[PATCH] struct path: convert bfs

2006-12-08 08:28:44 -08:00

cifs

[PATCH] cifs: change uses of f_{dentry, vfsmnt} to use f_path

2006-12-08 08:28:43 -08:00

coda

[PATCH] struct path: convert coda

2006-12-08 08:28:44 -08:00

configfs

[PATCH] configfs: change uses of f_{dentry, vfsmnt} to use f_path

2006-12-08 08:28:43 -08:00

cramfs

[PATCH] struct path: convert cramfs

2006-12-08 08:28:44 -08:00

debugfs

[PATCH] debugfs: add header file

2006-11-25 13:28:33 -08:00

devpts

[PATCH] inode-diet: Eliminate i_blksize from the inode structure

2006-09-27 08:26:18 -07:00

dlm

Merge master.kernel.org:/pub/scm/linux/kernel/git/steve/gfs2-2.6-nmw

2006-12-07 09:13:20 -08:00

ecryptfs

[PATCH] ecryptfs: change uses of f_{dentry, vfsmnt} to use f_path

2006-12-08 08:28:43 -08:00

efs

[PATCH] struct path: convert efs

2006-12-08 08:28:45 -08:00

exportfs

[PATCH] VFS: Make filldir_t and struct kstat deal in 64-bit inode numbers

2006-10-03 08:03:40 -07:00

ext2

[PATCH] LOG2: Implement a general integer log2 facility in the kernel

2006-12-08 08:28:51 -08:00

ext3

[PATCH] LOG2: Implement a general integer log2 facility in the kernel

2006-12-08 08:28:51 -08:00

ext4

[PATCH] ext4: change uses of f_{dentry, vfsmnt} to use f_path

2006-12-08 08:28:41 -08:00

fat

[PATCH] fat: change uses of f_{dentry,vfsmnt} to use f_path

2006-12-08 08:28:41 -08:00

freevxfs

[PATCH] struct path: convert freevxfs

2006-12-08 08:28:45 -08:00

fuse

[PATCH] struct path: convert fuse

2006-12-08 08:28:45 -08:00

gfs2

[PATCH] struct path: convert gfs2

2006-12-08 08:28:45 -08:00

hfs

[PATCH] struct path: convert hfs

2006-12-08 08:28:45 -08:00

hfsplus

[PATCH] struct path: convert hfsplus

2006-12-08 08:28:45 -08:00

hostfs

[PATCH] struct path: convert hostfs

2006-12-08 08:28:45 -08:00

hpfs

[PATCH] struct path: convert hpfs

2006-12-08 08:28:45 -08:00

hppfs

[PATCH] struct path: convert hppfs

2006-12-08 08:28:45 -08:00

hugetlbfs

[PATCH] struct path: convert hugetlbfs

2006-12-08 08:28:45 -08:00

isofs

[PATCH] isofs: change uses of f_{dentry, vfsmnt} to use f_path

2006-12-08 08:28:41 -08:00

jbd

[PATCH] make fs/jbd/transaction.c:__journal_temp_unlink_buffer() static

2006-12-07 08:39:40 -08:00

jbd2

[PATCH] jbd2: wait for already submitted t_sync_datalist buffer to complete

2006-12-07 08:39:42 -08:00

jffs

[PATCH] struct path: convert jffs

2006-12-08 08:28:46 -08:00

jffs2

[PATCH] struct path: convert jffs2

2006-12-08 08:28:46 -08:00

jfs

[PATCH] struct path: convert jfs

2006-12-08 08:28:46 -08:00

lockd

[PATCH] struct path: convert lockd

2006-12-08 08:28:47 -08:00

minix

[PATCH] struct path: convert minix

2006-12-08 08:28:47 -08:00

msdos

[PATCH] fat: add fat_getattr()

2006-11-16 11:43:38 -08:00

ncpfs

[PATCH] struct path: convert ncpfs

2006-12-08 08:28:48 -08:00

nfs

[PATCH] nfs: change uses of f_{dentry,vfsmnt} to use f_path

2006-12-08 08:28:41 -08:00

nfs_common

[PATCH] nfs_common endianness annotations

2006-10-20 10:26:41 -07:00

nfsd

[PATCH] nfsd: change uses of f_{dentry, vfsmnt} to use f_path

2006-12-08 08:28:42 -08:00

nls

[PATCH] fs: make nls_cp936.c handle some U00XY characters and U20AC correctly

2006-12-07 08:39:46 -08:00

ntfs

[PATCH] ntfs: change uses of f_{dentry, vfsmnt} to use f_path

2006-12-08 08:28:42 -08:00

ocfs2

[PATCH] struct path: convert ocfs2

2006-12-08 08:28:48 -08:00

openpromfs

[PATCH] struct path: convert openpromfs

2006-12-08 08:28:48 -08:00

partitions

[PATCH] Fix check_partition routines

2006-12-07 08:39:30 -08:00

proc

[PATCH] proc: change uses of f_{dentry, vfsmnt} to use f_path

2006-12-08 08:28:41 -08:00

qnx4

[PATCH] struct path: convert qnx4

2006-12-08 08:28:48 -08:00

ramfs

[PATCH] struct path: convert ramfs

2006-12-08 08:28:49 -08:00

reiserfs

[PATCH] struct path: convert reiserfs

2006-12-08 08:28:49 -08:00

romfs

[PATCH] struct path: convert romfs

2006-12-08 08:28:49 -08:00

smbfs

[PATCH] struct path: convert smbfs

2006-12-08 08:28:49 -08:00

sysfs

[PATCH] sysfs: change uses of f_{dentry, vfsmnt} to use f_path

2006-12-08 08:28:41 -08:00

sysv

[PATCH] struct path: convert sysv

2006-12-08 08:28:50 -08:00

udf

[PATCH] struct path: convert udf

2006-12-08 08:28:50 -08:00

ufs

[PATCH] struct path: convert ufs

2006-12-08 08:28:50 -08:00

vfat

[PATCH] fat: add fat_getattr()

2006-11-16 11:43:38 -08:00

xfs

[PATCH] xfs: change uses of f_{dentry,vfsmnt} to use f_path

2006-12-08 08:28:43 -08:00

aio.c

[PATCH] aio: remove ki_retried debugging member

2006-12-07 08:39:46 -08:00

attr.c

[PATCH] capable/capability.h (fs/)

2006-01-11 18:42:13 -08:00

bad_inode.c

[PATCH] Remove readv/writev methods and use aio_read/aio_write instead

2006-10-01 00:39:28 -07:00

binfmt_aout.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

binfmt_elf_fdpic.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

binfmt_elf.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

binfmt_em86.c

…

binfmt_flat.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

binfmt_misc.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

binfmt_script.c

…

binfmt_som.c

[PARISC] Fix fs/binfmt_som.c

2006-10-04 06:51:26 -06:00

bio.c

[PATCH] slab: remove kmem_cache_t

2006-12-07 08:39:25 -08:00

block_dev.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

buffer.c

[PATCH] hotplug CPU: clean up hotcpu_notifier() use

2006-12-07 08:39:39 -08:00

char_dev.c

[PATCH] BLOCK: Move extern declarations out of fs/*.c into header files [try #6]

2006-09-30 20:52:18 +02:00

compat_ioctl.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

compat.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

dcache.c

[PATCH] dcache: avoid RCU for never-hashed dentries

2006-12-07 08:39:41 -08:00

dcookies.c

[PATCH] slab: remove kmem_cache_t

2006-12-07 08:39:25 -08:00

direct-io.c

[PATCH] lockdep: annotate direct io

2006-07-03 15:27:06 -07:00

dnotify.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

dquot.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

drop_caches.c

[PATCH] drop-pagecache

2006-01-08 20:12:40 -08:00

eventpoll.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

exec.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

fcntl.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

fifo.c

[PATCH] pipe.c/fifo.c code cleanups

2006-04-11 13:53:33 +02:00

file_table.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

file.c

[PATCH] file: kill unnecessary timer in fdtable_defer

2006-12-07 08:39:32 -08:00

filesystems.c

[PATCH] Ban register_filesystem(NULL);

2006-09-29 09:18:20 -07:00

fs-writeback.c

[PATCH] BLOCK: Remove dependence on existence of blockdev_superblock [try #6]

2006-09-30 20:52:26 +02:00

generic_acl.c

[PATCH] Generic infrastructure for acls

2006-09-29 09:18:24 -07:00

inode.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

inotify_user.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

inotify.c

[PATCH] severing fs.h, radix-tree.h -> sched.h

2006-12-04 02:00:24 -05:00

internal.h

[PATCH] CONFIG_BLOCK internal.h cleanups

2006-09-30 20:52:32 +02:00

ioctl.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

ioprio.c

[PATCH] block layer: ioprio_best function fix

2006-10-12 15:09:51 +02:00

Kconfig

Fix typos in doc and comments

2006-11-30 05:32:19 +01:00

Kconfig.binfmt

[PATCH] frv: suppress configuration of certain features for FRV

2006-01-08 20:13:36 -08:00

libfs.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

locks.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

Makefile

[PATCH] fsstack: Introduce fsstack_copy_{attr,inode}_*

2006-12-08 08:28:40 -08:00

mbcache.c

[PATCH] slab: remove kmem_cache_t

2006-12-07 08:39:25 -08:00

mpage.c

[PATCH] BLOCK: Dissociate generic_writepages() from mpage stuff [try #6]

2006-09-30 20:52:26 +02:00

namei.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

namespace.c

[PATCH] slab: remove kmem_cache_t

2006-12-07 08:39:25 -08:00

nfsctl.c

Remove obsolete #include <linux/config.h>

2006-06-30 19:25:36 +02:00

no-block.c

[PATCH] BLOCK: Make it possible to disable the block layer [try #6]

2006-09-30 20:52:31 +02:00

open.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

pipe.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

pnode.c

[PATCH] core: use list_move()

2006-06-26 09:58:17 -07:00

pnode.h

[PATCH] unbindable mounts

2005-11-07 18:18:11 -08:00

posix_acl.c

[PATCH] kmemdup: some users

2006-10-01 00:39:19 -07:00

quota_v1.c

…

quota_v2.c

[PATCH] sem2mutex: quota

2006-03-23 07:38:11 -08:00

quota.c

[PATCH] BLOCK: Make it possible to disable the block layer [try #6]

2006-09-30 20:52:31 +02:00

read_write.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

read_write.h

[PATCH] Remove readv/writev methods and use aio_read/aio_write instead

2006-10-01 00:39:28 -07:00

readdir.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

select.c

[PATCH] enforce RLIMIT_NOFILE in poll()

2006-09-29 09:18:23 -07:00

seq_file.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

splice.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

stack.c

[PATCH] fsstack: Introduce fsstack_copy_{attr,inode}_*

2006-12-08 08:28:40 -08:00

stat.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

super.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

sync.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00

utimes.c

[PATCH] severing fs.h, radix-tree.h -> sched.h

2006-12-04 02:00:24 -05:00

xattr_acl.c

…

xattr.c

[PATCH] VFS: change struct file to use struct path

2006-12-08 08:28:41 -08:00