linux/arch/i386
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
..
boot [PATCH] x86-64: Fix numaq build error 2006-12-07 02:14:13 +01:00
crypto [CRYPTO] api: Get rid of flags argument to setkey 2006-09-21 11:41:02 +10:00
kernel [PATCH] i386: change uses of f_{dentry, vfsmnt} to use f_path 2006-12-08 08:28:42 -08:00
lib [PATCH] separate bdi congestion functions from queue congestion functions 2006-10-20 10:26:35 -07:00
mach-default [PATCH] irq-flags: i386: Use the new IRQF_ constants 2006-07-02 13:58:47 -07:00
mach-es7000 [PATCH] Compilation fix for ES7000 when no ACPI is specified in config (i386) 2006-03-23 07:38:04 -08:00
mach-generic [PATCH] i386: Avoid boot warning with apic=debug 2006-12-07 02:14:11 +01:00
mach-visws [PATCH] visws build fix 2006-10-28 11:30:52 -07:00
mach-voyager [PATCH] i386: replace kmalloc+memset with kzalloc 2006-12-07 02:14:19 +01:00
math-emu [PATCH] i386: fix must_checks 2006-12-07 02:14:00 +01:00
mm Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6 2006-12-07 08:59:11 -08:00
oprofile [PATCH] oprofile: ppro: need to enable/disable all the counters 2006-09-29 09:18:11 -07:00
pci [PATCH] x86: add write_pci_config_byte() to direct PCI access routines 2006-12-07 02:14:10 +01:00
power Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6 2006-12-07 08:59:11 -08:00
defconfig [PATCH] i386: Update defconfig 2006-12-07 02:14:00 +01:00
Kconfig [PATCH] Generic BUG for i386 2006-12-08 08:28:39 -08:00
Kconfig.cpu [PATCH] LOG2: Implement a general integer log2 facility in the kernel 2006-12-08 08:28:51 -08:00
Kconfig.debug [PATCH] paravirt: Patch inline replacements for paravirt intercepts 2006-12-07 02:14:08 +01:00
Makefile [PATCH] i386: always enable regparm 2006-12-07 02:14:12 +01:00
Makefile.cpu [PATCH] i386: Add support for compilation for Core2 2006-12-07 02:14:09 +01:00