linux/arch/frv
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] sanitize frv archclean 2006-09-22 17:48:56 -07:00
kernel [PATCH] initrd: remove unused false condition for initrd_start 2006-12-07 08:39:38 -08:00
lib [NET]: FRV checksum annotations. 2006-12-02 21:23:03 -08:00
mb93090-mb00 [PATCH] FRV: Use the generic IRQ stuff 2006-09-26 08:48:53 -07:00
mm [PATCH] struct path: convert frv 2006-12-08 08:28:45 -08:00
defconfig [PATCH] FRV: Add defconfig 2005-07-07 18:23:42 -07:00
Kconfig [PATCH] LOG2: Implement a general integer log2 facility in the kernel 2006-12-08 08:28:51 -08:00
Kconfig.debug [PATCH] frv: drop unsupported debugging features 2006-01-08 20:13:36 -08:00
Makefile [PATCH] sanitize frv archclean 2006-09-22 17:48:56 -07:00