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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>		18 years ago
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boot	Remove obsolete #include <linux/config.h>	19 years ago
configs	…
kernel	[PATCH] vmlinux.lds: consolidate initcall sections	19 years ago
lib	fix file specification in comments	19 years ago
mm	fix file specification in comments	19 years ago
platform-iss	[PATCH] const struct tty_operations	19 years ago
Kconfig	[PATCH] LOG2: Implement a general integer log2 facility in the kernel	18 years ago
Kconfig.debug	…
Makefile	…