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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>
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| .. | ||
| Kconfig | ||
| Makefile | ||
| mthca_allocator.c | ||
| mthca_av.c | ||
| mthca_catas.c | ||
| mthca_cmd.c | ||
| mthca_cmd.h | ||
| mthca_config_reg.h | ||
| mthca_cq.c | ||
| mthca_dev.h | ||
| mthca_doorbell.h | ||
| mthca_eq.c | ||
| mthca_mad.c | ||
| mthca_main.c | ||
| mthca_mcg.c | ||
| mthca_memfree.c | ||
| mthca_memfree.h | ||
| mthca_mr.c | ||
| mthca_pd.c | ||
| mthca_profile.c | ||
| mthca_profile.h | ||
| mthca_provider.c | ||
| mthca_provider.h | ||
| mthca_qp.c | ||
| mthca_reset.c | ||
| mthca_srq.c | ||
| mthca_uar.c | ||
| mthca_user.h | ||
| mthca_wqe.h | ||