Messages in this thread | | | Date | Fri, 25 Jul 2008 12:06:27 -0400 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] introduce lower_32_bits() macro |
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Joerg Roedel wrote: > The file kernel.h contains the upper_32_bits macro. This patch adds the other > part, the lower_32_bits macro. Its first use will be in the driver for AMD > IOMMU. > > Signed-off-by: Joerg Roedel <joerg.roedel@amd.com> > --- > include/linux/kernel.h | 6 ++++++ > 1 files changed, 6 insertions(+), 0 deletions(-) > > diff --git a/include/linux/kernel.h b/include/linux/kernel.h > index f9cd7a5..6fd2977 100644 > --- a/include/linux/kernel.h > +++ b/include/linux/kernel.h > @@ -73,6 +73,12 @@ extern const char linux_proc_banner[]; > */ > #define upper_32_bits(n) ((u32)(((n) >> 16) >> 16)) > > +/** > + * lower_32_bits - return bits 0-31 of a number > + * @n: the number we're accessing > + */ > +#define lower_32_bits(n) ((n) & 0xffffffffULL) > +
NAK. These are assymmetric with regards to type, which is the *last* thing we want.
The symmetric definition would be ((u32)(n)), but that's already idiomatic use, so why not use it as-is?
-hpa
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