Messages in this thread | | | Subject | Re: [KERNEL]: Avoid divide in IS_ALIGN | From | Joe Perches <> | Date | Tue, 20 Nov 2007 10:17:15 -0800 |
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On Tue, 2007-11-20 at 21:56 +0800, Herbert Xu wrote: > [KERNEL]: Avoid divide in IS_ALIGN > I was happy to discover the brand new IS_ALIGN macro and quickly > used it in my code. To my dismay I found that the generated code > used division to perform the test. > This patch fixes it by changing the % test to an &. This avoids > the division.
Perhaps this should use is_power_of_2?
#define IS_ALIGNED(x, a) \ ({ typeof(x) _a = (typeof(x))(a); \ is_power_of_2(_a) ? (((x) & (_a - 1)) == 0) \ : (((x) % _a == 0); })
gcc -o2/oS seems to do the right thing.
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