Messages in this thread Patch in this message | | | Date | Fri, 19 Nov 2010 15:19:49 -0800 | From | Andrew Morton <> | Subject | Re: abs() vs. abs64() (was: Re: [PATCH] fbdev: fix nearest mode search) |
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On Fri, 19 Nov 2010 15:04:11 -0800 Andrew Morton <akpm@linux-foundation.org> wrote:
> > Looks good to me. I posted essentially the same thing some 3 months ago > > (http://marc.info/?l=linux-kernel&m=128033094822201&w=2) but it then > > failed to get any traction. At any rate, I like your version better as > > it seems more readable. > > > > I spose we should document it. Does this look complete and accurate? > > --- a/include/linux/kernel.h~include-linux-kernelh-abs-fix-handling-of-32-bit-unsigneds-on-64-bit-fix > +++ a/include/linux/kernel.h > @@ -143,6 +143,13 @@ extern int _cond_resched(void); > > #define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0) > > +/* > + * abs() handles unsigned and signed longs, ints, shorts and chars. For long > + * types it returns a signed long. For int, short and char types it returns a > + * signed int. > + * abs() should not be used for 64-bit types (s64, u64, long long) - use abs64() > + * for those. > + */ > #define abs(x) ({ \ > long ret; \ > if (sizeof(x) == sizeof(long)) { \
Well that was a load of bollocks. 2nd attempt:
--- a/include/linux/kernel.h~include-linux-kernelh-abs-fix-handling-of-32-bit-unsigneds-on-64-bit-fix +++ a/include/linux/kernel.h @@ -143,6 +143,12 @@ extern int _cond_resched(void); #define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0) +/* + * abs() handles unsigned and signed longs, ints, shorts and chars. For all + * input types abs() returns a signed long. + * abs() should not be used for 64-bit types (s64, u64, long long) - use abs64() + * for those. + */ #define abs(x) ({ \ long ret; \ if (sizeof(x) == sizeof(long)) { \ _
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