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Date: Fri, 14 Mar 2008 09:34:51 -0700 From: Randy Dunlap <randy.dunlap@...cle.com> To: Harvey Harrison <harvey.harrison@...il.com> Cc: Andrew Morton <akpm@...ux-foundation.org>, LKML <linux-kernel@...r.kernel.org> Subject: Re: [PATCH 01/10] Add macros similar to min/max/min_t/max_t. On Thu, 13 Mar 2008 22:18:45 -0700 Harvey Harrison wrote: > Also, change the variable names used in the min/max macros to avoid shadowed > variable warnings when min/max min_t/max_t are nested. > > Small formatting changes to make all the macros have a similar form. > > > drivers/media/video/bt8xx/bttvp.h | 2 - > drivers/media/video/usbvideo/vicam.c | 6 --- > include/linux/kernel.h | 63 ++++++++++++++++++++++++---------- > 3 files changed, 45 insertions(+), 26 deletions(-) > diff --git a/include/linux/kernel.h b/include/linux/kernel.h > index 2df44e7..c74460c 100644 > --- a/include/linux/kernel.h > +++ b/include/linux/kernel.h > @@ -335,33 +335,60 @@ static inline int __attribute__ ((format (printf, 1, 2))) pr_debug(const char * > #endif /* __LITTLE_ENDIAN */ > > /* > - * min()/max() macros that also do > + * min()/max()/clamp() macros that also do > * strict type-checking.. See the > * "unnecessary" pointer comparison. > */ > -#define min(x,y) ({ \ > - typeof(x) _x = (x); \ > - typeof(y) _y = (y); \ > - (void) (&_x == &_y); \ > - _x < _y ? _x : _y; }) > - > -#define max(x,y) ({ \ > - typeof(x) _x = (x); \ > - typeof(y) _y = (y); \ > - (void) (&_x == &_y); \ > - _x > _y ? _x : _y; }) > +#define min(x, y) ({ \ > + typeof(x) _min1 = (x); \ > + typeof(y) _min2 = (y); \ > + (void) (&_min1 == &_min2); \ > + _min1 < _min2 ? _min1 : _min2; }) > + > +#define max(x, y) ({ \ > + typeof(x) _max1 = (x); \ > + typeof(y) _max2 = (y); \ > + (void) (&_max1 == &_max2); \ > + _max1 > _max2 ? _max1 : _max2; }) > + Where is some blurb/comment about what "clamp" means/does? min/max are well understood, but clamp? Is that a shop tool? I think I have a few out in my garage. So can we have some blurb here to explain clamp(), clamp_t(), and clamp_val()? (kernel-doc preferred, but not required) e.g: /** * clamp - returns a value that is restricted between min & max inclusive * @val: current value * @min: minimum value of the clamping region * @max: maximum value of the clamping region */ and explain the differences in clamp/clamp_t/clamp_val... /* > +#define clamp(val, min, max) ({ \ > + typeof(val) __val = (val); \ > + typeof(min) __min = (min); \ > + typeof(max) __max = (max); \ > + (void) (&__val == &__min); \ > + (void) (&__val == &__max); \ > + __val = __val < __min ? __min: __val; \ > + __val > __max ? __max: __val; }) > > /* > * ..and if you can't take the strict > * types, you can specify one yourself. > * > - * Or not use min/max at all, of course. > + * Or not use min/max/clamp at all, of course. > */ > -#define min_t(type,x,y) \ > - ({ type __x = (x); type __y = (y); __x < __y ? __x: __y; }) > -#define max_t(type,x,y) \ > - ({ type __x = (x); type __y = (y); __x > __y ? __x: __y; }) > - > +#define min_t(type, x, y) ({ \ > + type __min1 = (x); \ > + type __min2 = (y); \ > + __min1 < __min2 ? __min1: __min2; }) > + > +#define max_t(type, x, y) ({ \ > + type __max1 = (x); \ > + type __max2 = (y); \ > + __max1 > __max2 ? __max1: __max2; }) > + > +#define clamp_t(type, val, min, max) ({ \ > + type __val = (val); \ > + type __min = (min); \ > + type __max = (max); \ > + __val = __val < __min ? __min: __val; \ > + __val > __max ? __max: __val; }) > + > +#define clamp_val(val, min, max) ({ \ > + typeof(val) __val = (val); \ > + typeof(val) __min = (min); \ > + typeof(val) __max = (max); \ > + __val = __val < __min ? __min: __val; \ > + __val > __max ? __max: __val; }) > > /** > * container_of - cast a member of a structure out to the containing structure --- ~Randy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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