Messages in this thread Patch in this message | | | Subject | [PATCH 1/6] kernel: add clamp(), clamp_t() and clamp_val() macros | From | Harvey Harrison <> | Date | Tue, 11 Mar 2008 14:11:34 -0700 |
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Adds macros similar to min/max/min_t/max_t.
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.
clamp_val is useful when clamping to constants so all types are taken from typeof() the first arg.
Small formatting changes to make all the macros have a similar form.
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> --- Andrew, this is a rollup of my original patch already in -mm with checkpatch warnings fixed up and one additional macro based on limit_value found in the b43 driver, called clamp_val.
clamp_t is no longer used, but I introduce it anyway as some future user may want to force the return type similar to how min_t/max_t operate.
include/linux/kernel.h | 66 ++++++++++++++++++++++++++++++++++------------- 1 files changed, 48 insertions(+), 18 deletions(-)
diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 2df44e7..b9331ac 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -335,33 +335,63 @@ 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; }) + +#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; }) + +/* + * Useful when min and max are constants. + */ +#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; }) /* * ..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; }) /** * container_of - cast a member of a structure out to the containing structure -- 1.5.4.4.592.g32d4c
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