#ifndef _LINUX_KERNEL_H #define _LINUX_KERNEL_H #include #include /* * min()/max()/clamp() macros that also do * strict type-checking.. See the * "unnecessary" pointer comparison. */ #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; }) /** * clamp - return a value clamped to a given range with strict typechecking * @val: current value * @min: minimum allowable value * @max: maximum allowable value * * This macro does strict typechecking of min/max to make sure they are of the * same type as val. See the unnecessary pointer comparisons. */ #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/clamp at all, of course. */ #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; }) /** * clamp_t - return a value clamped to a given range using a given type * @type: the type of variable to use * @val: current value * @min: minimum allowable value * @max: maximum allowable value * * This macro does no typechecking and uses temporary variables of type * 'type' to make all the comparisons. */ #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; }) /** * clamp_val - return a value clamped to a given range using val's type * @val: current value * @min: minimum allowable value * @max: maximum allowable value * * This macro does no typechecking and uses temporary variables of whatever * type the input argument 'val' is. This is useful when val is an unsigned * type and min and max are literals that will otherwise be assigned a signed * integer type. */ #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; }) #endif /* _LINUX_KERNEL_H */