From: Herve Codina herve.codina@bootlin.com
[ Upstream commit c952c748c7a983a8bda9112984e6f2c1f6e441a5 ]
Introduce min_array() (resp max_array()) in order to get the minimal (resp maximum) of values present in an array.
Signed-off-by: Herve Codina herve.codina@bootlin.com Reviewed-by: Andy Shevchenko andy.shevchenko@gmail.com Reviewed-by: Christophe Leroy christophe.leroy@csgroup.eu Link: https://lore.kernel.org/r/20230623085830.749991-8-herve.codina@bootlin.com Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Eliav Farber farbere@amazon.com --- include/linux/minmax.h | 64 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+)
diff --git a/include/linux/minmax.h b/include/linux/minmax.h index d4bc394b449e..aac0b7d23768 100644 --- a/include/linux/minmax.h +++ b/include/linux/minmax.h @@ -168,6 +168,70 @@ */ #define max_t(type, x, y) __careful_cmp(max, (type)(x), (type)(y))
+/* + * Remove a const qualifier from integer types + * _Generic(foo, type-name: association, ..., default: association) performs a + * comparison against the foo type (not the qualified type). + * Do not use the const keyword in the type-name as it will not match the + * unqualified type of foo. + */ +#define __unconst_integer_type_cases(type) \ + unsigned type: (unsigned type)0, \ + signed type: (signed type)0 + +#define __unconst_integer_typeof(x) typeof( \ + _Generic((x), \ + char: (char)0, \ + __unconst_integer_type_cases(char), \ + __unconst_integer_type_cases(short), \ + __unconst_integer_type_cases(int), \ + __unconst_integer_type_cases(long), \ + __unconst_integer_type_cases(long long), \ + default: (x))) + +/* + * Do not check the array parameter using __must_be_array(). + * In the following legit use-case where the "array" passed is a simple pointer, + * __must_be_array() will return a failure. + * --- 8< --- + * int *buff + * ... + * min = min_array(buff, nb_items); + * --- 8< --- + * + * The first typeof(&(array)[0]) is needed in order to support arrays of both + * 'int *buff' and 'int buff[N]' types. + * + * The array can be an array of const items. + * typeof() keeps the const qualifier. Use __unconst_integer_typeof() in order + * to discard the const qualifier for the __element variable. + */ +#define __minmax_array(op, array, len) ({ \ + typeof(&(array)[0]) __array = (array); \ + typeof(len) __len = (len); \ + __unconst_integer_typeof(__array[0]) __element = __array[--__len]; \ + while (__len--) \ + __element = op(__element, __array[__len]); \ + __element; }) + +/** + * min_array - return minimum of values present in an array + * @array: array + * @len: array length + * + * Note that @len must not be zero (empty array). + */ +#define min_array(array, len) __minmax_array(min, array, len) + +/** + * max_array - return maximum of values present in an array + * @array: array + * @len: array length + * + * Note that @len must not be zero (empty array). + */ +#define max_array(array, len) __minmax_array(max, array, len) + /** * clamp_t - return a value clamped to a given range using a given type * @type: the type of variable to use