[v6,07/13] minmax: Introduce {min,max}_array()
Commit Message
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>
---
include/linux/minmax.h | 64 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 64 insertions(+)
Comments
Le 23/06/2023 à 10:58, Herve Codina a écrit :
> 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>
> ---
> include/linux/minmax.h | 64 ++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 64 insertions(+)
>
> diff --git a/include/linux/minmax.h b/include/linux/minmax.h
> index 396df1121bff..798c6963909f 100644
> --- a/include/linux/minmax.h
> +++ b/include/linux/minmax.h
> @@ -133,6 +133,70 @@
> */
> #define max_t(type, x, y) __careful_cmp((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
@@ -133,6 +133,70 @@
*/
#define max_t(type, x, y) __careful_cmp((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