[PATCH v4 07/13] minmax: Introduce {min,max}_array()

[Herve Codina]

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@xxxxxxxxxxx>
---
 include/linux/minmax.h | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index 396df1121bff..2cd0d34ce921 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -133,6 +133,42 @@
  */
 #define max_t(type, x, y)	__careful_cmp((type)(x), (type)(y), >)
 
+/*
+ * 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< ---
+ */
+#define __minmax_array(op, array, len) ({			\
+	typeof(array) __array = (array);			\
+	typeof(len) __len = (len);				\
+	typeof(__array[0] + 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
-- 
2.40.1