sys: util: add min3 and max3 single evaluation macros

Add three argument variants of the single evaluation min and max, seems
like there's few of these in the code we may as well have them.

Signed-off-by: Fabio Baltieri <[email protected]>

Author: fabiobaltieri

include/zephyr/sys/util.h

@@ -383,6 +383,19 @@ extern "C" {
 
 #define _minmax_cnt(op, a, b, cnt) \
 	_minmax_unique(op, a, b, UTIL_CAT(_value_a_, cnt), UTIL_CAT(_value_b_, cnt))
+
+#define _minmax3_unique(op, a, b, c, ua, ub, uc) ({ \
+		__typeof__(a) ua = (a);             \
+		__typeof__(b) ub = (b);             \
+		__typeof__(c) uc = (c);             \
+		op(ua, op(ub, uc));                 \
+	})
+
+#define _minmax3_cnt(op, a, b, c, cnt)            \
+	_minmax3_unique(op, a, b, c,              \
+			UTIL_CAT(_value_a_, cnt), \
+			UTIL_CAT(_value_b_, cnt), \
+			UTIL_CAT(_value_c_, cnt))
 /**
  * @endcond
  */
@@ -415,6 +428,13 @@ extern "C" {
 #define max(a, b) _minmax_cnt(MAX, a, b, __COUNTER__)
 #endif
 
+/** @brief Return larger value of three provided expressions.
+ *
+ * Macro ensures that expressions are evaluated only once. See @ref max for
+ * macro limitations.
+ */
+#define max3(a, b, c) _minmax3_cnt(MAX, a, b, c, __COUNTER__)
+
 #ifndef MIN
 /**
  * @brief Obtain the minimum of two values.
@@ -439,6 +459,14 @@ extern "C" {
 #define min(a, b) _minmax_cnt(MIN, a, b, __COUNTER__)
 #endif
 
+/** @brief Return smaller value of three provided expressions.
+ *
+ * Macro ensures that expressions are evaluated only once. See @ref max for
+ * macro limitations.
+ */
+#define min3(a, b, c) _minmax3_cnt(MIN, a, b, c, __COUNTER__)
+
+
 #ifndef MAX_FROM_LIST
 /**
  * @brief Returns the maximum of a single value (base case).

tests/unit/util/main.c

@@ -279,6 +279,26 @@ ZTEST(util, test_max_min_clamp) {
 #endif
 }
 
+ZTEST(util, test_max3_min3) {
+	/* check for single call */
+	zassert_equal(max3(inc_func(true), 0, 0), 1, "Unexpected macro result");
+	zassert_equal(inc_func(false), 2, "Unexpected return value");
+
+	zassert_equal(min3(inc_func(false), 9, 10), 3, "Unexpected macro result");
+	zassert_equal(inc_func(false), 4, "Unexpected return value");
+
+	/* test the general functionality */
+	zassert_equal(max3(1, 2, 3), 3, "Unexpected macro result");
+	zassert_equal(max3(3, 1, 2), 3, "Unexpected macro result");
+	zassert_equal(max3(2, 3, 1), 3, "Unexpected macro result");
+	zassert_equal(max3(-1, 0, 1), 1, "Unexpected macro result");
+
+	zassert_equal(min3(1, 2, 3), 1, "Unexpected macro result");
+	zassert_equal(min3(3, 1, 2), 1, "Unexpected macro result");
+	zassert_equal(min3(2, 3, 1), 1, "Unexpected macro result");
+	zassert_equal(min3(-1, 0, 1), -1, "Unexpected macro result");
+}
+
 ZTEST(util, test_max_from_list_macro) {
 	/* Test with one argument */
 	zassert_equal(MAX_FROM_LIST(10), 10, "Should return the single value.");