[PATCH v5 1/6] eal: introduce RTE_MIN_T() and RTE_MAX_T() macros

[Stephen Hemminger]

These macros work like RTE_MIN and RTE_MAX but take an explicit
type. Necessary when being used in static assertions since
RTE_MIN and RTE_MAX use temporary variables which confuses
compilers constant expression checks. These macros could also
be useful in other scenarios when bounded range is useful.

Naming is chosen to be similar to Linux kernel conventions.

Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
Acked-by: Konstantin Ananyev <konstantin.ananyev at huawei.com>
Acked-by: Andrew Rybchenko <andrew.rybchenko at oktetlabs.ru>
---
 lib/eal/include/rte_common.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/lib/eal/include/rte_common.h b/lib/eal/include/rte_common.h
index c1ba32d00e47..33680e818bfb 100644
--- a/lib/eal/include/rte_common.h
+++ b/lib/eal/include/rte_common.h
@@ -585,6 +585,14 @@ __extension__ typedef uint64_t RTE_MARKER64[0];
 		_a < _b ? _a : _b; \
 	})
 
+/**
+ * Macro to return the minimum of two numbers
+ * does not use temporarys so not safe if a or b is expression
+ * but is guaranteed to be constant for use in static_assert()
+ */
+#define RTE_MIN_T(a, b, t) \
+	((t)(a) < (t)(b) ? (t)(a) : (t)(b))
+
 /**
  * Macro to return the maximum of two numbers
  */
@@ -595,6 +603,14 @@ __extension__ typedef uint64_t RTE_MARKER64[0];
 		_a > _b ? _a : _b; \
 	})
 
+/**
+ * Macro to return the maxiimum of two numbers
+ * does not use temporarys so not safe if a or b is expression
+ * but is guaranteed to be constant for use in static_assert()
+ */
+#define RTE_MAX_T(a, b, t) \
+	((t)(a) > (t)(b) ? (t)(a) : (t)(b))
+
 /*********** Other general functions / macros ********/
 
 #ifndef offsetof
-- 
2.43.0