Define the macro for use in comparison functions. The macro has the same
semantics as systemd's CMP() macro with the difference that it returns
constant expressions if possible.
Signed-off-by: Ahmad Fatoum <ahmad@xxxxxx>
---
include/linux/minmax.h | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index 396df1121bff..9b6ddad7b3f6 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -166,4 +166,24 @@
#define swap(a, b) \
do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
+
+#define __compare3(x, y) ((x) < (y) ? -1 : (x) > (y) ? 1 : 0)
+
+#define __compare3_once(x, y, unique_x, unique_y) ({ \
+ typeof(x) unique_x = (x); \
+ typeof(y) unique_y = (y); \
+ __compare3(unique_x, unique_y); })
+
+/**
+ * compare3 - 3-way comparison of @x and @y
+ * @x: first value
+ * @y: second value
+ *
+ * returns -1 if x < y, 0 if x == y and 1 if x > y
+ */
+#define compare3(x, y) \
+ __builtin_choose_expr(__safe_cmp(x, y), \
+ __compare3(x, y), \
+ __compare3_once(x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y)))
+
#endif /* _LINUX_MINMAX_H */
--
2.38.5
