[PATCH v3 1/5] minmax: Add min_unsigned(a, b) and max_unsigned(a, b)

David Laight
2023-08-04T10:56:44Z

These can be used when min()/max() errors a signed v unsigned
compare when the signed value is known to be non-negative.

Unlike min_t(some_unsigned_type, a, b) min_unsigned() will never
mask off high bits if an inappropriate type is selected.

The '+ 0u + 0ul + 0ull' may look strange.
The '+ 0u' is needed for 'signed int' on 64bit systems.
The '+ 0ul' is needed for 'signed long' on 32bit systems.
The '+ 0ull' is needed for 'signed long long'.

Signed-off-by: David Laight <david.laight@aculab.com>
---
v3: No change.
v2: Updated commit message.
include/linux/minmax.h | 17 +++++++++++++++++
1 file changed, 17 insertions(+)

diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index 396df1121bff..531860e9cc55 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -73,6 +73,23 @@
*/
#define max(x, y) __careful_cmp(x, y, >)

+/**
+ * min_unsigned - return minimum of two non-negative values
+ * Signed types are zero extended to match a larger unsigned type.
+ * @x: first value
+ * @y: second value
+ */
+#define min_unsigned(x, y) \
+ __careful_cmp((x) + 0u + 0ul + 0ull, (y) + 0u + 0ul + 0ull, <)
+
+/**
+ * max_unsigned - return maximum of two non-negative values
+ * @x: first value
+ * @y: second value
+ */
+#define max_unsigned(x, y) \
+ __careful_cmp((x) + 0u + 0ul + 0ull, (y) + 0u + 0ul + 0ull, >)
+
/**
* min3 - return minimum of three values
* @x: first value
--
2.17.1