Add macros similar to min/max/min_t/max_t
Also, change the variable names used in the min/max macros to avoid shadowed
variable warnings when min/max min_t/max_t are nested.
Small formatting changes to make all the macros have a similar form.
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix v4l build]
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: Tejun Heo <htejun@gmail.com>
Cc: Michael Buesch <mb@bu3sch.de>
Cc: "John W. Linville" <linville@tuxdriver.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Dmitry Torokhov <dtor@mail.ru>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 53839ba..4d46e29 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -338,33 +338,90 @@
#endif /* __LITTLE_ENDIAN */
/*
- * min()/max() macros that also do
+ * min()/max()/clamp() macros that also do
* strict type-checking.. See the
* "unnecessary" pointer comparison.
*/
-#define min(x,y) ({ \
- typeof(x) _x = (x); \
- typeof(y) _y = (y); \
- (void) (&_x == &_y); \
- _x < _y ? _x : _y; })
+#define min(x, y) ({ \
+ typeof(x) _min1 = (x); \
+ typeof(y) _min2 = (y); \
+ (void) (&_min1 == &_min2); \
+ _min1 < _min2 ? _min1 : _min2; })
-#define max(x,y) ({ \
- typeof(x) _x = (x); \
- typeof(y) _y = (y); \
- (void) (&_x == &_y); \
- _x > _y ? _x : _y; })
+#define max(x, y) ({ \
+ typeof(x) _max1 = (x); \
+ typeof(y) _max2 = (y); \
+ (void) (&_max1 == &_max2); \
+ _max1 > _max2 ? _max1 : _max2; })
+
+/**
+ * clamp - return a value clamped to a given range with strict typechecking
+ * @val: current value
+ * @min: minimum allowable value
+ * @max: maximum allowable value
+ *
+ * This macro does strict typechecking of min/max to make sure they are of the
+ * same type as val. See the unnecessary pointer comparisons.
+ */
+#define clamp(val, min, max) ({ \
+ typeof(val) __val = (val); \
+ typeof(min) __min = (min); \
+ typeof(max) __max = (max); \
+ (void) (&__val == &__min); \
+ (void) (&__val == &__max); \
+ __val = __val < __min ? __min: __val; \
+ __val > __max ? __max: __val; })
/*
* ..and if you can't take the strict
* types, you can specify one yourself.
*
- * Or not use min/max at all, of course.
+ * Or not use min/max/clamp at all, of course.
*/
-#define min_t(type,x,y) \
- ({ type __x = (x); type __y = (y); __x < __y ? __x: __y; })
-#define max_t(type,x,y) \
- ({ type __x = (x); type __y = (y); __x > __y ? __x: __y; })
+#define min_t(type, x, y) ({ \
+ type __min1 = (x); \
+ type __min2 = (y); \
+ __min1 < __min2 ? __min1: __min2; })
+#define max_t(type, x, y) ({ \
+ type __max1 = (x); \
+ type __max2 = (y); \
+ __max1 > __max2 ? __max1: __max2; })
+
+/**
+ * clamp_t - return a value clamped to a given range using a given type
+ * @type: the type of variable to use
+ * @val: current value
+ * @min: minimum allowable value
+ * @max: maximum allowable value
+ *
+ * This macro does no typechecking and uses temporary variables of type
+ * 'type' to make all the comparisons.
+ */
+#define clamp_t(type, val, min, max) ({ \
+ type __val = (val); \
+ type __min = (min); \
+ type __max = (max); \
+ __val = __val < __min ? __min: __val; \
+ __val > __max ? __max: __val; })
+
+/**
+ * clamp_val - return a value clamped to a given range using val's type
+ * @val: current value
+ * @min: minimum allowable value
+ * @max: maximum allowable value
+ *
+ * This macro does no typechecking and uses temporary variables of whatever
+ * type the input argument 'val' is. This is useful when val is an unsigned
+ * type and min and max are literals that will otherwise be assigned a signed
+ * integer type.
+ */
+#define clamp_val(val, min, max) ({ \
+ typeof(val) __val = (val); \
+ typeof(val) __min = (min); \
+ typeof(val) __max = (max); \
+ __val = __val < __min ? __min: __val; \
+ __val > __max ? __max: __val; })
/**
* container_of - cast a member of a structure out to the containing structure