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SubjectRe: [PATCH 1/6] kernel: add clamp(), clamp_t() and clamp_val() macros
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On Wed, 2008-03-12 at 16:13 +0100, Michael Buesch wrote:
> So why not call it clamp_const()?
> One could even use __builtin_constant_p() and make clamp() use
> either clamp_const() or clamp_nonconst() from above automagically.
> I'd prefer that.

Did you mean something like this? No more clamp_val, just clamp and
clamp_t. clamp_t forces all the types, clamp looks at the min and max
args, and if they are constants, uses the type of val instead. If not
a constant, the strict typechecking is done.

From: Harvey Harrison <harvey.harrison@gmail.com>
Subject: [PATCH] kernel: add clamp(), clamp_t() macros

Adds 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.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
---
include/linux/kernel.h | 68 +++++++++++++++++++++++++++++++++++------------
1 files changed, 50 insertions(+), 18 deletions(-)

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 2df44e7..0d4cb5f 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -335,33 +335,65 @@ static inline int __attribute__ ((format (printf, 1, 2))) pr_debug(const char *
#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 max(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) _max1 = (x); \
+ typeof(y) _max2 = (y); \
+ (void) (&_max1 == &_max2); \
+ _max1 > _max2 ? _max1 : _max2; })
+
+#define clamp(val, min, max) ({ \
+ typeof(val) __val = (val); \
+ \
+ if (__builtin_constant_p(min)) { \
+ typeof(val) __min = (min); \
+ __val = __val < __min ? __min: __val; \
+ } else { \
+ typeof(min) __min = (min); \
+ (void) (&__val == &__min); \
+ __val = __val < __min ? __min: __val; \
+ } \
+ \
+ if (__builtin_constant_p(max)) { \
+ typeof(val) __max = (max); \
+ __val > __max ? __max: __val; \
+ } else { \
+ typeof(max) __max = (max); \
+ (void) (&__val == &__max); \
+ __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; })
+
+#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; })

/**
* container_of - cast a member of a structure out to the containing structure
--
1.5.4.4.592.g32d4c




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