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.
clamp_val is useful when clamping to constants so all types are
taken from typeof() the first arg.
Small formatting changes to make all the macros have a similar
form.
Signed-off-by: Harvey Harrison <[email protected]>
---
Andrew, this is a rollup of my original patch already in -mm with
checkpatch warnings fixed up and one additional macro based on
limit_value found in the b43 driver, called clamp_val.
clamp_t is no longer used, but I introduce it anyway as some future
user may want to force the return type similar to how min_t/max_t
operate.
include/linux/kernel.h | 66 ++++++++++++++++++++++++++++++++++-------------
1 files changed, 48 insertions(+), 18 deletions(-)
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 2df44e7..b9331ac 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -335,33 +335,63 @@ 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); \
+ typeof(min) __min = (min); \
+ typeof(max) __max = (max); \
+ (void) (&__val == &__min); \
+ (void) (&__val == &__max); \
+ __val = __val < __min ? __min: __val; \
+ __val > __max ? __max: __val; })
+
+/*
+ * Useful when min and max are constants.
+ */
+#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; })
/*
* ..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
On Tue, 11 Mar 2008 14:11:34 -0700 Harvey Harrison <[email protected]> wrote:
> 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.
>
> clamp_val is useful when clamping to constants so all types are
> taken from typeof() the first arg.
>
> Small formatting changes to make all the macros have a similar
> form.
>
> Signed-off-by: Harvey Harrison <[email protected]>
> ---
> Andrew, this is a rollup of my original patch already in -mm with
> checkpatch warnings fixed up and one additional macro based on
> limit_value found in the b43 driver, called clamp_val.
Well, this is why I dislike replacement patches. You don't know what
changed, and the replacement patch can fail to incproporate fixes from
third parties.
> include/linux/kernel.h | 66 ++++++++++++++++++++++++++++++++++-------------
> 1 files changed, 48 insertions(+), 18 deletions(-)
And so it did. You lost my patch which removes the clamp() implementation
from v4l. Instead it seems that you put it into [2/6]. Which means that
this patch on its own will break the build, thus screwing up life for
git-bisect users.
Please don't screw up git-bisect users' lives.
> clamp_t is no longer used, but I introduce it anyway as some future
> user may want to force the return type similar to how min_t/max_t
> operate.
eh, just nuke it.
> 1.5.4.4.592.g32d4c
Is all this new infrastructure actually used? We seem to be adding more
complexity than we're taking away.
On Tuesday 11 March 2008 22:11:34 Harvey Harrison wrote:
> 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.
>
> clamp_val is useful when clamping to constants so all types are
> taken from typeof() the first arg.
>
> Small formatting changes to make all the macros have a similar
> form.
>
> Signed-off-by: Harvey Harrison <[email protected]>
> ---
> Andrew, this is a rollup of my original patch already in -mm with
> checkpatch warnings fixed up and one additional macro based on
> limit_value found in the b43 driver, called clamp_val.
>
> clamp_t is no longer used, but I introduce it anyway as some future
> user may want to force the return type similar to how min_t/max_t
> operate.
>
> include/linux/kernel.h | 66 ++++++++++++++++++++++++++++++++++-------------
> 1 files changed, 48 insertions(+), 18 deletions(-)
>
> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> index 2df44e7..b9331ac 100644
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -335,33 +335,63 @@ 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); \
> + typeof(min) __min = (min); \
> + typeof(max) __max = (max); \
> + (void) (&__val == &__min); \
> + (void) (&__val == &__max); \
> + __val = __val < __min ? __min: __val; \
> + __val > __max ? __max: __val; })
> +
> +/*
> + * Useful when min and max are constants.
> + */
> +#define clamp_val(val, min, max) ({ \
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.
> + typeof(val) __val = (val); \
> + typeof(val) __min = (min); \
> + typeof(val) __max = (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; })
> +
> +#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
--
Greetings Michael.
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 <[email protected]>
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 <[email protected]>
---
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
On Wednesday 12 March 2008 17:54:26 Harvey Harrison wrote:
> 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.
> +#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; \
> + } })
Yeah, something like that.
Does returning of the value work over an indentation level, too?
I dunno this detail of the language.
But I'd prefer the following for readability anyway:
+ if (__builtin_constant_p(max)) { \
+ typeof(val) __max = (max); \
+ __val = __val > __max ? __max: __val; \
+ } else { \
+ typeof(max) __max = (max); \
+ (void) (&__val == &__max); \
+ __val = __val > __max ? __max: __val; \
+ }
+ __val; })
Probably you can also only put the pointer check into the constant check:
+#define clamp(val, min, max) ({ \
+ typeof(val) __val = (val); \
+ typeof(min) __min = (min); \
+ typeof(max) __max = (max); \
+ if (!__builtin_constant_p(min)) \
+ (void) (&__val == &__min); \
+ __val = __val < __min ? __min: __val; \
+ if (!__builtin_constant_p(max)) \
+ (void) (&__val == &__max); \
+ __val = __val > __max ? __max: __val; \
+ __val; })
But it seems that this evaluates the arguments twice, so my idea turns out
to be not too good anyway. hm..
--
Greetings Michael.
On Wed, 2008-03-12 at 18:20 +0100, Michael Buesch wrote:
> On Wednesday 12 March 2008 17:54:26 Harvey Harrison wrote:
> > 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.
>
> > +#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; \
> > + } })
>
> Yeah, something like that.
> Does returning of the value work over an indentation level, too?
> I dunno this detail of the language.
> But I'd prefer the following for readability anyway:
>
> + if (__builtin_constant_p(max)) { \
> + typeof(val) __max = (max); \
> + __val = __val > __max ? __max: __val; \
> + } else { \
> + typeof(max) __max = (max); \
> + (void) (&__val == &__max); \
> + __val = __val > __max ? __max: __val; \
> + }
> + __val; })
Yeah, that is better. (and even works).
Harvey